Arfa Daily wrote in message
...

"N_Cook" wrote in message
...
Arfa Daily wrote in message
...

"N_Cook" wrote in message
...

Having a great deal of experience of these, I feel they are a
fundamentally
well-designed and constructed amp - both electronically and mechanically,
and I don't think that I would contemplate altering any aspect away from
the
way it was designed, including the arrangement of the heatsink fins, and
the
airflow paths. The heatsinking and cooling of the heatsinks *is* adequate
as
designed, but becomes a bit marginal if the units are thrashed hard on a
regular basis, whilst the air intake vents are allowed to clog. If the
transistors / heatsinks of both channels are cleaned down and repasted
during the repair process, and the owner is alerted to the importance of
just scrubbing a soft paintbrush around the vents once in a while, they
are
unlikely to give further trouble. I've never had any repeat failure issues
with them, anyway.

I take your point about the inner 'row' of fingers, but I don't think I
would feel inclined to bend them in more than a few degrees, otherwise,
they
might actually block convection off the transistor cases ??

Arfa




I have to differ on the aerodynamics. This sort of 4mm wide double wall,
staggered finger design, is for convection not passage of air through. Walls
of 4mm gap blocked by 4mm finger repeated four times each side of the fan (2
h/s in line each side) is pretty effective wind break. Then 2 "gaps down the
sides of 3mm wide x 35mm high and 70 mm long is similarly "resistive". Most
cooling would be the 2 outer edges of 12 only of the 44 vanes each h/s where
there is unobstructed passage outside the heatsinks and out to the
surrounding duct