"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.

W4ZCB

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."

On Thu, 30 Oct 2008, Scott Dorsey wrote:

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.

And of course, one commonly written about trick in the old days was to
use a "useless" 400Hz transformer as an audio transformer, the operating
frequency being about where you'd want frequency response to start for
communication use. Since it moves the frequency up by six, the frequency
response is probably better at the higher frequencies.

That's only a useful trick, though, when 400Hz power transformers are
commonly available, and cheap because nobody can find a use for them.

Michael VE2BVW

Michael Black wrote:
And of course, one commonly written about trick in the old days was to
use a "useless" 400Hz transformer as an audio transformer, the operating
frequency being about where you'd want frequency response to start for
communication use. Since it moves the frequency up by six, the frequency
response is probably better at the higher frequencies.

That's only a useful trick, though, when 400Hz power transformers are
commonly available, and cheap because nobody can find a use for them.

I still see PLENTY of 400 Hz transformers coming out of the surplus
pipeline today, not to mention 400 Hz motors and brick power supplies.
You want some? I think I even have a box of 400 Hz fluorescent light
ballasts somewhere. Not even a little bit useful.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."