[ICOM] Headphone pre-amp

[mecker at peoplepc.com]

Headphones and related info.
I am also a hearing imparied ham, with a 70 decibel hearing loss
(but one heck of an x-ray tech, out of work though)

I use hearing aids that have direct input via a input cord that
connects to the back of both aids.

Most AF amplifiers will not output as much as modern hearing
aids and direct this energy into the ear canal as well as a hearing
aid does.

My hearing aids connect to my dsp unit and headphone jacks of my
radios (since I need the hearing aids anyway) I have to be
extremely  careful not to overdrive the hearing aids since
they are so small and dont handle heat dissipation and are easily
distorted.

Another way is to use the hearing aids T switch and an
inductance transmitter (this transmitter takes audio from your radio
and turns it into a magnetic field, which your hearing aid might
be able to pick up (if so equipped) and return it to audio.

Headphones will provide a  accross-the board eq response, which
you will need to adjust the eq first (an outboard eq unit) and then a rather 
high gain
amplifier, like heil clear speech or something, and then put your headphones
that jack, which is much higher amplified than your rigs
jack. Headphones, in general, are tough to use when your loss
reaches a certain level, yet consider what I have written here.

 Most of our HF rigs have some eq, but you will need
more than 5 bands because for the kind of amplification we
both need, it will cause severe pain to amplify too much of the
lows (to the point of operator intelligence understanding) and operator 
"static" fatigue. (unless you have a low frequency hearing loss, then you 
have it rough)

Lastly, you are being emailed by a guy who has a 70db loss and still
gets on 160M!! I have a heck of a time hearing sometimes, and politely
explain this to the other operators on the air. Quite often, I will be
able to check into a "cliq" net that others cant because I
must be so forthcoming and honest about my hearing, lest suffer the
consequence of other operators yelling at me cause I didnt understand
what they said. This is not a cure, and I still miss stuff, but
we hearing impaired hams know how to have fun while not
hearing every single word. Digital is the future for us.
-73s, Marc KE2BP

--- Original Message ----- 
From: "allan1 dejazzd.com" <allan1 at dejazzd.com>
To: <icom at mailman.qth.net>
Sent: Monday, August 04, 2008 9:41 PM
Subject: [ICOM] Headphone pre-amp


>I have a PRO 3 and thoroughly enjoying it it. I am hard of hearing in one 
>ear However when some sigs are in the noise and I can barely hear them, I 
>would like to turn the af higher, but it's already at the max. I have 
>additional rf pre-amps besides the internal ones. I realize that the s/n 
>won't change, but that's okay since I'll be able to copy it.
>
> Anyone have any thoughts?
> Thanks
> Allan W2TN
>
>


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