Ed Engelken wrote:
An ordinary filament transformer with a 120 volt primary and 12.6 volt
secondary will work well. The turns ratio is about 10 to 1 and that
yields an impedance ratio of 100 to 1. That will match a 600-ohm
output to a 6-ohm load and will provide a decent match to an 8-ohm or
4-ohm speaker. A small 1 amp. transformer is sufficient. --Ed

Note that the frequency response may be deficient... then again, it might
also be great. Those Western Electric wall warts that were used for
princess phones used to be flat from 50C-10KC easily and I saw more than
one broadcast station that used them as improvised audio transformers. On
the other hand if you buy a modern Talema toroid from Digi-Key you'll find
the response drops off dramatically above 100C or so... which is great for
keeping power line trash out of power supplies but not so good for audio.

If you don't know, run a 1 KC square wave through it with the loading you
intend to use and watch the output on a scope. The calibration output on
a Tek scope is just fine for the application.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."