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Some ideas for syncing analog gear directly to computer
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doctorvague



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PostPosted: Fri Sep 05, 2008 3:39 pm    Post subject: Some ideas for syncing analog gear directly to computer
Subject description: asking for your DIY suggestions & ideas (long w/photos)
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An alternative to MIDI sync > analog. Use audio pulses.
In the computer I created some sound files of 5ms square wave audio pulses maxed out, then lowered the level by various db's and created little sound files at various levels (link below). I placed these in my DAW, Digital Performer at every 16th note and looped them and setting everything at unity I got nice useable sync pulses. BTW, sound clips like clicks or other audio never worked right for me - you really need a solid pulse IMO. With the scope hooked up- out of my Ramsa DA7 console +4db aux send, the top voltage i could get was 9V and the various levels of files gave these outputs:
-10db = 4V
-8db = 5V
-6db = 6V
-3db = 8.5V It's starting to max out the 2408 output voltage
-2db = 9V maxed out no matter much higher you go

I didn't chart out the -10db RCA consumer outs of my MOTU 2408 audio interface that I ended up using but I settled on the "-3db" sound file which gave about a 2V pulse. A 5V pulse was not possible using consumer -10 outs, so I would need to build a buffer and boost the pulses a bit. My MonoPoly's like something closer to 7-8V to reliably trigger, for example. More later.

These pulses can be used to clock a sequencer or a whole analog system for that matter with various timing subdivisions if desired, directly trigger envelopes, create a DIN-sync signal, trigger occasional long term events- whatever.

Here's a link to a zipped folder that contains various levels of pulses saved as 16 bit wav files if you'd like to fool around with this:
http://idisk.mac.com/doctorvague/Public/Files/Audio_Sync_Pulses.zip

=========================
Musically speaking...
OK, now you might be wondering how is this different from MIDI sync, or other methods using MIDI?

It's a lot more solid than MIDI because you're looking at audio sample rates and can usually compensate for any latency issues in the DAW so you have dead-on consistent timing. Even with multiple tracks firing on 'one' they are all dead-on the 'one' - no serial waiting in line so to speak. I can personally vouch for this after having checked a few MIDI interfaces for timing against this method. That square wave on the oscilloscope ain't jumpin' 'round no more Very Happy

Double, half, quarter time, triplets, etc are instantly available, just for the tip of the iceberg. Try hooking a MIDI output to a Mobius sequencer and halving or doubling the tempo, i.e. via the MIDI stream or DAW for that matter. Very challenging indeed and subject largely to MIDI's idiosyncrasies. Even DAW's won't send out a half or doubled MIDI clock that I know of. To my knowledge there is no easy way to simply double or cut in half a MIDI clock. Seems strange to me from a musical standpoint. For example I would love to be able to switch the Mobius to half time or double time on the fly still sync'd to the DAW but there's no straightforward way to do this since MIDI is being used between the DAW and Mobius and there's not even a 'black box' available that will accomplish this that I have been able to find.

You can output ANY type of pulse you need, whether it's a reset every 4 bars, 16th notes, 24ppq for DIN sync, triplets, and with a little effort -complex pre-programmed rhythms, syncopation- you name it. One set straight, one with slight swing, etc. You'd have multiple simultaneous- totally time locked- pulse streams, up to the number of your audio interface's available free outputs.

You are always resolved to your DAW (or other software) as far as tight timing but also musically as far as where 'one' is, or where on and off beats are. This is BIG IMO. Using dividers, it's SO easy to end up on the wrong 16th note from what you want for example. If you switch a track on in the DAW that's been set up with off beat 8th note pulses, that's exactly what it will be, every time.

Whatever software you're using, you can set up multiple tracks to output different rhythmic divisions (up to your available outputs), a 'one' reset pulse, etc. Any software tricks are fair game - this is music!! You can pgm custom swing pulses or whatever. I haven't tried this, but one example that comes to mind in Reason would be using a Redrum Drum Machine and loading these pulse sound files as samples and trigger a left-right pair of outputs from the Redrum interface which includes presets, swing and other niceties. NOTE- don't send multiple tracks to the same output at the same time as you will be likely be maxing out your audio interface output when pulses hit simultaneously and your software adds them up. Another possibility in a linear song arrangement would be the ability to go to halftime pulses at a certain point in the song, program in muted sections, back to doubletime, tempo changes, etc. you can also combine musically complimentary pulse trains (more below). There's also the possibility of MIDI (or other) control of the tracks on the software side of things.

I used a couple of Pattern Gate plug-ins in DP on 2 tracks, 1 with 32nd note pulses and one with 16ths sent to the MonoPoly's and got all kind of rhythmic stuff happening very easily. This is a subtractive way of working in that you're starting from a steady stream of 32nd's for instance, and chopping out rhythmic divisions with the pattern gate - or any other similar plug or software approach you'd want to use.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Audio clips using a variation of the above method (about 1MB each):
http://idisk.mac.com/doctorvague/Public/Clips/Audio_clock_16_32A.mp3
http://idisk.mac.com/doctorvague/Public/Clips/Audio_clock_16_32B.mp3

Those were made syncing directly to the audio interface with no other circuitry using two +4db outs.

Then things got interesting when I realized I had 8 audio outs (RCA -10db consumer) available as I only use this interface for digital lightpipe to a Ramsa DA7 digital board. I used what I had - an ethernet cable to run 8 lines across the room- low tech DIY:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Tried this as an interface- 5 way rotaries using 5 DAW tracks. It's fun but it's not quite the deal for me personally as I really want random access, ideally. But it worked perfectly well:
Posted Image, might have been reduced in size. Click Image to view fullscreen.
I probably would like it a lot better with red chicken head knobs Smile

After playing around with this for a few days with different configurations (and LOVING it) I was convinced to take it all the way. The idea of 8 audio tracks- 8 pulse streams separately configurable= very cool. I do want to throw in, that even with less tracks/outputs- say 2, and using MIDI controllers for track changes from the computer you could have heaps of fun. The clips above were done with just 2 outputs. You certainly don't need 8 free audio outputs to use some of these ideas. But if you did have 8 tracks/outputs, then how to set them up?

Track 1- Whole Notes
Track 2- Half Notes
Track 3- 1/4 notes
Track 4- 1/8 notes
Track 5- 1/16 notes
Track 6- 1/32 notes
Track 7- 1/8 triplets
Track 8- 2 measure reset pulse
==========
Track 1- Whole Notes
Track 2- Half Notes
Track 3- Half notes offset 1/4 later (use to intersperse with track 1 and 2)
Track 4- 1/4 notes
Track 5- 1/4 notes offbeats (track 3+4 combined would make 8th notes but this way you can play back and forth between off and on beats)
Track 6- 1/8 note custom swing beat set up in the DAW
Track 7- 1/4 triplets
Track 8- 1/4 triplets offset (track 7+8=1/8 triplets)

It's more complex and a lot of fun.
Here' what Digital Performer looks like with some triplets and offset divisions:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Then wondered about this:

Track 1- Half Notes
Track 2- Next 16th note
Track 3- Next 16th note
Track 4- Next 16th note
Track 5- Next 16th note
Track 6- Next 16th note
Track 7- Next 16th note
Track 8- Next 16th note
and loop at the half measure.

Obviously you're just serially outputting pulses 1-8 to 8 outputs. Gee, you could switch them on and off with switches like a sequencer...hmmm. That led (after a while) to this idea:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

As mentioned earlier when using an older RCA interface (MOTU 2408 Mk1) I could only get about 2V pulses max so I put this together and breadboarded enough channels to get it working:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

This is why I've posted this here in DIY - I would really like your suggestions on both the interface and especially the schematic. I'm approaching this from very limited knowledge so perhaps I am on a completely wrong track here... although the breadboard of this worked fine. I used a simple Diode-OR to combine the pulse trains. I played around with the op amp gain until I got around 7V pulses (with the 2V input from the audio interface) which will work with everything I have.

From a DIY perspective, I know a lot of you don't care about or have any need to sync your analog gear to a computer. For those that do, consider this: for the price of a cheap audio interface (I found a 4-out PCI card for $100 US without shopping around at all), if your computer can spare the various overheads of course, and some modular expense (as little as a panel, switches, jacks, etc if you have +4db outputs available) you could easily rig a 4 or 8 channel interface between computer and analog/modular - completely configurable for anything from DIN-sync to a sequencer-like interface to a rotary switch or one SPDT. I know some of what I've mentioned could be done with MIDI but I like the idea of going direct to audio and a bit of circuitry and spanking the modular directly. It just feels better somehow and maybe that's just some personal bias. I'm likin' it on several levels Very Happy
One more thing I'd like to add is that if you think this is only useful for loop based or dance music- consider that even for some pretty abstract stuff you might occasionally want some kind of pulse to use for overdubbing rhythmic coherence, for example.

I hope I wrote this clearly - it was a lot to cover and try to make sense.
Thanks in advance for suggestions, ideas, criticisms...
Phil

PS special thanks to Jan (Blue Hell) for reading my first draft of this and suggestions

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Photon



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PostPosted: Fri Sep 05, 2008 5:19 pm    Post subject: Reply with quote  Mark this post and the followings unread

Awesome. Totally awesome. Thanks for posting. Very Happy
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elektro80
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PostPosted: Fri Sep 05, 2008 5:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice article! Very Happy I´m doing pretty much the same with Logic Studio and my dotcom rig. It works great. Well, I haven´t exactly followed this exact scheme, but in essence I´m doing much the same. It is well worth exploring.
That being said, the same basic techniques will work using multitrack tape as well.

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PostPosted: Fri Sep 05, 2008 9:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

Whoa! Thank you greatly for that incredibly insightful post! Surprised

Having received in the mail early this week, an Alesis MMT-8, I've been wondering at how to Sync it with my analog sequencers / Master Divider.

It does have a Click Out in it, but the voltage is too low. From reading your article now, I'll extend my thought of pumping the Click Out into a comparator, by throwing a pulse shaper onto the end of it to hopefully get something as compatible with my analog sequencers as possible. Smile
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doctorvague



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PostPosted: Sat Sep 06, 2008 6:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks guys!
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PostPosted: Sat Sep 06, 2008 8:09 am    Post subject: Reply with quote  Mark this post and the followings unread

BTW, there are a couple of very inexpensive dotcom modules that can be used for ramping up the audio pulse feed into something really trigger happy.
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PostPosted: Sat Sep 06, 2008 8:25 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks Phil !


my way to sync (sometimes):
I take the Nord modular to generate a Drumpattern,
this one is then fed to my Hardware modular,
first into a Gain stage ( i have 10x Gain) then into the Clock divider ( which also has direct outs of the incoming clock = multiple)

First i had a 16step Pattern, all steps set to the Knobs,
but then i made a Sequenzerpatch with several rows.
I mixed then some patterns, so i can mute for example all the offbeats ( to take a simple example )
Further one can make more rows of seqeunzes and switch them.
lots of possibilitys with the NM1.


Your approach is very interesting Phil, thanks
Syncing the modular is definitly a theme
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PostPosted: Sat Sep 06, 2008 3:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

This approach using pulse samples would also work very well on an Akai MPC drum machine, on the MPC1000 and MPC2500 (with JJOS) you can control the sample end point with a 'q-link' fader and do all sorts of cool stuff like dynamically control swing and change patterns on the fly.
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PostPosted: Sun Sep 07, 2008 4:26 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks a lot for this extremely interesting article.

what i have been doing is no where near as flexible..which has been driving my modular by playing a drum pattern in something like BFD, throwing that to a separate out on my motu traveler and feeding that into a comparator (often first through an opamp with a high gain)...i also like to play around with then putting that pulse through a slew module to get offset effects.

you know, i love your idea of the files as in logic, these could all be put onto a TEMPLATE track as HIDDEN files. they could be ALWAYS available, say on outputs 4-8.

however, that brings up my question..do these files stretch with tempo? (are they acidized? etc?)



thanks

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PostPosted: Sun Sep 07, 2008 4:29 am    Post subject: Reply with quote  Mark this post and the followings unread

ok

re-reading this.

i get it. i think i would just load these into REDRUM or the drum machine in Logic (ultra beat)

in fact, i could once again have them hidden...make one track with quarters, one with wholes,etc

thanks!!

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PostPosted: Sun Sep 07, 2008 6:45 am    Post subject: Reply with quote  Mark this post and the followings unread

This is very interesting.
My only problem would be getting extra outputs from my XFi card.
I'll have to think about this very carefully. Cool

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ENDIF



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PostPosted: Sun Sep 07, 2008 7:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

I just set up a pattern on the Moebius sequencer and slave it to midi clock.
And the VoS sequencer slaves to clock from that.

Haven't tried sending midi in to have it echo out through the CV jacks yet... maybe tonight.

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PostPosted: Mon Sep 08, 2008 5:34 am    Post subject: Reply with quote  Mark this post and the followings unread

ENDIF wrote:
I just set up a pattern on the Moebius sequencer and slave it to midi clock.
And the VoS sequencer slaves to clock from that.

Haven't tried sending midi in to have it echo out through the CV jacks yet... maybe tonight.


Yeah that's standard way of doing it and the whole point I was trying to make was avoiding MIDI sync altogetherwith it's limitations and idiosyncracacies. Using your method above (MIDI) there's no way to tell the Mobius to switch to half notes or 32nd notes against the MIDI clock on the fly. It's always stuck on 16th notes no matter what. What I wrote about is the opposite of that - i.e. not using MIDI to avoid those types of limitations.
---------------------------------------
I'm looking forward to hearing if these actually work in other scenarios you guys have mentioned (besides audio tracks in a DAW) like outputting from hardware sequencers. The output circuitry of the device will obviously play a role as far as available voltages at the output.

To answer an earlier question they are not "acidized" per se using this technique, but they don't need to be because there's no time stretching needed with 5ms sound files (See DP screen graphic above). The blips are always the same length and they will always follow the tempo if placed in metrical time divisions. So there's no time stretching needed (or wanted). If you place theses short little pulse sound files at 8th note positions those will be 8th notes at 68 bpm or 155 bpm and will always follow exact tempo as long as they are placed correctly and looped at the right place. In fact this method can track very complex tempo changes without a hiccup if you wanted. MIDI would have trouble with multiple mid-measure tempo changes for example and this method wouldn't at all. For example, if you have 32nd note pulses programmed and have a slow ritard at the end of a song those 32nd notes could EXACTLY follow the ritard tempo curve where MIDI has problems and tends to stairstep and hiccup trying do these types of things, especially betwen measure boundaries. That's been my experience anyway.

No comments on the DIY portion?? Comparators have mentioned a couple of times - perhaps I should be doing something different in my interface circuit using comparators? I don't think my method requires that, but perhaps someone could comment? I sort of get the concept but I haven't done much with comparators myself. Any comments or criticisms of my panel/interface design?

To echo Stein's idea - you don't need a bunch of circuitry to try this. Triggers can be boosted into range with simple modules you may already have. Multiple pulse streams can be OR'd together with diodes if needed:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Doesn't get much simpler than that!

Thanks for the idea flow Smile

Phil
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PostPosted: Mon Sep 08, 2008 6:08 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey, I've got a sound card on my motherboard.
If I enabled that in the BIOS it would show up as another output device in Cakewalk and could be used for exactly this purpose hey?
I wonder though whether it would mess with the Creative XFi card?

What about a conversion circuit which created a CV based on the amplitude of the pulse?

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PostPosted: Mon Sep 08, 2008 8:09 am    Post subject: Reply with quote  Mark this post and the followings unread

Peak Detect/S&H circuit could do that.

Or how about a circuit that could do AM demodulation (lo-pass filter) so a control signal can be sent through a standard sound card's output (including DC)?
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PostPosted: Mon Sep 08, 2008 9:45 am    Post subject: Reply with quote  Mark this post and the followings unread

doctorvague wrote:

To echo Stein's idea - you don't need a bunch of circuitry to try this. Triggers can be boosted into range with simple modules you may already have. Multiple pulse streams can be OR'd together with diodes if needed:

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Doesn't get much simpler than that!

Thanks for the idea flow Smile

Phil


Way back before midi, this was the way to step sequencers or whatever from multitrack tape. And this meant you would soon be forced to bring with you the tape based "clock" when playing stuff live. Laughing

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PostPosted: Mon Sep 08, 2008 11:33 am    Post subject: Reply with quote  Mark this post and the followings unread

Very interesting stuff Phil - I did this once with my Soundlab, but that was of course one voice at a time, and then just overdubbing to build a whole tune.

About your schematic: All those switches confuse me, but...what you are aiming for is to be able to mix (OR) the pulse trains together, right?
You could of course program the rythm as you want it in to your sequencer, but not much room for improv then...

On the schem: The 4M7 resistors are for pulldown to eliminate switch pops or what?

C

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PostPosted: Mon Sep 08, 2008 1:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

Coriolis wrote:
Very interesting stuff Phil - I did this once with my Soundlab, but that was of course one voice at a time, and then just overdubbing to build a whole tune.

About your schematic: All those switches confuse me, but...what you are aiming for is to be able to mix (OR) the pulse trains together, right?
You could of course program the rythm as you want it in to your sequencer, but not much room for improv then...

On the schem: The 4M7 resistors are for pulldown to eliminate switch pops or what?

C


Yes you've got The idea - mainly random instant access to all (or any combination of) 8 pulse streams via the physical interface vs computer mousing, etc. By OR'ing them, if 2 pulses happen to occur at one time you don't end up with a 10V pulse instead of 5V like you would if you used a mixer. This was so you never have to worry about how many streams you are using at once, or if there are simultaneous pulses happening between ones you have switched on.

The 3 banks (sets of 8 switches) set up 3 different rhythms, then each of the 4 outputs can be switched on the fly between the 3 banks to send to 4 different instruments or modules independently. Hope I explained that clearly! Smile

Yes the 4M7's are pulldowns. Without them the wave was square on the left side and tapered down gradually on the right. With the resistors it pulls down to a nice tight square pulse. May not affect actual operation though since the front edge is the trigger but I wanted it to look pretty on the scope Smile

Elektro - last time you mentioned the tape scenario I remembered (vaguely) something about Morton Subotnick doing that?? Not sure... I know it's been done.

Uncle K and JKSuperstar - your idea of deriving CV's and using S/H or AM modulation is very interesting!

Uncle K - I remembered my RCA outs after the fact too, as I've never used them (and they sound like crap on this old 2408 interface). I've only used the lightpipe outputs. Always nice when you can say "Hey, I already own that!"

We have jacks we so must plug them. Cool
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PostPosted: Tue Sep 09, 2008 4:41 am    Post subject: Reply with quote  Mark this post and the followings unread

I've been doing something similar using pulses to a hardware sequencer, since I don't have that many audio outputs on my pc. I use two output channels, one for the reset pulse and one for the clock pulse. The rest of the logic is done on the modular.

You can 'fake' slow tempo synced LFO's by a generating a bar of noise, then using clip envelopes in Ableton Live to create an amplitude envelope, then feed it to your modular's envelope follower.


There was an article online about Subotnic doing this stuff with a tape machine.

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PostPosted: Tue Sep 09, 2008 6:33 am    Post subject: Reply with quote  Mark this post and the followings unread

widdly wrote:
You can 'fake' slow tempo synced LFO's by a generating a bar of noise, then using clip envelopes in Ableton Live to create an amplitude envelope, then feed it to your modular's envelope follower.


Cool! Would a LPF work to filter out the noise and leave the LFO signal? This seems right next door to the AM-Demod idea that jksuperstar mentioned. As far as his idea of AM I was wondering, how you would generate the amplitude modulation at the computer? Is it possible to do some of these things with a ring modulator circuit on the demod side? This is beyond my knowledge at this point but I'd like to try to grasp this concept anyway.

Uncle Krunkus wrote:
What about a conversion circuit which created a CV based on the amplitude of the pulse?


I've been thinking about this. When I originally tried my idea I was wondering if a 5ms pulse would work as you're looking at 5ms of a DC voltage. I understand about input caps dropping DC but not sure about audio outs and DC voltages. Could these be 50ms or 500ms and still work? How far can you go outputting DC voltages from an audio out? How long is too long? An audio out will pass a sine wave obviously but what about a sine slowed down to .2Hz? Would it still output that voltage? I honestly don't know as I've never tried it.


OK, this is about generating control voltages, not triggers:
The 5ms is working, for me anyway, so let's assume that as a base point. So how about Uncle K's idea but with pulses closely spaced. What if you had various levels of 5ms pulses in an audio track with only 1 ms of space between? I'm not sure what software to use here, but somehow generate pulses rapidly then at the analog side maybe use a S/H and a slew limiter set up in such a way to read the pulses and derive a variable CV and smooth out the 1-2ms spaces between so you're left with a clean control voltage. This may be impractical but it's fun to discuss and might lead to something else yet. Cool

Are you Mac guys hip to Numerology at all? I use it a lot and seems like it could play into some of these ideas somehow:

http://www.five12.com/numerology.html

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PostPosted: Tue Sep 09, 2008 7:45 am    Post subject: Reply with quote  Mark this post and the followings unread

I hadn't thought of smoothing between the gaps, I was just thinking about getting an instant CV to mess with the tuning of a drum etc.
If you wanted a complete CV&Gate solution it would be easier to just output the note you want on one channel and pulses on the other. Then just do a frequency to voltage conversion to get a CV for the note.

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widdly



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PostPosted: Tue Sep 09, 2008 7:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

doctorvague wrote:
widdly wrote:
You can 'fake' slow tempo synced LFO's by a generating a bar of noise, then using clip envelopes in Ableton Live to create an amplitude envelope, then feed it to your modular's envelope follower.


Cool! Would a LPF work to filter out the noise and leave the LFO signal? This seems right next door to the AM-Demod idea that jksuperstar mentioned. As far as his idea of AM I was wondering, how you would generate the amplitude modulation at the computer? Is it possible to do some of these things with a ring modulator circuit on the demod side? This is beyond my knowledge at this point but I'd like to try to grasp this concept anyway.


Yeah an envelope follower is a lpf. Make sure you set the cutoff Loooow.

Amplitude modulation on the PC side is simple. If you figure out how to make a track in the your software louder or softer then you are there. For LFO's, you could check out a tremolo plugin. For arbitrary shapes, you want to check out the mixer in your software and see if you can add automation curves to a tracks fader.

Last edited by widdly on Thu Aug 05, 2010 10:06 pm; edited 1 time in total
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jksuperstar



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PostPosted: Tue Sep 09, 2008 11:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

Imagine an oscillator in the computer sending an 18kHz square wave (I chose this as it's close enough to be beyond human hearing, but before the 3db roll off of usual 20-20kHz specs of an audio output).

The tweak the output amplitude of that oscillator. What ever the setting of the amplitude is, it'll make it through that sound card's output at that amplitude.

The DIY interface would have a low pass filter, set way below 18kHz. Then, the only thing actually coming through would basically be the knob setting.

This could probably be calibrated so this technique could be used for 1v/oct type signals. Probably do something simple (or fancy) in SynthEdit or some other cheapo VST synth maker to tweak the knob to be linear, or exponential, or a step sequencer locked to tempo internal to the PC.
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Floppy



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PostPosted: Fri Jan 16, 2009 8:22 am    Post subject: Reply with quote  Mark this post and the followings unread

did you just sell that to motu ?
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doctorvague



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PostPosted: Fri Jan 16, 2009 2:38 pm    Post subject: Reply with quote  Mark this post and the followings unread

http://createdigitalmusic.com/2009/01/16/analog-meet-digital-motu-volta-connects-the-mac-to-cv-synths-effects-graphically/#more-4785
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