MOTM

I have an open question about something that's bugged me for years.

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.

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?

I've seen the same reversal in many other modules, even vocoders, where the
voice input is called the "carrier," when in fact it is being used to
modulate another input, and therefore should be called the modulator. Right?

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.

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.

Yet years later, I seem to be the only person who's ever heard of this. And
it seemed like such a good convention. Did my mentors make this up? It would
seem to be a pretty localized convention.

Thank you for indulging my crankiness.

In a message dated 99-10-25 09:09:04 EDT, you write:

<< 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.  >>



ken,
without dragging out all my old books to double check, i can`t recall 
anywhere in the literature that such a distinction was made. some just 
arbitrarily called them 'sawtooth" , others favored "ramp" and i don`t recall 
there ever being a mention about calling them different thing based on 
positive or negative slope.
best,
dave

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

No, you're right-it is an arbitrary distinction. But there was a movement to
MAKE a distinction that apparently didn't leave the East Coast.

		-----Original Message-----
		without dragging out all my old books to double check, i
can`t recall 
		anywhere in the literature that such a distinction was made.
some just 
		arbitrarily called them 'sawtooth" , others favored "ramp"
and i don`t recall 
		there ever being a mention about calling them different
thing based on 
		positive or negative slope.