Sirs,
The thread about quiet cooling of amplifiers made me think back to
my college days when among studies of alcoholic consumption,
music appreciation and techniques for attracting YL's I studied
pipe organ construction and repair.
The musicians do not want to hear the air blower mechanism when they're
keyboarding and neither does any audience or congregation.
What pipe organ builders do is to isolate the blower in another room
and use a "wind-column" to supply the wind chests under the pipes
with pressurized air.
Could not this technique be applied to amplifiers? Remove the noisy
blower from the shack and connect flexible hose to a clamped fitting
on any equipment needing cooling. A much beefier fan could be
employed than would fashionably fit on a rear apron, and a
manifold system could be arranged so that more than one piece of
gear could benefit