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Old October 30th 08, 03:18 PM posted to rec.radio.amateur.boatanchors
Scott Dorsey Scott Dorsey is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 774
Default Hammarlund SP-210 ?

Harold E. Johnson wrote:
"Henry Kolesnik" wrote in message
...
What's an easy way these days with limited audio xfrmrs around to get the
600 ohm spkr output to 4 or 8 ohms?

120 Volt to 12 Volt power transformer. Good at least down to 50 Hz or
better.


The problem isn't the low end, the problem is the high end. But the ratio
is about right, and if you pick a good transformer you'll be okay.

Problem is that a lot of cheap transformers have poor core material that
leads to a lot of distortion, and a lot of the better transformers are wound
to specifically limit the frequency response. For example, the Talema toroids
from Digi-Key are great at 60 Hz, but down 6 dB at 500 Hz and keep falling
above that. This is a great thing for a power transformer where you don't
want to leak noise into the power line or the other way around, but it's a
bad thing for audio.

But there are a lot of filament transformers out there that are quite
reasonable for audio, and they are cheap enough that you can try a whole
bunch of them and see which work best.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."