I have a 52/SC with 135’s all recently serviced by Naim.
One of my 135’s keeps closing itself down (overheating) when driven hard. I sent it back to Naim and they confirmed it’s all good, which is confusing.
I use Focal 967Be speakers with Witchhat Spectre cables.
Has anyone else had this issue or should I consider changing my power amps and if so what should I consider?
I would swap them over and see if the same one keeps shutting down.
If it does then it sounds like something isn’t quite right. If the other 135 now shuts down then it’s something in your system causing the issue.
But could it just be something as simple as the limit stat in one amp is slightly set lower or it’s range not quite the same after all these years and just cuts out slightly before the other one, rather than both at the same time.
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I’m wondering if the problem is due to instability somewhere. Are both 135s equally hot when this happens ( the thermal cutout acting a little sooner on the tripped 135, the other just about to trip out ) and has this problem suddenly appeared after servicing? Are the WH cables a recent change ?
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I’d suggest, check all your connections and interconnects carefully (e.g. make sure the connections are robust), including 'speaker cables – and as Dunc suggests change these over if you can on a step by step basis to see if you can isolate the cause.
The 135s should be able to play loud vis the Focals, unless you are really pushing them (fans on and all that), and if you push things too hard, especially via a digital source, it could be the 'speaker isn’t happy and causing the 135 issues e.g. somehow generating an intermittent short/ some clipping (latter unlikely - but who knows).
And things like coiled 'speaker cables should be avoided – and the cables should be the same length.
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Hi @NeilA1,
Are speaker cables hanging loose and unwound properly or bunched up or coiled?
I have had 52 SC 135s and drove system very hard. The fans came on all the time but never shut down.
Something is going on. Suggest you look at speaker cable dressing. Also when was 52 and Supercap serviced?
When I had your system everything was serviced and had no problems.
Also what’s your racking? Is there enough air around 135s? Or are they stacked on top of each other? Are they on shelving or in a cabinet. With no pics I am struggling to understand what’s going on.
With my 135s, the fans started quite often despite moderate load. I would suspect that it is not the fan from one channel that starts too early, but that the other channel’s fan does not work properly.
From an electrical point of view, the monos actually wanted nothing else than A5/A4. Does the WH cable actually meet these specifications?
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…and yes, several times they were so offended that they shut down. Never had this problem with the (fanless) 250…
My experience is that one 135 power amp would turn off when listening to it at a slightly loud volume. The repair shop couldn’t find the cause, and it was due to the hfe of the BC239C TR on the drive board.