[Amps] Acoustic Noise Comparison

[Jerry Kaidor]

> Spot on, Jim.
> The 76A and the 78 suffer from both vibration and turbulence, with the
> effects compounded by resonances in the sheet metal cover.

*** I do have some "Dynamat" left over from a car project.  I might try
a few pieces of that stuck to the top & sides - in places where there's
nothing for it to short out if it comes loose - which doesn't seem very
likely; the stickum on Dynamat is extremely agressive.   The casing is
pretty thick metal - but it sure does ring like a bell when you tap it.

>
> Better blower mounting and fuzz would help a lot, a scattering of braces
*** By "braces" I assume you mean narrow strips of metal welded to the
case so they stand up at right angles to it?  My cover has a couple real
good
scratches in the top, so it needs to be bodyworked anyway.  Unfortunately,
according to Mr. Magnet, it's aluminum.  I do have a spool gun for my MIG
welder that's supposed to be able to weld aluminum, but I've never tried
it yet.  And that's assuming it's a weldable *alloy*.

   The amp came to me without rear feet, so the back of the cabinet is
resting on the desk.  I have ordered new feet from RF Concepts, along
with the new blower.

                            - Jerry Kaidor