|[AMRadio] AM Speech processing|
jpl15 at panix.com
Mon Jan 23 15:06:23 EST 2006
In regard to the several very interesting threads regarding AM Hi-Fi,
intelligibility, and audio bandwidth / spectrum efficiency - I have some
personal observations, and devices I use in my shack...
It is sometimes quite instructive if a recording of your QSO can be made
- especially if adjustments are carried out during the course of the QSO.
Several folks on the bands are set up to record and playback over-the-air
- and there a few who can render these recordings into a computer file
which can be forwarded to you, or which you can can hear on a website.
This will go a long way toward helping 'tweak' the audio side of things.
There are multitudes of cheap audio processing devices available - on
eBay and elsewhere. Of course a "good" mike is number one, and in that
regard you generally get whatcha pay for. Then, it's hard to beat the
combo of a small audio equalizer feeding a compressor/limiter of some
The EQ allows you to tailor your audio bandwidth for the task at hand -
'broad' for HiFi work, 'narrow' for DX, or to eliminate some of the
(wasted) energy in the bottom octaves when intelligibility is the issue.
The compressor of course allows a maximum of audio energy to be applied
to the transmitter for a given modulation percentage - in my case with the
Valiant it's a very dramatic increase in signal level and 'punch'.
Generally you can get these two devices for around $100 total - then
it's possible that your microphone will need a pre-amp (if it's not
already "powered"). I'd certainly consider the Compressor first, though.
It's an easy 'fix' that might wake up some signals out there - good audio
Just my 200 millidollar...
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