CoVariant - MIDI to CV/Gate Audio Unit for iOS

Reaktor, MAX/MSP, VST/AU, etc. A place for all things soft....

Moderators: Joe., lisa, luketeaford, Kent

Post Reply
User avatar
(((EMP)))
Common Wiggler
Posts: 75
Joined: Sat Oct 19, 2019 9:38 pm
Location: Chromosphere

CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by (((EMP))) » Tue Mar 10, 2020 4:24 pm

Surprised nobody posted this yet.

CoVariant https://apps.apple.com/us/app/covariant/id1499681559

‘CoVariant is an Audio Unit that converts MIDI note and controller data to CV and Gate control voltages via a DC coupled audio interface allowing it to control analog synthesizers directly. It also includes two software generated ADSR envelopes that can be used to drive any voltage controlled parameter of the synthesizer.’

http://recurcv.com/

Looks really cool

And some discussion here: https://forum.audiob.us/discussion/3740 ... ter#latest``

User avatar
Switchzik
Common Wiggler
Posts: 189
Joined: Thu Jun 02, 2016 8:41 am

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by Switchzik » Fri Mar 20, 2020 8:51 am

I spotted this one too :)
I was wondering if I can get the clock output somehow, would be great !

AlanC
Learning to Wiggle
Posts: 30
Joined: Sat Apr 19, 2014 3:37 pm

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by AlanC » Fri Mar 20, 2020 4:33 pm

Developer saying "Hello"... ;)

At the moment it's MIDI notes and controllers to CV/Gate.

You can "fake" a clock output by putting, say, 1/16th notes in a track and using one of the envelope generators to create the necessary pulses since the attack and decay times will go down to 1ms. I've tried this and, while the output isn't a pulse wave, it drove a Pittsburgh TimeRunner without any problems.

A proper clock AU with a variable divider and pulse length is one of the additions I have planned.

User avatar
Switchzik
Common Wiggler
Posts: 189
Joined: Thu Jun 02, 2016 8:41 am

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by Switchzik » Sat Mar 21, 2020 8:42 am

Hi Alan,

Thanks for passing by. I think you app is great, we are missing midi to CV converter on ios.

So far I'm using midi only for sequencing but if everything can go througth cv it would be better. Im still confuse with the set up though.
How easy would it be, say, to get 3 gates + velocity out of patterning 2 ? How many covariant should I set up ? IS it even possible ?

I didn't make up my mind yet but follow this topic with high interest. I'm considering to switch to a eurorack case driven by an ipad + exper sleepers es-9. Covariant and cvquencer seems to be what I need ;)

AlanC
Learning to Wiggle
Posts: 30
Joined: Sat Apr 19, 2014 3:37 pm

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by AlanC » Tue Mar 24, 2020 6:45 am

Switchzik wrote:
Sat Mar 21, 2020 8:42 am
So far I'm using midi only for sequencing but if everything can go througth cv it would be better. Im still confuse with the set up though.
How easy would it be, say, to get 3 gates + velocity out of patterning 2 ? How many covariant should I set up ? IS it even possible ?
This one is a bit difficult for me to answer because I'm not familiar with Patterning. Plus a lot of iOS hosts are still very limited, only supporting a single stereo pair as outputs from an AU.

The best way to work out whether you can achieve what you want to do is to think of CoVariant as a software synth that outputs control voltages instead of audio. If you could achieve what you want using a synth AU then you should be able to do the same with CoVariant.

The easiest way to achieve three gate and velocity outputs would be to use AUM as a host since it can split MIDI data by note range. If you set up three instances of CoVariant, routed the MIDI output from Patterning to them and set the appropriate note ranges for each then they'd generate the gates and velocities.

A drum trigger AU that would assign specific notes to individual gates is another addition that I'm considering. Adding individual velocity outs was something I hadn't considered :doh: but it's an obvious plus now you mention it.

User avatar
Switchzik
Common Wiggler
Posts: 189
Joined: Thu Jun 02, 2016 8:41 am

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by Switchzik » Fri Mar 27, 2020 4:45 pm

Thanks for taking time to answer, really appreciate :)

AlanC
Learning to Wiggle
Posts: 30
Joined: Sat Apr 19, 2014 3:37 pm

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by AlanC » Thu Apr 23, 2020 4:05 am

A new beta version is available through TestFlight: if you’d like to try it out then please send me a PM or post in this thread and I’ll give you a link.

It contains two new AU’s: Clock and Trigger.

Image

Clock generates clock and run/stop or reset signals.
  • It’ll generate a beat clock or 24/48 ppqn clock for Roland/Korg or compatible DIN Sync devices.
  • When generating a beat clock it can divide and/or multiply the tempo, swing the beat and either generate a typical 50% square wave clock or a sequence of triggers with variable duration.
  • On the control side, it’ll generate a run/stop signal (on while the sequence is running) or reset trigger pulses when the transport starts, stops, or both.
  • The first clock can be skipped to prevent a sequencer advancing one step immediately after a reset, or can be delayed after the run/stop or reset to allow a sequencer time to respond.
  • It can generate V-Trig or S-Trig outputs, and the duration of the reset pulses can be set.
Trigger generates gate or trigger signals in response to MIDI note messages and also outputs a control voltage associated with the trigger which can be taken from the note velocity, aftertouch, or any MIDI controller. It can generate V-Trig or S-Trig outputs.
  • It can be set to respond to a specific note or any note on the selected MIDI channel.
  • When generating a trigger the duration of the pulse can be set.
  • The minimum time between successive triggers can be increased for devices that don’t respond to the default 1ms interval.
  • The control output can be set to change in a stepped fashion with the changes occurring at the same time as the trigger pulses, or continuously as the selected MIDI controller changes.
Known shortcomings of the beta:
  • There’s no documentation for the new AU’s (documentation for the main AU is displayed by the containing app).
  • Clock's DIN Sync modes haven't been tested against a hardware device.
  • There may be some inconsistent behaviour when Clock starts: if it’s started part way through a bar then it’s meant to wait for the start of the next bar so the sequencer it’s controlling will run in time with the host app.
  • Clock's sync to the host is still being developed. It's currently purely time based and so may not be perfectly accurate with respect to the host. The decision to implement it this way was down to some hosts providing inaccurate or incomplete timing information to the AU, but it appears sync to the host is necessary (if possible) since it can drift by around 2.5ms over 3 minutes.
Hosts:
  • Cubasis 2's MIDI appears to lag significantly behind the transport state information it sends to the AU, so the signals output by Clock will be around 17-25ms ahead of those output by Trigger (or any other AU). You can use the offset control to correct this.

User avatar
(((EMP)))
Common Wiggler
Posts: 75
Joined: Sat Oct 19, 2019 9:38 pm
Location: Chromosphere

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by (((EMP))) » Sun Apr 26, 2020 2:25 pm

Wow, this is shaping up nicely. Got all my gear packed up and ready to move or I’d definitely join the beta.

Great work!

Bobbfett
Learning to Wiggle
Posts: 8
Joined: Thu Oct 17, 2019 6:34 am

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by Bobbfett » Wed May 13, 2020 4:41 am

@os really likes covariant. He has his source code for es hardware published on github
viewtopic.php?f=16&t=221897&p=3259573#p3259573

AlanC
Learning to Wiggle
Posts: 30
Joined: Sat Apr 19, 2014 3:37 pm

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by AlanC » Thu May 14, 2020 5:40 pm

As a follow-up to the ES-9 thread, regarding the possibility of creating AUv3 encoders for the ES-5 / ESX-8GT / ESX-8CV expanders:

The Expert Sleepers open source plugins for VCV Rack and Max are multi-input and stereo (ES-5) or mono (ESX-8GT / ESX-8CV) out. I can quite easily build a set of Audio Units with equivalent capabilities, but I'm not aware of any hosts that would be able to correctly handle the multiple inputs. AUM can handle AU's with multiple stereo input or output busses, but I don't see any way to combine two mono sources (say, two triggers from different AUs) into the left and right channels of a bus.

Is this correct? And does anybody know of a host with AU multi-bus capabilities that are superior than AUM's? I've always regarded it as best-of-breed ;) with respect to its AUv3 implementation.

User avatar
djthopa
Super Deluxe Wiggler
Posts: 1788
Joined: Thu Mar 22, 2012 5:48 pm
Location: Somewhere between a nappy and a wire

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by djthopa » Fri May 15, 2020 11:12 am

Hey Alan, been testing the coVariant clock with my modular synced to aum, working good, i need to tweak some settings but overall good job.
Got a bit fustrated with the midi to cv out of my es8 but i think is because my diy vco is jot calibrated well.
Ill see how it goes today :)

AlanC
Learning to Wiggle
Posts: 30
Joined: Sat Apr 19, 2014 3:37 pm

Re: CoVariant - MIDI to CV/Gate Audio Unit for iOS

Post by AlanC » Sat May 16, 2020 5:58 am

djthopa wrote:
Fri May 15, 2020 11:12 am
Got a bit fustrated with the midi to cv out of my es8 but i think is because my diy vco is jot calibrated well.
Ill see how it goes today :)
Let me know how it goes. The calibration process is more about finding the CV range the oscillator responds to than trying to take out any non-linearities in its response. It works best with a simple waveform like a triangle and it does some low-pass filtering to get rid of any small irregularities in the waveshape, but if there's anything significant then the frequency counter could get fooled and you'd see spikes in the calibration graph.

If there are problems then I may be able to optimise it further, but it's a bit of a balancing act between making it insensitive to irregularities vs. responding to high frequencies.

Post Reply

Return to “Music Software”