MOTM

One cool thing I had noticed on the Serge Ring Mod has a control voltage
input over the Mode of operation, from VCA to AM to RM. Perhaps an idea
of this sort could be considered for the next MOTM Ring Mod.

Scott

Let's see: the Pan/Fade stuff will come with the 130.

I think along these lines at the moment:

Dual VCA, with one of them switchabe lin/expo,
and the other one switchable lin/RM, where RM means
continuously variable from direct signal over AM to RM
(like that Korg PS-3100 modulator, or the CS-80 Ringmod).

Just an idea - nothing promised yet. But I'll come up with something
you will love, and which will not make the 130 redundant.

JH.


-----Urspr\ufffdngliche Nachricht-----
Von: Scott Evans, Gen Mgr <esresource@...>
An: MOTM <motm@yahoogroups.com>
Gesendet: Dienstag, 30. April 2002 02:00
Betreff: [motm] Future idea for MOTM Ring Mod

> One cool thing I had noticed on the Serge Ring Mod has a control voltage
> input over the Mode of operation, from VCA to AM to RM. Perhaps an idea
> of this sort could be considered for the next MOTM Ring Mod.
>
> Scott
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>

At 8:02 PM -0600 2002/04/29, Adam Schabtach wrote:
>What's the difference between AM and RM? I mean, isn't a ring 
>modulator essentially a multiplier of two signals, which means that 
>the instantaneous output is the product of the instantaneous 
> amplitudes of the input, which means amplitude modulation?
>

RM is a four quadrant multiplier, whereas AM is only two quadrant. If 
the control voltage in an AM goes negative, the output signal is 
clamped at zero. If the control voltage in RM goes negative, the 
output signal is the inverse of the input signal (180 degrees out of 
phase).

You can see (hear?) this in operation with the 110. Put a 320 square 
wave into the CV input of the VCA (i.e. the AM half) and your 
favourite 300 waveform into the IN. The output goes on/off/on/off. 
Now try it with the RM half. The output is on/on/on/on with a bit of 
a click as the output waveform is switched between normal and 
inverted.

> RM is a four quadrant multiplier, whereas AM is only two quadrant.

Right you are. Thanks. George Kisslak wrote to me privately and suggested
that this might be the difference, which forced me to pull three different
books off my shelf in order settle the matter in my own mind. You're both
right. To quote one of my old college textbooks, "amplitude modulation
consists of causing the carrier amplitude to vary in correspondence with the
instantaneous magnitude of the audio frequency signal (called the modulating
signal)."

> You can see (hear?) this in operation with the 110. Put a 320 square
> wave into the CV input of the VCA (i.e. the AM half) and your
> favourite 300 waveform into the IN.

I'd love to, but I haven't received my 110s or 320s yet, and I haven't built
either of my 300s yet.  :-)

--Adam

> 
> I'd love to, but I haven't received my 110s or 320s yet, and I haven't built
> either of my 300s yet.  :-)

Well at least I'm only 1/2 to blame :)

Paul S.

>> 
>> I'd love to, but I haven't received my 110s or 320s yet, and I haven't built
>> either of my 300s yet.  :-)
> 
> Well at least I'm only 1/2 to blame :)

After sending that quip I realized that I could do Scott's demonstration by
using my 420, self-oscillating, in place of the 300.  :-)

--Adam