Moderator,

I have a long-term and developing problem with low-frequency “rumble” noise in one of my TRefs that I’ve commented on before. This noise is band limited to the bandwidth of the subwoofer, and when it occurs, it comes equally out of both bass drivers. The noise is never heard through the midrange drivers or tweeter. The noise is intermittent and varies in loudness. Usually, it will last for anywhere from ten seconds to a minute at more or less constant volume, then fade completely away. Other times it will get louder (once in a while it will get loud enough to be a concern), but then it will fade away again. The low level noise often appears within minutes after the sub amp has started up in response to music. Then it may be gone for an hour or more, only to reappear unpredictably some time later. I have been unable to find any kind of pattern, and believe me, I’ve tried. Because this is rare and unpredictable, it has taken me a long time to troubleshoot it. Note that it only happens in my right TRef. My left TRef has never had this problem, and it is located about the same distance as my right speaker from my other A/V components.

For a long time I’ve thought this is being caused by some kind of wifi interference, but I have systematically shut down (as in unplugged the power from) every component in the system, one at a time. I have disconnected the power from the TV. I have disconnected the power from the nearby Google Wifi point (which is fed by an ethernet cable from a room far away). I have shut down the main power amplifier, disconnected the speaker cables at the speaker, and disconnected the power cable at the speaker. Nothing I have tried has caused the noise to change. (The noise did disappear when I pulled power to the speaker, but it disappeared only after the 20 second or so grace period as the speaker amp power supply drained. During that grace period, the noise was unchanged.)

I am close to a large number of wifi networks, although my wifi strength is normally orders of magnitude larger than those. My wifi is operating on both 2.5 and 5 GHz bands.

Over time, this noise has slowly tended to get louder during the times it occurs. This has been going on for many months now, and I have waited and experimented until I have run out of options. Now I am well and truly stuck.

I’m now thinking that this may be a problem in the right speaker’s subwoofer amp. Crossover circuit? Subwoofer amp? Or, for that matter, sub power supply?

I’m hoping I can discuss this with someone knowledgeable toward resolving this. Maybe it needs a new amplifier board. For reasons I’m willing to discuss, taking this to the dealer (100 miles away) is not practical.

Any input would be appreciated.

Charlie

Sorry to hear about the frustrating ordeal you're going through. Have you tried swapping the right T Ref with the left T Ref?

anthem,

Interesting idea. No, I haven't tried that...

I'm not keen about schlepping these things around, there being some risk involved. Logically, I have a hard time seeing why this would make a difference, given the equipment layout. But you never know. Doing this would prove it's the speaker and not the wifi environment.

You have me thinking. It might be a good morning project.

Thanks,

Charlie

Are your T Refs connected to separate wall outlets? Theoretically, you wouldn't need to swap speakers. Just swap speaker wire, and for the time being, swap the T Ref power cords using extension cords if needed.

The last thing in the world I want to hear is that you have a bad amp module. The amps in the powered Tritions seem to be the weak link in these speakers.

Let us know what you find out.

anthem,

Both of my Trefs are connected to my PS Audio P20 powerplant. The cabling upstream from the speaker cannot be the problem, because I have disconnected speaker cables and the power plug at the speaker, and the noise has remained (for as long as the subwoofer amps stayed on).

Yesterday afternoon, I swapped the speakers, about a two hour job. I managed to not break anything, not even my back.

The results are preliminary. So far, no noise out of either speaker! Before I scream victory, I'll give the system another day or so. I'll let you know.

I agree about the power module. I have had a lot of Class D amp failures: one subwoofer (before GET), one channel of a stereo amp, and one of my Bel Canto monoblocks. I think there is a general, industry reliability problem with the power modules. I've gotten to the point where I have doubts about buying another Class D device. I think I may go back to A/B, which, of course, will slam me in the wallet.

Charlie

Hey Charlie:
So far, so good! If it Happens again, try plugging the T Refs directly into the wall, even if you have to use extension cords. If the problem goes away, could it be a problem with the PS Power Plant? If the problem remains in the offending speaker, it's more than likely the bass module.