So a pair of Koss PRO4AA headphones arrived today. These have
a 250 ohm impedance.
The discussions of higher Z is better seem to hold water. I've
noticed the following relatively dramatic improvements, compared to
my unusal low Z monitor headset:
1. The CW switching transient in the left headphone channel is
significantly reduced -- still there, but no longer an issue as far as
I'm concerned
2. The steady high pitched digital switching "whine" that many
observed early on with low Z phones is gone completely at normal
listening levels. If I crank THRESHOLD all the way up and then
crank AF gain all the way up I can still barely hear it -- but that's not
exactly normal operation :-) I think I recall that T-T fixed this in
newer production radios, so this may not have been something
many of you experienced.
3. High frequency background white noise that I always noticed with
my old headset is completely gone (and the Koss is a MUCH better
headset than the old one ... and a lot more comfortable in the
bargain ... so it isn't rolloff in the headset).
Probably just pointing out the obvious ....
Grant/NQ5T
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