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[HELP] Intermittent rattling sound coming from amp(CA Azur 340A)

vlatko

vlatko

New Member
Sound sample here. The rattle is at the 0:35 and 1:39 mark.

https://soundcloud.com/user-7676983...d&utm_medium=text&utm_campaign=social_sharing

Anyone have any idea what causes this? It happens sporadically, sometimes every 10 seconds, sometimes every 30 seconds, sometimes it doesn't happen for a while. It's very annoying.

I tried disconnecting all the inputs(CD, Chromecast Audio, TV via AUX) and it still happens.

I'm pretty sure it's the amplifier because it happens when I plug in my Beyerdynamic DT990 headphones as well.

The components;

Cambridge Audio Azur 340A integrated amp
Cambridge Audio Azur 340C CD player
KEF C5 speakers
Chromecast Audio
 
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I suspect it's some form of electromagnetic interference (conducted or radiated), getting in to the amp. This suggests a rectifying contact somewhere; a dry solder joint. Plus a source of interference; large electrical equipment nearby that has some pulsed operation? Or a large Russian radar installation...? (google 'woodpecker radar').

Its possible that there might be some circuit instability in the amp, but that would normally be a high frequency, not a tapping.
 
WaynerN said:
but really it sounds like a relay chattering briefly.
Click to expand...

That's a thought, but I was assuming it was coming through the playback chain (i.e. speakers), rather than the amp making mechanical sound itself. OP needs to clarify; I thought the headphone reference meant it was playback chain.
 
The sound is coming through my speakers and/or headphones if they are connected. It is not coming from the amp itself.

It is also subject to volume change, ie it is barely audible when the knob is at 25% volume, very audible at full volume (this was recorded at some 65% volume).

The amp is inside a cabinet. There is a lot of equipment there but everything is separated, though there's lots of wires behind probably touching (but it's like that for 15 years, this is only happening for maybe 2 years)

PS5, cable modem, STB from TV, AMP, CDP, TV above. Pic attached.

20220505_175643.jpg
 
cpt_paranoia said:
That means the problem is prior to the volume control.

Does it happen with all inputs, or just one? This will further isolate where the fault is.
Click to expand...
It's hapenning irrespective of the input selected. Like I said I tried disconnecting all the inputs(CDP, Chromecast Audio, TV AUX) with nothing but the speakers connected and it still happened.
 
vlatko said:
It's hapenning irrespective of the input selected. Like I said I tried disconnecting all the inputs
Click to expand...

Having the inputs disconnected is not the same as selecting different inputs.

If, when you select different inputs, the problem still occurs, then that isolates the problem to some point between the output of the input selector, and the volume control.

Or the power supply.
 
cpt_paranoia said:
Having the inputs disconnected is not the same as selecting different inputs.

If, when you select different inputs, the problem still occurs, then that isolates the problem to some point between the output of the input selector, and the volume control.

Or the power supply.
Click to expand...
Hmm... I understand. I'm pretty sure I noticed it on multiple inputs, between the 3 I use, but I will double check and report. Thanks!
 
@cpt_paranoia I just tested 2 inputs, AV/MD and tape, which were never used basically and I can confirm pretty much it happens no matter which input is selected.
 
Nearby as in inside the cabinet or under few meters vicinity? Inside the cabinet no but 2 phones are often somewhat near the cabinet, when me and the missus are home.

Fluorescent light is a nope.
 
Hmm.. I just disconnected my Chromecast audio from power source and it's been a couple of hours and I did not hear the rattle once.

Fingers crossed that is the culprit. Chromecast audio was right on top of the amplifier.
 
Try moving the Chromecast unit away from the amp. It might be RF bursts being picked up by the amp. .
I noticed from the trace on the audio sample that there appears to be a slight build up of noise just before the staccato burst..
This could be RF noise bursts being picked up be the amp and rectified into audio frequency pulses which is why it sounds like a staccato woodpecker.
 
Guys, just to let you know, I am 100% woodpecker free, haha. It was the Chromecast Audio. Moving it away from the amp solved the rattle.

Thanks all for the help and inputs.
 
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