Crackling NAP 500

Hi guys,

I have got a problem with a freshly DR-upgraded NAP 500. Perhaps one of you have had a similar problem.

I replaced my NAP 300 with a preowned NAP 500 from 2011 which has DR-ed at Naim last month. At the beginning it has played well - very very well to be honest. It is a big step in sound quality.

But after one day playing I noticed a kind of distortion on the left channel. It was like a crackling. I swapped the speaker cables at the output of the NAP 500 and the distortion went to the other speaker. Although it is not a speaker issue. Then I played a single frequency of 140 Hz from a ripped test-CD. When the volume gets over 8-9 o’clock an additional frequency was noticeable on the left channel. This additional frequency was quite louder and higher than the original frequency of 140 Hz. This problem only occurs on the left channel at different frequencies.

I also played this test signals from the CD over the analogue input of the pre. The same problem occurs. I reinstalled my 300 and everything was alright. I have done the cabling of the 500 completely new. I used spacers so that no cable touches another one.

I went to my hifi dealer to test the NAP 500 with his equipment. Astonishingly the distortion was not noticeable. But I only could test the 500 for about one hour. And the average volume was not so high than at home. Back home everything seemed to be alright, but only one day. Now the crackling is there again.

I do not really know what to do. Did anyone had a similar problem? Thanks for help in advance…

You’ve had it a day. I think you need to go back to the dealer. The 500 should still be under their warranty (and I assume they had Naim do the DR work, so that should be warranted too). If you aren’t happy with the 500 then the dealer should be able to get to the bottom of it. I wonder whether @NeilS has any ideas what may be at issue here?

Thanks Richard. Yes, I could claim the warranty. I only thought that it would be easier to check, whether anyone in this forum has an idea. I did not buy the 500 at my local Naim dealer, so I have to ship it - and that is no fun with such a big box.

Hi Chris,

I haven’t heard of your particular issue, but it sounds like it definitely has a faulty component affected by temperature. Transistors are a usually the smoking gun for crackling issues, which means it could also be oscillating.

I would recommend not using it until the fault is resolved, as further damage to the output stage (or worse, you speaker) may occur.

Hope you get it back on song soon.

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