N_Cook wrote:

This is the amp in question
http://home.graffiti.net/diverse:gra...net/peavey.jpg

That is about the worst excuse for a 'heatsink' I have seen in my entire life.
It's utterly pathetic. In fact it's completely WRONG in just about every way
possible.

I have seen another that came close to being that bad but even so at least there
were a few more vanes on it (C-Audio btw). The company I was with was
considering taking the C-Audio design as a OEM product and re-branding it, but
my tests showed a heatsink temp of up to 150C with a 40C ambient on music test
signal. This was enough to cause several of the output mosfets to fail
open-circuit and I only realised that when later bench testing it and finding
asymmetrical clipping.

After declining their offer of the product I later found they'd added more
heatsinking but it was a kludge.

Just for good measure, C-Audio also exhausted the searingly hot air right over
the PSU electrolytics ! These were well known to need regular replacement which
C-Audio justified as they said they were a 'service item'.

My own designs (including one in the local venue) are known for working day in,
day out for years on end. I think the one in there is getting on for 10 years
old now and is used every night although not every night is a 'loud' band. It
has had a 'blow through' or two of the heatsinks and 2 new level pots (only one
went crackly but it's best to replace both whilst you're at it, and yes, they're
NOT pcb mounted so it's an easy job too. Compare that with a QSC RMX 2450 I also
had to do the same to (labour time approx 4:1 ratio).

I never fail to be amazed at the number of amps that illustrate that the
designers are completely incompetent when it comes to thermal management.

And don't even get me started on power transformer design !


Graham