My EP500 makes frequent LF "burping noise" that has only been noticable in the last couple of weeks.

At first I thought it was interferance from my HTPC directly behind it or from the amp but these "burps" happen when everthing is off except the EP500 which I leave on. The sound is low volume and low freq so you only hear it when on pause or mute or the equipment is off.

Any idea what is causing it and any solutions (note: I do not have a filtered power supply feeding my AV equipment so I could try this)

Thanks
Nathan

Could the burps coincide with the amp going into standby mode?

I'll take a guess and say you have a ground loop.My 350 did the same thing,the occasional "burp".Sometimes I would fall asleep on the couch with everything turned off and the 350 would go nuts,choppers leaving Saigon loud,and shake me awake.Install cable lately ???? just a thought.

My 600 was doing that a couple days ago. Well at least I think it was the same thing…….

It would thump every now and then with the AVR off. It took me two days to figure out it was the sub. I thought it was something outside the house banging on the wall or possibly something in the framing that came apart. I just turned the sub off and back on again. It hasn’t done it since.

Thanks for the suggestions. My symptoms sounded a lot like mdrew's as it also took me awhile to work out the noise was from the sub. I've tried "rebooting" the EP500 and that seems to have worked for now - will keep an eye (or ear on it).
Thanks
Nathan

Does it coincide with meals and is the EP500 close to being under the dining room table?

Someone might not like their broccoli too much...poor EP500 might have stomach indigestion.

Mmmm more like a Scotch or two late at night....

Hi jmone (Nathan),

I just chatted with Tom Cumberland, Axiom's chief engineer who designed the amp and electronics for the EP500. We have never heard of this problem before, but we do have thoughts on the source. Here's how to trouble-shoot the problem, which may be related to the HTPC (presumably, it's interconnected through your system to the EP500).

First, remove the audio input cable(s) to the EP500, so it is only plugged into the AC wall plug, and has no other cables connected. Does it still burp? If not, then we know the disturbance is somehow coming down the sub audio line from elsewhere in your system.

Now find the hard OFF switch for the HTPC and turn it off. The HTPC would still remain alive in a standby or hibernate mode, and we think it may be a recycling glitch in the PC power supply. These typically have little of no shielding so that noise could be delivered through the interconnected grounds of your system.

Anyway, turn the HTPC hard off (no power), then re-connect the audio input to the EP500. If the sound is related to the HTPC's power supply, it should be gone.

Let us know how it turns out.

Regards,

Hey Alan,

I don't run a HTPC but it sounds as if I had the same thing happening. Like I said above, I turned the sub's main power switch off and back on again. My 600 has not had indigestion since I did this. I didn’t think to ask Axiom about it because it went away. But it was pretty weird for a couple days trying to figure out where this thump was coming from.

Hey mdrew,

Maybe turning it off then on again reboots the DSP chip but since it works, great. It's certainly standard procedure with other devices that use DSP chips when you get a hiccup or freeze-up in operation. You do a cold re-start and then things are usually fine.

Thanks for the feedback.

Thanks Alan, but I'm with ldrew. The LF noise went away as soon as I rebooted the EP500. If it returns I'll try to "disconnect" the EP500 as suggested to see if that also stops it and report back - but so far so good!
Nathan

reboot?

Yeah, reboot. You got a problem with that ?

A couple of weeks ago I had to take my father in for a firmware upgrade...

Apparently pacemakers now have flash memory and can be reprogrammed. I find that alarming in these days of viruses which can infect a Lexus through the Bluetooth interface.