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CV control of synths from Logic Pro X


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I'm curious if anyone is using Logic Pro X and a DC coupled audio interface to control their CV synths. I know there's software from Expert Sleepers, and MP3244 from Dialog Audio, and Volta from MOTU that can all generate the signals, but I was hoping for some firsthand experience with any of these (or other solutions I don't know about).

 

 

thanks!

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Are you asking only about Audio interfaces that double as CV outputs, or also dedicated MIDI-CV?

 

I've been using a Kenton Pro 2000 for many years. Easy to calibrate and scale, does both V/oct and V/Hz, and has been rock-solid.

 

One key to flexibility is to have all outputs and inputs, CV and audio, routed to a patchbay. Any audio signal is also a control voltage, and routing the aux send from a kick drum to the filter cutoff of a resonant four-pole or the pitch CV of an oscillator can be weird at least, bestial at best.

"The Angels of Libra are in the European vanguard of the [retro soul] movement" (Bill Buckley, Soul and Jazz and Funk)

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At this point, I wasn't planning on buying anything additional (aside from maybe some software). I have an Apollo interface, which is DC coupled, and a Moog Mother-32. So I don't have a true Eurorack system to which I can add modules. The software I mentioned all allows yo to create LFOs and/or sequences in your DAW and then send those signals out as CV through a coupled audio interface. Ableton Live has a plugin called CV Tools that does the same thing, but only for Ableton, and I'd prefer to work on Logic. Volta is a bit expensive. Expert Sleepers doesn't seem to be the easiest to use (according to some comments I've seen), and I haven't really heard anything about MP3244. I can try the demo versions, but I was hoping for some tips from people that have used these things (or others).
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Expert Sleepers was great when it worked but it was reliant on the right kind of interface. I was using MOTU 828 and when that packed up my new interface wasn't compatible. Very powerful plugin though as it provides a lot of modulation options but quite tricky to set up (special cables etc.)

 

I have used Kenton boxes in the past and they are very good. But as time went by I found I was rarely using them so sold them. The Pro 2 had some great features and for things like automating filter sweeps it was easy to use and had two configurable aux CV outs. I would recommend it as a reliable and quite powerful interface.

 

When I need MIDI-CV I use one of my Behringer synths. My fave is the Odyssey which has CV/Gate/Trigger out and sends MIDI received from the USB input to the CV/Gate jacks. As well as CV and Gate it sends portamento too. I sometimes used the Neutron but any Behringer synth with CV/Gate should work. They cost a bit more than a Kenton interface but they are excellent synths and many of them provide patch points for LFO/ENV out etc.

 

There are other digital synths from Korg and Roland (System 8) that also provide CV/Gate but this won't provide the automation you are after.

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I know there's software from Expert Sleepers, and MP3244 from Dialog Audio, and Volta from MOTU that can all generate the signals, but I was hoping for some firsthand experience with any of these (or other solutions I don't know about).

 

Yup. There is DIY. Clearly not as systematic as the software solutions you mention. We are spoilt with great tools these days. But you would be putting yourself in the shoes of DIY champs like Tomita and Carlos, who had to retune oscillators every couple of octaves :freak: in order to make mind-blowing music. So if you don't mind getting fiddly and you want to get started right away ...

 

At this point, I wasn't planning on buying anything additional (aside from maybe some software). I have an Apollo interface, which is DC coupled, and a Moog Mother-32.

 

Nice gear. :thu:

 

So to summarize, you might want Oscillators, Envelopes, and Triggers as CV possibly? You have non-audio rate LFO's, Envelopes and certain types of triggers (e.g. arpeggiators) in the MIDI FX section of every channel strip. Your Mother has a MIDI in and accepts four CC's as well as a few other things like sequencer start/stop, note ons, etc. That is already a ton of potential sound design. :thu:

 

But is there anything we can do with your Mother 32's lovely CV ins? Yes as a matter of fact. Every Logic synth is now a complex audio rate oscillator (and noise source) going into your Mother 32's patch points through your Apollo. Want an additional modulation source? Add a channel strip and load a synth. Your limitation would be the number of audio outputs in your Apollo. I would begin with single-cycle waves but you can waveshape (PWM, clipping), smooth (LPF, portamento) and animate (LFO, ADSR) these signals using the synthesis tools within each Logic synth.

 

So that gives you audio rates ... but what if I want full range oscillators to go from extremely low frequencies to dog whistle? That's where it gets fiddly. You already have super slow LFOs in MIDI (Modulator, in MIDI FX has a max cycle time of 100 seconds) and you know you can get awesome audio rate oscillators from the Logic synths. In between those extremes you could repitch the Logic synths (use Modifier to transpose notes downward and a calculator like THIS to dial in any specific frequencies.) Fiddly right? :D

 

Sooner or later, you might want something more systematic and encompassing, but until then hopefully Logic Pro will give you a lot of sound-design with the great gear you already have. Hope this helps. ð

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Thanks! I didn't know that Logic could do that! I found out that I already had the software to do what I was initially looking to do. Reaktor's Blocks has a module to output CV. I set it up last night, and it works great, It even has a tuning process where it will send voltages to your oscillators, and calibrate what voltages it needs to send so that it's in tune. But I;m going to try those things in Logic tonight. That could be even more straightforward. Thanks again!
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I didn't have any luck doing anything usable straight from Logic. I put Retrosynth on a channel and set it to output to the a specific output on the Apollo and then sent that to the Mother-32's VCO 1V octave input. While a one-note sequence was playing on the M32, I tried playing various pitches in Retrosynth (at both ends of the pitch range) and I also set up a very slow very wide vibrato and although it changed the sound of the M32, it only aded some raspiness. It didn't;t change the pitch (as it would when I was using that same output coming of to Reaktor. I think I;m missing something from you explanation.

 

 

thanks!

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I didn't have any luck doing anything usable straight from Logic. I put Retrosynth on a channel and set it to output to the a specific output on the Apollo and then sent that to the Mother-32's VCO 1V octave input. While a one-note sequence was playing on the M32, I tried playing various pitches in Retrosynth (at both ends of the pitch range) and I also set up a very slow very wide vibrato and although it changed the sound of the M32, it only aded some raspiness. It didn't;t change the pitch (as it would when I was using that same output coming of to Reaktor. I think I;m missing something from you explanation.

 

I'm sorry you didn't have any luck right away. Pitch is the best place to begin. :thu: You will likely find a) that signal strength is always an issue when turning audio into CV, and b) it helps to keep things simple at first and enlarge your palette of tricks from there. If I had to guess your situation, the signal strength into the Moog is too low and the waves from Retrosynth are too complex to clarify what they are doing (if anything, at the low levels).

 

I tried playing various pitches in Retrosynth (at both ends of the pitch range)

 

One way of getting a specific pitch out of a synth which normally tracks the keyboard, is to defeat the keyboard tracking by adding a Modifier plugin in the MIDI FX of the channel strip. (Input Event = Note Number, Re-Assign to = Note Number, Scale = 0%, and Add = a number representing the note you want.)

 

Ideally, with any soft-synth you might want to begin by outputting a square wave and measuring the low-to-high pitch range the signal is giving you. You may need to insert a hardware mixer or amp module to amplify the signal of the Apollo to the CV range the Mother is expecting. If you are getting appropriate amplitudes out of Reaktor, why not stay with it? Sure it takes longer to patch, but you have precise control and you can save a vocabulary of templates as you go. Regardless of the soft synth, you want to begin with a square/pulse wave in order to make measurements. Ideally you can make adjustments until the square wave can move your Mother 32's oscillator from A0 (27hz) to C8 (4k hz) to start, from the low point of the square wave to the high point. Or a musically useful range which may be less than that ideal range, more likely a few octaves. Personally, I used a voltmeter at first, but later allowed my ears to guide me. The square wave will need to run at less than 5 HZ (vibrato speed) for you to be able to hear these high and low pitches as steps. That's where I would begin to scale the signal strength you will need. This will give you confidence as you diversify into other modulations. You are doing very brave stuff. It might take trial and error before things begin to work. All the best. I hope this helps. ð

 

PS: I am doing something different but similar. If you need more context, my approach is summarized in this post at the Moog forums.

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