The 1937 Speech Amplifier

After Restoration
1937 Homebrew Speech Amp
This speech amp has three inputs, two can be seen on the front.  The input
on the left is for a high-Z mic.  The center jack and one on the rear apron
are for high level, low-Z balanced sources.
For the mic input, the tube line-up is a type 57, a 2A6, then to a pair of 56's for
the output.  All inter-stages and the output are transformer coupled with UTC's.
The line level inputs bypass the 57 and are transformer coupled to a separate
2A6 for each input.
Remarkably, this amp worked without anything being replaced, even the power
supply filter caps.  It is still working now and I have been using it on my BC-610
with very good reports.

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