I have 2 systems. Main one is all Naim 500. I have bought a Sugden Sapphire for my other system. They run very hot so I am interested in getting a substitute for when it’s hot, like at present. I have an option of keeping the NAP250DR which is what’s giving way to the Sugden. Alternatively, I’m thinking about a non-DR NAP500 which will still be a bit pricey. Advice please. I obviously can’t try out an old NAP500
Isn’t it the case that Naim power amps work best with Naim pre amps?
A quick look suggests the Sugden kit operates in Class A (Naim is much cooler Class AB), so it will run hot if left switched on (with accompanying electric bill), even when ambient is far cooler than the recent UK heatwave has been.
Can you be more precise on what you’re actually seeking and why, as the kit list in your profile indicates you have a 500DR?
A simple answer would be to turn the Sugden kit off when not required, as it should warm-up in short order.
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The Confidence 20 is a bit of a handful so I see why you may want something more than the 250DR. Having the Sugden and swapping it for something else when the weather is hot seems a bit excessive, and how will you judge the ‘too hot’ point. Running a power guzzling Class A amp is environmentally dubious too. I’d return the Sugden, sell the 250DR and get a pair of New Classic 350s. Great sound, all year round, with no faffing about swapping things over. A few on here use 350s with Linn and are really happy with the combination.
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For the purpose of this topic, I’d say that “hot” isn’t a number. What ambient room temperature are we talking about?
If you wish to go cheapskate, Rega do a number of good half width amps for a substitute.
They doesn’t cost an arm and leg, are superb sounding but do get a bit warm on the cabinet.
Not as much as Class A Sugden though.
Another substitute is a Nait 50, maybe it even wipe the 500 series.? 
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Thanks HungryHalibut. It’s a long story. I have amassed a large amount of kit I don’t use or need anymore and found a dealer who would take it all in part-ex. For personal reasons it is expedient to downsize. The Sugden was the outcome as the dealer was the best bet by a long way. Also, it’s a one box and I’m a bit fed up with separate power supplies (my main room has 7 boxes). I think I will take your advice and let the 250 go - it’s part of the part-ex. Installation of the Sapphire is next Tues. I will post what I think of it
There’s more accurate than number, the touch. If you can’t let your fingers on, it’s a problem. Better switch it off.
Apart tubes amps.
Ah, I thought it was the power amp, hence the idea of the 350s. The Sugden looks lovely but I’d feel guilty using all that power. We don’t have many hot days really, and having one amp you use all the time seems much easier. I don’t have any spare equipment at all, just the Atom HE and three Qbs, all of which are in regular use.
There are two sentences there. I disagree with both of them (sorry). The first, touch is subjective and not more accurate than a temperature reading. The second, it depends on the amp. Many are designed within ambient temperature tolerances and heatsinks can reach to near boiling by design. Or somewhere less hot but again, subjectively uncomfortable for some hands.
I would again state that “hot” is not really helpful in gagueing the problem. If the OP is an Eskimo they might be talking about a room temperature of just 25C which would be cool to someone else and certainly not a problem for any amp.
As a side note, given the great cost of these amps, air conditioning will cost less than an equivalent cool running amp.
FZ, you took too seriously my sentence.
Generally, letting outside the Eskimos or people with special sensitivity, touching an amp , even class A, should not burn your fingers. Not?
My class AB AV receiver is pretty hot. About 50C.
Some class A amps you absolutely cannot touch. It really depends on the design. And some people have different pain thresholds.
I can think of a couple amps you could fry an egg on.
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Ok Doc Zen, I surrender.
Call me little beetle.
Years ago I had original Quad 57 speakers. I ran them with the Bedini 25/25 which was class A and ran rather hot. NYC can get hot in the summer and the amp never posed a problem. A classic pairing I might add. After about 30 years of being discontinued, their web site says it is now back in production.
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I think Sugdens are a great amps I really like them. They do run hot but they are designed to and even in warmer ambient temps will be fine. The components used are designed for high temperatures some well in excess of 100 deg c.
Unlike amps such as Naim it is normal even recommended (by Sugden) to switch them off while not in use.
When you switch a Sugden on from cold it should reach optimum in about 20 mins give or take.
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Thank you all. I will let the 250 go and see how the Sapphire works out. It is a bit like Xmas approaching! Very exciting - I haven’t used anything other than Naim amplification for more than 20 years but my NAP 500DR will always be Number 1
Not so. Class A amps can sit there happily with cooling fins at 60c or more, too hot for more than the briefest of touches.
@pumpexch is your concern the amp temperature, or its effect on the room temperature?
If the former, check with Sugden (it may be in the amp spec) for the maximum environment temperature, and only be concerned if the location where the amp sits exceeds it. FWIW I have my amp, also class A, in a cupboard with louvre doors and big rear vent holes, but have a thermostatically controlled fan in the back of the cupboard to create an airflow through and across the amp’s heatsinks. I also always turn the amp off between sessions - it only takes half an hour or less to get to full operating temperature.
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I have Sugden Sapphire amps - the DAP 800 pre and the FBA 800 power amp. Being a Class A amp the heatsinks on the side of the power amp do get hot to touch as it’s designed to.
The Sugden FBA 800 amp is excellent and I’m pleased with mine. I also have a Sugden A21SE integrated which I use occasionally as spare and that runs even hotter!
Unlike Naim, Sugden amps are not designed to be left powered on when not in use for obvious reasons. I’ve had no issues running mine. I hope you enjoy yours.
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