Decware SE34I.5 Owner's Manual page 11

O W N E R S M A N U A L

GROUND LOOPS, POWER STRIPS, HUM!

Whenever we connect more than one audio component together we run the risk of

creating a ground-loop which causes hum.

A ground loop happens when the path to ground in one component ﬁnds an easier

(less resistive) path through another component via the ground or shield wire in your

interconnects. This is a common problem when components are plugged into different

outlets or a power strip is used, as the resistance varies at the ground point of each

receptacle.

Ways to combat the problem are - try to plug everything into the same outlet when

possible, do not use power strips, try to keep the length of the power cords the same.

If all else fails, you can try lifting the ground on one or more component until the hum

goes away.

How to tell if you have a ground loop causing hum - simply remove all your

interconnects from the input jacks of your ampliﬁer so that the only thing hooked to it is

your loudspeakers. You should hear no hum on all but the most efﬁcient speakers and

even those would sound quiet from the listening chair some 6 or 8 feet back. If you do

hear hum, then it's likely the ampliﬁer assuming your speaker wires are not wrapped

around a power cord somewhere. The most likely cause if it is the ampliﬁer itself would

of course be tubes. Start by installing a new rectiﬁer tube and see if that corrects it. If

not you can systematically try the remaining tubes in the ampliﬁer.

If the amp is acceptably quiet just hooked to your loudspeakers with no inputs

connected, then hook your inputs up one component at a time and listen for hum. If

you get hum, then you either have a ground loop between that component and the

ampliﬁer, or that component is bad.

Decware High Fidelity Engineering Co., East Peoria IL, USA www.decware.com

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