MOTM

This has come up before so you might check the archives for more details. 
Basically, a lag processor is a very flexible control device that allows you to
modify the rate of change from one voltage to another.  The classic usage is as a
portamento on a keyboard (rise time = fall time, slope exponential or linear
depending on the circuit).  However, this just scratches the surface of such a
versatile module.  Here are a few more examples:

- Simple AR EG
- Self-triggering "pulser" with variable rise and fall times
- Low pass filter, of sorts

There are lots of uses for this module.  I plan to get more than one, eventually.

Eric

--- kpeek1@... wrote:
> Forgive my ignorance but I have always wondered what a lag processor 
> does. Or, what does it allow you to do?
> Explanations?
> Thanks.
> 
> 

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The most "famous" use is called portamento (or glide). You insert a lag
processor
in between a CV source (say, a CV out keyboard) and a VCO. The lag "slides"
the notes
by the lag. The GLIDE on a TB-303 is a lag process.

Other things to use it for:
a) turn a GATE into a AR envelope generator
b) turn a pulse/square LFO signal into bizarre shapes (linear setting works
best)
c) it's a natural 6dB low-pass filter

100's of uses, everyone needs one. As far as I know, the MOTM-820 is the
most advanced lag processor
in any modular ever made.

Paul S.


----- Original Message -----

From: <kpeek1@...>
To: <motm@egroups.com>
Sent: Monday, April 03, 2000 9:05 PM
Subject: [motm] What does a VC Lag do?


> Forgive my ignorance but I have always wondered what a lag processor
> does. Or, what does it allow you to do?
> Explanations?
> Thanks.
>
>
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>

I have been searching the archive for about the last hour and 
stumbled upon a post made over a year ago about the MOTM Lag 
processor.  It says it can be used for things other than "glide", 
like "turning pulse/square LFO's into bizzare shapes".  So how does 
the Lag do this?  What do the up, down, up/down and shape controls do 
when running an LFO (or audible audio for that matter) through the 
Lag?


John Parks


> Other things to use it for:
> a) turn a GATE into a AR envelope generator
> b) turn a pulse/square LFO signal into bizarre shapes (linear 
setting works
> best)
> c) it's a natural 6dB low-pass filter

Just think about what is happening when you hit a low key on the keyboard (a
low voltage comes out) and then a high key ( a high voltage comes out). Now
hit the low key again...

That "low / high / low" voltage is the beginning of a very low frequency
pulse wave ("square" only if your timing is perfectly even).

The 'glide' that the lag adds to that for normal 'portamento' use is to slow
the transition, sort of "angling" those up and down transitions.

There's conceptually no difference between changing the slew rate, as it is
often called, of that hand-generated pulse and one coming out of an LFO or
VCO. (The only difference would be if the lag processor was range-limited to
a low frequency, but you know with MOTM modules that ain't gonna happen.)

So essentially, that's how you can use the lag as a type of waveshaper.

Put in a pulse wave (LFO or VCO) and add some lag, and you will get
something approaching a triangle, and with more, a sine wave (a lag is
essentially a special type of lowpass filter after all).

Put in a pulse and adjust *only* the up or down, and you will start to get a
waveform approaching and then becoming a sawtooth / ramp wave.

And of course, the lag is voltage-controllable, so all of this is under VC.
You can morph from one to the other. Try setting up one of the above sounds,
but mult-out the output and feed some of it back into the CV for the lag,
see what you get!

 -----Original Message-----
From: 	John [mailto:jpyyz@...] 
Sent:	Thursday, 26 April, 2001 1:55 AM
To:	motm@yahoogroups.com
Subject:	[motm] VC Lag

I have been searching the archive for about the last hour and 
stumbled upon a post made over a year ago about the MOTM Lag 
processor.  It says it can be used for things other than "glide", 
like "turning pulse/square LFO's into bizzare shapes".  So how does 
the Lag do this?  What do the up, down, up/down and shape controls do 
when running an LFO (or audible audio for that matter) through the 
Lag?


John Parks


> Other things to use it for:
> a) turn a GATE into a AR envelope generator
> b) turn a pulse/square LFO signal into bizarre shapes (linear 
setting works
> best)
> c) it's a natural 6dB low-pass filter



 

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

If you connect one VCO to the input and another to the Up/Down modulation
control then the VC Lag makes a pretty nice timbre modulator or waveshaper.
The output will still be periodic and therefore harmonic, but will have many
shifting overtones due to the frequency offsets of the two VCOs.
Controlling the modulation input VCO frequency or amplitude creates
additional animation of the signal.  This works into the low to mid audio
frequency range.

John Loffink
microtonal@...

>
> I have been searching the archive for about the last hour and
> stumbled upon a post made over a year ago about the MOTM Lag
> processor.  It says it can be used for things other than "glide",
> like "turning pulse/square LFO's into bizzare shapes".  So how does
> the Lag do this?  What do the up, down, up/down and shape controls do
> when running an LFO (or audible audio for that matter) through the
> Lag?
>
>

This makes me ask the question how does this affect the negative portion of
a wave? Seeing that a square wave would be -5 to +5, wouldn't running it
through the lag cause strange clipping effects?>
>
>
>Just think about what is happening when you hit a low key on the keyboard (a
>
>low voltage comes out) and then a high key ( a high voltage comes out). Now
>
>hit the low key again...
>
>
>
>That "low / high / low" voltage is the beginning of a very low frequency
>
>pulse wave ("square" only if your timing is perfectly even).
>
>
>
>The 'glide' that the lag adds to that for normal 'portamento' use is to slow
>
>the transition, sort of "angling" those up and down transitions.
>
>
>
>There's conceptually no difference between changing the slew rate, as it is
>
>often called, of that hand-generated pulse and one coming out of an LFO or
>
>VCO. (The only difference would be if the lag processor was range-limited to
>
>a low frequency, but you know with MOTM modules that ain't gonna happen.)
>
>
>
>So essentially, that's how you can use the lag as a type of waveshaper.
>
>
>
>Put in a pulse wave (LFO or VCO) and add some lag, and you will get
>
>something approaching a triangle, and with more, a sine wave (a lag is
>
>essentially a special type of lowpass filter after all).
>
>
>
>Put in a pulse and adjust *only* the up or down, and you will start to get a
>
>waveform approaching and then becoming a sawtooth / ramp wave.
>
>
>
>And of course, the lag is voltage-controllable, so all of this is under VC.
>
>You can morph from one to the other. Try setting up one of the above sounds,
>
>but mult-out the output and feed some of it back into the CV for the lag,
>
>see what you get!
>
>
>
>
>
>
>
> -----Original Message-----
>
>From:       John [mailto:jpyyz@...]
>
>Sent:      Thursday, 26 April, 2001 1:55 AM
>
>To:      motm@yahoogroups.com
>
>Subject:      [motm] VC Lag
>
>
>
>I have been searching the archive for about the last hour and
>
>stumbled upon a post made over a year ago about the MOTM Lag
>
>processor.  It says it can be used for things other than "glide",
>
>like "turning pulse/square LFO's into bizzare shapes".  So how does
>
>the Lag do this?  What do the up, down, up/down and shape controls do
>
>when running an LFO (or audible audio for that matter) through the
>
>Lag?
>
>
>
>
>
>John Parks
>
>
>
>
>
>> Other things to use it for:
>
>> a) turn a GATE into a AR envelope generator
>
>> b) turn a pulse/square LFO signal into bizarre shapes (linear
>
>setting works
>
>> best)
>
>> c) it's a natural 6dB low-pass filter
>
>
>
>
>
>
>
>
>
>
>
>Your use of Yahoo! Groups is subject to
><http://docs.yahoo.com/info/terms/>http://docs.yahoo.com/info/terms/
>
>
>
>
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Please reply to:
nate@...
www.etanstudios.com

I'm not sure I know what you mean by clipping.

Going from negative-to-positive makes no difference... that's what AC (i.e.,
signal) is all about, right?. And a lag module is a [typically 6 db/octave]
lowpass filter. So it would "round off" the tip of an input triangle in
either phase.

I may not have understood your question though.

The keyboard example of, say, going from "1v" to "10" by pressing low & high
keys is creating a fluctuating voltage, but of course, since it is always
positive it can be said to have a DC offset. 

 -----Original Message-----
From: 	Nathan Hunsicker [mailto:nate@...] 
Sent:	Thursday, 26 April, 2001 1:52 PM
To:	motm@yahoogroups.com
Subject:	RE: [motm] VC Lag

This makes me ask the question how does this affect the negative portion of
a wave? Seeing that a square wave would be -5 to +5, wouldn't running it
through the lag cause strange clipping effects?>