using the hum eliminator™ hum eliminator - … · hum eliminator™ applications ... related hum...

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Hum Eliminator™ Applications Hum Eliminator™ General Instructions The Hum Eliminator™ does more than just prevent AC hum from being picked up by your sound systems. It also can be used as one of the most cost-effective ways to convert unbalanced signals to true balanced signals. GROUND LOOPS - The Hum Eliminator™ prevents ground loop antennae from forming and picking up AC hum. AC hum & noise is almost always caused by a loop antenna effect across signal lines between two or more pieces of gear, or by long unbalanced cables picking up noise. Loop antenna(e) are basically a type of radio antenna, which tend to pick up the 60Hz and harmonics (50Hz in other parts of the world) AC signal being broadcast by a building's electrical current. These loop antennae are closed circuits usually along the ground wires and hence are commonly called ground loops. BALANCED / UNBALANCED - Unbalanced signals are more susceptible to picking up electrical noise & RF interference than balanced signals are. The longer the unbalanced cable, the greater the chance of a problem. The Hum Eliminator™ is one of the most cost-effective ways to convert between unbalanced signals and true balanced signals. MIXERS/RECORDING - Many mixers have either unbalanced or "impedance balanced" monitor outs / aux sends. Use a Hum Eliminator™ to get true balanced monitor outs for noise-free performance. When using more than one mixer (or submixing), there's a huge chance of getting ground loops (and that buzz!). Use Hum Eliminators™ to prevent these ground loops. Eliminating hum is one of the biggest challenges facing studios. Many studios will run all of their line level gear through Hum Eliminators™ to help ensure noise- free recording. KEYBOARDS / SAMPLERS / SYNTHS · Most keyboards, samplers, and synthesizers have unbalanced -10dBV outputs. Use a Hum Eliminator™ to balance the signals if using with other -10dBV equipment. To use a - 10dBV unbalanced device with a +4dBu balanced device, use an EBTECH® Line Level Shifter™. LIVE SOUND / DJ MIXERS - A common problem with live performance is long unbalanced cables picking up hum along the way. Balanced signals are more immune to picking up noise. Use the Hum Eliminator™ to balance long unbalanced signals. Mobile DJs or bands never know when setting up their system if they're going to get a hum or not. The electrical wiring changes from one building to another. What works fine at one gig might not work at the next. It's worth the low cost to keep a Hum Eliminator™ available, nobody can afford to lose a gig because of hum problems. Some DJs run everything in their rig through Hum Eliminators to play it safe. The main outs on most DJ mixers are -10dBV unbalanced RCA. When using with a +4dBu power amp, over 2/3rd's of the amp's volume can be lost. Use an EBTECH® Line Level Shifter™. POWER AMPLIFIERS - Running multiple amplifiers can create ground loops between the amplifiers, which will pick up the dreaded hum and buzz. Run each amplifier's input line through a Hum Eliminator™ to prevent this problem. GUITAR OR BASS - Whenever possible, we recommend you use our Hum X product for GROUND RELATED hum issues on a guitar or bass rig setup. If your are in apart of the world where the Hum X cannot be used, the Hum Eliminator is the next best solution. If any of your FX pedals have a 3 prong ground power plug, you will need to put the Hum Eliminator on the audio feed to the amp. When using two or more guitar amplifiers (with stereo FX or ABY splitters), ground loops can form between the amplifiers. Bass amps can get ground loop from the DI connection to the PA; simply run that DI feed through the Hum Eliminator. COMPUTER SOUND CARDS - Most sound cards have unbalanced inputs and outputs. Balance these with the Hum Eliminator™. Even balanced sound cards have tremendous susceptibility to ground loops because of the computer's power supply. If you hear a buzz, use a Hum Eliminator™. BROADCASTING / VIDEO - Press Boxes have many feeds all going to different gear; which can create lots of ground loops and hum. Use a Hum Eliminator™ on these feeds to eliminate the problem. Using a Hum Eliminator™ on the audio feed of a video camera can help prevent video hum (snow). Rev. Jun 19, 2012 WHAT WILL THE HUM ELIMINATORSOLVE? The Hum Eliminatoris a unity gain signal and ground path isolator designed to break ground loops. Hum and noise caused by the presence of a ground loop can be stopped by inserting the Hum Eliminatorin the line level signal path (+4dBu or -10dBV). This eliminates the ground loop without degrading your signal. The Hum Eliminatorwill not reduce hum or noise normally generated by a piece of equipment. In other words, for noisy preamps, noisy single coil pickups or noise caused by faulty tubes, other corrective action would apply. USING THE HUM ELIMINATOR™ Identify the ground loop causing the trouble; not all ground loops cause noise or hum. For complex systems you may need to repeat these steps starting with a different piece of equipment in various combinations to locate the problem: 1) Strip the system down to one piece, such as the mixer, by disconnecting all interconnects and AC cords except for the mixer. 2) Add one piece of equipment at a time; hook up AC and interconnects (making sure all grounds are connected and in good condition) then listen for hum or noise. 3) Turn on and off the power each time you switch equipment to avoid pops/shorted outputs. 4) Proceed until you find the offending piece(s) causing the problem. 5) Plug the Hum Eliminator™ in all lines between the offending equipment and the rest of the system. For example, insert the line outs of the keyboard into the inputs of the Hum Eliminator™, then insert the line outs of the Hum Eliminator™ into the inputs of the mixer. IMPORTANT: Never use the Hum Eliminator™ between an amplifier and speaker or the equipment may become damaged. Use only on non-powered line level signals. With a rack of amplifiers, we recommend putting an 8 channel single rack space Hum Eliminator™ in front of your amps' inputs so you do not have to solve ground loop problems during sound checks. A common path for ground loops is through a chassis into the rack and then into another chassis. Test this by removing the chassis from the rack. The Hum Eliminator™ will help but you should also try isolating the chassis from the rack with electrical tape and insulating the rack screws with nylon washers. Most ground loop problems can be solved using the Hum Eliminator™. Patience is a necessity when attempting to solve ground loops! Many popular mixers with TRS balanced line inputs do not have common mode rejection. They drop the inverted signal, creating unbalanced inputs! To get the benefits of balanced inputs, run your balanced line into the Hum Eliminator™ and run a mono 1/4" line from the Hum Eliminator outputs to the mixer's TRS inputs. This way you are running a balanced line all the way up to the Hum Eliminator™ and you will not lose common mode rejection.

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Page 1: USING THE HUM ELIMINATOR™ Hum Eliminator - … · Hum Eliminator™ Applications ... RELATED hum issues on a guitar or bass rig setup. If your are in apart of the world where the

Hum

Elim

inato

r™ A

pplic

atio

ns

Hum

Elim

inato

r™ G

enera

l Instru

ctio

ns

The H

um

Elim

inato

r™ does m

ore

th

an ju

st

pre

vent

AC

hum

fro

m bein

g pic

ked up by your

sound

syste

ms. It a

lso c

an b

e u

sed a

s o

ne o

f the m

ost c

ost-e

ffectiv

e w

ays to

convert u

nbala

nced s

ignals

to tru

e

bala

nced s

ignals

.

GRO

UN

D L

OO

PS - T

he H

um

Elim

inato

r™ p

revents

gro

und lo

op a

nte

nnae fro

m fo

rmin

g a

nd p

ickin

g u

p A

C

hum

. AC

hum

& n

ois

e is

alm

ost a

lways c

aused b

y a

loop a

nte

nna e

ffect a

cro

ss s

ignal lin

es b

etw

een tw

o

or m

ore

pie

ces o

f gear, o

r by lo

ng u

nbala

nced c

able

s pic

kin

g u

p n

oise

. Loop a

nte

nna(e

) are

basic

ally

a ty

pe

of ra

dio

ante

nna, w

hic

h te

nd to

pic

k u

p th

e 6

0H

z and h

arm

onic

s (5

0H

z in o

ther p

arts

of th

e w

orld

) AC

sig

nal b

ein

g b

roadcast b

y a

build

ing's

ele

ctric

al c

urre

nt. T

hese lo

op a

nte

nnae a

re c

losed c

ircuits

usually

alo

ng th

e g

round w

ires a

nd h

ence a

re c

om

monly

calle

d g

round lo

ops.

BA

LA

NC

ED

/ UN

BA

LA

NC

ED

- Unbala

nced sig

nals a

re m

ore

susc

eptib

le to

pic

kin

g u

p e

lectric

al n

oise

& R

F

inte

rfere

nce th

an bala

nced sig

nals

are

. The lo

nger

the unbala

nced cable

, th

e gre

ate

r th

e chance of

a

pro

ble

m. T

he H

um

Elim

inato

r™ is

one o

f the m

ost c

ost-e

ffectiv

e w

ays to

convert b

etw

een u

nbala

nced

sig

nals

and tru

e b

ala

nced s

ignals

.

MIX

ERS/R

EC

ORD

ING

- Many m

ixers

have e

ither u

nbala

nced o

r "im

pedance b

ala

nced" m

onito

r outs /

aux se

nds. U

se a

Hum

Elim

inato

r™ to

get tru

e b

ala

nced m

onito

r outs fo

r noise

-free p

erfo

rmance. W

hen u

sin

g

more

than o

ne m

ixer (o

r subm

ixin

g), th

ere

's a

huge c

hance o

f gettin

g g

round lo

ops (a

nd th

at b

uzz!). U

se

Hum

Elim

inato

rs™ to

pre

vent th

ese

gro

und lo

ops. E

limin

atin

g h

um

is one o

f the b

iggest c

halle

nges fa

cin

g

stu

dio

s. M

any s

tudio

s w

ill run a

ll of th

eir lin

e le

vel g

ear th

rough H

um

Elim

inato

rs™ to

help

ensure

nois

e-

free re

cord

ing.

KEYBO

ARD

S / S

AM

PLERS / S

YN

TH

S · M

ost k

eyboard

s, sam

ple

rs, and sy

nth

esize

rs have u

nbala

nced -1

0dBV

outp

uts. U

se a

Hum

Elim

inato

r™ to

bala

nce th

e sig

nals if u

sing w

ith o

ther -1

0dBV

equip

ment. T

o u

se a

-10dBV

unbala

nced d

evic

e w

ith a

+4dBu b

ala

nced d

evic

e, u

se a

n E

BTEC

H® L

ine L

evel S

hifte

r™.

LIV

E S

OU

ND

/ DJ M

IXERS - A

com

mon p

roble

m w

ith liv

e p

erfo

rmance is

long u

nbala

nced c

able

s p

ickin

g

up hum

alo

ng th

e w

ay.

Bala

nced sig

nals

are

m

ore

im

mune to

pic

kin

g up nois

e.

Use th

e H

um

Elim

inato

r™ to

bala

nce lo

ng unbala

nced sig

nals.

Mobile

D

Js

or

bands

never

know

w

hen se

tting u

p th

eir

syste

m if th

ey're

goin

g to

get a

hum

or n

ot. T

he e

lectric

al w

iring c

hanges fro

m o

ne b

uild

ing to

anoth

er.

What

work

s fin

e at

one gig

m

ight

not

work

at

the next.

It's w

orth

th

e lo

w cost

to keep a H

um

Elim

inato

r™ a

vaila

ble

, nobody c

an a

fford

to lo

se a

gig

because

of h

um

pro

ble

ms. S

om

e D

Js ru

n e

very

thin

g

in th

eir

rig th

rough H

um

Elim

inato

rs to

pla

y it

safe

. The m

ain

outs

on m

ost

DJ m

ixers

are

-1

0dBV

unbala

nced R

CA

. When u

sin

g w

ith a

+4dBu p

ow

er a

mp, o

ver 2

/3rd

's o

f the a

mp's

volu

me c

an b

e lo

st.

Use a

n E

BTEC

H® L

ine L

evel S

hifte

r™.

PO

WER A

MPLIF

IERS - R

unnin

g m

ultip

le a

mplifie

rs c

an c

reate

gro

und lo

ops b

etw

een th

e a

mplifie

rs, w

hic

h

will p

ick u

p th

e d

readed h

um

and b

uzz. R

un e

ach a

mplifie

r's in

put lin

e th

rough a

Hum

Elim

inato

r™ to

pre

vent th

is p

roble

m.

GU

ITA

R O

R BA

SS -

Whenever

possib

le,

we re

com

mend you use our

Hum

X

pro

duct

for

GRO

UN

D

RELA

TED

hum

issues o

n a

guita

r or b

ass rig

setu

p. If y

our a

re in

apart o

f the w

orld

where

the H

um

X

cannot b

e u

sed, th

e H

um

Elim

inato

r is th

e n

ext b

est s

olu

tion. If a

ny o

f your F

X p

edals

have a

3 p

rong

gro

und p

ow

er p

lug, y

ou w

ill need to

put th

e H

um

Elim

inato

r on th

e a

udio

feed to

the a

mp. W

hen u

sing

two o

r more

guita

r am

plifie

rs (with

stere

o F

X o

r ABY sp

litters), g

round lo

ops c

an fo

rm b

etw

een th

e a

mplifie

rs. Bass a

mps c

an g

et g

round lo

op fro

m th

e D

I connectio

n to

the P

A; sim

ply

run th

at D

I feed th

rough th

e H

um

Elim

inato

r.

CO

MPU

TER S

OU

ND

CA

RD

S - M

ost so

und c

ard

s have u

nbala

nced in

puts a

nd o

utp

uts. B

ala

nce th

ese

with

the

Hum

Elim

inato

r™. E

ven b

ala

nced so

und c

ard

s have tre

mendous su

sceptib

ility to

gro

und lo

ops b

ecause o

f the

com

pute

r's p

ow

er s

upply

. If you h

ear a

buzz, u

se a

Hum

Elim

inato

r™.

BRO

AD

CA

STIN

G / V

IDEO

- Pre

ss Boxes h

ave m

any fe

eds a

ll goin

g to

diffe

rent g

ear; w

hic

h c

an c

reate

lots o

f gro

und lo

ops

and hum

. U

se a H

um

Elim

inato

r™ on th

ese

fe

eds

to elim

inate

th

e pro

ble

m.

Usin

g a H

um

Elim

inato

r™ o

n th

e a

udio

feed o

f a v

ideo c

am

era

can h

elp

pre

vent v

ideo h

um

(snow

).

Rev. J

un 1

9, 2

012

WH

AT W

ILL T

HE H

UM

ELIM

INA

TO

R™

SO

LV

E?

The H

um

Elim

inato

r™ is

a unity

gain

sig

nal

and gro

und path

is

ola

tor

desig

ned to

bre

ak g

round lo

ops. H

um

and n

ois

e c

aused b

y th

e p

resence o

f a g

round lo

op c

an b

e

sto

pped b

y in

sertin

g th

e H

um

Elim

inato

r™ in

the lin

e le

vel s

ignal p

ath

(+4dBu o

r -10dBV

). This

elim

inate

s th

e g

round lo

op w

ithout d

egra

din

g y

our s

ignal. T

he H

um

Elim

inato

r™

will n

ot re

duce h

um

or n

ois

e n

orm

ally

genera

ted b

y a

pie

ce o

f equip

ment. In

oth

er

word

s, fo

r nois

y p

ream

ps, n

ois

y s

ingle

coil p

ickups o

r nois

e c

aused b

y fa

ulty

tubes,

oth

er c

orre

ctiv

e a

ctio

n w

ould

apply

.

USIN

G T

HE H

UM

ELIM

INA

TO

R™

Identify

the g

round lo

op c

ausin

g th

e tro

uble

; not a

ll gro

und lo

ops c

ause n

ois

e o

r hum

. For c

om

ple

x s

yste

ms y

ou m

ay n

eed to

repeat th

ese s

teps s

tartin

g w

ith a

diffe

rent

pie

ce o

f equip

ment in

vario

us c

om

bin

atio

ns to

locate

the p

roble

m:

1)

Strip

th

e syste

m dow

n to

one pie

ce,

such as th

e m

ixer,

by dis

connectin

g all

inte

rconnects

and A

C c

ord

s e

xcept fo

r the m

ixer.

2)

Add one pie

ce of

equip

ment

at

a tim

e;

hook up A

C and in

terc

onnects

(m

akin

g

sure

all g

rounds a

re c

onnecte

d a

nd in

good c

onditio

n) th

en lis

ten fo

r hum

or n

ois

e.

3) T

urn

on a

nd o

ff the p

ow

er e

ach tim

e y

ou s

witc

h e

quip

ment to

avoid

pops/s

horte

d

outp

uts

.4) P

roceed u

ntil y

ou fin

d th

e o

ffendin

g p

iece(s

) causin

g th

e p

roble

m.

5)

Plu

g th

e H

um

Elim

inato

r™ in

all

lines betw

een th

e offe

ndin

g equip

ment

and th

e

rest o

f the s

yste

m. F

or e

xam

ple

, insert th

e lin

e o

uts

of th

e k

eyboard

into

the in

puts

of th

e H

um

Elim

inato

r™, th

en in

sert th

e lin

e o

uts

of th

e H

um

Elim

inato

r™ in

to th

e in

puts

of th

e m

ixer.

IMPO

RTA

NT:

Never

use th

e H

um

Elim

inato

r™ betw

een an am

plifie

r and speaker

or

the equip

ment

may becom

e dam

aged.

Use only

on non-p

ow

ere

d lin

e le

vel

sig

nals

.

With

a ra

ck o

f am

plifie

rs, w

e re

com

mend p

uttin

g a

n 8

channel s

ingle

rack s

pace

Hum

Elim

inato

r™ in

front o

f your a

mps' in

puts

so y

ou d

o n

ot h

ave to

solv

e g

round lo

op

pro

ble

ms d

urin

g s

ound c

hecks.

A com

mon path

fo

r gro

und lo

ops is

th

rough a chassis

in

to th

e ra

ck and th

en in

to

anoth

er

chassis

. Test

this

by re

movin

g th

e chassis

fro

m th

e ra

ck.

The H

um

Elim

inato

r™ w

ill help

but y

ou s

hould

als

o try

isola

ting th

e c

hassis

from

the ra

ck w

ith

ele

ctric

al ta

pe a

nd in

sula

ting th

e ra

ck s

cre

ws w

ith n

ylo

n w

ashers

.

Most

gro

und lo

op pro

ble

ms can be solv

ed usin

g th

e H

um

Elim

inato

r™.

Patie

nce is

a

necessity

w

hen atte

mptin

g to

solv

e gro

und lo

ops!

Many popula

r m

ixers

w

ith TRS

bala

nced lin

e in

puts

do not

have com

mon m

ode re

jectio

n.

They dro

p th

e in

verte

d

sig

nal,

cre

atin

g unbala

nced in

puts

! To get

the benefits

of

bala

nced in

puts

, ru

n your

bala

nced lin

e in

to th

e H

um

Elim

inato

r™ a

nd ru

n a

mono 1

/4" lin

e fro

m th

e H

um

Elim

inato

r outp

uts

to th

e m

ixer's

TRS in

puts

. This

way y

ou are

ru

nnin

g a bala

nced lin

e all

the

way u

p to

the H

um

Elim

inato

r™ a

nd y

ou w

ill not lo

se c

om

mon m

ode re

jectio

n.