Will a simultaneous power up cause damage?

We’re currently having the bathroom converted to a wet room and things haven’t gone smoothly - not least the fact that the fuse box is the old Wylex type so the fitting of the new shower can’t be signed off.

I’ve just got back from taking my Dad for a hospital appointment to find that the electrician has called round to look at the fuse box and possible work rounds, despite being told yesterday there would be no work done today.
He’s turned off the power to look at the fuse board with both systems powered up. What is the likelihood that the simultaneous power up of the Naim boxes (main system: CDS3/XPS2, NAC 252/SCDR, NAP300DR & PS, SuperLine/SCDR, 2nd system Nait 5i & CD5i) has caused damage? I’m a bit miffed because I’ve been powering down each night in anticipation of the power being switched off.

When my wife told me what had happened I checked both systems and they were powered up as normal - the only clue being the lit up input selectors. I would have anticipated (hoped?) that the fuses would have blown and protected the boxes. The fact they didn’t leaves me a little worried. Should I be worried @Richard.Dane ?

Other then breakers tripping (or with an oldie worlde supply, the circuit fuses blowing), what is at risk is the speakers from a power on surge. If they sound okay at all levels, then it would seem no damage has been done.

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Cheers. Just checked there was sound from all sources and in both channels - haven’t turned the wick up yet so fingers crossed …

Chances of any damage are highly unlikely. Powering all up together happens at times like after a power cut. Ive never heard of anyone having any kit damaged afterwards.
Anyhow, if its all back on and working then you’re definitely ok :+1:


In what way are speakers at risk with a simultaneous power on vs independent power on?

I’ve had a couple of power down/up with full system going back on at the same time. Same click in the speakers from my NAP500 as when doing it the right way. The pre turning on is a super small tick, not anywhere near the one in the 500. Nothing that could take out a speaker.

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If the power amp goes live and manages to pick up some kind of signal then it can go full output without the control of the pre amp. This could damage the speakers.


Never heard of this and I don’t understand technically how this would happen either. “Pick up some kind of signal”?

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If the power amp has come fully on before the preamp properly powers up, or if pre and power come up to power (and volume control not at zero) before a connected source component kicks in, there could be a “switch on thump” through to the speakers. Practical possibility and likelihood that simultaneous switch on will depend on the exact equipment In use.

Similarly, a simultaneous switch off can cause a thump because the power amp has reserve in its reservoir capacitors.

That is why good practice is always to turn the power amp on last and off first.

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I’d imagine it will be fine. Naim kit is typically robust. We have regular little power cuts here - usually when the live wires that run down from the road get touched by tree branches or a squirrel gets zapped. Often everything comes back on within 30 seconds or so and I’ve not lost any of the Naim kit yet as a consequence. Let’s hope I haven’t just jinxed myself now…


I now power down each night. One plug pulled on the dc blocker that feeds the 552/300/ (4 boxes), streamer (3 boxes), phono stage (2 boxes), and P8.

No problems with either shut down or start up.

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My old NAP500 (non DR) make a rather big thump sound when powered on even though it’s the last box I put on. I have understood that is how it was designed. DR boxes doesn’t sound much at all. Also, there is a pre-amp delay meaning it can never be turned on fully prior to the amp when the full kit is powered on at the same time. I’d say the risk for anything potentially happen to the speaker is extremely low. I believe the biggest risk is for the power boxes/amp being turn off and on too quickly so the caps haven’t discharged fully. It is often read in manuals to not put on and amp earlier than around 30s from when turned off. My former tube amp blew a capacitor once when I turned off/on too quick swapping tubes. Naim amps are for sure more solid.


Thanks for the replies. Feeling a lot happier now.

When you say ‘old Wylex type’, does this mean you don’t have the modern-day RCBOs fitted to any of the house circuits?

If an outcome here is the need for a new consumer unit (a.k.a. ‘board’), be careful that the right type of ‘breakers’ are fitted – I think type Cs, as others can trip due to the surge currents involved with some Naim kit at switch on.

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My equipment is always left on, unless an electrical storm is forecast (with lightning flashing around). It may add a few pounds to my annual electricity bill, but I know that it’s ready to play music at any time.

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That’s correct. They’re the old type where you rewire the fuse if it blows.
The main problem is the new type boards won’t fit in the space where the Wylex board currently resides. I believe they’re looking at installing a single modern type fuse for the shower. Not sure of the legal implications but as the wet room is funded through a disability grant with input from the local authority I don’t think corners will be cut.

I had two power cuts early on in the morning a few days ago apparently a high voltage issue with the network, nearly 2000 houses in my area lost power. The second one was presumably due to them trying to get the last 450 houses back and instead accidentally caused more of us to disconnect again. I was stalking live updates on the power network’s website.

My ps5 is a giant drama queen when it looses power every single time it has to pretend to repair the entirely undamaged storage and remind me not to turn it off improperly (as if I had anything to do with it). And the router takes a good 10 minutes to sort itself out.

The naim kit was totally fine and behaved like normal no issues at all.

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I had my Wylex consumer unit replaced recently, the new unit fits in the space that the old one did, there was even room to fit a double pole isolator switch for the consumer unit itself.

You can fit push-in breakers instead of the fuse which is what I had in place for many years.

The normal type B is fine even on my XPS DR which are known to be troublesome.

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Have had simultaneous power ups many times thanks to power cuts whilst I was out or away. Never been an issue. If you leave your system on then both turn the volume down and mute your current input there is effectively zero chance of an issue.

I also don’t see how the pre/power thing works. If they’re on the same circuit then the pre is on and soft resetting with a mute on. The pre would have to fail because of some kind of power surge. Frankly the most likely component to fail/blow a fuse in that scenario is the power amp.

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That’s exactly what I do.

The pre doesn’t control how much output the amp makes, really. It only controls how much signal is going into the amp. If the pre is off when the power amp turns on, then no signal is going into the power amp. The only way that a problem could then arise is if there is something odd about the pre - such as feeding a voltage spike into the power amp when it turns on. I don’t think Naim amps do that. I used to get that sometimes with another pre-amp (one that I made) but never with a Naim. We used to get loads of power cuts here and never had a problem when the power came back on.