On 21 Dec 2006 05:36:58 -0800, "Telstar Electronics"
wrote in
. com:

wrote:
Why would you put any energy into an audio speech processor?
You yourself have even discounted the usefulness of audio speech
processing when commenting in the past about Lou Franklins model.
Are you trying to tell us that you can re-invent a more useful wheel?

You are absolutely right... I don't like Lou's design. His design clips
the hell out of the audio signal... and then attempts to filter his way
to sucess. Nice idea, but doesn't work well. However, I never said that
other types of processing didn't work.. or weren't effective. Reinvent
the wheel... no... Analog Devices has already taken care of that... I'm
just using their IC chip in my design. The audio distortion is very low
with this chip.


The distortion specs for the chip are given so the designer can decide
whether the chip is good enough for the studio or stage; for CB radio
it's overkill. Regardless, you missed the point once again: audio
compression -IS- distortion. IOW, hook it up to a distortion meter,
crank it up to 15:1, start talking and that needle will bounce all
over the place. The chip also has some other issues that you really
need to research first.

Want a decent compression circuit? Start with a bucket-brigade chip
like the old SAD-1024. That way the control signal can be adjusted for
a peak -before- it slams into the VCA. This eliminates the need for
frequency compensation, which is a common problem with real-time and
feedback types of compression circuits, including the SSM2166. It also
allows you to get higher compression with no distortion from spurious
harmonics that would otherwise need filtering. And the circuit has a
couple other benefits: it reduces feedback which is great when some
dope modifies his radio for talkback, and you can use the chip to make
some really cool sound effects such as echo and reverb.

But I suppose it's easier to hack someone else's design than learn
things for yourself, isn't it, Brian?