[Icom] Icom 756-Pro II audio/mic input alternatives

Sun, 2 Jun 2002 15:50:35 -0500

Hi Marty

I think you and Adam may be talking apples and oranges. I am also interested
in high end audio and fully appreciate the musicality inherent in the low
bass (my subwoofer and its built-in amp would pay for a pretty good radio
receiver). But when I am trying to break through an HF pile-up to get some
rare DX, I want to get maximum "bang for the buck" out of my ham system,
which means cutting the highs and the lows as recommended by Bob Heil and
implemented by him in his microphone products and by Icom in the 756 Pro
circuits if desired.

Bob Heil, incidentally, is also a professional musician who has recorded
organ CD's (lots and lots of bass!!) and was one of the first pioneering
experts in rock concert amplification--incredible amounts of bass--ear
splitting! The "mellow full AM sound" may be fun to play with on HF SSB, but
efficient it is not. You might even argue that the attempts at "mellow
sound" on SSB violate the FCC regulations' restraints against using "any
more power on HF than is necessary to establish readable communications"
:-) I think relatively few hams are interested in sounding like a broadcast
station as opposed to putting out the most efficient signal possible. It is
certainly a legitimate endeavor, however, if that is your interest and you
can resist the temptation to use "California kilowatts" like many do,
splattering all over the band.

Andy  K5VM

----- Original Message -----
From: "HFSSB" <[email protected]>
To: <[email protected]>
Sent: Sunday, June 02, 2002 2:08 PM
Subject: RE: [Icom] Icom 756-Pro II audio/mic input alternatives

>
> It's unusual to find fault with Adam's outstanding contributions to our
hobby
> but re-reading Adam's comment here I see that the error is in the latter
part of
> this statement, "... to cut off low-frequency components of the microphone
> output (below 250~300 Hz). These components contribute virtually nothing
to
> articulation at the receiver,..."
>
> If we could take everything out of normal conversation below 250-300 Hz we
would
> quickly miss the richest sounding component of the human voice, the bass.
By
> putting this lower audio component back into the SSB signal we are adding
the
> fullness in the human voice giving it a more "life-like" natural sound.
Adam's
> statement is then only true if you receive with filters cutting off these
lower
> frequencies.  Today however, there is tremendous interest in SSB audio
> improvement and you have Hams listening on rigs with filters opened up
from 0 Hz
> to 3-4k, even 6k if conditions allow.
>
> The problem comes when a novice in HiFi SSB (of course, we all start out
as
> novices) over-drives the low frequencies which then overpowers the mids
and
> highs, that's when you hear comments like "mushy audio".  There is a
learning
> curve to the Ham audio hobby as in most things worth while.  With the
exception
> of prejudice against the audio hobby itself, everyone who listens to a
properly
> balanced Hi-Fi audio SSB transmission on a properly adjusted and capable
> receiver (meaning filters open from 0-50 Hz to 3k or more and a decent
spkr or
> studio headphones) is at awe of the sounds that can come through in SSB
mode.
> It is not unusual to hear comments like "Sounds like FM broadcast
station".
>
> I have heard half a dozen or so 756 users who use the acc jack and without
> exception said they get better audio results by going direct to the
balanced
> modulator.
>
> Marty
> http://groups.yahoo.com/group/hfssbaudio/
>
> -----Original Message-----
> Adam I don't know what you know technically and I respect your knowledge
> however I am amble to run my Heil HC5 through the W2IHY EQ and noise gate
> and get a nicer and more full range of audio by going direct through the
> balance modulator than through the front mic input ...
> 73, Steve
> ----- Original Message -----
> > Larry,
> >...the design intent
> > is probably to cut off low-frequency components of the microphone output
> (below
> > 250~300 Hz). These components contribute virtually nothing to
articulation
> at
> > the receiver, ....
> > Best 73,
> > Adam, VA7OJ/AB4OJ
>
>
> ----
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