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In a Moog Mood? Here's a forum for discussion of general Moog topics.
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Kevin Lightner
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Post by Kevin Lightner » Sat Jan 27, 2007 8:59 pm

Fwiw, the MS-50 had a different filter than either MS-20.
It uses a fairly rare IC which funny enough is also used in Moog 901 oscillators.
A CA3019 diode array.

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museslave
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Post by museslave » Sat Jan 27, 2007 10:46 pm

Kevin Lightner wrote:Fwiw, the MS-50 had a different filter than either MS-20.
It uses a fairly rare IC which funny enough is also used in Moog 901 oscillators.
A CA3019 diode array.
Heh, thanks Kevin! : )
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CTRLSHFT
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Post by CTRLSHFT » Mon Jan 29, 2007 5:00 am

here's an idea i fleshed out a little bit for a new CP unit w/ env gen:

http://moogmusic.com/forum/viewtopic.php?t=4135
www.ctrlshft.com

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Post by museslave » Mon Jan 29, 2007 12:25 pm

CTRLSHFT wrote:here's an idea i fleshed out a little bit for a new CP unit w/ env gen:

http://moogmusic.com/forum/viewtopic.php?t=4135
Oh, my gosh CTRLSHFT, that is perfect. Absolutely perfect! I would love it if they would employ your design, as that would perfectly round out a MoogerFooger system! I also like the inclusion of the Clipper and Rectifier portions... as I use my .com Q130s a LOT. In fact, I bought TWO of them because they are so cool for shaping of both audio AND control signals. The sine wave becomes a VERY cool waveform when you have clippers and rectifiers. : )

Hey, Moog! Make CTRLSHFT's Mooger idea! : )
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eric coleridge
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Post by eric coleridge » Mon Jan 29, 2007 2:56 pm

museslave wrote: Oh, my gosh CTRLSHFT, that is perfect. Absolutely perfect!
Right on CNTRLSHFT--- you pretty much called the 107 too-- you should probably go into design development for Moog Music.
museslave wrote: I would love it if they would employ your design, as that would perfectly round out a MoogerFooger system! I also like the inclusion of the Clipper and Rectifier portions... as I use my .com Q130s a LOT. In fact, I bought TWO of them because they are so cool for shaping of both audio AND control signals. The sine wave becomes a VERY cool waveform when you have clippers and rectifiers. : )
Museslave, what do retifiers/clippers do to ext. audio signals (if anything) and/or CVs? I've read the clipper description on the dotcom site--but don't really get it...

You know what I just discovered last night--- I made a frequency divider-- I guess it's just the same as an octave pedal, sub-oscillator, and/or a clock divider on a Doefpher (and others)... but it's really cool running audio frequncies though it. It's mainly just one chip called a binary counter which divides down the frequency in multiples of 2. It sounds crazy on guitar outputting a vascillating square wave (kind of sounds like modem sounds)--not smooth like a typical octaver.

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Post by museslave » Mon Jan 29, 2007 5:09 pm

eric coleridge wrote:
Right on CNTRLSHFT--- you pretty much called the 107 too-- you should probably go into design development for Moog Music.
I agree with Eric!
eric coleridge wrote:
Museslave, what do retifiers/clippers do to ext. audio signals (if anything) and/or CVs? I've read the clipper description on the dotcom site--but don't really get it...
I didn't exactly understand it, either... but I liked the idea that it could "create new waveforms." If you've read the description, you know it cuts the peaks off of sine waves. It also works with triangles. I think less so with saw, and not at all with square. What it ends up sounding like is PWM for sines! I mean, it's different... and it depends on what modulation you direct into it, but the effect with a sine audio wave ends up sounding like a weird sort of PWM with sines. With CV sine, it would end up basically giving you a square wave with rounded sides... with experimentation you can get interesting LFO-varying effects. It would be a GREAT tool for a person who only had a sine/tri based LFO. You hear the rise... then there is a flat plateau it reaches, and then the descent. With modulation of the signal it gets quite unique and complex.
I tend to view my electronic music in a sort of needlessly purist way, so I don't tend to mix pure electronic music with musique concrete... but WOW... I have no IDEA what it would do to an audio signal other than a waveform! I'm curious now! I have also not messed around with it with multiple waveforms... something I should definitely try. Interesting!
Very useful tool!
The rectifier, as best I can understand as NOT an electronics person: it takes negative part of the waveform and flips it into the positive, effectively doubling the frequency. It only works on waveforms that have a negative part. If I'm not mistaken, square waves go from zero up, so they are not affected by rectification. Again, sine waves work well. It ends up working like a upper-octaver for sines! Again, I have NO idea what it would do to a complex audio signal!


eric coleridge wrote:You know what I just discovered last night--- I made a frequency divider-- I guess it's just the same as an octave pedal, sub-oscillator, and/or a clock divider on a Doefpher (and others)... but it's really cool running audio frequncies though it. It's mainly just one chip called a binary counter which divides down the frequency in multiples of 2. It sounds crazy on guitar outputting a vascillating square wave (kind of sounds like modem sounds)--not smooth like a typical octaver.
That sounds very cool!
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Kevin Lightner
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Post by Kevin Lightner » Mon Jan 29, 2007 10:13 pm

A rectifier can be used to clip a waveform.

Imagine a sinewave on a scope.
Center line is ground.
If a rectifier (same as a diode here) is connected to that sine signal, the other side to ground, only one half of the wave will be visible.
Depending on the direction of the diode (they're polarized), it can be the bottom or the top half.

Common guitar distortion boxes use two diodes, each in a different direction.
This clips both the top and bottom halves of the signal.
Of course the signals are lower in volume then, but a gain stage afterwards is usually provided to boost it back up (or beyond.)

In modular voltage control, a diode can be used for lots of things, including making sure a cv doesn't go negative (below ground), vc'd waveform processing, env follower creation, etc.


There are all kinds of variations, of course, but maybe this gives you an idea.

CTRLSHFT
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Post by CTRLSHFT » Tue Jan 30, 2007 12:33 am

Glad you guys dig it, thanks for taking a look.

btw, on the dot com site theres some very helpful diagrams to help clear up what rectifiers and clippers do:

Image

note that in my mock-up design, the clipper has a summed output of the + and -, so both sides of the waveform would be clipped.
www.ctrlshft.com

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Post by electrical_engineer_gEEk » Tue Jan 30, 2007 11:46 am

you can also do a half wave rectifier. Dunno what the difference in sound would be:

Image

eric coleridge
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Post by eric coleridge » Tue Jan 30, 2007 12:30 pm

Kevin Lightner wrote:A rectifier can be used to clip a waveform.
Imagine a sinewave on a scope.
Center line is ground.
If a rectifier (same as a diode here) is connected to that sine signal, the other side to ground, only one half of the wave will be visible.
Is a rectifier the same thing as a Schmitt Trigger?

I was just telling Museslave about my Freq Divider, but what I didn't mention is that it took me a week to get it to work. I finally put a Schmitt Trigger before the input-- and then it worked. My understanding of the ST is very similar to what you've described here as a Rectifier. Same thing?

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Kevin Lightner
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Post by Kevin Lightner » Tue Jan 30, 2007 11:44 pm

Is a rectifier the same thing as a Schmitt Trigger?
No. (and fwiw, I was gonna suggest you add one also.) :)

A schmitt trigger is more of a design concept than a part.
There ARE schmitt trigger chips, but they're usually standard packages utilizing Schmitt designs.
Put simply, a schmitt changes logic levels using hysteresis, which is a sort of positive feedback.
It makes the chip more immune to noise and allows signals that aren't at standard logic levels to be at standard logic levels.
For practical purposes, they're used to "clean up" signals for logic use.

You can think of it sorta like this...

On a gun, one can pull the trigger to fire.
That will pull back the hammer, but it takes a very definite pull and to a certain depth.
A schmitt is more like cocking the gun first. It's ready to fire and only requires a light force and the trigger need not be pulled all the way.

Actually a lame analogy, but I'm not a very good teacher.
Can someone say this better or more accurately? :)

eric coleridge
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Post by eric coleridge » Wed Jan 31, 2007 1:52 am

what I read was going on--in case anyone's interested in schmitt triggers-- is a "squaring" of the signal in terms of making it an on/off or digital signal like a +5 to ground pulse wave...

Of course this may be wrong- or I may have read it wrong... but I was thinking (again, probably read it somewhere) since the binary divider/sub needed a square wave I'd try the schmitt pre-stage.

But it's strange, because it wasn't working even when I inputed it a square wave---until I dropped in that Schmitty. Now it works, and with any kind of input... and it's really bizarre sounding... I'm sure theres something I could do to make it more smoothed out sounding--but then it would just sound like a square wave, not like a modem, and not as weirding.

eric coleridge
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Post by eric coleridge » Wed Jan 31, 2007 1:55 am

..and that's why it seemed like it could be similar to the clipper, as described. But then many things that outwardly seem similar, in actuality-- aren't.

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Re: Post Subject

Post by LWG » Wed Jan 31, 2007 5:39 am

Hello,

Five octave controller keyboard. Fairly slim footprint (approximate size of Vger kbd extended to five octaves w/ everything aft of the panel hinge removed). Slightly larger dimensions required for cv/midi pcb, and internal supply, but a wall wart would work if need be.
CV (1 or several channels)/MIDI (for full polyphony), velocity, pressure.

Regards,


Lawrence

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Kevin Lightner
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Post by Kevin Lightner » Wed Jan 31, 2007 11:30 am

That's a pretty good idea.
Moog's accomplished more difficult things before.
It would also allow a shallow keyboard on a stage, without a panel blocking the view.
Then people could be seen with a MOOG keyboard, but still playing their other synths.

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