An issue with my stereo amp emitting a choppy noise - any ideas of its cause?

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Delicieuxz

[H]ard|Gawd
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As you might've seen in another thread, I recently got a Martin Logan Forte stereo amp, which has wifi functionality. It takes maybe 40 seconds or so for the wifi to initialise after the amp is powered-on. And until the wifi initialises, the amp is appropriately quiet, except for any audio I'm playing through it. Once the wifi initialises, the amp starts emitting, through the connected speakers, a helicopter-like choppy noise, and it continues to do that indefinitely. And there's no option to just turn-off the amp's wifi.

Here is a sound clip I recorded using my phone, with the clip's volume boosted a bit to make it easier to hear:


View: https://voca.ro/1hHlsm70Kyvf

I've tested two different sets of monitors with the Forte, and the same thing happens with both. I've tried turning-off all electronics in the room other than the amp, to see if it's interference of some kind. But the sound occurs even when the amp is the only thing in the room turned on, including when there's no audio source connected to the amp. Also, when I put the amp into mute mode, I can still faintly hear the choppy sound coming from the speakers, though it does become quieter.

The amp has two wifi modes: Access Point Mode (which is the regular mode that it defaults to) and WPS Mode. When I switch the amp to WPS mode, the perpetual, choppy sound becomes slower, and changes its pattern to something like 16 quick beats, then a short pause, then 3 or 4 slower beats, then a pause. And it repeats that pattern over and over, until it automatically defaults back to Access Point Mode, after which it returns to doing the constant helicopter-like, choppy sound.

I messaged Martin Logan about this issue, and they chose to replace the amp. But the replacement amp does the same thing.

Does anyone have an idea what could be causing this, and how I might be able to fix it?
 
they are picking up the wifi signal. the change in pulsing when in wps mode is because its waiting to receive a pairing signal from another device. try shorter wires or putting a ferrite choke on them. if youve got any old vga cables kicking around you might be able to salvage some.

edit: if im understanding the manual correctly, if you connect the ethernet cable the wifi should disable and the noise should stop.
 
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Perhaps you should get a professional electrician to check your power lines, meter, breakers, and outlets..... cause this sure sounds like "dirty power" to me....which means that something, somewhere, is providing interference or feedback, either electrical, radiological, acoustic, or just random spikes/flucations into your circuits...
 
pendragon1 said:
they are picking up the wifi signal. the change is pulsing when in wps mode is because its waiting to receive a pairing signal from another device. try shorter wires or putting a ferrite choke on them. if youve got any old vga cables kicking around you might be able to salvage some.
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The amp makes the noise even without a sound source connected to it. So, the only wires I could shorten are the stereo wires coming from the amp. The sound plays in both my monitors and my subwoofer. The sub has a well-shielded RCA cable connecting it.

pendragon1 said:
edit: if im understanding the manual correctly, if you connect the ethernet cable the wifi should disable and the noise should stop.
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I tried hooking a dummy cable (a short cable, not connected to anything on the other end) up to the ethernet port, and it didn't stop it. I'd rather not be running an ethernet cable through my room. But I'll give it a try.

dogDAbone said:
Perhaps you should get a professional electrician to check your power lines, meter, breakers, and outlets..... cause this sure sounds like "dirty power" to me....which means that something, somewhere, is providing interference or feedback, either electrical, radiological, acoustic, or just random spikes/flucations into your circuits...
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Hope it doesn't take that. But I'll keep that in mind.
 
pendragon1 said:
the ethernet needs to be active.
could also try making sure everything is plugged into the same socket/strip.
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The amp is connected to the same power strip as my PC, monitor, subwoofer, and some other stuff. The good news is that connecting it to an active ethernet cable stopped the noise. The bad news is that I have to be running an ethernet cable into the room, from outside of the room, to do that.

Maybe this amp has very-poor shielding? If so, I wonder if I could do something to improve it.
 
Delicieuxz said:
The amp is connected to the same power strip as my PC, monitor, subwoofer, and some other stuff. The good news is that connecting it to an active ethernet cable stopped the noise. The bad news is that I have to be running an ethernet cable into the room, from outside of the room, to do that.

Maybe this amp has very-poor shielding? If so, I wonder if I could do something to improve it.
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k, that would eliminate any ground loop causing it. thats what i was suspecting, poor shielding.
got an old router or hub switch? something that could feed it an inactive signal but be able to give it an ip, to try and trick it.
edit: could try shielding it some how. put a metal pot over it, see if it stops it...
 
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I'm currently using the amp with an ethernet cable plugged into it, to stop the wifi noise. If I put my ear right next to the subwoofer, I can still hear some extremely-faint activity sounding in the speaker, but I need to have my head immediately next to the sub to hear it. So, it's not an issue for normal use.

Since I was sent a replacement amp, I have two on-hand - both of which have the same issue. The instructions to connect the amp to a wifi network say to press the modem / router WPS button, or use DTS Play-Fi software to connect it. My modem doesn't have a WPS button, so I installed the software and tried connecting via it. There were issues in the process, with the software not losing sight of the amp while trying to connect it. But I got it connected. Having it connected to the wifi network drastically cuts-down on the thumping noise coming through the speakers, but doesn't entirely eliminate it. There are still occasional, faint thumping sounds coming through, from the wifi.

The DTS Play-Fi software also wanted to update the amp, which I let it do. The updating process kept failing from losing detection of the amp (the wifi signal strength in the room is full, and it's what I connect my PC and other devices to for internet), or otherwise stalling on the finalisation of 2 of 3 updates. After maybe an hour or so of trying to get it to complete the update process, I let it run for another almost-an-hour while the software said that it was finalising update 2 out of 3, with there being no option to cancel the update process. And then I restarted my PC, to force it to stop, so I could try over again.

After my PC booted up, the amp wouldn't pass sound normally: no audio came through the monitors, while an extremely-faint, mid-frequency sound came through the subwoofer. I swapped the 2nd Forte amp with the 1st one, and the 1st one played normally. I connected the 2nd amp again, and it still wasn't passing sound. Powering it off and on, and factory resetting it wasn't fixing it. It was either running the DTS Play-Fi software update again (which eventually completed all 3 updates - and quickly, with no wait time on finalising the 2nd of 3 updates) that fixed it, or many more power cycles and factory resets - I don't recall when it suddenly started passing sound again. But at some point it did just start passing sound again.

However, after that, when the software said it was fully updated and it was passing sound properly again, I noticed, while sitting at my PC, with the amp under the desk, that the amp unit was emitting an electronic, fast, ticking noise - sort of like coil whine (but lower-pitched and sounding more ticky than I've heard coin whine do). And I didn't notice anything like that coming from the amp before this ordeal. I unplugged and plugged it in again multiple times, power-cycling and factory-resetting it, and that noise hasn't gone away. Whenever the power cable is plugged into the amp, and the amp is turned on, the unit is emitting that ticking noise from the chassis - including when there is nothing else connected to the amp.


So, after all this, I've reconnected the 1st amp, which doesn't emit that ticking noise, and am running it with an ethernet cable connected to it, to disable the wifi, and have no plan to let the software update it. In this state, the amp is silent when not playing audio, and sounds great when playing audio. The whole ordeal probably took me at least 6 hours, and possibly permanently borked the 2nd amp.

Maybe these amps were discounted so hugely because there are significant issues with them. Given all the issues I've had, and that this one is functioning usefully only conditional to being connected to an ethernet cable (which means I lose its wifi features - not that I expected to use them), I'm thinking of looking for something else and selling this one.

pendragon1 said:
k, that would eliminate any ground loop causing it. thats what i was suspecting, poor shielding.
got an old router or hub switch? something that could feed it an inactive signal but be able to give it an ip, to try and trick it.
edit: could try shielding it some how. put a metal pot over it, see if it stops it...
Click to expand...
I do have an unused, old router. For now, I think I'd better stick to the ethernet cable method.
 
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Delicieuxz said:
I do have an unused, old router. For now, I think I'd better stick to the ethernet cable method.
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yeah thats what it would be for. just plug the cable into that router that isnt hooked to anything. the amp will detect that it has an active connection, even though there is no internet, and should disable the wifi. then just hide the router.
 
Some more feedback on Pendragons Wi-Fi notes
1. Huge amount of RF pollution present in everyday world, can use a SDR to pinpoint sources or use this https://www.sigidwiki.com/wiki/Signal_Identification_Guide
https://www.sigidwiki.com/wiki/802.11n
2. Any jack or cable can function like an antenna.
3. Even a monitor sends out a RF blip when entering sleep or power down mode. Auto keyfob is 315/316 MHz pollution
4. We have a company PowerPoint presentation on using a SDR if interested. I will post if peeps are interested.
 
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I will add, with the 1st amp connected and its wifi disabled with an ethernet cable, the amp, monitors, and sub are sounding great together, and practically inaudible in terms of white noise when no audio is passing through. The amp automatically goes to sleep after it's been idle for maybe 10 minutes, and wakes up again when playing audio. I think the amp should have some more configuration options, such as setting or disabling the sleep timer, and disabling the wifi / network feature completely - I wonder if I could desolder it or cut it out without breaking the rest of the amp's functionality.

drutman said:
4. WE have a company PowerPoint presentation on using a SDR if interested. I will post if peeps are interested.
Click to expand...
Sure, it could be useful.
 
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