On Mon, 27 Sep 2004 17:23:18 -0700, Rick Williams wrote:
>Is there any add-on device that can be used to take the
>rig audio and shift it up or down a few hundred hertz in an attempt to
>optimize my friend's limited hearing range?
You do NOT want to shift the pitch, you DO want to adjust the frequency
response to emphasize the highs and de-emphasize the lows. An IF shift can
do this to some extent and may be enough in some receivers. But the most
common method is simply to apply audio equalization to the receiver output.
You want an equalizer, which is simply a high priced word for what are
essentially fancy and more versatile "tone controls."
Many pro audio companies make equalizers, and good ones should be pretty
easy to find on EBay for not a lot of money. One caution though -- look for the
better units that don't have RF interference problems. One of the better
companies in this regard is Rane, based near Seattle. One of their octave
(good), 2/3 octave (better),or parametric (best) equalizers should work quite
well. Tapco is another good mfr, but they didn't make the parametric type.
Ashley and White are some other good companies.
Your friend would use these between the audio output and his headphones.
Unless he has really severe hearing loss, most would probably drive good pro
headphones directly (he will need to make a simple cable adapter to plug in the
headphones to the unit's output). If his loss is more severe, he might also
want
to add a headphone amplifier. Rane and Shure both make good headphone
amplifiers.
Jim Brown K9YC
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