Amp problem solved?

Been away for a few days, system powered down completely (power amp first) and unplugged.

Back today, powered it back up (power amp last) and found, to my surprise, when the CDX2 was playing a disc but volume on 202 reduced all the way anti-clockwise, the MF unit and tweeter on the RH speaker still worked, playing the music consistently. Turning the volume up brought all the other drivers on, LH too, and all sounded fine. Reduced the volume again to zero and the RH MF/tweeter carried on playing. There was also a faint short buzz from the RH speaker when operating buttons on the NARCOM 4. Otherwise, everything seemed fine.

Tried a bit of simple troubleshooting, to no avail. Eventually, powered down the 202 & 200 (not the CDX2, since the troubleshooting suggested this wasn’t at fault) and, to my surprise, it seems to have solved the problem. Everything is now as expected, reducing volume to zero does exactly what you’d expect.

Both amps were serviced in 2022. Is this a sign that something might be amiss, or is it just one of those things?

Mark

In the absence of a firm diagnosis I would be a little suspicious of a fault condition developing in the amp that might have nasty consequences for your speakers. Personally I would keep the amp powered down until you can get it properly checked out.

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Update:

  • Left system on overnight to stabilise.
  • This morning, problem had returned, exactly as yesterday. Power-cycled just the NAPSC (and so also the 202’s logic circuits). Problem slightly improved, but still there.
  • Left a disc playing whilst out for an hour or so. Problem remained on return. Left well alone whilst having lunch.
  • Problem then seemed to have gone, so put on a CD. It’s sounding great. Problem seems to be coming back, but it’s much reduced.

Will give the dealer who arranged the service a call.

Mark

To me… (YMMV…) this sounds like a problem with the 202 - :thinking:

I’m not disagreeing, but the dealer was sanguine, saying he thinks this is a normal artefact of the way the volume control works. He’s going to check with their rep and get back to me.

Mark

I wonder whether this might give any clues to @NeilS as to what may be happening here?

I’ve only ever heard anything like this at a very low level when operating the volume or balance - probably just picking something up from the motors when they are in use.

So… why only on 1 channel - not both…?

I thought so too, but that symptom seems to have stopped!

Currently, I’m getting a tiny amount of sound from HF and MF units on both speakers when volume is reduced to minimum with a CD playing. It’s nothing if not inconsistent!

If anyone else with a 202 could quickly check whether anything similar happens with theirs, I’d appreciate it…

Mark

Virtually the same thing happened to my 202/200 system over the Christmas holidays. Whilst streaming music through my NDX2 the balance of the sound abruptly changed with the left speaker decreasing in volume and the sound becoming ‘tinny’ with a loss of mid/bass. Turning the volume up brought the full sound back. I then turned the volume down to zero but sound still came out of the right speaker, the left was silent. I tried using the remote to alter the balance but it only produced an extremely loud static noise, so I stopped.

I spoke with Naim technical support a couple of days ago and they asked me to try a few things as they believed any one of the Naim boxes could be at fault, though they believed it would end up being the 202.

Placing the NDX in standby and back on again made no difference. Using the tuner input rather than CD made no difference. Powering down the amps and then back on again (leaving the NDX streaming) immediately resolved the problem for a while but it returned after a few hours. The next suggestion was to replace the amps with an old AV amp, but this requires a new lead which I’m waiting to be delivered.

I’m convinced it’s the 202. My dealer doesn’t reopen until Monday so if the AV amp works fine, I will box up the 202 and get it sent back to Naim then.

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Gosh, that is similar… though not identical to what I’m experiencing! The sound with the volume at anything other than zero or near-zero is absolutely fine, as always, including the L/R balance.

Currently I’m on my second album today and it’s fine at the moment. Normal volume sound is great. Turning volume to zero with music playing still leaves something coming out of the HF & MF units, but it’s very low level now: only just audible from my usual listening position (~4m from the speakers).

Thanks for the suggestions for further troubleshooting if it gets worse. Until and unless it does, or I hear back from my dealer, I’m minded to leave it alone.

Mark

I would expect some HF bleed-through to occur with an analogue pot when at the minimum position. This is due to inconsistencies within the volume pot & crosstalk via the pot wires.
Also some pot motor noise will be picked up by the gain stage which is downstream of the volume pot. (FYI this noise will be exacerbated when not using a PSC).
@Ebor if these issues are very low level, this sounds normal.
@KIT your unit sounds like it has a fault.

Regards
Neil.

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Thank you, @NeilS - I’ll be periodically checking nothing changes, but that’s very reassuring.

The house was quite cold when I first switched the system on and has now had chance to warm up. I wonder if that’s why the symptoms were worse (and only evident on one channel) at first but have now settled.

Mark

Thank you @NeilS, no doubt my 202 will be arriving back at the factory next week!

makes others wonder if power quality affected use/audio…

I used to live in a suburb with REALLY POOR quality power.
When using a power board with DIP switches that allowed setting high and low voltage cut offs, there was not setting open enough to let the power companies ‘power’ come through. (the result being an abruptly shut down projector, something I wished to avoid)

When living in a suburb with such poor quality power, what became obvious with regards to audio/audio systems were a few things…

At certain times of day (say ‘people home from work’) everyone in the neighbourhood would increase their power needs… (in a suburb already underdelivering)
(so ‘air con’ in summer/‘heating’ in winter)

During such times, music quality changed.
Some equipment even installed ‘gremlins’ (acted unusual)

Knowing that the 3rd iteration of the Nait XS3 limits 2ohm and 1ohm output (vs the XS2) whilst otherwise still having the same headroom characteristics; might Naim be doing some great tricks in their power deliver systems and having the equipment vary its’ operating mode/‘modus operandi’

Perhaps when the power gets less than ideal, it has a fallback mode that operates a little differently as in the cases highlighted above?

(not really confident this is the case, but ‘food for thunk’)

Dealer got back to me, having checked with their Naim rep.

The volume pot used is a unit which sounds good, hence why Naim use it, but it does suffer from a certain non-linearity at very low settings. Therefore, they’re happy to say that my observations are normal and nothing to worry about, as also suggested by Neil.

I think I can probably relax now.

Mark

When the volume is at zero on my 52 I can still hear the music from both speakers albeit very quietly. Just reminds me to pause the streamer when I go to bed :blush:

Having done a further check just now, there’s now barely anything audible from either speaker (with a track playing and the volume right down) - I now need to have my ear right up to the speaker to hear it. When I started the thread it was much louder: easily audible from several metres away. I suspect warming the system (and house!) up has settled everything down.

Mark

I always switch inputs to what I’m using then switch it off when not.
Just select an input not running.
I always stop the device playing when not required but leave them switched on in not playing mode.

I think you may be talking at cross purposes with Naim and/or the dealer. This is NOT normal. Sounds like an issue with the volume pot. Have you tried rotating the pot up and down all the way about 20 times to clear any rubbish off the track and see if this gets rid of the problem?

At the risk of stating the obvious, me too. The only thing that made me do differently last week was that I was powering the system up from cold, so had the volume at zero. Slightly absent mindedly, I wanted to get a CD playing straight away to help everything warm up, so started playing one but forgot the volume was still on zero, hence why I heard an effect most of us never normally encounter.

Anyway, the responses I’ve had from dealer and @NeilS, plus the lessening of the effect as time has gone on and the fact that my system is now sounding every bit as good as ever all add up to my being satisfied all is well.

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