NAP 135 warm up

Hi everyone

Just purchased a nice pair of olive 135s whichvI intend to get serviced.
I swapped them with my 250 just to make sure they were ok etc and they sound pretty good.
I used to own a pair of chrome bumper 135s back in the 90s and remember turning them on about half an hour before use and then off again afterwards…sometimes overnight.

Is there any consensus on how long they take to warm up properly?

Many thanks


My 250 sounds fine in a few minutes - but better after maybe 1 hour…?


Yes, I left my 250 on permanently oddly. Just assumed the 135s are meant to be powered down?


IME, and to my ears, Naim kit of this era was designed to be left switched-on, the primary reason being to retain warmth in the large toroidal transformers.

Personally, I wouldn’t be powering down if you intend to listen to the system regularly.


Why would you assume that 135s are meant to be powered down when not in use and not 250s? Naim have always recommended that all their equipment is left powered up for optimum performance.
There has of course been discussion here recently of how that might be avoided due to soaring energy costs, and even occasional concessions that we might be destroying the planet by using too much energy. In that context it has been discussed that a power amp might warm up quicker than a source and preamp, and that turning off just the power amp could be an acceptable compromise, although I don’t ever recall the 135 being singled out for such treatment.
My dealer has in the past left power amps powered up overnight to make sure that they are giving their best in a demo the following day.


Interesting subject. Perhaps after servicing I’ll experiment with leaving them on permanently as long as the fans dont kick in when not being listened too. (My old chrome bumpers did that having never been serviced)


There’s certainly something wrong if the fans run when the amps aren’t playing anything! I would only expect to hear them kick in after extended play at high volume unless there was a problem with speaker compatibility, mismatched speaker cables, or a fault.

I would be tempted to leave them on for a while, then maybe start turning them off overnight and see if you notice any difference.

Leaving on vs. turning off.

“On” will sound better instantly, but will cost electricity and the capacitors are likely to require replacement earlier (heat accelerates their demise).
“Off” will mean it takes 30 minutes or so to sound good.

From a sound perspective, leave it on. For cost and capacitor life, turn it off.
A balanced position is to turn it off when not in use, and turn it on 30 minutes before use.

On the other hand the switch on inrush currents in the power supply cause a LOT more stress on components than does running in steady state.


Yes, the only time I’ve had problems with components is when switching them on. All my hifi is left on 24/7 unless there’s a compelling reason to turn them off.


It’s all a balance. Don’t forget the wear on the switch, naim’s liking for eating fuses…All depends how much you use your set up. If i’m away all week the lot is turned off. At weekends, just the power amp goes off at night.

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All great contributions…thank you.


Keep them switched on all the time. Switching them on and off all the time is more likely to cause problems with blowing something such as relay. Also the initial surge of power turning them on isn’t great doing it daily. You’re pitentially trip your circuit breaker with the big inrush of current.

They will be cool in temperature when left on with nothing playing and will warm up when played loud. The fans kick in at higher volume extremes.

Enjoy your 135s.

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Should be serviced every 10 years. Not using amps dries caps up. I leave on all the time unless I go away or threat of lightning strike.

If there is threat of lightning I unplug everything including router.

Hi Clive, If these were bought from Tom I wouldn’t bother servicing them just yet as they are sounding lovely and haven’t had a hard life. They should be left powered up for the best sound. Hope you enjoy them, they are a big step up from a 250.

Leave them always on - after an hour they sound good.
But even when you start to listen music with all system switched permanently on it sounds better after 1 hour music flow… but this could also be the other components or ears relaxing

They were indeed bought from Tom…lovely chap!

Paperwork says they were last serviced in 2010 or 11. Think they probably could do with a visit to Class A to be on the safe side.


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I have left mine on 24/7 for the last 5 years. The only time the fans come on is during a heatwave and when playing loud at the same time. Even then you can barely hear them between tracks. If they are sounding great now then no rush to get serviced but you will hear the difference when you do. :blush:

I would get them serviced by Darran and hang on to the 250 if you haven’t sold it yet. Then sell the 250 once 135s are back.

I’m still surprised this question gets asked. Unless you’re uncomfortable with leaving gear on, powered on is the best practice for optimal performance.

This is not exclusive to Naim. I even leave my tube gear powered on.

Oh and btw the 135s take a lot longer than 1 hour to sound best. If they’ve been switched off for a long period of time I’ve noticed improvements after many days. I’ve had two pairs of olive 135s. Serviced and prior to servicing the results were always the same. Leave on.

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