[R-390] Sound powered headphones?

[Dan Merz]

Robert,  I have a couple of pairs that I bought for crystal sets - they are
great and better than the venerable Baldwins that I used before.  I think they
are around 200 ohm impedance ,  depending on whether they are hooked series or
parallel for the two ear pieces.  I bought input transformers to use to get a
good match.  As you probably know,  there's plenty of info online regarding
various transformers in the xtal set domain..   I can't think why they would
enhance a 390 or 392 since there's plenty of audio gain available.  For a one
tube regen,  there would probably be an advantage for weak stations - you would
have to have an appropriate transformer,  high to low impedance.  I'll have to
try this sometime with some of the simpler regen sets I have. Dan

Robert Goff wrote:

> Does anyone have any experience using sound powered headphones with a tube
> radio?
> They're prized by crystal radio builders for their extreme sensitivity.  I
> have a pair of "deck talkers" and have wondered how they would work with an
> R-390/392 or even a one tube regen set.  If I'm not mistaken, the impedence
> is a bit lower, something on the order of 100 ohms, so they would require
> some sort of matching network.
> Anybody have experience with this?
> Thanks,
> Robert Goff
> W7MKA
>
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