Sun, 6:50 am. I can hear my subwoofer. This puts a weed up my arse.

[wgscott]

He gave the stock answer. It is hooked up that way. But the main point is this is a very quiet (by comparison) noise that does NOT change when you disconnect the speak-on and/or RCA input cables.

 

Before you buy it, tun it on with nothing attached in a quiet room, and see if you hear anything, however faint. We are talking about something that is no louder than a fluorescent light ballast (a properly operating one, that is).

[Audio_ELF]

As for Rel, I never came across a company (a) so disinterested in selling me something in the first place, and (b) so reluctant to honor their warranty. Plus, I had to drive the thing all over the place (Four 75+ mile trips).

My impression is REL have gone severely down hill since Richard Lord sold to Sumiko...

[tranz]

I asked my dealer about this and here is his response:

 

"Even with the longbow (wireless unit) It sounds great using the Neutrik Speak-On connector (our preferred method). If there is a buzz just hook the black lead to one of the negative binding post on the amplifier."

 

That is an incorrect answer and your dealer needs to read the manual. For amps with floating signal ground you do not want to connect it to the speaker terminal. Class D and fully balanced amps require a slightly different setup.

[wgscott]

It depends whether or not the class D amp is balanced or not. With mine, I have to hook up the (single) negative lead to the negative terminal (which is the ground, BTW). When I was listening to the NAD 390 DD, I had to hook up the negative lead to the chassis.

[Bob Stern]

It's quite possible that the power transformer in the subwoofer amp would buzz even in the absence of DC offset in the mains power. It may be cheaply built, or the bolts intended to hold the laminations tight enough to prevent buzzing may have loosened. (The laminations should be both glued and bolted.)

[Jud]

It's quite possible that the power transformer in the subwoofer amp would buzz even in the absence of DC offset in the mains power. It may be cheaply built, or the bolts intended to hold the laminations tight enough to prevent buzzing may have loosened. (The laminations should be both glued and bolted.)

 

Yes. Or the transformer may simply be of a type that tends to hum, and the enclosure is resonating enough to make it audible. Nothing electrical need be wrong.

[tranz]

Yes. Or the transformer may simply be of a type that tends to hum, and the enclosure is resonating enough to make it audible. Nothing electrical need be wrong.

 

Indeed. Likely the way it was designed.

 

That is one of the reasons I love what McIntosh does with their power amps and pot those transformers in some heavy tar to deaden the noise. Wish they all did that.

 

At pro-audio stores you can buy noise deadening material like foam or heavy rubber matting type. Might be another DIY solution that is cheaper than a new sub. Sweetwater.com is a good place for this.

[wgscott]

I'm afraid I have portrayed the problem to be worse than what it is -- i.e., a minor irritant that I can only hear if the dog isn't breathing too heavily. It doesn't warrant drastic actions. I was just hoping something simple would fix it. I'm going to try moving it around first, extending the power cord, trying it at work or at Bob's house, and try his buzz-killer.

[sedest]

It's quite possible that the power transformer in the subwoofer amp would buzz even in the absence of DC offset in the mains power. It may be cheaply built, or the bolts intended to hold the laminations tight enough to prevent buzzing may have loosened. (The laminations should be both glued and bolted.)

If this is the case (DC offset), I would suggest you AVA Humdinger. It solved my problems with transformer mechanical noise.

avahifi - AVA HumDinger

[junker]

Hmm... any chance it's just the transformer buzzing?

 

If you can localize the sound to not be originating from the driver itself you might be able to damp the transformer with some rubber grommets or some other damping/sound absorbing material such as Dynamat:

 

Amazon.com: Dynamat 10415 10" x 10" x 0.067" Thick Self-Adhesive Sound Deadener with Xtreme Speaker Kit - Pair: Automotive

[Sam Lord]

OK, the first thing you should have done was listen to muted inputs, i.e. a CD player turned on but playing nothing. Now, you said, "I can only hear it when the audio is off." But you didn't say *for certain* whether the hum was still there when connected to powered-on source components. That's important!

 

If the hum still occurs in the above case, go to #2: short the line-level inputs as suggested. Only change connections with power OFF. You can buy cheap RCA interconnects, cut them, and tie the bared signal and ground wires together TIGHTLY, then wrap them with electrical tape.

 

Or just buy RCA shorting plugs here.

 

It is inconceivable that the speaker level inputs could need shorting, but let's cross that bridge later. If the sub hums with shorted inputs, it needs internal repair of some kind. Most electronic faults originate with mechanical faults. If your sub amp's power supply is an SMPS, the hum isn't likely from the transformer.

 

Good luck wg!

 

It is quite sad that most sub manufacturers have gone down the Class D route to save money and end up with an inferior product.

 

Sad is the persistence of class AB amps in subwoofers, a silly application today.

 

...it has two RCA inputs and a speaker-level input. Is doing this on one sufficient?

 

No, do both, even though you have source selection.

 

Stop sticking weed up your arse and find another way to indulge :-)

 

But I heard th

[jamesg11]

Hmmm, commiserations ... I think, but could be the Mephistophelean 'misery loves company' ... My Rel R301 sub doesn't hum, class D & all, but my stupid-expensive 2-tier power amp does, class A & all. It's definitely tranny hum, & a bit noisier than yours from the description. Can't bring myself to send it back, fish hooks in eye & all, but mainly cos I love the sonics, & the maker won't fix it anyways. So, I just put up with the elevated noise floor. Until ... I eventually work up the courage to entrust it to a tech, who may or may not improve matters ... Where was I then, oh yeh, commiserations.

[beanbag]

OMG, don't buy a shorting plug; don't take a perfectly good cable and cut it up. Do what I said to short the input. Sheesh.

[4est]

There really is no need to buy anything. Short the plugs as noted, and the power switch to check the transformer hum. Get an idea as to how long it will make sound with no power, and then cycle the power switch to hear if the hum changes when the on-off state changes.

OMG, don't buy a shorting plug; don't take a perfectly good cable and cut it up. Do what I said to short the input. Sheesh.

[sandyk]

OMG, don't buy a shorting plug; don't take a perfectly good cable and cut it up. Do what I said to short the input. Sheesh.

 

 

A few shorting plugs, or with say 1K resistors in them, are a handy thing to have as they make it much easier to take measurements. In this case you would need a pair of them. They can also often be of benefit when plugged into unused inputs of preamps too. In any event, many people are likely to have cheap and nasty RCA leads laying around that came with older gear that can be sacrificed for the purpose as another poster said.

[mac_and_dac]

FWIW, I recently bought a REL G2 and it is absolutely silent, 100% hum-free. (It had bloody better be for the price.)

 

I have noticed though that it is very sensitive to inputs and cheap cabling. It was completely unusable, for instance, with the .1 out of my Philips home theatre system. The hum was violent.

[tranz]

FWIW, I recently bought a REL G2 and it is absolutely silent, 100% hum-free. (It had bloody better be for the price.)

 

I have noticed though that it is very sensitive to inputs and cheap cabling. It was completely unusable, for instance, with the .1 out of my Philips home theatre system. The hum was violent.

 

Sorry to OP.

 

This reminds me, I threw out the cheap antenna cable provided by Rel and bought some Canare twisted pairs instead to connect to the Neutrik.

 

You have no buzzing the first few seconds when turning it on, when the front LED display is settling in? No very light hum, almost like a fan noise when sticking the ear to the speaker?

[AudioDoctor]

Bill, I think you are going to have to give up on the sub...

[Sam Lord]

To short the input is very simple. Hook a short RCA cable up to the inputs, and then on the other end of the cable, use a metal object to touch the inner pin to the outer. The noise should go down by half if you have both R and L inputs.

 

Sure. But when I have a very expensive subwoofer to test, I don't make intermittent connections at the inputs; I don't assume the failure mode of the system is stable. It nearly always *is* stable, especially with minor hum, but I prefer caution.

 

OMG, don't buy a shorting plug; don't take a perfectly good cable and cut it up. Do what I said to short the input. Sheesh.

 

...You might make an RCA shorting plug. Take a junk interconnect, cut it to about 6 inches and just twist the wires together.

 

^^ like that.

I didn't say to use a "perfectly good" interconnect. The cheapest unshielded kind, like a $4 pair for all the 4 plugs the OP needs, are easiest for this simple operation. And shorting plugs are very useful tools. As sandyk said, using a low resistance in series (a simple mod to the cut-interconnect method) lets you make easy measurements.

[wgscott]

Bill, I think you are going to have to give up on the sub...

 

along with the speakers and everything else.

[beanbag]

Sure. But when I have a very expensive subwoofer to test, I don't make intermittent connections at the inputs; I don't assume the failure mode of the system is stable. It nearly always *is* stable, especially with minor hum, but I prefer caution.

 

Fine. Take a wad of aluminum foil, and jam it between the inner pin and outer shell of the RCA cord you already own. Cost: $0.00001

[AudioDoctor]

along with the speakers and everything else.

 

Now that is just crazy talk. Maybe just give up on the REL and get a Zu sub.

[Gilbert1212]

Humdinger

 

Van Alstine sells a DC blocker called a Humdinger for $125:

avahifi - AVA Humdinger

 

Van Alstine doesn't state whether he uses a diode bridge like PS Audio or capacitors like Bryston.

 

Many Thanks Bob. I have now solved my problem!

 

Similarely to the OP, my Rel Stentor III was buzzing every time my wife was using her hair dryer (most of the time on the low setting). I receiced th Humdinger today and voilà...

 

 

Gilbert