NAIT 5 faint rumbling / hideous noise when powered on

Hi all, first post and excuse my lack of knowledge.
I have owned a NAIT 5 from new (20+ years!) which connects to my Rega P3 via a Project phono stage. I listen to vinyl daily and to say this setup has serviced me well is an understatement!

I get a faint background rumbling through the speakers when no music is being played, This is intermittent but fairly regular, i.e. I notice it most days. It got so bad I turned the amp off. When powered back up it makes a terrible collection of pops and clicks, from what I can tell this is only on the left channel. This continues while the amp is muted, until the mute button switches off at which point the noise stops.

I should mention I had the amp serviced a year ago by an unauthorised servicer who have unfortunately gone out of business. This was mainly because of the power-on noise. Post service it still made the noise and was sent back a second time which seemed to resolve the issue.

I suppose my question is - before I bite the bullet and send this back to NAIM for another service, is there any way this is a problem with something external to the amp i.e. power cord, speaker cables etc. I have powered up with only the speakers connected and still makes the noise.

Welcome Mat. Firstly just to say I’ve made a small edit to ensure your post complies with forum rules regarding unauthorised modification/service discussion.

As to the NAIT 5 I reckon the expert to advise here would be @NeilS.

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It very much sounds as though the problem is internal to the Nait 5. One way to eliminate the cables is to either borrow some from a dealer, or take your amplifier to the dealer and check it there.

Assuming it’s the amplifier, you don’t have to send it to Naim. Class A in Sheffield are the only Naim approved service agent in the U.K., using Naim supplied parts. They - well Darran actually, as it’s only him - is cheaper than Naim and considerably quicker if you don’t want to be without music for weeks. He can usually turn stuff around with a week. I’ve sent stuff to him, as have many others, and I can strongly recommend him.

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Rumbling is often a sign a capacitor has gone out of tolerance, perhaps a decoupling capacitor.
I would get the amp servicedby an authorised servicer - if not Naim themselves

Simon

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Plus 1 for Class A. Used him a couple of times now and he is very good.

DG…

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Hi Mat, does your Nait still do this with all of the inputs disconnected?

Worth checking that the flexi-link at the back is undamaged.

Regards
Neil.

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Thanks, I’ll look up Class A.

Funnily enough I did this yesterday after posting this. I haven’t noticed any noise yet (except for the power-on noise which persists). It has been powered off for a week or so so i’ll mornitor for a couple of days.

A good call from Neil here. The flexi link on the NAIT 5 was always a bit of an achilles heel - so easily accidentally damaged, you can see why a fully shrouded solid link was used thereafter on the integrated amps that followed.

Carefully unplug it (while the NAIT is switched off) and check it over then plug it back in. Just doing this a few times will clean the pins and sockets anyway, which might actually cure the issue (fingers crossed!).

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Check the ribbon connector, as Richard says.

Being non-techie, the best I would be able to do would be hold it up to a window and see if the metal tracks were complete.

C.

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Make sure you get it properly repaired, the original Nait 5 is a great amp. It’s hifi, refinement, timbre, versatility but also fun. If paired with easy loudspeakers.

My ribbon is broken need to get a replacement.

Can you define an easy loudspeaker in this context please? Typically the most benign loads are large exotic high efficiency speakers with an ultra simplified cross over if at all providing a pretty flat impedance curve. Perhaps not the typical match for a Nait 5. For example often the smaller the speaker the harder the amp needs to work for a high grade performance.

I guess you mean relatively large high efficiency two driver speakers?

Simon

Many years ago I bought a SuperNait 1. I paired this with B&W CM1’s. I needed loudspeakers for my tv too, so I bought the CM5’s. Both were fine with my SuperNait. I got an offer and bought the original Nait 5. Got it serviced so that it was in good condition. I was very much surprised by the quality and performance of my Nait 5 but it was paired with the CM5’s. I wondered why I bought the SuperNait in the first place really since the 325 euro Nait 5 could do more or less the same as the SuperNait. Then I tried the cm1’s with my Nait 5 and the difference became clear. It was a grey, uninvolving sound. Nothing of the joy of the SuperNait driving the cm1’s (for this reason I call my SuperNait a slave driver since it seems to enjoy giving a bit power). My assumption has always been that the efficiency of the CM5’s compared to the CM1’s was the difference.

The Nait 5 now does well with my CM5’s but at some point in the future I’m looking to find the ideal loudspeakers for my Nait 5 and build a system around the amp. I like it very much.

If anyone has recommendations …

Thanks for explaining.

This is a paradox I’ve long wondered about. Everything about small speakers - price, size, limited bandwidth, limited SPLs - implies that they’re most at home with similarly modest amplification and sources, yet I’ve found that they usually need a higher quality signal than their bigger counterparts to really show what they’re capable of.

To put it another way, I’m currently very happy with my ProAc Tablette 10 Signatures but, if for some reason I had to replace my entire system with something more basic, I’m not certain I’d buy them again. At the very least, I’d audition alternatives in different sizes and designs, and in different price ranges.

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Simon,

I used to have Klipsch Heresy III - not very exotic, nor very large and didn’t even have a simplified crossover… But were sensitive enough at 96+dB.
As sometimes happens when you have gear stated to be simple to pair with other gear, I spent days studying the best type of amp. :slight_smile: I ended up learning funny things about loudspeaker/amp matching.

It seems that sensitivity is not the most important parameter to consider; impedance and its phase pattern are more. I learned that an LS3/5A, with its 92.5 dB/11 ohm load, is considered a very easy speaker for amps, especially tube ones. My super sensitive Heresy never seemed to be happy with any amp. They just sounded fun and energetic with a PrimaLuna EVO 100, push-pull of EL34.

To sum it up, the more a speaker system is seen by the amp as a pure resistive load, the happier the amp. Watts are just a means to make it sound louder. But I’m sure you know all this already. To me it meant ceasing to predict a system’s behavior and plan a given result.
Now I rely on luck, looks and low expectations. :slight_smile:

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It looks like something going bad with heat. Hopefully not a transistor. How’s it going since you last posted?

@Mat what happened next?