In article ,
Frank Stearns wrote:
(Scott Dorsey) writes:

Frank Stearns wrote:
I need to cobble together a single-channel two-way mic splitter -- one
output "flow through" and the other transformer isolated.

I've got an ancient Triad line-to-line audio transformer: each side has
600 ohms with taps for 250 and 50 ohms. (Model number is rubbed off, but
it's a metal can, 3/8" stud mount, roughly the size of a shot glass with
leads coming out through the stud,)

This is not the right sort of transformer for a bridging splitter. For
a bridging splitter you want a high-Z-to-low-Z transformer, so that the
bridging load does not much affect the load that the microphone sees.

Well, heck. I rumaged around and found a UTC 0-1: 50K on one side and
500/200/50 on the other and also another Triad with 85K on one side and
600/250/50 on the other.

I figured 50K+ through a transformer might be too high to drive the low
side with any respectable amount of level. I'll try it.

Thanks, Scott.

A 50K to 600 is going to be just fine from the standpoint of the mike...
your only worry is that this is such a high ratio that you may wind up
with poor S/N on the split output because you're knocking the voltage down
so much. Try it and see!

Note that the $12 Tamura 600:600 microtran types from digi-key are actually
not bad if you use them for dual isolated splits. They can't handle very
high levels before the low end drops off, but for stage mikes they're really
not bad. Their higher ratio transformers are pretty awful, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."