Soft hum in RF-7's

[arthurs]

When running my system with nothing playing there is a soft hum in my rf-7's. Is this normal? It's not loud nor terribly noticeable, but it is there. Any advice? Or should I just stop being paranoid?

My System

RF-7's

RC-7

rb-5II surrounds

B&K Ref30

B&K 7250

Denon 4800

Monster HTS2600 PowerCenter

[prodj101]

it's probably the receiver picking up hum from something. nothing to worry about, as long as it doesn't get too loud. It can be hard to get completely rid of hum, so my advice is just get used to it, and don't make it into a big deal unless it is audible when you are listening to music or about 10 feet away.

[boa12]

arthurs, i have the ref 30 also & had a ground loop hum/buzz until i defeated the safety ground on both the ref 30 & amp using a 3-2 cheater plug on their power plugs. do you by chance have a tv &/or cable tv box running into/through the ref 30? things for that too but the only thing that completely removed it for me was the cheater plugs.

b&k tech told me that the way they use the safety ground its not needed for safety anyway. said they really don't need a 3-prong plug.

[arthurs]

Can I get cheater plugs anywhere? And yea, just routed my cable box through. hadn't thought of that.

[boa12]

cheater plugs at any hardware store or maybe even the hardware section of the grocery store are about 75 cents. u may also need one on the sub plug. they're usually those bright orange thingies.

you could also try a ground loop isolator on the cable tv cable in but a good one of those that may or may not work is like the mondial magic box for $99.

[Soundthought]

I wonder if it's federal law to have a grounded plug on electronics that use power above a specified wattage.

Anyone know?

[boa12]

ar, may be that. but b&k puts a safety ground on their pre/pro too. guy at b&k told me that it was more for appearance than anything for safety.

though it does seem sporadic how they do it. like pre/pros w/ low power have them while some receivers w/ high power don't.

this is just b&k though. may be a shock hazard removing the safety ground on other makers' equipment. & i said i'd never get into another ground loop discussion again.

[Soundthought]

It is kinda weird, huh?

My B&K 2140 has one.

My Denon 3801 doesn't

My Makita sawzall has one.

My Craftsman sawzall doesn't.

Both the Denon and the Craftsman have the greater power demands.

Go figure.

Might be like you said.

Probably part cosmetic, and part build quality.

Interesting.

[Doug C]

For a long time I was fighting a slight hum from my mains also. I did a bunch of things and finally have dead quiet speakers. Some of the things I did include:

I had no grounding rod tied into my main breaker box so I installed one and tied it into the neutral buss bar at the breaker.

Had clicks & hum when the frig and AC would come on. Installed Monster power conditioner strips which helped further.

Wiring from breaker box to wall outlets were a mess. At some outlets hot & neutral were switched so I corrected this problem. Found one outlet was not grounded and corrected that also.

Also found one of my interconnects between the preamp and amp was not making good contact causing low level hiss & hum. I now use Homegrown cables with locking barrels.

Doug C