Bass Noise/RF Thump when Sub is Idle

TONYGVISINET · January 2003

I am battling a problem with my PSB Subsonic II (90 Watt) giving Bass Noise/RF Thump when Sub is Idle (on standby)

For example; when the Heat Pump kicks in, I get a low level low frequency thumping which is driving us near madness. It does it when the vacuum cleaner is turned on, etc.

I called the PSB folks first, and they said it may be Radio Frequency (RF) interference in the electrical outlet.

So, I bought a Panamax 8 surge suppressor with RF eliminator, and even tried different electrical outlets in the vicinity, but it still does it very often.

The last solution is to turn the sub on/off separately, which is kind of a PITA.

Any thoughts, and your time is appreciated in advance!!!
Tony G
** My Setup **
Polk SDA 2b
Polk Monitor 5jr
NAD 3400 Integrated Amp (100w)
PSB Subsonic II Powered Subwoofer (90w)
Sony CDP-302 CD Player
NAD 6340 Cassette Player
Kenwood KT-31B Tuner
**************

MxStYlEpOlKmAn · January 2003

All I can say is - Unplug it for a while, and try again later. It will eventually go away tho

Dr. Spec · January 2003

You may have a ground loop. Buy a cheater plug and plug the sub into that and see what happens.

TONYGVISINET · January 2003

What if the Sub Plug has no ground pin? (Only has the two blades)

Dr. Spec · January 2003

Then that wasn't the problem. Guys - anything else?

MxStYlEpOlKmAn · January 2003

Originally posted by MxStYlEpOlKmAn
All I can say is - Unplug it for a while, and try again later. It will eventually go away tho

TONYGVISINET · January 2003

It does not go away after unplugging it for 5 mins.

wlrandall · January 2003

It won't go away. Had one of mine in an outlet on the same circuit as the light for our fish tank. Every time I turned the light off I got a nice 60 hZ THUMP from the sub. Moved it to the other side of the room to a different circuit and the problem is gone.

I would make sure that the neutrals and grounds aren't crossed in the outlets and for the heat pump. Not knowing anything about your house you may be SOL. I lived in one several years ago that was so underpowered that I had to manually turn the A/C off while recording. Every time the compressor came on my CD player would pause from the voltage drop.

An isolation transformer is another idea, albeit a pricey alternative to just turning it off.

Wally

TONYGVISINET · January 2003

I called a Hi End Stereo store: the advice the gave was to buy a Cable TV Ground loop isolator adapter and install it to the location where the cable tv enters the house (at the split).

What do we think of that?

wlrandall · January 2003

Those are for eliminating hum from cable ground problems (ground loop as Doc pointed out-your house has its ground and the cable has its own). Yours is surge related and I don't think it will do anything since your problem has nothing to do with your cable.

Some steps:
1) Call your electric company. A lot of them will come out and do a free analysis.
2) Go to your local Rat Shack and get an Outlet Analyzer. Part #22-141, cost $6. If your neutrals and grounds are crossed it will tell you.
3) Your entire home may be underpowered. I have 200A service coming into mine and still have lights flicker if too many appliances are running and the HVAC cycles.
4) Make sure your heat pump is properly grounded.
5) The breaker for your heat pump may be too close in the panel to the breaker for the circuit your sub is using (long shot on this one).
6) Move the sub to a circuit furthest away from its current location and not on the same circuit. This one's tricky with the way they wire houses, hopefully your breaker panel is marked. Leave it in standby and cycle the power to the HVAC, turn the vacuum cleaner off and on. If the thump is gone, the problem is the circuit where you normally have the sub.

Just some thoughts, if I have any more I'll post them.

Wally

Bass Noise/RF Thump when Sub is Idle

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