[Boatanchors] Speech Amp Again

[J Forster]

IMO, it's a good idea. The filament transformer will be somewhat lossy above a
KHz or so and will saturate at high levels under 50 Hz so, but you are not
going to broadcast concerts.

-John

===============

Rich Post wrote:

> Hi Barrie,
>
> Do you have a junk box 12 volt power transformer capable of an amp or
> two?  Check the no-load voltage with 120 in.  If you find it at 13 or, best
> of all worlds, 14 or 15 volts,  hook it up in reverse to your 8 ohm output
> amp.  It will likely work quite well.  The 15 volts gives a turns ratio of
> 8 to 1 which, when squared, gives an impedance ratio of 64 to one.  Fed
> with the amp's 8 ohms out, you will match 512 ohms in the secondary.  With
> 14 volts, you will match 587 ohms.
>
> This note will probably start another flame session but "been there - done
> that".  As has already been mentioned, it's not that critical.
>
> 73,
> Rich KB8TAD