Amp volume fluctuating....help!

Hi All,

I’ve got a NAIT 5 amp which I use with a CD5 player and external inputs (laptop or phone) via a 3.5mm plug/DIN lead.

When I play anything through the 3.5mm plug, the volume at the speaker surges up and down, constantly and seemingly at random. I’ve been running this setup for months but this problem seems to have only gradually phased in over the past couple of weeks. It’s showing no sign of going away. The CD player through the same amp/speakers sounds great without a trace of a problem.

Can anyone offer any advice on how to resolve this?

Thanks.

Is there anything that might emit an IR signal when you use the 3.5 mm plug? Does it still happen if you cover up the IR sensor on the amp so that no light gets through?

Hi, thanks for the note. Nothing nearby emitting IR to my knowledge and I’ve covered up the sensor and the problem persists…

Is it a NAIT 5 or NAIT 5i?

If the former then have you tried a different input for the 3.5mm to DIN cable. And have you tried the CD player on the input that you were having problems with the 3.5mm cable? Just wanting to nail down whether it’s an issue with a particular input.

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Have you tried connecting headphones to the phone output to confirm whether the fluctuation is happening in the phone or the amp?

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Richard…terrified I’ll jinx this now but you seem to have deftly identified then and provided a practical solution to my issue. Thank god for all those input ports and thank you very much for your help.

Putting the CD player through the ‘defective’ port didn’t seem to compromise the sound of it either! Happy days…

That’s good news but still something of a mystery.

Yep. The phone and laptop outputs are fine. Thanks for the note.

Cheers, yep. I’m hoping it’ll be another couple of decades before I need to move onto the next port though. Might paste a reminder onto the back of the unit, just in case…

Nait 5 and CD5 is a nice pairing. Why not add a flatcap to power both?

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Couldn’t this simply be a poor connection, somewhere…? Try a different lead or two…?

Or - does the NAIT5 have its DIN sockets PCB mounted - and so could be strained by connecting…?

Well, the reason why I asked for clarification as to whether it s a NAIT 5 or a NAIT 5i is because the former amp has some unique facilities, such as each input having adjustable gain. It could be that one input has an issue with that. Otherwise, what is a known issue with some of the early NAIT 5s (but not the very earliest) is that the TI volume encoder can go faulty. Naim updated this to an ON encoder with later units, or any afflicted early units. However, AFAIK this would affect all inputs, not just one. I wonder whether @NeilS has any ideas here…?

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Yes, great idea, and very worthwhile.

Hi Guys,

This sounds like a classic case of the early single gang volume pot going noisy/faulty. The volume pot drives the resistor ladder with voltage rather than an audio signal, when the pot fails or becomes noisy it causes fluctuations in the voltage & hence the audio level.
Sorry to say that I surmise the issue will rear its head again before long & the fact that you have only witnessed it on one input is possibly a coincidence.
The revised double gang pot & PCB have so far proved more reliable.

Regards
Neil.

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Hi all and thanks for all the comments. @Ardbeg10y, re flatcap, something to think about assuming the NAIT isn’t on its last legs (and I can find a spare £1k…). @Richard.Dane, pretty sure it’s a 5, not a 5i as it’s got 8 buttons on the front? @NeilS, oof, just when things were looking up, it’s behaved fine for a day now but wait and see I guess…are the issues you describe economically repairable? Cheers.

Yes, we would perform all of the updates on any N5 returned to base.
If you drop tech support a line, they will be able to give you an idea of service cost.

Regards
Neil.

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