kenneth d. stewart - duke university - phd dissertation document

124
Phase Locked Loop and Modulo Games, The Dogma Loops; and “Finding Ibrida” by Kenneth D. Stewart Department of Music Duke University Date:_______________________ Approved: ___________________________ Scott Lindroth, Supervisor ___________________________ Stephen Jaffe ___________________________ Philip Rupprecht ___________________________ Thomas DeFrantz Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Music in the Graduate School of Duke University 2016

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Page 1: Kenneth D. Stewart - Duke University - PhD Dissertation Document

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Phase!Locked!Loop!and!Modulo!Games,!!

The!Dogma!Loops;!and!“Finding!Ibrida”!

by!

Kenneth!D.!Stewart!

Department!of!Music!Duke!University!

!

Date:_______________________!Approved:!

!___________________________!Scott!Lindroth,!Supervisor!

!___________________________!

Stephen!Jaffe!!

___________________________!Philip!Rupprecht!

!___________________________!

Thomas!DeFrantz!!!

Dissertation!submitted!in!partial!fulfillment!of!the!requirements!for!the!degree!of!Doctor!

of!Philosophy!in!the!Department!of!Music!in!the!Graduate!School!

of!Duke!University!!

2016!

Page 2: Kenneth D. Stewart - Duke University - PhD Dissertation Document

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ABSTRACT!!

Phase!Locked!Loop!and!Modulo!Games,!!

The!Dogma!Loops;!and!“Finding!Ibrida”!

by!

Kenneth!D.!Stewart!

Department!of!Music!Duke!University!

!

Date:_______________________!Approved:!

!___________________________!Scott!Lindroth,!Supervisor!

!___________________________!

Stephen!Jaffe!!

___________________________!Philip!Rupprecht!

!___________________________!

Thomas!DeFrantz!!

An!abstract!of!a!dissertation!submitted!in!partial!fulfillment!of!the!requirements!for!the!degree!of!Doctor!of!Philosophy!in!the!Department!of!

Music!in!the!Graduate!School!of!Duke!University!

!2016!! !

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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Copyright!by!Kenneth!D.!Stewart!

2016!!

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iv!

Abstract

This!dissertation!consists!of!two!independent!musical!compositions!and!an!

article!detailing!the!process!of!the!design!and!assembly!of!an!electric!guitar!with!

particular!emphasis!on!the!carefully!curated!suite!of!embedded!effects.!!

The!first!piece,!UPhase!Locked!Loop!and!Modulo!GamesU!is!scored!for!electric!

guitar!and!a!single!echo!of!equal!volume!less!than!a!beat!away.!One!could!think!of!the!

piece!as!a!15!minute!canon!at!the!unison!at!the!dotted!eighth!note!(or!at!times!the!

quarter!or!tripletYquarter),!however!the!compositional!motivation!is!more!about!

weaving!a!composite!texture!between!the!guitar!and!its!echo!that!is,!while!in!theory!

extremely!contrapuntal,!in!actuality!is!simply!a!single![superhuman]!melodic!line.!

The!second!piece,!UThe!Dogma!LoopsU!picks!up!a!few!compositional!threads!left!

by!‘Phase!Locked!Loop’!and!weaves!them!into!an!entirely!new!tapestry.!UPhase!Locked!

LoopU!is!motivated!by!the!creation!of!a!complex!musical!composite!that!is!for!the!most!

part!electronically!transparent.!UThe!Dogma!LoopsU!questions!that!same!notion!of!

composite!electronic!complexity!by!essentially!asking!a!question:!`what!are!the!inputs!to!

an!interactive!electronic!system!that!create!the!most!complex!outputs!via!the!simplest!

musical!means!possible?`!

UThe!Dogma!LoopsU!is!scored!for!Electric!Guitar!(doubling!on!Ukulele),!Violin!

and!Violoncello.!All!of!the!principal!instruments!require!an!electronic!pickup!(except!the!

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Uke).!The!work!is!in!three!sections!played!attacca;![Automation!Games],![Point!of!

Origin]!and![Cloning!Vectors].!!

The!third!and!final!component!of!the!document!is!the!article!UFinding!Ibrida.U!

This!article!details!the!process!of!the!design!and!assembly!of!an!electric!guitar!with!

integrated!effects,!while!also!providing!the!deeper!context!(conceptual!and!technical)!

which!motivated!the!efforts!and!informed!the!challenges!to!hybridize!the!various!

technologies!(tubes,!transistors,!digital!effects!and!a!microcontroller!subsystem).!The!

project!was!motivated!by!a!desire!for!rigorous!technical!and!handsYon!engagement!with!

analog!signal!processing!as!applied!to!the!electric!guitar.!‘Finding!Ibrida’!explores!

sound,!some!myths!and!lore!of!guitar!tech!and!the!history!of!electric!guitar!distortion!

and!its!culture!of!sonic!exploration.!

!

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to#Dr.#Ethan#Frederick#Greene#(198272015)#

Thank#you#for#your#guidance#and#your#wit.##

May#you#rest#in#peace,#brother.#

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Contents

Abstract(........................................................................................................................(iv!

List(of(Tables(.................................................................................................................(x!

List(of(Figures(.............................................................................................................(xi!

1.(Phase(Locked(Loop(and(Modulo(Games(.........................................................(1!

1.1(Synopsis(...........................................................................................................................(1!

1.2(Logistics(...........................................................................................................................(1!

1.3(Notation(...........................................................................................................................(2!

1.3.1!Composite!Staves!.............................................................................................................................!2!

1.3.2!Tempo!Changes!(and!the!resulting!rhythmic!realignments)!........................................!3!

1.3.3!Tuning!Changes!.................................................................................................................................!3!

1.4(Electronics(......................................................................................................................(4!

1.4.1!Technical!Requirements!...............................................................................................................!4!

1.4.2!Block!Diagram!of!the!Setup!with!Octave!Doubling!............................................................!5!

1.5(Recommended(Stage(Setup(.......................................................................................(5!

1.6(Program(Notes(...............................................................................................................(6!

1.7(The(Score(.........................................................................................................................(7!

2.(The(Dogma(Loops(................................................................................................(20!

2.1(Synopsis(........................................................................................................................(20!

2.2(Logistics(........................................................................................................................(20!

2.2.1!Duration!.................................................................................................................................!20!

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2.2.2!Movements!(with!specific!instrumentations)!........................................................!20!

Automation!Games!..................................................................................................................................!20!

Point!of!Origin!............................................................................................................................................!20!

Cloning!Vectors!.........................................................................................................................................!21!

2.2.3!Required!Personnel!...........................................................................................................!21!

2.2.4!General!....................................................................................................................................!21!

2.2.5!Tuning!.....................................................................................................................................!22!

2.3(Special(Notation(.........................................................................................................(22!

2.3.1!Fragments!in!the!Score!....................................................................................................!22!

DNA!................................................................................................................................................................!23!

Empty!Control!Vectors!...........................................................................................................................!23!

2.3.2!Software!Delay!Changes!..................................................................................................!25!

2.3.3!EHX!Freeze!Sound!Retainer!Pedal!..............................................................................!25!

2.3.4!EHX!Pitchfork!Pitch!Shifter!Pedal!...............................................................................!26!

2.4(Figuration(as(Constrained(Improvisation(.........................................................(27!

2.4.1!General!....................................................................................................................................!27!

2.4.2!Inserts!......................................................................................................................................!27!

•!General!.......................................................................................................................................................!27!

•!Elaborated!Form!of!the!Inserts!.......................................................................................................!28!

2.5(Electronics(...................................................................................................................(29!

2.5.1!Computer!and!Software!Requirements!....................................................................!29!

2.5.2!Specific!Hardware!Requirements!...............................................................................!29!

2.6(Stage(Setup(and(Amplification(..............................................................................(30!

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2.7(Mixer,(Interface(and(Hardware(Effects(Setup(..................................................(31!

2.8(Program(Notes(............................................................................................................(31!

2.9(The(Score(......................................................................................................................(34!

3.(Finding(Ibrida:(Building(an(Electric(Guitar(with(Embedded(Effects(...(51!

3.1(The(electric(guitar(and(signal(distortion(...........................................................(56!

3.2(The(Fuzz(Pedal(............................................................................................................(63!

3.3(Vacuum(Tubes(............................................................................................................(68!

Tube!Selection!and!the!Caveats!of!Tube!Design!...............................................................!68!

1AD5!subminiature!sharpZcutoff!pentode!..........................................................................!70!

Pentode!comparison!....................................................................................................................!71!

3.4(The(Transition(from(Tubes(to(Transistors(.......................................................(73!

The!Arbiter!(now%Dunlop)%Fuzz!Face!.....................................................................................!73!

The!AC128!Germanium!Transistor!........................................................................................!78!

3.5(The(Integrated(Circuits(&(Subsystems(used(in(Ibrida(...................................(81!

Reverberation!as!a!discrete!effect!..........................................................................................!81!

Integrated!Circuits!........................................................................................................................!82!

The!Princeton!PT2399!Integrated!Circuit!..........................................................................!85!

3.6(Design(of(the(Power(System(...................................................................................(89!

3.7(The(Prototyping(and(Assembling(of(Ibrida(.......................................................(94!

From!Prototype!to!Boutique!Guitar!...............................................................................................!101!

Bibliography(...........................................................................................................(107!

Biography(................................................................................................................(112!

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!

List of Tables

Table!1:!Comparison!of!1AD5!vs.!6SJ7!.....................................................................................!71!

(

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List of Figures

Figure!1:!Schematic!of!the!signal!path!of!a!typical!guitarYamplifier!system.!.....................!57!

Figure!2:!Sine!wave!of!nonYclipped!and!clipped!signal!........................................................!58!

Figure!3:!Advertisement!of!LRE!Lafayette!“Fuzz!Sound”20!..................................................!64!

Figure!4:!Schematic!for!the!FuzzYaYtort!....................................................................................!65!

Figure!5:!Spectrogram!of!a!sineYsweep!from!82.406891!hz!to!1108.730469!hz!(the!low!E!of!the!guitar!to!the!C#!of!the!typical!highest!fret)!directly!recorded!from!oscillator!to!computer!memory.!......................................................................................................................!66!

Figure!6:!Spectrogram!of!the!same!sineYsweep!through!an!original!LRE!Fuzz!Sound!enabled!on!its!lowest!fuzz!setting.!............................................................................................!66!

Figure!7:!Spectrogram!of!the!same!sineYsweep!through!the!LRE!Fuzz!Sound!with!the!fuzz!setting!on!maximum.!.........................................................................................................!66!

Figure!8:!Spectrogram!of!the!sineYsweep!audiofile!through!the!Dunlop!Silicon!Fuzz!Face!(the#effect#is#enabled#and#is#on#its#lowest#fuzz#setting)!..................................................................!67!

Figure!9:!Spectrogram!of!the!same!sineYsweep!through!the!Silicon!Fuzz!Face!with!the!fuzz!setting!on!maximum!(the#volume#was#not#altered)!...........................................................!67!

Figure!10:!The!1AD5!vacuum!tube!...........................................................................................!69!

Figure!11:!The!schematic!of!the!Fuzz!Face!with!its!sections!labeled!...................................!77!

Figure!12:!The!schematic!of!the!Fuzz!Face!as!it!appears!in!Ibrida!with!a!positive!power!supply!(identical#but#with#a#different#battery#placement#in#the#schematic)!.................................!78!

Figure!13:!Schematic!block!diagram!from!the!patent!of!Accutronics!6Ypin!reverb!brick!.!84!

Figure!14:!The!Accutronics!6Ypin!reverb!brick!........................................................................!84!

Figure!15:!the!power!consumption!for!filament!of!the!1AD5!...............................................!89!

Figure!16:!Battery!Specifications:!Alkaline!AA!Battery:!2450!mAh;!!Alkaline!9v!Battery:!565!mAh!........................................................................................................................................!90!

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Figure!17:!The!power!consumption!of!the!DS!1666!Digital!Resistor/Potentiometer!.........!91!

Figure!18:!Power!consumption!(supply!current)!for!Accutronics!‘Brick’!IC!......................!92!

Figure!19:!The!guitar!body!used!for!Ibrida!.............................................................................!95!

Figure!20:!The!electronics!mounted!onto!a!cover!plate.!........................................................!96!

Figure!21:!The!‘breadboard’!prototyping!of!electronics!........................................................!97!

Figure!22:!The!main!circuit!board!shown!outside!Ibrida’s!pickup!cavity!..........................!98!

Figure!23:!Back!of!guitar!shown!with!the!9v!battery!compartment,!external!power!jack!and!Arduino!installed!................................................................................................................!99!

Figure!24:!Main!board!shown!placed!into!the!body!of!Ibrida!............................................!100!

Figure!25:!The!new!guitar!body!design!for!fully!integrated!electronics!...........................!101!

Figure!26:!Hofner!‘Violin!Bass’!as!popularized!by!Paul!McCartney!.................................!103!

Figure!27:!Louis!Guersan,!France.!Pardassus!de!Viole,!1759!..............................................!103!

Figure!28:!Ibanez!Model!882!Electric!Guitar,!Japan,!1963!...................................................!104!

Figure!29:!Diagram!of!the!effect!control!and!signal!flow!from!pickup!to!output!amplifier!with!Arduino!control!via!digipots!..........................................................................................!105!

Figure!30:!Final!prototype!of!Ibrida!showing!the!suite!of!embedded!effects!...................!106!

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1. Phase Locked Loop and Modulo Games

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1.1 Synopsis

Phase#Locked#Loop#and#Modulo#Games!is!a!solo!electroacoustic!work!for!electric!

guitar!and!a!single!echo!of!equal!volume!rendered!by!a!delay!pedal.!The!effect!is!always!

on!and!there!are!no!changes!to!the!pedal’s!settings.!Thus,!the!counterpoint!between!the!

guitar!and!the!pedal!is!continuous.!

1.2 Logistics

1.2.1$Duration$$

! ! 15!Minutes!

1.2.2$Instrumentation$

Electric!Guitar!!

! ! ! •!One!or!two!conventional!amplifiers!

•!Delay!pedal!set!to!a!single!repetition!at!the!time!interval!of!

500ms;!most!delay!pedals!should!be!able!to!accomplish!this.!

! ! ! •!Pitch!shift!pedal,!!(for!optional!doubling)!!

!$ 1.2.3$General$

! ! •!Scordatura:!E!A!D!G!Bb!Eb!

•!in!measures!252Y253:!retune!Bb!string!to!B§;!!

resultant!tuning:!E!A!D!G!B§!Eb!

1

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•!in!measures!260Y262!retune!Eb!string!to!E§;!!

resultant!tuning!E!A!D!G!B§!E§!!

•!The!score!is!in!C!and!sounds!an!octave!lower!than!written.!

•!Rubato!is!encouraged,!however!even!slight!manipulations!of!

tempo!for!expressive!effect!create!audible!changes!to!the!delay!composite.!

Should!this!occur,!do!not!overYcorrect;!rather,!one!should!regain!the!

desired!composite!gradually,!without!sudden!changes!of!tempo.!

1.3 Notation

1.3.1$Composite$Staves$

!

Melodic$Composite$

The!‘Melodic!Composite’!staff!shows!the!prominent!musical!line!created!

by!the!accented!notes!of!both!the!live!guitar!and!its!echo.!!

Sonic$Composite$

The!‘Sonic!Composite’!staff!shows!the!complete!woven!line!between!the!

live!guitar!and!its!echo.!!

2

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1.3.2$Tempo$Changes$(and$the$resulting$rhythmic$realignments)$

Throughout!the!piece,!tempo!changes!indicated!in!the!live!guitar!

part!create!new!rhythmic!relationships!between!the!player!and!the!echo.!

The!new!tempo!requires!the!notation!of!the!delay!to!change!accordingly.!

These!points!are!indicated!with!the!new!tempo!in!BPM,!the!new!rhythmic!

value!of!the!echo!and!the!absolute!time!value!of!both!of!these!in!given!in!

milliseconds.!For!example:!

q. = 60 (1000ms)

DELAY INTERVAL: e. (500ms)

If!a!metric!modulation!also!occurs!at!this!point,!the!notation!

reflects!it.!For!example:!

! ! !

1.3.3$Tuning$Changes$

•!the!retuning!of!the!Bb!string!to!B§!in!measures!252Y253!is!notated:!

!

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•!the!retuning!of!the!Eb!string!to!E§!in!measures!260Y262!is!notated:!

!

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1.4 Electronics

1.4.1$Technical$Requirements$

Phase#Locked#Loop#and#Modulo#Games#can!be!performed!with!a!minimal!

setup!consisting!of!an!electric!guitar,!a!delay!pedal!and!an!amplifier.!While!this!

fulfills!the!necessary!requirements!to!perform!the!piece,!a!more!elaborate!setup!

with!the!guitar!signal!doubled!at!an!octave!(with!reverb),!delayed!by!the!same!

time!interval!as!the!normal!octave!and!sent!to!its!own!amplifier!with!the!EQ/tone!

controls!adjusted!for!optimal!fidelity!of!the!higher!frequencies!is!preferred.!This!

was!the!setup!at!the!premiere!and!it!is!useful!to!consult!a!recording!of!the!piece!

for!information!on!balance.!

! !

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1.4.2$Block$Diagram$of$the$Setup$with$Octave$Doubling$

! !

1.5 Recommended Stage Setup

! 5

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1.6 Program Notes

Phase#Locked#Loop#and#Modulo#Games!contains!stories.!Little,!poemYsized!short!

stories!filled!with!puzzles!and!riddles.!These!proseYpoems!with!sewnYtogether!

unfoldings!and!refoldings!of!ideas!are!always!in!transition,!ever!changing!and!stuck!in!a!

perpetual!state!of!becoming.!As!the!story!progresses!the!boundaries!between!the!stories!

erodes!the!many!into!a!single!continuous!utterance.!(Note:#In#the#above#descriptive#image#

‘story’#is#intended#to#mean#a#musical#narrative#and#‘game’#or#‘riddle’#means#a#pitched,#rhythmic#

or#metric#device#used#to#develop#the#principle#theme.)!

In!more!technical!terms,!the!notes!of!this!moto#perpetuo!are!treated!using!a!

modulus.!A!form!of!division!of!whole!numbers,!a!modulus!emphasizes!the!remainder!

rather!than!the!quotient.!A!14Ynote!musical!idea!is!transformed!thusly!while!other!

materials!use!similar!patterned!processes!of!rhythmic!accumulation,!acceleration!and!

deceleration.!The!piece!moves!from!these!stricter!processes!into!a!pastiche!of!stylistic!

and!melodic!music!that!expands!smaller!motives!into!larger!songYlike!phrases.!(Note:#A#

reoccurring#palindrome#is#the#central#device#to#this#particular#musical#process.)!

In!other!words,!Phase#Locked#Loop#and#Modulo#Games!uses!evolving!loops!to!move!

into!several!lightly!contrasting!grooves!that!themselves!are!locked!in!the!steadyYstate!

change!of!transition;!ever!changing,!and!always!becoming.!

! !

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Page 19: Kenneth D. Stewart - Duke University - PhD Dissertation Document

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Page 20: Kenneth D. Stewart - Duke University - PhD Dissertation Document

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Page 32: Kenneth D. Stewart - Duke University - PhD Dissertation Document

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2. The Dogma Loops

2.1 Synopsis

The!Dogma!Loops!is!an!electroacoustic!work!for!a!trio!consisting!of!

electric!guitar!(doubles!on!ukulele),!violin,!violoncello!and!a!combination!of!

software!and!hardware!operated!by!a!fourth!member!of!the!ensemble!to!create!

large!electronic!composite!textures.!In!key!moments!of!the!piece,!these!textures!

overwhelm!the!acoustic!instruments,!only!to!be!pulled!away!revealing!the!

acoustic!input!in!its!simplest!form.!

2.2 Logistics

2.2.1 Duration

Approx.!20!minutes,!depending!on!the!length!of!the!prologue!

2.2.2 Movements (with specific instrumentations)

$ $ Automation$Games$

Musician!1:!Electric!Guitar!(with#live#electronic#manipulations)##

Musician!2:!Violin!(with#live#electronic#manipulations)##

Musician!3:!Violoncello!(with#live#electronic#manipulations)##

Engineer!1:!Live!electronic!manipulations!of!all!three!instruments!

with!software!and!hardware#

$ $ Point$of$Origin$

! Musician!1:!Ukulele!(no#electronics)#

20

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! 21!

# Violin,!Violoncello,!Engineer!1!Y!Tacet!

Cloning$Vectors$

! Musician!1:!Ukulele,!Live!Electronics!(as!Engineer!2)!

Musician!2:!Violin!(with#live#electronic#manipulations)##

Musician!3:!Violoncello!(with#live#electronic#manipulations)##

Engineer!1:!Live!Electronics!

2.2.3 Required Personnel

•!Musician!1:!Electric!Guitar,!Ukulele,!Live!Electronics!(referred!to!

as!Engineer!2)!

•!Musician!2:!Violin!(with!pickup)!

•!Musician!3:!Violoncello!(with!pickup)!

•!Engineer!1:!Supervises!the!computer,!interface!and!audio!

hardware!for!electronic!processing!

2.2.4 General

•!The!score!is!in!C!and!the!electric!guitar!sounds!an!octave!lower!

than!written.!

•!An!engineer!is!required!to!trigger!changes!in!the!electronics!

indicated!in!the!score.!She!should!do!this!either!from!a!position!within!the!

ensemble!or!while!seated!directly!on!the!computer!at!the!mixing!desk.!

21

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! 22!

•!The!task!of!the!ensemble!is!to!sit!neatly!‘in!the!pocket’!with!one!

another!while!playing!into!a!continuously!evolving!network!of!delays,!

reverbs!and!transposition!states.!

•!Rubato!is!encouraged,!however!even!slight!manipulations!of!

tempo!for!expressive!effect!create!audible!changes!to!the!delay!composite.!

Should!this!occur,!do!not!overYcorrect;!rather,!regain!the!desired!

composite!gradually,!without!sudden!changes!of!tempo.!

2.2.5 Tuning

The!top!two!strings!on!both!the!guitar!and!the!ukulele!are!tuned!down!a!

half!step.!

! ! ! •!Ukulele:!G,!C,!Eb,!Ab!

! ! ! •!Guitar:!E,!A,!D,!G,!Bb,!E!

2.3 Special Notation

2.3.1 Fragments in the Score

! ! ! !

22

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! 23!

DNA$

The!DNA$fragment!must!be!presented!at!the!beginning!of!the!

work!either!before!or!during!the!Empty$Control$Vectors$(α,!β,!γ,!δ,!ε,!ζ,!η).!

Its!twoYvoice!texture!serves!as!a!prologue!composed!by!the!ensemble.!The!

fragment!should!be!collaboratively!realized!in!such!a!way!that!it!

foreshadows!the!unique!decisions!by!the!ensemble!at!the!end!of!the!third!

and!final!movement.!!

The!three!instruments!(plus!the!electronics)!can!achieve!this!

realization!by!any!means!necessary.!As!an!example,!one!or!two!of!the!

instruments!could!realize!the!notes!of!the!DNA!fragment!acoustically!as!

melodic!lines!in!counterpoint!while!another!member!doubles!

electronically!(either!with!the!delays!or!the!pitch!shifters).!This!possible!

scenario!is!also!true!if!it!is!presented!on!top!of!the!seven!Empty$Control$

Vectors$[ECV],!as!long!as!the!motivic!thread!of!the!ECVs!is!maintained!

by!at!least!one!of!the!members!of!the!ensemble.!The!DNA!fragment!is!

provided!in!the!score.!

Empty$Control$Vectors$

•$General$

Empty$Control$Vectors$[ECV]!begin!the!notated!music!and!are!

the!rhythmic!backbone!of!the!piece!as!it!composites!into!the!delays.!There!

23

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! 24!

are!seven!ECVs$labed!alpha!to!eta!(α,!β,!γ,!δ,!ε,!ζ,!η).!The!phrases!move!

attacca!into!one!another.!If!the!DNA!is!realized!to!overlap!with!the!ECVs,!

they!can!be!played!in!any!order!and/or!looped!until!the!DNA!fragment!of!

the!prologue!has!concluded.!The!seven!ECVs!are!provided!in!the!score.!

# #

$

$

Different$Barlines$as$Phrase$Marks$

•!Final!Bar!Y!wide#gap;#attacca;#delays#contained;#phrase#concluded#

•!Double!Bar!Y!narrow#gap;#medium#phrase#division;#!

•!Single!Bar!Y!no#gap;#visual#indication#of#bar7like#emphasis!

•Partial!Barline!Y!no#gap;!not#through#a#system;#visual#indication#of#

beat7like#emphasis.! ! #

24

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! 25!

2.3.2 Software Delay Changes

•!All!state!changes!operated!by!the!Engineer!1!and/or!Engineer!2!

•!The!changes!to!the!instrument’s!software!delay!settings!are!indicated!

as:!*"software"delay"added"(A)’"

•!If!two!or!more!delays!are!affected!at!once!the!indication!is!notated!as:!‘*"

abrupt"delay"configuration"change’,"followed!by!a!description!of!the!change!

that!has!occurred,!i.e.!‘(B)"added;"(A,"C)"removed’!

2.3.3 EHX Freeze Sound Retainer Pedal

•!Operated!by!the!Engineer!1!and/or!2!

! !

!

25

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! 26!

2.3.4 EHX Pitchfork Pitch Shifter Pedal

•!Operated!by!the!Engineer!1!and/or!2!

$ $

•!Given!the!note!‘C’!as!input,!the!available!transposition!states!are!as!follows:!

! !

!

!

!

26

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! 27!

2.4 Figuration as Constrained Improvisation

2.4.1 General

As!the!work!unfolds,!the!performers!are!invited!to!decorate!their!musical!

lines!through!the!emulation!of!figuration!found!within!the!notated!music.!!

During!passages!labeled!FIGURATION,!performers!play!their!parts!as!written!

and!in!the!gaps!between!the!notes!add!their!own!decorations!of!the!given!

pitches.!The!performers!should!choose!notes!and!rhythms!that!are!consonant!(in!

a!similar!fashion!to!the!composed!material),!and!if!they,!or!any!member!of!the!

ensemble!is!within!the!delay!networks!at!the!time,!the!figuration!should!not!

derail!the!ensemble!from!their!composite!rhythmic!grid.!

! !

2.4.2 Inserts

! ! ! !

$ •$General$$

The!inserts!supply!the!harmonic!material!for!the!subsections!Cloning#

Vector#(1,#2,#etc.).!As!part!of!the!preparation!for!the!piece,!each!musician!should!

27

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!

! 28!

get!a!good!feel!for!the!inserts!on!their!instrument.!Play!through!them!in!different!

ways!and!try!and!be!imaginative.!A!mature!interpretation!of!the!work!has!each!

musician’s!individual!stamp!on!the!basic!materials!provided.!Below!the!static!

harmonies!is!an!example!of!something!the!performers!!

$ •$Elaborated$Form$of$the$Inserts$

!

!

! !

A!slightly!elaborated!form!of!the!inserts!shows!two!possibilities!for!

expansion/exploration.!!It!should!be!noted!that!the!chords!of!the!INSERTS!are!

designed!to!combine!with!the!same!chord!and!voicing!directly!transposed!a!fifth!

down!or!up!in!conjunction!with!the!EHX!Pitchfork!pedal.!!

28

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! 29!

2.5 Electronics

2.5.1 Computer and Software Requirements

•!A!Macintosh!computer!running!Logic!Studio!or!Ableton!Live!

•!An!audio!interface!with!3!channels!of!input!minimum!and!6!channels!of!

output!minimum!

•!A!hardware!controller!such!as!the!Korg!NanoKontrol!2!or!similar!!

2.5.2 Specific Hardware Requirements

! •!Hardware!is!controlled!by!the!Engineer!1!and!/or!Engineer!2!

! ! •!One!Strymon!Timeline!Stereo!delay!pedal!

The!TAPDIV!parameter!in!PARAMS!of!the!delay!preset!is!the!

specific!setting!adjustment!for!the!third!movement!of!the!piece.!

! !

! ! •!One!ElectroYHarmonix!(EHX)!Freeze!sound!retainer!pedal!

•!Two!mixers!with!a!minimum!of!8!channels!of!input!and!2!channels!of!

output!with!at!least!1!aux!bus!for!each!mixer!

•!One!piezoYbased!pickup!each!for!the!violin!and!the!cello!(two!total),!i.e.!

the!‘Mighty!Mini’!pickup!system!available!online!at!the!

www.ElectricViolinShop.com!

29

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! 30!

•!Three!ElectroYHarmonix!(EHX)!Pitchfork!pitch!shifting!pedals!

controlled!by!Engineer!1!and/or!Engineer!2!

2.6 Stage Setup and Amplification

Recommended$Stage$Setup$

$ $

Note$on$Amplification$and$Balance$

The!amount!of!electronic!signal!and!amplification!required!naturally!

depends!on!the!performance!space,!but!it!should!never!cover!the!acoustic!sound!

of!the!instruments.!Furthermore,!the!electric!guitar!should!always!be!evenly!

balanced!with!the!violin!and!the!violoncello!and!may!need!to!use!a!volume!pedal!

(or!volume!knob!on!the!guitar)!to!adjust!her!balance!throughout.!

30

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! 31!

2.7 Mixer, Interface and Hardware Effects Setup

!

The!above!diagram!presents!the!complete!electronic!signal!of!the!piece.!The!

engineer!oversees!this!signal!path!from!their!station!within!the!ensemble!(as#shown#in#

2.6.1#Recommended#Stage#Setup).!

2.8 Program Notes

! In!Phase#Locked#Loop#and#Modulo#Games,#my!previous!work!for!live!instrument!and!

electronic!delay!line,!an!echo!of!equal!volume!along!with!its!input!are!woven!together!

creating!a!complex!musical!composite!that!is!intended!to!be!electronically!transparent.!

The#Dogma#Loops!picks!up!where!Phase#Locked#Loop!left!off.!It!extends!the!scope!of!inquiry!

by!challenging!that!same!notion!of!complexity!vs.!transparency!through!the!use!of!

31

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!

! 32!

carefully!accumulated!electronic!processing!and!an!output!system!of!hardware!effects!

that!places!the!transformations!in!a!chamber!music!context.!!The!music!for!the!three!

instruments!explores!this!question:!`Via!the!simplest!musical!means!possible,!what!are!

the!inputs!that!result!in!a!deeply!expressive!musical!output?”.!!!

The!form!of!The#Dogma#Loops!borrows!from!the!science!of!molecular!biology,!

specifically!cloning!and!DNA!splicing.!The!processes!by!which!synthetic!DNA!is!

prepared!for!replication!serve!as!models!for!the!compositional!devices!of!the!work.!

“A!given!restriction!enzyme!cuts!DNA!segments!within!a!

specific!nucleotide!sequence,!at!what!is!called!a!restriction!site.!These!recognition!

sequences!are!typically!four,!six,!eight,!ten,!or!twelve!nucleotides!long!and!

generally!palindromic!(i.e.!the!same!nucleotide!sequence!in!the!5U!Y!3U!direction).!

Because!there!are!only!so!many!ways!to!arrange!the!four!nucleotides!that!

compose!DNA!(Adenine,!Thymine,!Guanine!and!Cytosine)!into!a!fourY!to!

twelveYnucleotide!sequence,!recognition!sequences!tend!to!occur!by!chance!in!

any!long!sequence.!Restriction!enzymes!specific!to!hundreds!of!distinct!

sequences!have!been!identified!and!synthesized!for!sale!to!laboratories,!and!as!a!

result,!several!potential!`restriction!sites`!appear!in!almost!any!gene!or!locus!of!

interest!on!any!chromosome.!Furthermore,!almost!all!artificial!plasmids!include!a!

(often!entirely!synthetic)!polylinker!(also!called!`multiple!cloning!site`)!that!

contains!dozens!of!restriction!enzyme!recognition!sequences!within!a!very!short!

32

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!

! 33!

segment!of!DNA.!This!allows!the!insertion!of!almost!any!specific!fragment!of!

DNA!into!plasmid!vectors,!which!can!be!efficiently!`cloned`!by!insertion!into!

replicating!bacterial!cells.”!

!

This!description!of!DNA!fragmentation!quoted!from!Wikipedia.!URL:!

https://en.wikipedia.org/wiki/Restriction_digest!(accessed!on!April!1,!2016)!

!

!

! !

33

Page 46: Kenneth D. Stewart - Duke University - PhD Dissertation Document

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Page 63: Kenneth D. Stewart - Duke University - PhD Dissertation Document

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! 51!

3. Finding Ibrida: Building an Electric Guitar with Embedded Effects

Ibrida!is!an!electric!guitar!with!an!embedded!suite!of!carefully!curated!analog!

electronic!signal!processing!effects.!Latin!for!hybrid,!Ibrida!synthesizes!into!a!single!

instrument!innovations!of!the!last!60!years!of!audio!hardware!technologies!as!viewed!

through!the!lens!of!the!electric!guitar.!The!signal!processing!technologies!range!from!

hollowYstate!(vacuum!tube)!amplifiers!of!the!early!and!midY20th!century,!transistorized!

and!solidYstate!analog!technologies!of!the!late!20th!century,!to!the!current!embedded!

designs!that!combine!digital!signal!processing!with!inexpensive!consumerYlevel!

microcontrollers.!!

The!project!sits!at!an!intersection!of!electric/electronic!instrument!design!and!

related!subfields!such!as!audio!signal!effects!and!amplifiers,!analog!and!digital!signal!

processing,!transducer!and!instrument!pickup!technologies,!and!alternative!sensorY

based!physical!interfaces.!This!article!documents!the!design!and!assembly!of!Ibrida!and!

develops!a!conceptual!frame!that!motivated!the!efforts!to!hybridize!these!technologies.!

The!ultimate!goal!was!to!create!a!uniquely!expressive!electric!instrument!by!installing!

effects!within!the!body!of!the!electric!guitar!!

In!Ibrida,!the!signal!originates!at!the!magnetic!pickup,!moves!through!two!effect!

stages!Y!a!fuzz!distortion!and!reverberation!Y!and!culminates!with!amplification!and!

colorization!at!the!output.!This!paper!describes!the!design!challenges!including!power!

51

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distribution!problems,!battery!limitations!and!difficulties!with!noise!isolation.!Solving!

these!common!problems!informed!the!guiding!principles!and!creative!decisions!

throughout!the!process.!

Ibrida!participates!in!contemporary!trends!of!electronic!lutherie,!digital!effect!

control!and!human/electronic!interface.!These!trends!are!situated!within!a!UvintageU!

aesthetic!that!drives!the!marketplace!of!boutique!electric!guitar!manufacturing!and!

exotic!guitar!effects!design.!Ibrida!gains!expressive!power!by!hybridizing!historical!and!

contemporary!technologies.!It!explores!sound,!myths!of!guitar!lore,!and!the!history!of!

the!electric!guitar!and!its!culture.!Indeed,!Ibrida!presses!further!by!borrowing!from!

designs!of!the!18th!century,!thus!crossing!lines!of!culture!and!musical!genre!to!begin!

anew!with!a!rich!network!of!technologies!and!performance!practices.!

Assembling!Ibrida!involved!many!phases:!selecting!effects!to!include,!selecting!

the!guitar!body,!building!the!effects,!and!many!phases!of!testing!in!between.!The!final!

product!is!a!guitar!with!a!particular!fuzz!distortion!effect,!reverberation,!a!digital!signal!

selector/router!and!a!vacuum!tube!output!stage!that!is!powered!by!two!batteries!within!

Ibrida.!

This!project!required!a!rigorous!technical!and!practical!understanding!of!analog!

signal!processing!as!applied!to!the!electric!guitar.!Six!categories!of!electronic!

technologies!are!incorporated!in!Ibrida:!vacuum!tubes,!discrete!semiconductor!or!

transistorYbased!technologies,!linear!integrated!circuits!(ICs),!digital!logic!

52

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complementary!metal!oxide!semiconductor!(CMOS)!ICs,!`black!box`!digital!ICYbased!

effects,!and!digital!microcontroller!technologies!(an!Arduino!Micro).!Three!of!these!

categories!are!used!for!signal!processing!and!the!remaining!three!are!for!signal!routing!

and!effects!control.!

At!the!tail!of!the!signal!chain,!Ibrida!contains!a!pentode!vacuum!tube.!It!is!a!

voltage!amplifier,!a!directlyYheated!cathode!subminiature!vacuum!tube!coupled!into!a!

current!amplifier,!a!junction!field!effect!transistor!(JFET),!deployed!in!a!sourceYfollower!

configuration.!These!amplifiers!are!the!output!stage!of!the!guitar.!Because!it!would!be!

nearly!impossible!to!fit!an!entire!power!amplifier!and!loudspeaker!into!the!body!of!

Ibrida,!an!effort!was!made!to!create!an!output!stage!that!colors!every!other!effect!in!a!

similar!way!to!a!conventional!guitar!amplifier!by!running!the!entirety!of!the!signal!

through!it,!while!at!the!same!time!having!a!small!enough!formYfactor!to!allow!this!stage!

to!be!installed!in!the!body!along!with!the!other!effects.!As!noted!by!Barbour!and!others,!

vacuum!tube!amplifiers!are!quite!often!preferred!for!their!‘superior’!sound!qualities1.!!

For!Ibrida,!the!combination!of!the!vacuum!tube!type,!the!amplifier!topology!and!

the!particular!powering!technique!seek!to!faithfully!emulate!the!tone!and!timbre!

imparted!onto!any!signal!running!into!a!typical!tube!amplifier.!In!Ibrida,!the!tube!type!is!

a!pentode.!This!choice!was!made!because!pentodes!still!offer!a!different!quality!of!tone!

to!triodes,!with!a!little!more!oddYharmonic!content!and!a!‘glassy’!sound.!When!over!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

1!Eric!Barbour,!“The!Cool!Sound!of!Tubes,”!(IEEE!Spectrum,!August!1998).!

53

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driven!they!can!also!produce!an!expressive!compression!effect!as!the!average!screen!

current!increases.!In!some!ways!they!can!be!thought!of!as!simulators!of!powerYamp!

distortion,!but!at!lower!volume.2!Additionally,!the!pentode’s!plate!(the!positive!terminal)!

uses!9!volts,!which!is!much!lower!than!the!typical!voltage!range!of!30Y67.5!volts.!This!

technique!is!called!‘starvedYplate!operation’!which!increases!the!amount!of!natural!

distortion!of!the!tube.3!

The!`blackYbox`!digital!IC!effects!comprise!another!included!technological!

category!of!signal!processing.!These!digital!IC!effects!are!a!delay!and!a!reverb.!Both!the!

delay!and!reverb!ICs!create!long!decaying!sonic!textures!and!immediately!precede!the!

tube!output!stage!in!the!signal!chain.!

The!delay!processor!selected!is!an!IC!that!utilizes!an!internal!analogYtoYdigital!

converter!(ADC),!44K!of!memory!and!a!digitalYtoYanalog!converter!(DAC).!By!varying!

the!clock!pulse!speed!of!this!IC,!the!delay!time!can!be!varied.!The!particular!IC!is!the!

Princeton!Technologies!PT2399,!an!IC!commonly!found!inside!many!guitar!pedal!effects!

as!well!as!analog!synthesizer!modules.!Unfortunately,!challenges!of!power!bus!noise,!

electromagnetic!interference!(EMI)!and!total!harmonic!distortions!inside!the!IC!rendered!

the!noise!floor!too!great!to!be!useful.!A!lack!of!signal!integrity!prevented!this!effect!from!

being!incorporated!into!the!final!version!of!Ibrida.!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

2!Merlin!Blencowe,!Designing#Tube#Preamps#for#Guitar#and#Bass,!(Wern!Publishing,!2013).!!

3!Eric!Barbour,!“The!Cool!Sound!of!Tubes,”!(IEEE!Spectrum,!August!1998).!

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Remaining,!however,!is!a!reverb!unit!comprised!of!a!single!6Ypin!`brick`!IC.!This!

IC!was!originally!designed!to!be!a!replacement!for!an!analog!spring!reverb!tank!found!

inside!most!vintage!guitar!amps.!In!use,!this!effect!is!very!simple!and!straightforward.!

With!very!few!passive!components!(resistors!and!capacitors)!the!guitar!signal!is!

reverberated,!with!no!option!to!vary!any!parameters!of!this!effect.!It!was!the!simplicity!

that!made!this!brick!reverb!ideal!for!Ibrida,!although!this!simplicity!resulted!in!high!

power!consumption.!

Inside!Ibrida,!there!are!two!effects!that!substantially!transform!the!timbre!of!the!

signal.!As!was!previously!described,!the!reverb!is!a!timeYbased!effect!that!simulates!the!

reflections!of!an!acoustic!signal!in!an!enclosed!space.!Moving!up!the!signal!chain,!the!

next!effect!is!a!waveshaping!distortion!that!intensifies!and!saturates!the!attack!and!

sustain!of!the!guitar:!the!Fuzz!Face.!The!classic!Fuzz!Face!distortion!utilizes!vintage!

germanium!transistors.!Many!guitarists,!most!notably!Jimi!Hendrix,!popularized!the!

DallasYArbiter!Fuzz!Face!in!the!late!1960s.4!In!Ibrida,!this!effect!is!at!the!head!of!the!

signal!chain!immediately!following!the!pickup,!and!can!be!bypassed!by!flipping!a!

switch.!The!Fuzz!Face’s!control!parameter!is!a!single!potentiometer!that!allows!the!

player!to!dial!in!the!amount!of!distortion,!from!relatively!mild!overdrive!to!a!very!hardY

clipped!fuzz.!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

4!R.G.!Keen,!“The!Technology!of!the!Fuzz!Face,”!Geofex.com,!http://www.geofex.com/article_folders/fuzzface/fftech.htm!(accessed!March!7!2016).!

55

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3.1 The electric guitar and signal distortion

The!electric!guitar!is!in!itself!passive,!meaning!it!does!not!require!external!power,!

such!as!a!battery,!to!generate!a!sound!signal.!The!voltage!at!the!output!of!the!electric!

guitar!is!created!when!the!magnetic!strings!vibrate!within!the!electromagnetic!field!of!a!

coil,!known!as!the!pickup.!The!induced!voltage!is!the!signal!source.!!

This!signal!is!weak;!the!voltage!is!small!(200Y300mV),!and!there!is!barely!any!

current!(5Y10nA).!In!order!to!be!audible,!the!signal!must!be!amplified!by!increasing!both!

the!voltage!and!the!current.!Once!the!signal!is!passed!through!the!amplifier,!the!guitar!

becomes!electric.!!

A!guitar!amplifier!actually!consists!of!a!set!of!amplifiers!that!work!together!to!

increase!the!voltage!and!current!in!stages.!A!basic!amplifier!has!an!input!stage!for!signal!

conditioning!and!an!output!stage!for!power!amplification.!Signal!conditioning!takes!the!

weak!signal!from!the!guitar!and!increases!the!voltage.!This!higher!voltage!signal!is!

coupled!to!the!output!stage,!which!increases!the!current.!Finally,!the!high!current/high!

voltage!signal!powers!a!loudspeaker!(Figure!1).!Each!stage!changes!the!signal!ever!so!

slightly!as!it!passes!through!the!system.!These!changes!lead!to!subtle!differences!in!

sound,!leading!some!guitarists!to!prefer!certain!amplifiers!over!others.!!

!

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!

Figure$1:$Schematic$of$the$signal$path$of$a$typical$guitarTamplifier$system.$

!

If!the!amplification!factor!is!large!enough,!these!differences!are!no!longer!subtle.!

Operating!these!amplifiers!at!their!extreme!levels!i.e.,!‘overYdriving’!them,!creates!an!

audio!phenomenon!called!clipping.!Clipping!is!a!form!of!signal!distortion!which!cuts!off!

the!waveform!at!its!maximal!point5!(Figure!2).!This!distortion!adds!additional!harmonic!

content!to!the!signal6!7,!resulting!in!a!sound!that!is!harsher!and!more!piercing!than!the!

unprocessed!signal.!!

!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

5!Steve!Waksman,!Instruments#of#Desire:#The#Electric#Guitar#and#the#Shaping#of#Musical#Experience,!(Massachusetts:!Harvard!University!Press,!2001),!137.!!!6!Mitch!Gallagher,!Guitar#Tone:#Pursuing#the#Ultimate#Guitar#Sound,!(Massachusetts:!Cengage!Learning,!2012),!88.!7!Steve!Waksman,#Instruments#of#Desire:#The#Electric#Guitar#and#the#Shaping#of#Musical#Experience,!(Massachusetts:!Harvard!University!Press,!2001),!137Y138.!

57

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!

Figure$2:$Sine$wave$of$nonTclipped$and$clipped$signal8$

$!

The!composer!Alan!Strange!notes!that!“because!harmonics!are!of!lower!

amplitude!than!the!fundamental,!and!due!to!a!certain!amount!of!loss!(referred!to!as!

“insertion!loss”)!in!the!filter!and!shaping!device,!an!amplifier!is!usually!needed!to!bring!

the!multiplied!product!back!up!to!its!original!levels.”9!

“Wave!shaping”!is!the!term!for!any!process!that!changes!the!harmonic!content!of!

a!sound.!As!a!sound!becomes!brighter,!it!is!able!to!cut!through!a!musical!texture!more!

easily.!In!the!late!1950’s,!a!time!when!the!overall!volume!of!amplified!music!was!

increasing,!the!ability!to!cut!through!a!loud!musical!texture!was!most!useful.!Rather!

than!simply!becoming!louder,!Robert!Palmer!described!the!sounds!of!the!electric!guitar!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

8!Mikhail!Ryazanov,!“Clipping!Waveform,”!Wikimedia!Commons!https://commons.wikimedia.org/wiki/File:Clipping_waveform.svg!(accessed!March!9,!2016).!9!Alan!Strange,!Electronic#Music:#Systems,#Techniques#and#Controls,!(Wm.!C.!Brown!Company!Publishers,!1973)!20.!!!

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at!this!time!as!becoming!raw!and!ferocious.10!This!is!another!indication!of!the!bright!and!

brittle!sound!of!the!upper!harmonics!by!adding!waveshaping!distortion.!!

Electric!blues!artists!such!as!Muddy!Waters,!Chuck!Berry!and!Jackie!Brenston,!

each!associated!with!the!Chess!Record!Label,!were!taking!full!advantage!of!these!

overdriven!sounds.11!This!shift!took!place!from!the!earlyYmid!1950’s!through!the!early!

1960’s!and!can!be!heard!in!recordings!such!as!Chuck!Berry’s!“Maybellene”!(Chess!1604)!

or!Jackie!Brenston!and!the!Delta!Cats’!“Rocket!88”!(Chess!1458).!At!this!time!electric!

blues!guitarists!pushed!their!music!further!in!the!distorted!direction12!with!the!bright!

and!overdriven!sound!of!Elmore!James13!as!a!fine!example.!

These!recording!artists!strove!to!achieve!the!raw!sound!by!any!means!necessary,!

including!damaging!their!amplifiers.!Rockabilly!guitarist!Paul!Burleson!explains!that!

after!dropping!his!guitar!amplifier!while!on!tour!the!sound!of!his!electric!guitar!was!

altered.!In!Burleson’s!case,!it!was!serendipitous!accident!that!allowed!him!to!discover!

this!raw!and!ferocious!sound.!When!using!the!‘damaged’!amplifier,!Burleson!noticed!an!

altered!sound!quality.!He!later!replicated!the!effect!by,!in!spite!of!the!safety!hazard,!

routinely!reaching!into!his!amplifier!and!loosening!the!tubes!to!the!point!that!they!were!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

10!Robert!Palmer,!Deep#Blues,!(New!York:!Penguin!Books,!1981).!11!Steve!Waksman,!Instruments#of#Desire:#The#Electric#Guitar#and#the#Shaping#of#Musical#Experience,#(Massachusetts:!Harvard!University!Press,!2001),!120.!12!Ibid.,!116.!13!Tom!Wheeler,!The#Soul#of#Tone:#Celebrating#60#years#of#Fender#Amps,!(Wisconsin:!Hal!Leonard!Corporation,!2007),!42.!

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nearly!falling!out.14!15!He!later!recorded!this!sound!alongside!Johnny!Burnette!in!the!1956!

recording!“Train!Kept!AYRollin”.!

!

Sound$File$1:$“Train$Kept$ATRollin”$

!

There!are!many!other!anecdotes!of!instrumentalists!damaging!or!modifying!their!

amplifiers!to!obtain!the!desired!distorted!timbre,!but!this!is!in!no!way!practical!or!

reliable,15!as!such!modifications!bring!with!them!the!challenge!of!consistency!in!

repeating!the!desired!amplifier!timbre!in!differing!performance!and!recording!

environments.!Destructive!modifications!were!irreversible!and!costly,!and!there!were!

safety!concerns!within!the!high!voltage/high!current!technology!of!tube!amplifiers.!In!

the!1950’s,!it!was!rare!to!find!the!redundant!safety!precautions!of!grounded!outlets!and!

plugs!in!concert!venues!and!homes,!thus!blindly!reaching!into!the!amplifier!with!

voltages!ranging!between!two!and!five!hundred!volts16,!introduces!a!risk!of!severe!burns!

and!even!electrocution.!

As!stated!above,!these!brighter!distorted!tones!can!be!made!without!modification!

by!simply!overdriving!the!amplifier.!This!too!is!problematic.!Overdriving!the!amplifier!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

14!Art!Thompson,#Stompbox:#A#History#of#Guitar#Fuzzes,#Flangers,#Phasers,#Echos#and#Wahs,!(California:!Miller!Freeman,!1997)!14.!15!Jas!Obrecht,!“Paul!Burlison:!The!Complete!Rock!‘n!Roll!Trio!Interview,”!Jas!Obrecht!Music!Archive,!http://jasobrecht.com/paulYburlisonYcompleteYrockYnYrollYtrioYinterview!(accessed!March!9,!2016).!16!RCA,!“Receiving!Tube!Manual,”!RCA!Technical!Series,!(New!Jersey:!Radio!Corporation!of!America,!1950).!

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to!achieve!expressive!distortion!can!be!extremely!loud,!making!it!difficult!to!maintain!

balance!among!the!members!of!the!ensemble.!Additionally!it!is!difficult!to!move!from!

one!desired!tone/volume!state!to!another.17!

Today,!the!reasons!for!not!modifying!or!excessively!overdriving!the!amplifier!far!

outweigh!the!reasons!to!modify!the!amplifier.!This,!however,!is!a!contemporary!

perspective.!Without!specific!devices!that!enable!the!player!to!achieve!an!expressive!

distorted!sound!through!simpler!means,!it!is!easy!to!imagine!why!these!artists!turned!to!

such!extreme!measures.!It!was!the!sound!itself!that!was!leading!these!artists!in!this!

direction.!They!were!striving!to!make!their!guitars!evoke!unique!sounds!or!the!timbres!

of!other!instruments!by!reaching!outside!the!linear!range!of!their!amplifiers,!well!

beyond!what!was!commercially!available!for!the!electric!guitar!at!this!time.!!

The!timbre!of!distortion!was!often!compared!to!the!saxophone.!Turning!again!to!

extreme!amplifier!modification,!Obrecht!notes!how!a!distressed!loudspeaker!creates!this!

‘fuzz’!timbre.!In!the!aforementioned!“Rocket!88”!of!Jackie!Brentson,!there!is!the!direct!

juxtaposition!of!the!fuzz!timbre!and!a!saxophone!section.18!Note!the!similarity!and!

effective!blend!between!the!timbre!of!the!distorted!guitar!and!the!saxophone.!

!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

17!Mitch!Gallagher,!Guitar#Tone:#Pursuing#the#Ultimate#Guitar#Sound,!(Massachusetts:!Cengage!Learning,!2012)!160.!18!Jas!Obrecht,!“Paul!Burleson:!The!Complete!Rock!‘n!Roll!Trio!Interview,”!Jas!Obrecht!Music!Archive,!http://jasobrecht.com/paulYburlisonYcompleteYrockYnYrollYtrioYinterview!(accessed!March!9,!2016).!

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Sound$File$2:$[sound$example$of$Rocket$88$by$Jackie$Brenston$and$his$Delta$

Cats]$

Unbeknownst!to!artists!that!willfully!risked!the!integrity!of!their!amplifiers!(and!

their!health),!a!new!technology!would!soon!come!about!at!the!end!of!the!1950’s!that!

would!enable!such!sounds!to!be!created!with!relative!ease:!the!transistor.!

!

!

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3.2 The Fuzz Pedal

A!compelling!device!at!this!time!of!musical!transition!is!the!LRE!Fuzz!Sound!

guitar!pedal.!Introduced!between!1968!and!1970,!the!pedal!sold!for!$14.95!via!catalog!by!

Lafayette!Radio!Electronics,!an!electronics!parts!supplier!with!deep!connections!to!the!

hobbyist!market19!(Figure!3).!The!description!of!the!timbre!is!directly!compared!to!the!

saxophone,!which!indicates!a!desire!among!guitarists!for!this!kind!of!sound,!even!within!

the!hobbyist!market.!This!effect!was!also!sold!and!distributed!by!three!other!companies!Y!

Mica,!Monacor!and!Melos!(under!the!name!of!the!‘Fuzzder’),!with!Mica!later!rebranding!

the!same!effect!as!the!‘Wailer’.!Apollo!also!sold!the!effect!under!the!name!of!the!‘no.!843!

Fuzz!King’.!Olson!sold!it!as!the!‘Fuzz!Master’.20!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

19!Jack!Ward,!“The!First!Germanium!Hobbyist!Transistors”,!Transistor!Museum,!2009!http://semiconductormuseum.com/MuseumLibrary/HistoryOfTransistorsVolume1.pdf!(accessed!March!7,!2016).!20!Effects!Database,!“LRE!Fuzz!Sound,”!EffectsDatabase.com,!http://www.effectsdatabase.com/model/lre/fuzzsound!(accessed!March!9,!2016).!

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!

Figure$3:$Advertisement$of$LRE$Lafayette$“Fuzz$Sound”20$

!

These!six!guitar!pedals!are!actually!the!same!effect!which!today!are!available!on!

the!vintage!pedal!market!for!around!$250!Y!$300,!nearly!22!times!the!original!price.!

Because!it!is!not!well!known!that!different!manufacturers!released!the!same!circuit!there!

are!varying!degrees!of!aftermarket!desirability!and!cost!of!these!particular!fuzz!effects!

on!the!vintage!pedal!market.!They!all!have!the!same!distinctive!chassis!and!unique!

formYfactor!with!the!knobs!on!the!back!of!the!pedal!facing!away!from!the!player.!Also!

unique!to!these!pedals!is!the!use!of!three!germanium!transistors!and!the!extremely!rare!

use!of!a!single!AA!battery!as!its!only!power!source.!!

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The!schematic!of!the!LRE!Fuzz!Sound,!et!al.!originally!appeared!in!the!Jan./Feb.!

1968!edition!of!the!Elementary#Electronics!magazine!(Figure!4).!The!article!instructs!the!

reader!how!to!wire!up!and!build!a!‘FuzzYaYtort’,!a!fuzz!effect!which!creates!the!“deep,!

throaty!sound!of!the!saxophone”.21!The!schematic!in!Figure!4!was!published!before!the!

LRE!Fuzz!Sound!came!on!the!market!and!the!“FuzzYaYtort”!predates!any!reference!to!the!

Fuzz!Sound!or!any!other!of!the!same!fuzz!effect!with!a!different!name.!Note!the!use!of!

the!1.5v!AA!battery.!!

!

Figure$4:!Schematic!for!the!FuzzYaYtort!

!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

21!American!Radio!History,!“Elementary!Electronics!Hobbyist!and!Experimenter!magazine!published!from!1960!to!1981,”!AmericanRadioHistory.com,!http://www.americanradiohistory.com/Elementary_Electronics_Master_Page.htm!(accessed!March!9,!2016).!

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To!illustrate!how!this!effect!alters!the!timbre!of!an!input!signal,!three!spectra!are!

provided!to!show!the!effect!of!LRE!Fuzz!Sound!at!its!minimum!and!maximum.!(Figures!

5,!6,!7)!In!the!provided!spectra!the!brightness!of!the!white!indicates!volume,!the!Y!axis!

specifies!logarithmic!frequency!from!20Y20,000!Hz,!and!the!X!axis!is!time.!

!

Figure$5:$Spectrogram$of$a$sineTsweep$from$82.406891$hz$to$1108.730469$hz$(the$low$E$of$the$guitar$to$the$C#$of$the$typical$highest$fret)$directly$recorded$from$oscillator$to$

computer$memory.$

!Figure$6:$Spectrogram$of$the$same$sineTsweep$through$an$original$LRE$Fuzz$Sound$

enabled$on$its$lowest$fuzz$setting.!

!

Figure$7:$Spectrogram$of$the$same$sineTsweep$through$the$LRE$Fuzz$Sound$with$the$fuzz$setting$on$maximum.$

!

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Note!the!harmonics!added!to!the!fundamental!frequency!of!the!sine!wave!in!Fig.!

7.!Additionally!the!overall!power!of!the!signal!is!distributed!among!the!harmonics!in!the!

spectrum,!reducing!the!overall!volume,!a!phenomenon!predicted!by!Strange!in!the!

earlier!discussion!of!wave!shaping.22!

For!comparison,!the!following!two!spectra!are!from!a!brandYnew!Dunlop!siliconY

transistor!based!Fuzz!Face!pedal!(Figures!8,!9).!!

!

Figure$8:$Spectrogram$of$the$sineTsweep$audiofile$through$the$Dunlop$Silicon$Fuzz$Face$(the"effect"is"enabled"and"is"on"its"lowest"fuzz"setting)!

!

!Figure$9:$Spectrogram$of$the$same$sineTsweep$through$the$Silicon$Fuzz$Face$with$the$

fuzz$setting$on$maximum$(the"volume"was"not"altered)$

$

Note!the!presence!of!additional!upper!harmonics!indicating!the!brighter!(or!

hasher)!timbre.!Also!of!note!is!the!more!prominent!fundamental!frequency.!The!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

22!Alan!Strange,!Electronic#Music:#Systems,#Techniques#and#Controls,!(Wm.!C.!Brown!Company!Publishers,!1973).!!!

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combination!of!the!louder!harmonic!lines!and!fundamental!frequency!indicate!a!

substantially!louder!signal!than!the!original!signal.!It!is!brighter!and!louder!than!the!

vintage!germanium!fuzz!effect!shown!in!Figs.!6!and!7.!

!

3.3 Vacuum Tubes

$

Tube Selection and the Caveats of Tube Design

The!original!pentode!vacuum!tube!selected!for!Ibrida!was!the!1V6.!The!first!

prototype,!however,!exhibited!serious!flaws!and!was!ultimately!eliminated!from!the!

design.!To!ensure!this!error!was!with!the!tube!itself,!two!additional!tubes!of!this!type!

were!tested!and!all!had!the!same!fundamental!flaw.!!

!

Soundfile$3$T$1V6$tube$ringing$

$

The!main!component!of!this!sound!is!the!very!high!pitch!ringing,!an!artifact!that!

is!unique!to!this!particular!model!of!tube.!Two!separate!1V6!tubes!were!purchased!and!

tested!in!circuit!with!no!eradication!of!the!ringing.!The!60hz!hum!of!the!circuit!is!a!result!

of!the!long!tube!leads!and!the!lack!of!adequate!shielding!on!the!circuit!board.!When!this!

tube!is!used!as!a!very!high!frequency!oscillator,!like!the!ones!found!in!antique!AM!

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radios,!this!ringing!less!of!a!problem.!In!Ibrida,!however,!the!ringing!was!a!major!

detractor!from!the!desired!sound.!!

!

!

Figure$10:$The$1AD5$vacuum$tube$

!

Instead,!Ibrida!uses!the!1AD5!vacuum!tube!(Figure!10),!which!has!almost!the!

same!characteristics!of!the!1V6,!but!does!not!introduce!the!highYpitched!ring.!In!tube!

circuits,!stray!capacitances!commonly!associated!with!printed!circuit!boards!can!

introduce!hum!and!noise!to!the!signal.!Moving!away!from!the!copper!lines!etched!

closely!together!on!fiberboard!to!pointYtoYpoint!wiring!on!a!turretYboard!reduced!these!

additional!noises.!PointYtoYpoint!wiring!is!common!in!both!vintage!and!modern!tube!

amplifiers!and!it!makes!the!amplifier!operate!more!quietly.!

!

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1AD5 subminiature sharp-cutoff pentode

The!next!audio!example!is!a!signal!amplified!with!the!1AD5!and!illustrates!the!

importance!of!effective!shock!absorption!when!mounting!a!vacuum!tube.!

$

Soundfile$4$T$1AD5$thumping$to$demonstrate$microphonics$

$

The!thumping!sound!is!a!phenomenon!known!as!microphonics,!a!consequence!of!

mechanical!vibrations!inside!the!vacuum!tube.23!Microphonics!are!not!unique!to!

subminiature!tubes,!in!fact,!slight!microphonics!are!a!reality!of!nearly!every!vacuum!

tube!ever!manufactured.23!This!is!perhaps!yet!another!reason!why!the!move!away!from!

tubes!to!transistors!was!nearly!universal!within!the!electric!guitar!community.!

! The!realYworld!characteristics!of!exotic!or!unconventional!vacuum!tube!types!for!

audio!applications!are!largely!undocumented.!Since!they!are!purchased!online,!they!

often!arrive!untested!and!thus!unheard.!These!tubes!could!sound!beautiful!or!at!the!very!

least!interesting.!The!joy!of!exploring!doYitYyourself!tube!audio!in!this!way!comes!from!

discovering!what!sounds!circuits!like!these!can!produce.!

Table!1!shows!how!the!tube!used!in!Ibrida!compares!to!one!of!identical!type!and!

similar!application!in!an!amplifier!circuit.!The!1AD5!used!in!Ibrida!is!compared!with!the!

pentode!found!in!the!early!Fender!Champ!amplifier!introduced!in!1964.!Barbour!goes!as!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

23!Eric!Barbour,!“The!Cool!Sound!of!Tubes,”!(IEEE!Spectrum,!August!1998).!

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far!as!to!call!the!Champ!‘the!standard’!of!the!“tube!amp”!sound.24!With!the!Champ’s!

small!size!and!lowYcost,!he!notes!that!it!possesses!the!sound!of!the!amps!found!in!the!

recordings!of!early!rock!‘n’!roll.!The!Champ!is!likely!very!similar!to!the!amplifier!with!

loosened!vacuum!tubes!used!by!Paul!Burleson!in!the!sound!example!of!‘Train!Kept!AY

Rollin’.!

$

Pentode comparison

!! !! Filament$ !! Grid$ Screen$$ Screen$$ !! AC$Plate$$ TransT$Tube$#$ Type$ Voltage$ Current$$ Plate$$ Bias$ Grid$ Grid$$ Plate$$ Resistance$ conductance$$$ $$ $(V)$ (mA)$ (V)$ $(V)$ $(V)$ (I)$mA$ (I)$mA$ $$ $$

!! !! !! !! !! !! !! !! !! !! !!

6SJ7!Sharp!Cutoff! 6.3! 300! 100! Y3! 100! 0.9! 2.9! 700000! 1575!

!! !Pentode! !! !! 250! Y3! 100! 0.8! 3! 1000000! 1650!

!! !! !! !! !! !! !! !! !! !! !!

1AD5!Sharp!Cutoff!! 1.25! 40! 30! 0! 30! 0.16! 0.45! 700000! 430!

!! Pentode! !! !! 67.5! 0! 67.5! 0.75! 1.85! 700000! 735!

$

Table$1:!Comparison$of$1AD5$vs.$6SJ7$

$

The!1AD5’s!lower!plate!voltage!requirements,!current!output,!substantially!

lower!power!consumption!result!in!a!much!lower!amplification!factor.!This!factor!is!

known!as!transconductance!(Gm),!which!is!calculated!by!dividing!the!amplification!

factor!by!the!plate!resistance.!In!general,!transconductance!provides!a!circuit!designer!a!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

24!Eric!Barbour,!“The!Cool!Sound!of!Tubes,”!(IEEE!Spectrum,!August!1998).!

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useful!value!for!how!well!a!given!tube!conducts!in!an!ideal!amplification!environment.!

The!unit!of!transconductance!is!‘mho’,!the!unit!of!resistance!(ohm)!spelled!backward,!

and!is!generally!given!in!microYmhos.25!The!pentode!enables!the!preamplifier!to!serve!as!

power!amplifier!emulation,!thereby!coloring!the!timbre!of!the!previous!signals!and!

effects.!As!noted!earlier,!the!colorization!that!occurs!through!mild!distortion!helps!

generate!the!most!desirable!tone!of!the!amplified!electric!guitar.!!

!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

25!RCA,!“Receiving!Tube!Manual.”!RCA!Technical!Series,!(New!Jersey:!Radio!Corporation!of!America,!1950.)!

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3.4 The Transition from Tubes to Transistors

Much!like!the!aforementioned!vacuum!tube,!boutique!pedal!manufacturers!and!

collectors!alike!seem!to!prefer!periodYappropriate!technologies!inside!vintage!circuits.!

The!use!of!the!germanium!transistor!is!an!excellent!example.!In!the!1960’s,!the!time!the!

Fuzz!Face!was!originally!designed,!most!transistors!were!manufactured!with!

germanium,!whereas!today!nearly!all!transistors!are!made!of!silicon.!There!is!a!

difference!between!the!two!materials,!and!Ibrida!employs!the!original!transistor!material!

rather!than!the!more!modern!alternative.!

$

The Arbiter (now Dunlop) Fuzz Face

As!described!above,!many!electric!guitarists!modified!their!amplifiers!to!add!

expressive!distortion!to!the!sound!of!their!instruments.!Indeed,!artists!were!willing!to!go!

to!great!lengths!to!achieve!a!fuzz!sound.26!The!fuzz!pedal,!an!external!device!that!could!

be!purchased!in!a!department!store,!guitar!shop!or!mail!order!catalog,!enabled!these!

same!artists!to!obtain!this!sound!without!modifying!the!amplifier.!The!fuzz!pedal!is!a!

touchstone!in!the!technologic!and!musical!evolution!of!the!electric!guitar.!While!

popularized!by!Jimi!Hendrix!in!recordings!such!as!“Purple!Haze”,!artists!such!as!Cream,!

The!Who,!The!Animals,!and!the!Beatles!on!their!album!Abbey#Road!also!used!this!effect.27!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

26!Obrecht,!Jas,!“Paul!Burlison:!The!Complete!Rock!‘n!Roll!Trio!Interview”,!Jas!Obrecht!Music!Archive.!http://jasobrecht.com/paulYburlisonYcompleteYrockYnYrollYtrioYinterview/!(accessed!March!9,!2016).!27!Art!Thompson,!“The!Fuzz!Makers!Roundtable”,!(Guitar!Player,!September!20,!2011),!76.!

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It!sits!at!the!intersection!of!the!evolution!of!rock!and!roll!and!the!burgeoning!tech!

revolution!that!was!taking!place!in!the!late!1960’s.!!

The!Fuzz!Face!uses!two!transistors!to!amplify!the!input!signal!to!the!point!of!

extreme!distortion!in!a!controlled!manner.!Like!the!LRE!Fuzz!Sound,!the!Fuzz!Face!

achieves!its!effect!through!wave!shaping.!It!“delivers!a!soft!asymmetrical!clipping!that!

changes!to!hard!clipping.”28!Its!only!effect!parameter!(beyond!output!volume)!is!the!fuzz!

amount.!There!have!been!countless!clones!of!the!Fuzz!Face!dating!from!the!time!of!its!

introduction!through!today.!As!described!by!Keen,!“This!simple,!two!transistor!circuit!

remains!for!many!the!very!definition!of!the!guitar!effects!stomp!pedal.”29!The!Jim!

Dunlop!Corporation!currently!manufactures!this!pedal.!A!customer!purchasing!a!fuzz!

pedal!today!from!The#Musician’s#Friend!catalog!can!choose!from!139!options,!

exemplifying!the!evolution,!variation,!and!continued!demand!for!this!effect.30!

Many!variations!of!the!Fuzz!Face!have!been!generated!due!to!availability!of!the!

parts!and!changing!tastes!in!the!‘proper’!fuzz!sound!along!with!the!ready!availability!of!

the!components.31!As!so!many!changes!have!taken!place!over!the!years,!the!doYitY

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

28!Electrosmash,!“Fuzz!Face!Analysis,”!Electrosmash.com,!http://electrosmash.com/fuzzYface!(accessed!March!7,!2016).!29!R.G.!Keen,!“The!Technology!of!the!Fuzz!Face”,!Geofex.com,!http://www.geofex.com/article_folders/fuzzface/fftech.htm!(accessed!March!7th!2016).!30!Musician’s!Friend,!“Fuzz!and!Boost!Effect!Pedals,”!MusiciansFriend.com,!http://www.musiciansfriend.com/fuzzYboostYeffectsYpedals!(accessed!March!9,!2016).!31!Art!Thompson,!“The!Fuzz!Makers!Roundtable”,!Guitar!Player,!September!20,!2011,!76.!

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yourself!electronics!community!has!taken!great!pains!to!map!the!evolution!of!the!Fuzz!

Face.32!

The!first!Fuzz!Face!dating!from!1966!utilized!germanium!transistors.!Germanium!

is!the!element!found!in!the!earliest!manufactured!transistors,!diodes,!and!other!

semiconductors!that!“were!widely!used!in!consumer!electronics!until!more!consistent!

and!more!reliable!silicon!components!became!available!in!the!late!1960s.”33!Silicon!

transistors,!though!more!reliable,!altered!the!distortion!effects!of!the!fuzz!pedal!by!

yielding!a!harsher!timbre!(see!figs.!6Y9).!

Germanium!transistors!are!inconsistent!from!one!to!the!next.!“Although!different!

makes!of!germanium!transistors!often!had!different!characteristics,!the!more!desirable!

types!are!considered!to!yield!a!sound!that!is!warm,!rich!and!extremely!dynamic.!They!

can!also!range!from!crispy,!bright,!and!jagged!to!muffled,!smooth!and!dark,!or!

anywhere!in!between…they!are!universally!considered!to!be!extremely!tactile,!yielding!

a!great!playing!feel.”31!!

This!complexity!of!sound!and!nuance!of!feel!is!subjective!to!the!player!and!

highly!sensitive!to!the!particular!characteristics!of!the!semiconductors!used.!If!a!less!

bright!and!softer!clipped!timbre!is!desired,!germanium!is!necessary.!In!contrast,!if!the!

player!or!producer!wants!the!brighter!and!louder!sound,!then!silicon!is!the!better!choice.!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

32!Electrosmash,!“Fuzz!Face!Analysis,”!Electrosmash.com,!http://electrosmash.com/fuzzYface!(accessed!March!7,!2016).!33!Dave!Hunter,!“What’s!the!Big!Deal!about!Germanium!Transistors?,”!(Guitar!Player,#January!2014),!138.!

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Just!as!a!maker!of!acoustic!instruments!can!affect!the!sound!quality!in!subtle!ways,!so!

can!the!choice!of!semiconductor!technologies!and!schematic!topologies!result!in!

particular!timbres!that!have!come!to!define!the!ideal!fuzz!effect.!The!inconsistency!of!

germanium!as!a!satisfactory!semiconductor!technology!for!today’s!digital!applications!

has!rendered!germanium!nearly!obsolete,!though!the!niche!market!of!loYfi!audio!has!

made!certain!germanium!transistors!a!highly!sought!after!item!for!their!unique!sound!

qualities34,!and!sometimes!can!be!difficult!to!find.!!

Roger!Mayer,!a!BritishYborn!effect!designer!whose!designs!have!been!used!by!

Jimmy!Page,!Jeff!Beck!and!Jimi!Hendrix,!described!the!process!of!finding!the!right!

germanium!transistor:!“the!reality!is!that!you’ve!got!to!buy!thousands!of!them,!and!then!

you’ve!got!to!sit!down!and!test!them!all.!There!are!maybe!30!percent!that!you!can!use,!

but!it!was!always!like!that”.35!!With!the!difficulty!in!identifying!a!quality!transistor,!it!is!

easy!to!see!why!silicon!eventually!dominated!the!market,!Mayer,!when!comparing!

germanium!to!silicon,!stated:!!

“the!diodeYjunction!voltage!parameters!as!the!device!begins!to!conduct!are!

smoother!for!a!germanium!transistor,!which!means!the!transistor!goes!in!to!

distortion!more!musically.!The!overall!current!and!voltage!gain!of!germanium!

transistors!is!less!than!silicon!and!also!not!as!linear.!In!musical!terms!this!means!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

34!Dave!Hunter,!“The!Arbiter!Fuzz!Face,”!(Guitar!Player,!July!2015),!114.!35!Dave!Hunter,!“What’s!the!Big!Deal!about!Germanium!Transistors?,”!(Guitar!Player,!January!2014),!138.!

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the!circuit!changes!as!the!level!changes,!so!the!circuit!becomes!more!player!

friendly!in!terms!of!dynamic!feel.”36!!

This!musical!advantage!is!why!germanium!transistors!are!still!sought!today!for!musical!

effects.!!

Given!the!variability!in!germanium!transistors,!selecting!the!proper!transistor!is!

crucial!when!assembling!or!designing!an!effect.!Germanium!transistors!are!seen!today!

as!a!transitional!technology.!In!the!context!of!Ibrida,!which!embodies!this!transition!on!

the!historical!timeline!of!electronic!innovation,!their!inclusion!in!Ibrida!was!essential.!

Therefore,!Ibrida!utilized!germanium!transistors!to!integrate!a!fuzz!effect.!!

!

Figure$11:!The$schematic$of$the$Fuzz$Face$with$its$sections$labeled$!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!

36!Art!Thompson,!“The!Fuzz!Makers!Roundtable”,!(Guitar#Player.!September!20,!2011),!76.!

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$

!

Figure$12:$The$schematic$of$the$Fuzz$Face$as$it$appears$in$Ibrida$with$a$positive$power$supply$(identical"but"with"a"different"battery"placement"in"the"schematic)$

$

The AC128 Germanium Transistor

Online!retail!vendors!have!become!the!primary!source!for!hard!to!find!and!other!

original!or!obsolete!components!of!this!era.!These!are!known!as!‘New!Old!Stock’!parts.!

These!parts!were!manufactured!during!their!original!era,!but!remain!unused!and!can!be!

purchased!as!“new.”!They!are!often!expensive,!and!bidding!for!these!parts!can!be!

competitive,!as!they!are!available!in!limited!quantities.!One!of!the!germanium!

transistors,!which!can!be!purchased!as!‘New!Old!Stock’!primarily!for!use!in!various!

clones!of!the!first!Fuzz!Face!is!the!AC128.!(Figs!11,!12).!According!to!Keen:!

“It! seems! likely! that! the! AC128! was! picked! for! its! cost! and!

availability!(in!retrospect)!rather!than!any!superior!sound!qualities…!the!

fact!is!that!the!AC128!is!not!a!super!high!quality!transistor,!and!wasnUt!at!

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the! time.! It! is! a! moderate! gain! (90! typical)! device! with! only! modest!

frequency! response.! It! was! HIGHLY! variable! in! gain…! I! measured!

several! hundred! AC128Us! for! gain,! and! they! vary! from! a! gain! of! 16! to!

probably! 180…! probably! because! the! measured! gains! actually! turn! in!

numbers!up! to!500!or! so,!which!are!clearly! leaky!devices,!not!high!gain!

devices…The! variation! in! gain! is! important! because! it! is! crucial! to! the!

tone!of!the![Fuzz!Face].”37!

When!considering!the!AC128,!this!variability!can!be!desirable!quality.!I!chose!the!

AC128!with!the!expressed!purpose!of!building!this!historical!technology!into!Ibrida.!!

In!direct!contrast!to!the!unreliable,!inconsistent!germanium!transistor,!a!more!

standard!technology!existed!at!the!time!of!its!invention:!the!vacuum!tube.!By!the!1950s!

the!vacuum!tube!was!an!established!technology!across!the!electronic!landscape.!Simply!

put,!a!vacuum!tube!takes!a!small!signal!at!its!input!and!amplifies!it!according!to!a!

function!of!gain.!As!amplification!is!increased,!so!is!distortion.!This!is!identical!to!the!

transistor,!however,!a!vacuum!tube!amplifies!the!voltage!or!current!of!an!electronic!

signal!by!the!means!of!a!phenomenon!called!thermionic!emission.!This!refers!to!enabling!

the!flow!of!electrons!from!one!point!to!another!when!a!doped!piece!of!metal!is!heated.!A!

plate!with!a!positive!potential!is!placed!near!the!glowing!piece!of!doped!metal!and!a!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

37!R.G.!Keen,!“The!Technology!of!the!Fuzz!Face,”!Geofex.com,!(http://www.geofex.com/article_folders/fuzzface/fftech.htm!(accessed!March!7th!2016).!

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varying!voltage!with!a!mostly!negative!potential!regulates!the!flow!of!electrons!between!

the!two!complementary!potentials.38!

At!the!time!of!the!introduction!of!transistors,!vacuum!tubes!offered!many!

advantages!to!the!inconsistencies!noted!above.!The!first!vacuum!tube!amplifiers!date!

back!to!the!early!20th!century,!and!by!the!midY1940s,!tube!technology,!particularly!

subminiature!vacuum!tubes,!had!become!extremely!reliable.!The!device!was!

manufactured!to!rigorous!military!specification.!It!was!highly!stable,!extremely!low!

power!and!able!to!withstand!the!high!temperatures,!gYforces!and!atmospheric!pressures!

of!the!first!reliable!radio!detonated!artillery!shells.39!The!subminiature!tube!is!cited!as!the!

specific#technology!that!led!to!the!defeat!of!the!devastating!kamikaze!attacks!in!the!

Pacific!theater!of!WWII.!An!additional!application!of!the!subminiature!tube!includes!

enabling!the!first!portable!battery!powered!hearing!aids.40!!The!significance!of!this!

innovation!along!with!its!durability!and!small!formYfactor!made!the!subminiature!tube!

ideal!for!Ibrida.!!

!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

38!John!A.!Harper,!“Tubes!201,”!JohnYAYHarper.com,!http://www.johnYaYharper.com/tubes201/!(accessed!March!9,!2016).!39!MIT!Museum,!“The!Subminiature!Vacuum!Tube:!The!Cycle!of!Technology,”!Flash!Video,!http://video.mit.edu/watch/theYsubminiatureYvacuumYtubeYtheYcycleYofYtechnologyY2574!(accessed!March!9,!2016).!40!Ibid.!

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3.5 The Integrated Circuits & Subsystems used in Ibrida

!

Reverberation as a discrete effect

!

Reverberation!is!the!cumulative!reflection!of!sound!within!an!enclosure!that!is!

added!to!and!persists!after!the!original!sound!has!ceased.!!!Reverberation!is!manually!

described!as!the!time!required!for!a!sound!in!an!enclosure!to!die!away!to!oneYmillionth!

of!its!original!intensity!or!decrease!by!60dB.!!The!reverberation!time!of!any!enclosure!

may!be!calculated!by!the!formula:!

! ! ! T!=!V!x!0.049!/!AS!! ! where,!! ! ! T!is!the!reverberation!time!in!seconds!! ! ! V!is!the!volume!of!the!enclosure!in!cubic!feet!! ! ! A!is!the!average!absorption!coefficient!of!the!enclosure!! ! ! S!is!the!total!surface!area!in!square!feet41!!

The!purpose!of!reverberation!is!to!add!depth!to!a!sound!and!to!create!the!illusion!

that!the!signal!was!originally!recorded!in!a!large!auditorium.!Equalization!may!be!

necessary!as!the!reverberation!chamber!distorts!the!original!frequency!characteristics!

due!to!the!frequency!response!of!the!enclosure.42!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

41!Tremaine,!Howard!M.,!Audio!Cyclopedia,!(Indianapolis,!Kansas!City,!New!York:!Howard!K!Sams!&!Co.!Inc!&!The!BobbsYMerrill!Co.,!Inc,!1969),!44!42!Ibid.,!69!

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In!1947!the!Hammond!Organ!Co.!was!granted!a!patent!on!a!reverberation!device!

that!used!two!or!more!springs!in!a!metal!enclosure,!hence!the!name!“spring!reverb”.!!A!

dedicated!driver!induced!the!signal!at!one!end!of!the!springs!and!a!pickup!at!the!other!

end!translated!the!movement!of!the!spring!into!timeYdelayed!reverberation.!This!method!

is!still!used!in!many!guitar!amplifier!manufacturers!designs!through!licensing!from!

Hammond.!!The!amplifiers!used!in!the!drivers!and!receivers!have!in!many!cases!

followed!amplifier!technology!from!vacuum!tubes!to!transistors!to!integrated!circuits.43!

$

Integrated Circuits

Over!time!the!manufacture!process!of!the!silicon!transistor!achieved!great!

precision.!Its!low!power!consumption!(substantially!less!that!the!1AD5!subminiature!

vacuum!tube)!and!considerable!reduction!in!size!led!to!the!development!of!the!

semiconductor!integrated!circuit!(IC)!in!1960.!In!its!earliest!days!the!IC!contained!

thousands!of!transistors!and!by!2010!contained!millions.44!Jim!Handy!wrote!in!Forbes#

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

43!Hammond,!L.!Electrical!Musical!Instrument.!US!2,230,836.!Filed!July!15,!1939!and!accepted!February!4,!1941.!44!Intel,!“The!Story!of!the!Intel®!4004,”!Intel!Museum,!http://www.intel.com/content/www/us/en/history/museumYstoryYofYintelY4004.html!(accessed!March!9!2016).!

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that!2,913,276,327,576,980,000,000!(2.9!sextillion)!transistors!have!shipped!since!the!

technology!was!invented.45!

Further!innovations!to!the!integrated!circuit,!such!as!programmable!digital!

processing!devices,!have!made!significant!improvements!in!miniaturized!reverberation.!!

Modern!devices!like!the!Princeton!PT2399,!a!single!integrated!circuit,!can!be!used!for!

reverb!as!well!as!echo!delays.!!In!1997!Belton!/!Accutronics!was!granted!a!patent!on!a!

device!that!used!multiple!PT2399Us!(figure!13)!as!well!as!additional!devices!and!code!to!

create!a!6!pin!“brick”!IC!(figure!14)!capable!of!emulating!the!decay!of!several!

reverberant!room!styles.46!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

45!Jim!Handy,!“How!Many!Transistors!Have!Ever!Shipped?,”!(Forbes!Magazine,!May!26,!2014)!http://www.forbes.com/sites/jimhandy/2014/05/26/howYmanyYtransistorsYhaveYeverYshipped/#2b3a09f012b5!(accessed!March!9!2016)!46!Brian!Neunaber,!2012,!Apparatus!and!Method!for!Artificial!Reverberation,!US!8,204,240!B2,!file!June!25!2008,!and!issued!June!19!2012.!

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!

Figure$13:$Schematic$block$diagram$from$the$patent$of$Accutronics$6Tpin$reverb$brick$

!

Figure$14:$The$Accutronics$6Tpin$reverb$brick$

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!

The Princeton PT2399 Integrated Circuit

The!discrete!PT2399!delay!IC!was!going!to!be!included!into!the!final!prototype!of!

Ibrida!as!the!third!effect,!however!it!introduced!a!high!amount!of!noise!and!was!omitted!

from!the!design!(Sound!File!5).!!

!

Sound$File$5:!Delay$Board$Idle$Noise!

!

Sound!File!5!is!the!idling!noiseYfloor!of!the!circuit!with!no!signal!applied!

whatsoever.!Under!these!conditions!the!effect!should!have!operated!silently,!however,!

this!was!not!the!case.!Tracking!down!the!cause!of!the!noise!and!eliminating!it!was!not!

feasible,!thus!the!delay!was!removed!from!Ibrida.!

Ibrida!uses!additional!integrated!circuits!to!accomplish!a!more!nuanced!control!

in!the!signal!side!of!the!circuit.!ICs!called!digital!potentiometers!(digipots)!allow!the!

microcontroller!to!vary!a!signal,!akin!to!a!knob!on!a!volume!control!but!without!

physically!moving!parts.!

Selecting!and!utilizing!digipots!can!be!a!dark!art!because!there!are!countless!

types!of!digipots!with!many!varying!technical!specifications.!These!specifications—

typically!presented!in!a!table!or!spreadsheet—contain!parameters!like!number!of!

positions,!communication!protocols,!voltage!requirements,!current!limitations!and!so!on.!

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In!addition,!these!parameters!often!vary!widely!from!manufacturer!to!manufacturer.!

This,!of!course,!is!a!complexity!not!found!in!conventional!potentiometers.!

As!was!often!the!case,!the!choices!of!available!values!of!these!conventional!

potentiometers!became!the!firm!starting!point!for!the!design!of!the!original!circuits.!This!

makes!it!even!more!difficult!to!recreate!and!retrofit!these!circuits!with!digital!

potentiometers,!since!the!choice!of!resistance!values!with!digipots!is!often!limited!to!the!

decades!of!10!beginning!with!1000!ohms.!

The!large!number!of!parameters!became!a!limiting!factor!when!choosing!the!

specific!circuits!and!parts!for!Ibrida’s!design.!Of!the!two!digital!potentiometers!in!the!

guitar,!one!creates!a!variable!feedback!loop!effect!in!the!reverb!by!routing!the!input!

directly!to!the!output;!the!other!adjusts!the!amount!of!fuzz!in!the!Fuzz!Face!distortion.!

In!order!to!understand!the!interaction!of!the!signal!conditioning!devices!in!

Ibrida,!it!may!help!to!interpret!each!constituent!electronic!subsystem!as!a!different!organ!

in!the!human!body.!In!this!analogy,!the!power!system!functions!like!the!heart!pumping!

blood!(or!electrons)!through!Ibrida.!The!individual!effects!are!like!internal!organs!that!

do!specific!tasks,!like!how!the!liver!and!the!kidneys!filter!the!blood.!The!inductive!

pickup!acts!like!the!senses,!as!a!gateway!to!the!“external!world”!of!the!magnetic!strings.!

In!Ibrida’s!anatomy,!an!Arduino!(an!openYsource!microcontroller!prototyping!device!

and!platform!used!by!many!as!an!introduction!to!the!field!of!electronics)!serves!as!the!

brain!since!it!is!responsible!for!operation!of!the!instrument’s!many!subsystems.!Like!the!

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brain,!the!Arduino!microcontroller!enables!higherYlevel!control!functions,!with!the!pins!

acting!like!the!nervous!system!as!they!relay!information!to!the!appropriate!destination.!

The!Arduino!is!responsible!for!three!individual!tasks.!First,!it!is!the!subsystem!of!

signal!routing!and!effect!selection,!that!is,!it!provides!virtual!switches.!Second,!it!controls!

the!effect’s!parameters;!virtual!knobs.!Finally,!it!regulates!the!human!interface!

electronics!(i.e.,!the!things!we!see!or!touch!directly).!In!each!case,!the!ArduinoUs!pins!

toggle!between!a!high!or!low!state!depending!on!the!required!configuration!for!the!

desired!effect.!Either!directly!or!in!tandem!with!the!specific!ICs,!these!pins!are!able!to!

automatically!toggle!between!or!combine!effects.!

A!lightYemitting!diode!(LED)!is!a!semiconductor!similar!to!a!transistor,!which!

enables!the!Arduino!to!control!the!signal!flow!without!the!need!of!physical!switches.!

The!circuit!is!built!upon!‘Blink’,!the!circuit!in!the!first!LED!light!tutorial!that!beginners!

use!to!learn!Arduino.!Like!the!familiar!‘Hello!World’!of!physical!computing,!‘Blink’!is!a!

simple!yet!powerful!paradigm,!that!affords!flexible!signal!interactions!through!easily!

implementable!means,!without!specialized!parts.!

A!component!called!a!lightYdependent!resistor!(LDR),!which!is!!makes!easy!

signal!switching!possible.!The!LDR!is!a!resistor!that!lowers!its!resistance!value!in!

proportion!to!the!level!of!light,!meaning!that!it!operates!by!proximity!to!a!light!source!

without!being!directly!connected!to!the!microcontroller.!It!keeps!each!system!isolated!

from!one!another.!

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The!Arduino!subsystem!is!made!of!blinking!lights!and!touch!sensors.!A!single!

threeYcolor!LED!glows!red,!blue,!or!green!and!each!color!represents!the!signal!state!of!

Ibrida:!red!is!reverb!“on”!and!blue!is!reverb!“off”.!!

The!Arduino!uses!a!touch!capacitance!sensor!to!switch!between!states.!A!touch!

sensor!pulses!a!voltage!connected!to!a!piece!of!metal!through!a!resistor!and!then!senses!

how!long!it!takes!to!charge!the!metal!to!that!emitted!voltage.!As!a!finger!touch!is!ACY

coupled!to!the!metal,!it!drains!some!residual!current!to!ground.!This!delays!the!charging!

time,!thereby!allowing!the!microcontroller!to!time!this!event!and!‘know’!its!sensor!pin!is!

being!touched.!This!sensed!value!is!then!able!to!toggle!the!various!states!inside!the!

Arduino!without!the!need!for!physical!switches!or!buttons.!

!

!

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3.6 Design of the Power System

Ibrida!gets!its!power!from!two!sources,!a!9v!battery!and!a!1.5v!AA!battery.!The!

AA!powers!the!filament!of!the!vacuum!tube,!which!is!essentially!a!light!bulb!making!it!

the!simplest!component!in!Ibrida!to!power.!The!filaments!of!more!common!types!of!

wallYpowered!vacuum!tubes!typically!draw!currents!in!the!range!of!150mA!(milliamps)!

up!to!several!amps.!According!to!the!datasheet!(figure!15),!the!power!consumption!of!

the!1AD5!is!40mA!because!it!is!a!lowYpower!subminiature!type!designed!specifically!for!

the!AA!battery.!!

!

Figure$15:$the$power$consumption$for$filament$of$the$1AD5$

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$

The!filament!is!the!only!thing!the!AA!powers,!while!the!9v!battery!powers!the!

rest!of!the!circuit,!including!the!signal!electronics,!the!selector,!and!the!Arduino.!

Comparing!the!capabilities!of!a!9v!to!a!AA!battery!in!terms!of!current!reveals!the!largest!

challenge!to!the!current!prototype.!A!single!AA!supplies!enough!current!to!power!a!

device!that!draws!2.45!amps!for!one!hour,!whereas!under!those!same!conditions!a!9v!

would!power!that!current!load!for!13.8!minutes!(figure!16).!An!AA!battery!supplies!1/6th!

of!the!voltage!potential!of!a!9v,!but!4.5!times!the!current.!The!rest!of!the!circuit!in!Ibrida!

is!powered!by!the!single!9v!battery!and!yet!draws!substantially!more!current!than!the!

filament!alone.!!

$$ !

Figure$16:$Battery$Specifications:$Alkaline$AA$Battery:$2450$mAh;$$Alkaline$9v$Battery:$565$mAh$

!

To!roughly!estimate!the!power!consumption!of!the!rest!of!the!circuit,!let!us!note!

the!essential!devices!that!draw!current!from!the!9v!battery.!The!digital!potentiometer!

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ICs!draw!5.5mA!(4.5mA!+!1mA)!each,!thus!getting!the!result!of!11mA!for!the!two!

(Figure!17).!!

!

Figure$17:$The$power$consumption$of$the$DS$1666$Digital$Resistor/Potentiometer$

$

The!reverb,!while!simple!to!use,!requires!5v!and!draws!100ma;!it!consumes!more!

power!than!any!other!stage!of!Ibrida.!The!simplicity!of!this!effect!comes!at!a!great!cost.!It!

is!unclear!if!this!is!quiescent!current,!which!means!that!the!internal!amplifiers!are!at!rest!

with!no!input!signal!to!process!or!if!it!means!total!current!draw!under!it’s!normal!

working!conditions!(Figure!18).! !

!

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!

Figure$18:!Power$consumption$(supply$current)$for$Accutronics$‘Brick’$IC$

This!means!that!in!powering!the!vacuum!tube!filament,!a!single!AA!battery!with!

a!current!load!of!40mA!can!last!for!61.5!hours.!However,!the!rest!of!the!circuit,!powered!

by!a!9v!battery,!has!an!estimated!current!load!of!(150mA)!which!can!only!last!for!

approximately!4!hours,!but!that!is!only!including!these!two!ICs,!not!the!Arduino,!the!

7805!voltage!regulator,!the!charge!pump,!and!the!4049!buffer!IC!used!as!the!signal!

selector.!The!amount!of!time!is!significantly!less.!A!pessimistic!estimate!of!300mA!for!the!

entire!circuit!(excluding!the!vacuum!tube)!predicts!the!9v!battery!to!last!for!1.8!hours!

and!the!AA!to!last!much!longer.!

Practically!speaking,!a!more!robust!power!system!for!the!electronics!should!be!

integrated!in!a!future!prototype!of!Ibrida.!Borrowing!from!smartphones!and!laptop!

computers,!rechargeable!lithium!ion!batteries!provide!greater!power!output!without!the!

need!for!costly!battery!replacement!or!wall!plug.!The!audio!signal!integrity!could!be!

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further!insured!by!physically!separating!the!vital!signal!electronics!from!the!power!

system,!the!sensors!and!the!microcontroller.! $

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3.7 The Prototyping and Assembling of Ibrida

Prototyping!Ibrida’s!electronics!took!place!in!three!phases.!The!first!phase!was!an!

assembly!in!which!the!instrument’s!setup!was!completely!overhauled!and!prebuilt!

effects!were!installed!with!minimal!modifications.!The!second!phase!consisted!of!

separating!the!effects!from!the!instrument!for!experimentation!and!more!careful!design.!

The!third!and!final!phase!applied!the!knowledge!gained!from!the!first!two!phases!to!the!

implementation!of!the!final!prototype:!a!fully!integrated!guitar!and!effect!system.!

The!Ibrida!project!began!by!assembling!the!first!few!effects:!the!Fuzz!Face,!the!

delay!board!(now!removed),!and!the!reverb!brick!IC.!Each!effect!is!installed!on!the!

smallest!possible!circuit!board!so!they!would!fit!inside!the!guitar!pickup!cavity.!Once!a!

guitar!was!purchased,!I!would!have!effects!to!incorporate!right!away.!

The!guitar!used!for!this!project!was!purchased!from!a!pawnshop!in!Durham,!

North!Carolina!(Figure!19).!The!manufacturer!is!unknown,!but!the!shape!is!like!a!Gibson!

SG,!one!of!Gibson’s!first!solid!body!electric!guitar!designs!first!introduced!in!1961.!The!

original!electronics!and!parts!were!immediately!removed.!Most!of!these!original!parts!

were!dirty!and!rusted,!and!the!inside!had!a!distinct!odor.!After!disassembly!and!

cleaning,!the!instrument!needed!to!be!overhauled.!!

!

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!

Figure$19:$The$guitar$body$used$for$Ibrida$

!

The!action!of!the!strings!over!the!frets!was!too!high,!and!the!existing!setup!of!the!

bridge!was!too!low.!I!shimmed!the!neck!to!increase!the!angle!of!the!strings!to!the!

fretboard.!To!increase!the!strings’!downward!tension!upon!the!instrument,!I!raised!the!

bridge.!!I!replaced!the!tuning!machines!and!drilled!a!new!hole!for!a!sideYfacing!output!

jack!to!maximize!internal!cavity!space!rather!than!keeping!it!on!the!nowYremoved!

pickguard.!

After!this!was!completed!I!did!a!first!assembly!of!the!guitar!with!the!Fuzz!Face,!

the!reverb!and!the!voltage!regulator,!with!no!control!of!the!effects!whatsoever.!This!

assembly!was!done!to!determine!the!space!constraints!of!the!guitar!cavity!and!to!

experiment!with!different!mounting!techniques!for!the!circuit!boards.!First,!I!made!a!

crude!top!plate!for!the!instrument!and!mounted!the!electronics!to!this!plate.!!This!design!

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had!many!flaws.!These!effects!needed!to!be!adjusted!as!Ibrida!developed,!and!sealing!

the!effects!within!the!cavity!by!attaching!them!to!a!cover!plate!prevented!access!to!the!

effects.!Additionally,!installing!the!cover!plate!onto!the!body!made!its!removal!from!

under!the!strings!very!difficult.!Aesthetically,!this!method!also!cluttered!the!face!of!the!

instrument!with!screw!heads!and!washers!from!the!effect!mounting.!For!these!reasons,!

other!options!to!mount!the!effects!to!the!body!were!used!(Figure!20).!!

!

!

Figure$20:$The$electronics$mounted$onto$a$cover$plate.$

!

To!address!the!issues!encountered!with!mounting!the!electronics!to!the!cover!

plate,!I!separated!the!effects!from!the!guitar!to!a!piece!of!hardboard.!This!hardboard!had!

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the!individual!electronic!effects,!like!the!tube!preamp!or!the!Fuzz!Face!securely!installed!

to!the!underside!with!jumper!wires!running!through!the!board!to!the!top!so!the!circuits!

could!be!breadboarded,!prototyped!and!connected!to!one!another!with!relative!ease.!

Essentially,!it!served!as!an!effect!prototyping!station.!On!top,!surrounding!the!

breadboard,!I!mounted!¼”!jacks!for!input!and!output,!a!jack!for!a!power!supply,!a!

power!switch!and!indicator!LED,!and!the!digital!potentiometers!that!adjust!volume!or!

fuzz!(Figure!21).!

!

Figure$21:$The$‘breadboard’$prototyping$of$electronics$

!

I!installed!the!pickup!on!the!guitar!as!it!would!be!in!final!assembly!and!directly!

wired!it!to!the!output!jack.!This!created!a!streamlined!guitar!I!could!use!to!test!the!sound!

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of!the!effects!while!I!worked.!I!was!able!to!focus!my!attention!on!the!parts!of!the!design!

that!I!needed!to!without!worrying!about!infrastructural!and!power!supply!concerns.!

Once!the!important!design!concerns!had!been!solved!on!the!prototyping!stations,!

I!transferred!my!work!to!the!guitar!once!again.!In!this!stage!I!was!guided!by!the!

knowledge!gained!from!previous!attempts.!I!carefully!installed!the!effects!I!knew!were!

finished!and!left!room!for!modifications.!The!unknown!at!this!point!was!the!main!circuit!

board!that!included!the!voltage!regulator,!the!charge!pump!IC,!the!two!digital!

potentiometers,!a!timer!IC!for!the!digipots!and!the!hex!inverter!IC!I!was!using!for!the!

signal!selection!(Figure!22).!

!

!

Figure$22:$The$main$circuit$board$shown$outside$Ibrida’s$pickup$cavity$

$

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Saving!space!was!the!focus!of!this!stage!of!the!assembly.!The!body!needed!two!

major!modifications!to!increase!the!space!available.!I!installed!a!selfYcontained!battery!

compartment!routed!into!the!back!of!the!guitar.!This!allowed!me!to!keep!the!power!in!

one!place!making!the!layout!cleaner!(Figure!23)!

!

!

Figure$23:$Back$of$guitar$shown$with$the$9v$battery$compartment,$external$power$jack$and$Arduino$installed$

!

To!gain!additional!space!for!the!main!circuit!board,!I!installed!the!Arduino!on!the!

back!of!the!guitar!so!that!it!would!not!take!up!room!inside!the!front!cavity.!An!

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additional!benefit!of!this!solution!is!that!the!wires!run!from!the!Arduino!directly!into!the!

cavity!underneath!the!main!circuit!board!(Figure!24).!

!

!

!

!

!

!

!

!

!

!

$

Figure$24:$Main$board$shown$placed$into$the$body$of$Ibrida$

!

Working!within!the!constraints!of!the!body!of!the!guitar!provided!a!unique!

challenge.!Through!the!design!and!retrofitting!of!this!guitar,!it!was!possible!to!

understand!what!a!new!guitar!body!designed!explicitly!for!Ibrida!would!look!like.!

!

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From$Prototype$to$Boutique$Guitar$

Constructing!a!guitar!from!scratch,!its!own!set!of!caveats!notwithstanding,!can!

solve!many!problems!and!pitfalls!of!Ibrida’s!prototype!and!layout.!A!new!guitar!

wouldn’t!have!to!be!retrofitted!with!custom!electronics!inside!an!existing!pickup!cavity.!

The!electronics!cavity!could!be!designed!hand!in!hand!with!the!embedded!effects!and!

signal!flow.!Special!plates,!covers,!circuit!boards!and!mountings!could!be!manufactured!

to!fit!the!exact!design!requirements.!

If!one!envisions!a!new!guitar!that!is!designed!from!the!ground!up!with!an!

embodied!historical!narrative!at!its!core,!what!might!it!look!like?!What!if!this!guitar!took!

inspiration!from!Ibrida’s!electronics!and!used!an!idea!of!divergent!histories!as!the!

conceptual!impetus!for!the!body!design?!Would!it!solve!some!of!the!challenges!of!the!

retrofitted!prototype?!(Figure!25).!

!

!

!

!

!

!

Figure$25:$The$new$guitar$body$design$for$fully$integrated$electronics$

!

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The!inspiration!for!the!new!guitar!shape!is!the!Hofner!Violin!Bass!(Figure!26)47,!

played!most!notably!by!rock!and!roll!luminary!Paul!McCartney.!Since!this!instrument!is!

a!bass,!there!is!a!historical!precedent!for!the!shape!of!this!instrument!to!borrow!from!the!

bowed!string!families!even!though!it!is!an!unusual!shape!for!an!electric!guitar.!The!

design!also!borrows!from!the!Pardassus!de!Viole!(Figure!27)48,!and!the!Ibanez!guitar!

(Figure!28)49.!This!is!a!particularly!strange!hybridization.!On!one!hand!there!is!an!

instrument!popularized!and!played!among!the!French!aristocracy!before!the!French!

revolution.!On!the!other!hand,!the!Ibanez!guitar!is,!at!the!time!of!this!writing,!currently!

listed!on!eBay!for!$55!($27!shipping);!an!unlikely!marriage!across!the!centuries!and!

cultures.!Through!design,!the!outline!of!the!body!aims!to!reconcile!these!fundamentally!

different!genealogies.!

!

! !

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

47!Wikipedia!s.v,“Hofner,”!https://en.wikipedia.org/wiki/H%C3%B6fner!(accessed!March!9,!2016).!48!Kevin!Coates,!Geometry,#Proportion,#and#the#Art#of#Lutherie,!(New!York:!Oxford!University!Press,!1986),!54.!49!Tony!Bacon,!Electric#Guitars:#The#Illustrated#Encyclopedia,!(California:!Thunder!Bay!Press.!2000)!201.!

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!

Figure$26:$Hofner$‘Violin$Bass’$as$popularized$by$Paul$McCartney$

$

This!viol!was!made!nearly!200!years!before!the!manufacture!of!the!embedded!

vacuum!tube.!“Like!the!hurdyYgurdy,!the!pardessus!was!in!vogue!for!a!short!period!in!

the!eighteenth!century,!when,!irrespective!of!its!musical!value,!it!was!thought!to!be!a!

suitably!bucolic!accessory!to!the!pastoral!pose!of!fashionable!ladies…[n]ot!surprisingly,!

it!was!of!no!further!use!after!the!French!revolution.”50!

Figure$27:$Louis$Guersan,$France.$Pardassus$de$Viole,$1759$

!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

50!Kevin!Coates,!Geometry,#Proportion,#and#the#Art#of#Lutherie,!(New!York:!Oxford!University!Press,!1986),!54.!

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!

Figure$28:$Ibanez$Model$882$Electric$Guitar,$Japan,$1963$

!

Ibanez,!a!Japanese!guitar!company,!mostly!sold!cheaply!made!copies!of!classic!

guitars!in!the!US.!The!guitar!in!figure!28!is!a!preYcopy!era!Ibanez,!not!unlike!the!

‘orphaned’!pawnshop!guitar!used!throughout!this!project.51!!

In!addition,!further!integration!of!the!electronics!at!the!ergonomic!level!of!a!

musical!instrument!enables!a!more!expressive!deployment!of!these!technologies.!Such!

integration!enables!unusual!electronic!sensors!(pressure,!ribbon!and/or!light!sensors,!

etc.)!and!human!interface!technologies!(capacitive!touch!sensors!or!touchscreens)!

alongside!additional!signal!or!effect!indicators!(LEDs,!signal!meters,!etc.).!By!artfully!

embedding!these!sensors!into!the!surface!of!the!guitar,!thereby!fusing!electronic!design!

with!lutherie,!Ibrida!would!further!satisfy!its!own!aims!of!meaningful!hybridization.!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

51!B!Tony!Bacon,!Electric!Guitars:!The!Illustrated!Encyclopedia,!(California:!Thunder!Bay!Press.!2000)!201.!

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Ultimately,!Ibrida!met!the!goals!that!were!set!at!the!beginning!of!this!project.!

Ibrida!is!a!functional!guitar!with!integrated!electronic!effects!(Figure!29)!that!represent!

the!past!and!present!of!guitar!technologies.!The!proposed!design!for!an!original!guitar!

body!will!bring!Ibrida!into!the!future!(Figure!30).!!

!

!

Figure$29:$Diagram$of$the$effect$control$and$signal$flow$from$pickup$to$output$amplifier$with$Arduino$control$via$digipots$

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!

Figure$30:$Final$prototype$of$Ibrida$showing$the$suite$of$embedded$effects$

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Biography

Kenneth!D.!Stewart!(BMI)!is!a!bit!of!a!Renaissance!man.!Overall!his!work!touches!

on!many!areas!including!composition,!musical/theatric!performance,!and!various!

technological!research!interests!engaging!with!the!digital!humanities.!Scored!for!a!range!

of!instrumental!forces,!Kenneth’s!compositions!often!weave!together!live!instruments,!

voice,!physical!interfaces!and!sound!processing!into!works!with!rich,!melodious!textures!

and!an!underpinning!of!the!ambient!electronic!avantYgarde.!His!musical!research!

engages!concepts!of!instrument!modification!and!design!and!his!nonYcompositional!

creative!work!of!signal!processing!(linear!and!digital)!and!the!hacking!and!modifications!

of!electronic!and!acoustic!musical!instruments!and!their!electronic!effects.!

In!2008,!KennethUs!work,!UDivergenceU!won!the!ASCAP!FoundationUs!Morton!

Gould!Young!Composer!Award.!The!piece!UThetastateU!was!given!a!studio!recording!by!

the!jazz!trio!The!Bad!Plus!and!was!released!online!by!Duke!University!in!conjunction!

with!Duke!Performances.!Other!ensembles!that!have!recorded!or!performed!his!music!

include!Speculum!Musicae,!the!Duke!New!Music!Ensemble,!the!Tucson!Symphony!

Orchestra!and!the!Wet!Ink!Ensemble.!

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