Olive NAP 250 going 'mute' overnight

Need to pick my fellow Forum friends' brains before I turn to the Support.

My vintage, olive set (72 / HiCap / 250) was re-capped in October 2016 and has been a joy to listen to.  It's paired with Quad ESL-63s.
I use it every day, as my office set.

During the last 2-3 weeks I noticed that every second or so day, NAP 250 'mutes' itself overnight. Unplugging it, waiting for the caps to discharge and powering it up again helps.

Any theories what may be causing this?

Thanks

 

Adam

Original Post

Difficult one Adam - it's going into protection (i take it the front panel light is on but it's muted until you power off / on again). I'd power down the whole system and check all is well with all the connections and see if that helps. If not, then i'd get it checked out by Naim. 

Richard Dane posted:

Is it going into protection mode?

Do your ESL63s have the crowbar protection circuits fitted or are they later units? 

I think they do have it fitted, but I need to double check with the previous owner.
I also asked the Naim service department to have a 'quad-mod' fitted to the NAP250 at a time of service (hope they remembered to do it).

james n posted:

Difficult one Adam - it's going into protection (i take it the front panel light is on but it's muted until you power off / on again). I'd power down the whole system and check all is well with all the connections and see if that helps. If not, then i'd get it checked out by Naim. 

James - exactly the symptoms - lights are on, but nobody's home...

Not sure if this helps.... I noticed the problems started appearing when I added my trusted nDAC to the setup (the source is a Yamaha streamer NP-S 2000, which is actually a surprisingly capable 'beast'). Coincidence? 

It could be related Adam so it would be worth giving everything a thorough check to see that you've got no loose connections.

If this doesn't find anything, to rule out the speakers causing the problem (as it appears to happen overnight when you are not using the system, especially if their Crowbar protection is triggering for no reason) then can you substitute your ESL's for another pair of speakers to see if the problem stops ?

Adam, IIRC the Quads need to have their protection updated as the old crowbar type did its best to kill amps - essentially presenting the amp with a short circuit. Naim used to warn against using earlier ESL63s with Naim amps. It won't be doing your NAP250 any good, even if is robust enough (for now) to withstand such abuse.

A short update - checked with a fellow Forum friend, who supplied the speakers...

The ESLs have the OTA protection which is quite mild so it should not be a problem.  I reckon it could be voltage surges when the office block empties and electricity consumption is reduced.

I guess I will just switch the power amp off over night - this should be ok. It’s the the pre-amp being powered that is most important.

 

Adam Zielinski posted:

I guess I will just switch the power amp off over night - this should be ok. It’s the the pre-amp being powered that is most important.

 

No, I think it's the other way around, the pre-amp can be powered off, but the amp should stay on for the best in sound quality.

In addition I will run some tests of course, including different speakers to see what is causing this issue. I might take my NAP250 home at some stage to see how it behaves when part of my home systems.

I also have another theory - there seems to be a lot of static electricty in the office these days - new carpets, new furniture. It’s porobably affecting ESL63s which in turn affect the amp. So I will probably start with a different speaker test....

Adam Meredith posted:
badlands posted:

No, I think it's the other way around, the pre-amp can be powered off, but the amp should stay on for the best in sound quality.

This would be news to me - and everyone else but you?

Everyone else but me? How about every major amplifier maker!  Below is a sample from another manufacturer, and there are more examples.

I guess I'm not the only one who believes this to be true.

Operating the 880M
 
We recommend leaving your 880M powered up at all times to maintain optimal performance. When you plan on being away for a few days, it may not be a bad idea to power off your amplifier. Please keep in mind that once fully “broken-in”, your  880M requires several hours of operation before reaching optimal performance after powering it up again.

 

 

badlands posted:

Everyone else but me? How about every major amplifier maker!  Below is a sample from another manufacturer, and there are more examples.

I guess I'm not the only one who believes this to be true.

Operating the 880M
 
We recommend leaving your 880M powered up at all times to maintain optimal performance. When you plan on being away for a few days, it may not be a bad idea to power off your amplifier. Please keep in mind that once fully “broken-in”, your  880M requires several hours of operation before reaching optimal performance after powering it up again.

Which says NOTHING about whether the pre-amplifier should be turned off.

You also have to wrestle with:

"On and Off Sequence

To avoid having any annoying noises (ie. “thumps” and“pops”) emanate from your speakers when powering your880M on or off, you should always power up your pre-amplifier prior to powering up your 880M.

As well, always power down your 880M prior to powering down your pre-amplifier."
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