MOTM

In a message dated 10/25/99 6:09:17 AM, Ken.Tkacs@... writes:

>Many synth modules have two inputs that act upon each other, and these
>are
>typically called the "carrier" and "modulator." Now common sense says that
>the "carrier" ought to be the signal that is being modified, and the
>"modulator" is the one doing the modifying. At least whenever such a
>distinction can be made.


I usually refer to these as signal source and modulation source respectively.

>In the case of a balanced modulator, the question is sort of moot because
>both inputs are being symmetrically multiplied. Paul side-stepped this
>whole
>issue by just using "X" and "Y" which pretty much tells the story. But
>other
>BM's-notably ones with built-in sine wave oscillators for the shift (for
>example, the Blacet 'Klang Werk')-call the LFO the "carrier." Doesn't common
>sense dictate that this should be the "modulator," since you're using it
>to
>tweak the sound of another, more primary wave that you are supplying?


Yeah, I think Paul's designation of X and Y is more better since it refers to 
the cross product output rather than Balanced Modulation (or Ring Modulation) 
which I'd think have more applications in radio applications -- there are 
radios called "single side band" which use a ring modulator and either a high 
pass or low pass filter to cut the unwanted side bands.


>A friend suggested that, since much of our audio-shaping circuitry was
>originally inspired by radio & telephone engineering, that some of the
>lingo
>may have been ported over poorly as the circuits were being swiped, that
>the
>reversal may have made more sense in the original applications. Could be.
>I know it's nit-picky, but these are the things that keep me up at night.


Well, as I understand it, in radio telephony (i.e., the old days -- even pre 
Bradley!), the voice "modulated" the microphonic diaphragm which ... and 
finally "modulated" the speaker. In AM communications the microphonic signal 
modulates the amplitude of a fixed frequency "carrier" wave. So you are 
right, because you are wrong.

>As long as I'm being crabby on a Monday morning, and the coffee is taking
>forever to brew, let me air out another, similar grievance. I fully realize
>that a "positive-going" sawtooth wave and a "negative going" one have
>identical harmonics, differing only in their phase alignment. But when
>used
>in control applications (LFO), this becomes an important distinction. When
>I
>was taught electronic music many yahrens ago, I was beaten into calling
>positive-going waves "ramps" and negative, "sawtooths," with full knowledge
>that these were arbitrary names for otherwise identical waves. But I was
>told that these were agreed-upon conventions in the E-Music world to help
>make things simple.


Never heard of this -- though I like the method of pedagogy (beating the 
knowledge in, you can't beat that)! I have seen Moe drag a saw across other 
Stooges heads before, seemed pretty negative going to me.

Oscillator alligator!
John Barlow
41 for a little while longer
(almost unbearably) sunny So Cal
Miles Davis Complete Bitches Brew Sessions -- current fave