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

[sandyk]

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

 

If shorting plugs are used, it also gives the opportunity to measure before and after noise levels at the output sockets using a digital meter.

 

 

 

No, the stupid LED circuit isn't going to affect things.

 

Wrong. It can, and often does. More often than not, the power for the LEDs is picked up before any voltage regulators.

Multiplexed LED displays can also cause minor noise problems, which is why you are sometimes given the option to turn them off.

[wgscott]

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.

 

No, the stupid LED circuit isn't going to affect things.

 

To check for DC on the mains, use a voltmeter in DC mode.

 

Otherwise, you have to go inside the box and start poking around. For example use the AC mode on the voltmeter to measure any signals across the woofer wires.

 

If this sounds scary, I suggest you take this sub to work and have a grad student look at it. Some of them might have good electro-mechanical aptitude.

 

A lot of them do. Especially the engineering one I have. But I meant "scary" in the sense of warranty invalidation...

[beanbag]

I would rather invalidate a warranty than stick a fish hook thru my eye.

[wgscott]

It seems to vary between 0 and about 25 mV DC on the most sensitive setting. I'm guessing this means zero DC offset?

[Bob Stern]

DC on the mains

 

Measuring the DC offset is of minimal practical relevance because you know it's non-zero, but you don't know what value would be high enough to cause the transformer in that particular subwoofer amp to hum.

 

I suggest blocking the DC to see whether it solves the problem. The economical solutions would be a used PS Audio "Hum Buster" (not manufactured for several years) or soldering large capacitors in series with the AC power input to the subwoofer amp. I believe all Bryston amps use such capacitors. An expensive solution would be a mains isolation transformer.

[speavler]

this is why i never sold my humbuster. it's a part of my troubleshooting tackle box when i encounter hums. your power cord isn't coiled up or anything is it?

[Bob Stern]

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.

[tranz]

One more thing, in case you have not already tried...If you are using the high level neutrik connector, the ground can be tricky if your amp is either Class D or fully balanced. The ground lead of the neutrik would need to be connected to the amp chassis instead of the negative speaker terminal. The manual has a small section on it.

 

Any possibility of trying a non-class D sub from your local shop?

 

Cheers

[wgscott]

this is why i never sold my humbuster. it's a part of my troubleshooting tackle box when i encounter hums. your power cord isn't coiled up or anything is it?

 

Coil implies a tidiness element that does not exist. "Random coil" as we would say in the protein structure business. But, yes, to answer your question.

[wgscott]

One more thing, in case you have not already tried...If you are using the high level neutrik connector, the ground can be tricky if your amp is either Class D or fully balanced. The ground lead of the neutrik would need to be connected to the amp chassis instead of the negative speaker terminal. The manual has a small section on it.

 

Any possibility of trying a non-class D sub from your local shop?

 

Cheers

 

Yes, and I have been through this. But remember, I get this even when it is disconnected. It is inherent to the sub itself.

[firedog]

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.

 

I had a DC transformer hum with my class A/B amp and the AVA Humdinger solved it. It costs only $125, and you can return it for a refund if it doesn't do the trick. As mentioned, it's a useful tool to have around anyway.

 

I wouldn't try measuring DC on the line, you can hurt yourself if you don't know what you are doing.

 

Is the hum constant or is it sometimes stronger and sometimes weaker? DC caused hum tends to vary in intensity, and sometimes stop and then start again.

 

If you can get the family out of the house again, you can test and get an idea if the hum is the result of DC from something in your house:

 

Turn off and unplug EVERYTHING and close all the circuit breakers. Flip them up one by one and see each time if the hum starts. If not, plug each device back in and see if one of them when running causes the hum. Typical culprits are computer printers, hair dryers, and refrigerators.

 

If none of this causes the hum, you may have a neighbor on the grid who's causing DC on your line.

[Audio_ELF]

Solution to buzzing sub...

 

Stop sticking weed up your arse and find another way to indulge: doesn't stop the sub buzzing but you no longer worry so much :-)

[beanbag]

Just take the sub to another location with a different outlet to test, sheesh.

[robcentola]

Grateful Dead bootlegs.

 

 

LOL!

 

If it were only that easy and enjoyable.

[One and a half]

Makes you wonder why just the sub and not the main amp? If there was DC offset, the main amp 'should' be affected the same way, or even wall warts getting really hot.

Take the sub to another location as advised, if it still happens, send it back to the shop you bought it from, again. There's no disclaimer on the amount of DC offset the sub can take is there? Then it's a manufacturing fault.

[tboooe]

Oh man this worries me! I am about to purchase the S2 (newer version of the 218). Ive contacted my dealer to see if he has had this same issue. I will report back.

[tranz]

That sucks. Looks like it is time to trade it in for a different sub.

[wgscott]

Solution to buzzing sub...

 

Stop sticking weed up your arse and find another way to indulge: doesn't stop the sub buzzing but you no longer worry so much :-)

 

Most users report opposite symptoms.

[wgscott]

I wouldn't try measuring DC on the line, you can hurt yourself if you don't know what you are doing.

 

I measured it on a GFCI, just to be safe.

 

Is the hum constant or is it sometimes stronger and sometimes weaker? DC caused hum tends to vary in intensity, and sometimes stop and then start again.

 

Constant. I also want to emphasize that it is barely audible.

 

If you can get the family out of the house again, you can test and get an idea if the hum is the result of DC from something in your house:

 

Turn off and unplug EVERYTHING and close all the circuit breakers. Flip them up one by one and see each time if the hum starts. If not, plug each device back in and see if one of them when running causes the hum. Typical culprits are computer printers, hair dryers, and refrigerators.

 

I did do this. Even with all other circuits turned off, and everything else on that circuit off, it persists, so it is definitely internal.

 

If none of this causes the hum, you may have a neighbor on the grid who's causing DC on your line.

 

Except I can't seem to measure any significant DC offset.

[wgscott]

That sucks. Looks like it is time to trade it in for a different sub.

 

It is at the threshold of audibility under normal ambient conditions.

[wgscott]

Oh man this worries me! I am about to purchase the S2 (newer version of the 218). Ive contacted my dealer to see if he has had this same issue. I will report back.

 

Get the B&W PV1D.

 

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).

[4est]

Do you hear it more from the electronics "plate" side (mechanical hum) or the driver side(electronic circuit hum)? Off the cuff: driver side- power supply, electronics or design issue; plate side- loose transformer or DC on the mains.

I can't feel it on the driver/cone. But absence of evidence isn't evidence of absence. I can't seem to measure it.

 

I am embarrassed to admit I have no clue how to detect DC on the mains, or what to do about it.

[wgscott]

Well, the driver is on the bottom (down-firing sub). It seems delocalized, but I think it is internal.

[tranz]

It is at the threshold of audibility under normal ambient conditions.

 

In the end it is what you can live with.

 

But I do think it will continue to irritate, and not just because you know it is there. Just because the music is louder does not mean your ear is not still registering, interpreting and filtering those buzzing signals. The increased noise floor will be more fatiguing if sensitive to it. I know I could not live with it, and I went through many shops sticking my ear to the subs and listening for buzzing. And a few home auditions made me realize also that Class D subs were fatiguing to me even if they were not outright buzzing.

 

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. Reminds me of the fate of the Pioneer Kuro plasmas.

 

Cheers

[tboooe]

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."