EMUSIC-L Digest Volume 53, Issue 01 This issue's topics: Analogue synth VCO sync (2 messages) And now for something completely different... (5 messages) Moog Oscillators Your EMUSIC-L Digest moderator is Joe McMahon . You may subscribe to EMUSIC-L by sending mail to listserv@american.edu with the line "SUB EMUSIC-L your name" as the text. The EMUSIC-L archive is a service of SunSite (sunsite.unc.edu) at the University of North Carolina. ------------------------------------------------------------------------ Date: Fri, 25 Jun 1993 09:52:24 BST From: S L Gilbey Subject: Analogue synth VCO sync I am designing a MIDI-controlled two-oscillator analogue synth module to supplement my LA synth setup with some good ol' analogue bass. I see that a lot of analogue synths have a switch to sync their VCOs together: is it worth me adding this facility? Can any analogue synth experts out there tell me what difference synchronising the oscillators makes to the sounds you can produce? -------------------------------------------------------------------------- | | email: Steve.Gilbey@bristol.ac.uk | | Steve Gilbey | ---------------------------------------------- | | Bristol University, UK | 'They were all of them fond of quotations' | | | Lewis Carroll, The Hunting of the Snark | -------------------------------------------------------------------------- ------------------------------ Date: Sun, 27 Jun 1993 00:08:42 EDT From: Sean Henriques Subject: Re: Analogue synth VCO sync Oh man, sure its worth it to add the sync feature on your analog oscillators. I have an old Moog Rogue, with the sync feature and its especially useful for getting a handle on phasing when playing super bass parts. And on top of that it makes for great special effects in the upper registers!!! ------------------------------ Date: Fri, 4 Jun 1993 12:11:22 EDT From: ronin Subject: Re: And now for something completely different... in answer to the last question first, i wear patch cords instead of ties. in brief answer to the earlier set of questions... you're not likely to be ab;e to produce 'yamaha-like' fm on your system. the parts list that you provide appears to only allow you exponential fm, in which a 1 volt/octave response means that a 2 volt pp control will swing the carrier an octave up and an octave down, shifting the apparent center pitch. the yamaha uses linear fm, in which the carriers deviate by linearly equal amounts up and down. a 1khz carrier, for instance, might swing between 900 and 1100hz, maintaining the pitch center. later model moog oscillators did have a linear cv input, but i don't think you've got those. not that this means you can't do fm. exponential fm is a wonderfully klangerous tone. it's just that you can't do pitch ornamentation. with your available parts, you can however do pitch ornamentation without screwing up the carrier if you do am. you've got the vcas, so that's easy. a variation that you might find interesting is ring modulation: vco-&-( - )--------------& & &---> mix----> & &---> &-( + )------->vca---& /\ & & vco how you split the carrier into positive and negative phases is up to you. the moog vcas invert signals that are patched through them non-diagonally. so, for instance, patch the vco into the upper left signal input. the upper right signal output will produce that signal 180 degrees out of phase, and the lower right will produce it in phase. note, btw, that the vcas will do this to any voltage that you patch through them, even dc. you can produce inverse filter tracking (where the sound gets darker instead of brighter as you go up in pitch) by patching the keyboard's cv out through the inverting vca before the cv inout to the lopass. anyway, back to ringmod. put the second vca at about 50% gain, and the second vco needs to be audio rate, not lfo. also, when you patch through that second vca, make sure that you maintain polarity - positive phase in, positive phase out. the whole trick finally comes down to the mix. raise the mixer input for the modulated tone about three quarters, then slowly bring up the unmodulated tone, until you hear the carrier disappear. voila... amplitude modulation with cancelled carrier - ring (or balanced) modulation. btw, this comes from page 128 of alan strange's "electronic music: systems, techniques, and controls" (2nd ed), which is the book you *must* have if you're going to live with one of these beasts. -----------< Cognitive Dissonance is a 20th Century Art Form >----------- Eric Harnden (Ronin) or The American University Physics Dept. 4400 Mass. Ave. NW, Washington, DC, 20016-8058 (202) 885-2748 (with Voice Mail) ---------------------< Join the Cognitive Dissidents >------------------- ------------------------------ Date: Fri, 4 Jun 1993 12:38:30 EDT From: ronin Subject: Re: And now for something completely different... the 3340 is great for echo... not only can you independently specify play/record/syn/source for each track, but you can source and play on the same track, which is really useful for echoing with minimal mixing facilities. and don't forget stereo echo. record sound source to track 1. route playback of 1 to record on 3. route playback of 3 to mix back into record on 1. hoo ha. -----------< Cognitive Dissonance is a 20th Century Art Form >----------- Eric Harnden (Ronin) or The American University Physics Dept. 4400 Mass. Ave. NW, Washington, DC, 20016-8058 (202) 885-2748 (with Voice Mail) ---------------------< Join the Cognitive Dissidents >------------------- ------------------------------ Date: Mon, 7 Jun 1993 09:25:01 EDT From: wbf@ALUXPO.ATT.COM Subject: Re: And now for something completely different... Eric Harnden (Ronin) said: > the 3340 is great for echo... not only can you independently specify > play/record/syn/source for each track, but you can source and play on > the same track, which is really useful for echoing with minimal mixing > facilities. and don't forget stereo echo. record sound source to track > 1. route playback of 1 to record on 3. route playback of 3 to mix back > into record on 1. hoo ha. A common technique I used in emusic class was to do four channel tape echo. HOO Hoo hoo (hoo) HA Ha ha (ha)! Keep those thechniques a flyin'! Bill ------------------------------ Date: Mon, 7 Jun 1993 09:58:12 EDT From: wbf@ALUXPO.ATT.COM Subject: Re: And now for something completely different... Eric Harnden (Ronin) suggests AMSC (Amplitude Modulation, Suppressed Carrier: vco-&-( - )--------------& & &---> mix----> & &---> &-( + )------->vca---& /\ & & vco Just to be sure that I'm correctly reading your ASCIImatic: Carrier VCO inverted output feeds mixer; carrier VCO non-inverted output feeds VCA which feeds mixer; Modulator VCO (set to the audio range) controls the VCA. Yes? > btw, this comes from page 128 of alan strange's "electronic music: systems, > techniques, and controls" (2nd ed), which is the book you *must* have if > you're going to live with one of these beasts. I think I might have this one but I'm not sure. It might not be the same title or edition but it is definitely Strange. (Well, you know what I mean!) Thanks for the exp/lin FM information. Don't the Moog oscillators have an exponentiator in them? Mybe I can add an exp/lin switch to bypass that part of the circuit. Hmmm.... Bill Fox ------------------------------ Date: Wed, 9 Jun 1993 10:52:29 EDT From: ronin Subject: Re: And now for something completely different... asciimatic interpretation is correct. the moog 901b oscillators don't actually have the exponentiator built into them, it's in the 901a oscillator controller. i forget which oscillator model you said you have, the 901 or the 921. if you've got the 921, then there's a linear input on the panel. if you've got the 901 set, then it appears from the schematic that you might be able to either 1) bypass the controller entirely. its function is to add control voltages and exponentiate the result. if you don't care about summed controls, you might try dropping a voltage across pins 5 and 7 on its card edge. it looks like they provide a scaling reference for the oscillator's frequency vernier. i'll take a look at the updated schematics later and see if this is dealt with in more depth. 2) if you want the adding function, it looks like you can tap the oscillator controller before the summed cv is exponentiated. if the card is labeled, try tapping from between r16 and p4, and between r13 abd pin 8 of the second ca3019. or do you just want this stuff faxed somewhere? -----------< Cognitive Dissonance is a 20th Century Art Form >----------- Eric Harnden (Ronin) or The American University Physics Dept. 4400 Mass. Ave. NW, Washington, DC, 20016-8058 (202) 885-2748 (with Voice Mail) ---------------------< Join the Cognitive Dissidents >------------------- ------------------------------ Date: Wed, 9 Jun 1993 13:32:31 EDT From: wbf@ALUXPO.ATT.COM Subject: Moog Oscillators Eric Harnden (Ronin) on Moog oscillators: > the moog 901b oscillators don't actually have the exponentiator built > into them, it's in the 901a oscillator controller. i forget which oscillator > model you said you have, the 901 or the 921. if you've got the 921, then Oops, sorry. No 900 series oscillators. The oscillator bank I have consists of two Micromoog boards. Total = six VCOs. I'm not sure if I have the schematics for these. But Stew gave me all the Moog schematics he had collected which do include the 901 set. -- Bill Fox * Fox's Den Recording Studio * Nazareth, PA * wbf@alux1.att.com ------------------------------------------------------------------------ Heisenberg may have slept here... or here... or here... or here... or here... or here... ------------------------------ End of the EMUSIC-L Digest ******************************