[R-390] Headphone recommendation

[Tisha Hayes]

If you can find them a 8:600 ohm audio transformer is a better match than a
AC power transformer of the same ratio. What may be overlooked is that
there is a frequency response to a transformer and that by taking a
transformer that was intended for 60 Hz service and putting it to 300-3000
Hz audio service is not going to give you ideal results.

Looking at it simplistically, the winding ratio may be right but the
performance will be sub-par. They are really going to roll off at higher
frequencies.

I have found external radio speakers that were intended for connection to a
300/600 ohm audio source. Hammarlund made some, some were made like the
LS-474U were made for the US Navy (4 watt, 200-5000 Hz, 600 ohm input
impedance). I really do like the LS-474/U, it is a very smart looking
speaker in a grey metal case. There is even a blank knockout so you can
install an audio level pot on the front of the speaker.

For headphones I bit the bullet and bought a set of "cans" an AKG K-240
"studio" headphones. You can get them for about $100. Be aware that there
are different versions of the K-240 (studio, sextett, monitor, DF" and they
have different impedances. Beyond those headphones would be something like
the Sennheiser HD 25-13 II for around $300. These are all recording studio
grade headphones but are available at 600 ohms.

If you do find a speaker like the Hammarlund or the LS-474/U you can add a
jack after the transformer so you can plug in conventional 8 ohm headphones
to the front of the speaker (another use for that blank knockout on the
LS-474/U.

-- 
Ms. Tisha Hayes/ AA4HA

*Republics decline into democracies and democracies degenerate into
despotisms.*