PS Audio Humbuster HBAC Owner's Reference Manual - page 7
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Eliminating Noise 3
®
Eliminating Noise
Owner’s Reference
Humbuster HBAC
©2004 PS Audio International Inc. All rights reserved.
Every audio/video system has some degree of either audible or visual hum or buzz. If your system
has some of these noises, and they are at a level that is noticeable or bothersome to you, there are a
few things you can do to fi x these problems.
Sometimes hums and buzzes are quite obvious, sometimes not. The ‘hum noise’ usually comes in
two fl avors, a low non-irritating drone (50 or 60 Hz) or a slightly higher pitched buzz or raspy/irritating
‘angry insect’ sound (100 or 120 Hz). Video hum is usually seen as diagonal bars across the TV or
screen of a projector.
If your system has a bit of hum, is it the transformer or the speakers, or both? How do you
determine the source of hum and what can you do about it?
We fi rst need to divide our search into two categories; mechanical or electrically induced hum.
A mechanically induced hum or buzz is easy to determine. Place your ear very near to each piece
of your electrical equipment and listen for hum and buzz. If you hear a hum emanating from within
your equipment, we would refer to this as mechanically induced noise (as opposed to an electrically
induced noise).
The HBAC should lower or eliminate this internal mechanical hum.
To see if it is an electrical problem, make sure your system has been on and warmed up for at least
10 minutes, then simply place your ear near the loudspeaker (with no music playing) and listen to
determine if the hum or buzz is coming from your speaker. If it is, then at least one component of
your problem is electrical.
Electrical noises are usually caused by one of two main problems: proximity or ground loops.
Proximity hums can be identifi ed by listening to the speaker for a low humming sound and electrical
ground loops can typically be identifi ed by a raspy buzzing sound.
Proximity refers to how close one piece of equipment is to another. Since transformers work by
generating magnetic fi elds, these fi elds can be rather large and if the fi eld gets too close to another
audio or video product, noise (hum) can be induced into the product from the transformer. This
type of sensitivity is typically restricted to high gain pieces of equipment like phono stages, but even
preamplifi ers sitting in close proximity to a power amplifi er can have hum induced into it.
Solving proximity problems is relatively easy: simply move the equipment further apart.
Ground loops hums are perhaps the most diffi cult to track down. Ground loops are a result of
differing ground potentials. This means that the ground of one AC source is at a different level than
the ground of another AC source. This difference is usually amplifi ed in the form of audible or visible
hum. Visible hum is usually seen as diagonal bars across the video screen.
First determine
what type of hum
you have
Electrical or
mechanical?
Mechanical
Electrical
Proximity
Ground loops