[BC] nominations for best sounding AM in your area?

Mark Humphrey mark3xy at gmail.com
Tue Feb 23 11:00:25 CST 2010


Let's talk some more about asymmetry.  It's standard practice today to
put an all-pass network ("phase rotator") ahead of the AGC,
compressors and limiter and then make the waveform artificially
asymmetrical by clipping negative peaks harder than positive, but is
there a practical way to eliminate the phase rotator and let the
natural asymmetry of voices pass through, thus reducing some of the
clipping distortion?    Wiring all of the in-house mics for the
correct polarity may not be difficult, but then we have to deal with
material produced elsewhere which has a 50/50 chance of coming in the
way we want it.   What's the consensus on this?

Some have also argued that the phase rotator improves action of the
compressor and limiter, but it seems a shame to destroy the natural
quality of voice when asymmetrical modulation is indeed beneficial.
Many AM processors designed 20-30 years ago had an automatic polarity
flipper, but as I recall these didn't always work well.  Our original
limiter at WCJW was a Gates "Solid Statesman" with a relay circuit of
this type.

In my collection of junque, I have a Kahn "Good-n-Loud" (salvaged from
the dumpster of a station in Buffalo) which was designed to force
asymmetry by increasing gain on the positive half of the waveform,
rather than clipping the negative.   Leonard Kahn once gave me the
sales pitch for this box at an SBE show and it seemed to make sense.
He admitted that the process adds even-order harmonic distortion, but
that's considered "good" and increases loudness, hence the name.   Who
still uses one of these?

Mark



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