[BC] Mac Amps

[R J Carpenter]

From: "Owner" <owner at broadcast.fm>
Subject: [BC] Mac Amps

> One of Mac's best tricks was an amp they built earlier than the
MC-240 and
> MC-275. I think it
> was called the 20W2 or similar, and it got an honest 20 watts RMS
out of a
> pair of 6V6's.

> The tube manual says you get 10 watts max. But McIntosh not only
tapped the
> transformer
> primary, they had additional primaries in series with the CATHODES!
I took
> the one I had to one
> of the Mac Test Clinics, and Dave changed the tubes, and ran the
curves. 22
> watts out at 20 Hz.

I wouldn't be surprised if that was one of the designs that Peter
Sulzer did for Frank MacIntosh.  MacIntosh lived in the DC area as did
Sulzer.  I know Pete did at least one Mac amplifier, probable more.
He was quite prolific as a designer.  You might remember the high
stability James Knights crystal oscillators - a Sulzer design.  The
Heathkit very low distortion 3-digit switch-tuned audio oscillator - a
Sulzer design.  The amazing thing about Sulzer prototypes was that
they were "basket-weave" construction - not built on a chassis. His
lab had the prototypes hanging on nails on the wall.  He built one or
more vacuum tubes while in high school back in the late 1930s..

When we sold WHFS, MacIntosh's son became chief engineer.  Let us say
he didn't have the old man's genius.  And they never asked me to help
straighten the technical things out after they maved the station and
were off the air for an extended period.  That was well before Jake
Einstein's ownership..

bob c.