PS Audio BHK Signature Preamplifier Instructions For Use Manual - page 19
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Troubleshooting
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Rev A
Troubleshooting
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Owner’s Reference
BHK Signature Preamplifier
be caused by a ground loop, a light dimmer in the home, poor AC power, or any number of causes.
The quickest way to determine where to start your search is to simply turn the BHK Preamplifier off,
disconnect the audio cables between it and the amplifier, and see if the hum goes away when you
turn the amplifier back on. If it does, it’s most likely a a problem with you power amplifier. Please refer
servicing questions to the manufacturer.
If this doesn’t solve the problem, reconnect the BHK Preamplifier and follow these easy humbusting
tips.
The easiest way to figure out where ground loop problems lie is by the process of elimination. You
need to determine where the hum or buzz is coming from within your system.
If you’ve determined, through the first step in this tutorial, that the power amplifier does not have
hum when disconnected from the system, your next step would be to disconnect all inputs to the
preamplifier. Once these are disconnected, and the preamp is connected only to the power amplifier,
turn the system on and again, listen for hum. Should the hum now appear, it is likely a ground loop
interaction with the power amp. Try an AC cheater plug to break the ground loop. Cheater plugs
are simple devices that convert a three prong AC plug into a two prong AC plug and in the act of
converting three prongs, to two prongs, the ground from the wall socket is disconnected. Try one of
these on the preamp, or the power amp, or both.
If you determine that there is still no hum present when the preamp and power amp are connected
with no inputs, then selectively begin plugging in your various sources to the preamplifier one at a time.
After each connection, check for hum until you discover the humming culprit.
Cable and set top boxes for televisions, surround processors, and any device that is connected to
a television cable or satellite dish can cause a loud buzz and should always be suspect. If, by the
process of elimination described above, you determine it is a component like a cable box that is
causing the hum/buzz to occur, and using a cheater plug doesn’t help matters, it may be necessary to
isolate the cable connection (CATV) with an isolation transformer. This inexpensive device is available
at most Wal Mart, Radio Shack or department store type outlets and is sometimes called a ‘matching
transformer’. If you have problems finding one, call your local cable TV company for advice. The
matching transformer will be placed between the cable TV and the set top box, cable converter, or
surround/video processor.
Just remember, take the system down to its simplest level of connection. Find a way to hook the
system up with as many pieces of the system missing or not connected. Keep it simple and get it
to the point where the hum’s gone. Then start adding back components one at a time until the hum
returns.
Finding the problem is 9/10th of the work in finding a solution.
Hum Busting
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