The fan in the 425 is a custom assembly that TT made out of standard parts,
augmented with rubber grommets to insulate the vibration. After years of
use they get hard and lose their insulating ability. The grommets are
pretty standard, and I recall finding the sizes I needed in a Radio Shack
assortment pack when I replaced mine about two years ago. TT no longer has
replacement fan assemblies.
There is also a piece of foam insulation strip (the kind with the sticky
stuff on the back that comes in a roll at most hardware stores) that goes
between the squirrel cage output manifold and the opening it fits into in
the box with the tube sockets. It acts as both sound insulation and a
gasket to keep air from leaking out. If this has moved or has deteriorated,
it could cause the rattling noise. Also, a bad motor bushing could cause
IIRC I needed to remove the filament wires from the back connector to remove
the fan to be worked on. Also, getting the new foam insulation strip back
into place was a real magic trick in itself!
----- Original Message -----
Sent: Monday, December 24, 2007 3:52 AM
Subject: [TenTec] how to quiet fan noise on 425 amp
> Are there any proven approaches to quieting down the fan noise on the
> TT 425 Titan amp? Slow speed is tolerable (but not great), but High speed
> just causes lots of "rattling" noise.
> de Doug KR2Q
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