Poly CV control

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welhamc
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Poly CV control

Post by welhamc » Thu Jan 30, 2020 7:09 pm

Evening muff

One of the projects I've always dreamed of undertaking is a polyphonic modular set up. I understand what is required in terms of voice modules (ie an osc, ADSR, VCA and ideally filter per voice), and I am not far off having suitable modules for a four voice MOTM system. However I am still uncertain on best way to control the voices polyphonically. I am looking for a DIY build

Some of the options I have considered are

Yarns (possibly the best option, unsure whether the PIC is available)
Hexinverter midi2CV (discontinued.. PCB and panel available on synthcube but for a hefty price. Plus I am in UK)
Midibox seq4 (not 100% sure whether this unit supports polyphonic channel splitting, the midibox pages are quite hard to navigate/interpret)

Does anyone have any pointers/suggestions to do this?

Schlumpfhut
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Re: Poly CV control

Post by Schlumpfhut » Fri Jan 31, 2020 1:09 am

If you want to go the DIY route the PolyDAC might be your warpon of choice.

https://www.elby-designs.com/contents/en-us/p92.html

The Elby page shows a 19 inch version but in can be put behind a 3U MOTM panel
Like so:

https://www.ecalpemos.nl/sdiy/motm-modu ... cv3_front/

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Synthbuilder
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Re: Poly CV control

Post by Synthbuilder » Fri Jan 31, 2020 4:47 am

Yarns all the way. Buy a second hand Yarns from Muffs or Ebay (I paid 110GBP for mine) and rehouse if you need it to be a 5U format. Personally, a nice little Eurorack system, with the Yarns included, atop your 5U set up can add a lot of functionality. All you then need is a bunch of 1/4" jack to 3.5mm jack leads.

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josaka
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Re: Poly CV control

Post by josaka » Fri Jan 31, 2020 10:16 am

the CV_OCD is also a great option..
2017-07-12T07 01 36.459Z-DSC05784.JPG
if I was a builder the midibox would be on the list.. its a great sequencer.
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sbuge
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Re: Poly CV control

Post by sbuge » Fri Jan 31, 2020 12:28 pm

For that price I thought that the the CV_OCD was DIY project, but it is fully assembled? :goo: :goo: :goo:
Nice!!


If I ever need MIDI this is definitely the way.
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josaka
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Re: Poly CV control

Post by josaka » Fri Jan 31, 2020 2:08 pm

sbuge wrote:
Fri Jan 31, 2020 12:28 pm
For that price I thought that the the CV_OCD was DIY project, but it is fully assembled? :goo: :goo: :goo:
Nice!!
If I ever need MIDI this is definitely the way.
yep ..:) around £100 from the site.. got a lot of settings options !

welhamc
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Re: Poly CV control

Post by welhamc » Sat Feb 01, 2020 6:31 am

Thanks everyone! I think I'm most tempted by a DIY yarns in a small euro rack

What would be your must have euro modules to accompany an MOTM set up? (ie to fill a small row)

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Re: Poly CV control

Post by KSS » Sat Feb 01, 2020 5:55 pm

Synthbuilder wrote:
Fri Jan 31, 2020 4:47 am
Yarns all the way. Buy a second hand Yarns from Muffs or Ebay (I paid 110GBP for mine)
based on your comment I looked at this. Could not find any reference to its CV voltage range -and was surprised by that!- outside of a -3 to 7+ mentioned in the manual as part of the calibration. Many specs given, but how did Emilie leave this out? did see 5V gate spec.

As a separate issue, CV.OCD I believe is only 0-5V CV. Great little box, but I expect 10V CV range.

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josaka
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Re: Poly CV control

Post by josaka » Sun Feb 02, 2020 1:01 am

cv.ocd is 8v and the most flexible box I have seen..

http://www.six4pix.uk/cvocd/manual.pdf
Last edited by josaka on Sun Feb 02, 2020 10:30 am, edited 2 times in total.

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Synthbuilder
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Re: Poly CV control

Post by Synthbuilder » Sun Feb 02, 2020 5:09 am

KSS wrote:
Sat Feb 01, 2020 5:55 pm
Could not find any reference to its CV voltage range -and was surprised by that!- outside of a -3 to 7+ mentioned in the manual as part of the calibration. Many specs given, but how did Emilie leave this out? did see 5V gate spec.
Yeah, the documentation could be improved. I found it somewhat confusing too, and the all important midi note 36 = 0V default setting is only found in the Quick Start manual.

That said, it is a very comprehensive unit with a very accurate Key CV output. The range is -3V to +7V, which tallies up nicely with the default settings on the Synthesizers.com midi interface. I've not tried changing the range on the Yarns, but if you can change it, I'm guessing the upper limit is set by the 12V supply, which after the polarity protection circuits and op-amp limitations cannot be much more than 8.5V.

I've not measured the outputs of the regular CV outputs. I'm guessing it's 0 to +5V but I will look into that perhaps today.

Tony

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magman
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Re: Poly CV control

Post by magman » Sun Feb 02, 2020 12:18 pm

I’ve already built a 4-voice Poly from modules using Oakley modules (My PolyOakley).

I use a Hexinverter 4 Chanel MIDI2CV, that I have adapted to 5U MOTM format, you are welcome to the panel design if you go down this route. I also use an Oakley MIdiDAC controller to give me things like pitchbend, aftertouch and velocity, so that I can mult these out to the voices for other effects. MIDI from the keyboard goes the the Midi DAC first then through to the MIDI2CV.

I recently picked up another CV to MIDI adapter from a UK source that I plan to use next though. This is the CV-12 from Midimuso - http://midimuso.co.uk/index.php/cv-12/. This has 12 outputs, so after 4 CV’s and 4 gates, I can choose what to use the other 4 outputs for. Very cheap as well. I have not built this yet, but plan on putting it together in the next few months. Of course, I could always add another 2 voice sets to the PolyOakley to make it 6 voice :goo:

Regards

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Next Liverpool Synth Meet - it’s 11th April 2020

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Re: Poly CV control

Post by KSS » Mon Feb 03, 2020 5:20 pm

josaka wrote:
Sun Feb 02, 2020 1:01 am
cv.ocd is 8v and the most flexible box I have seen..
Thank you

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Re: Poly CV control

Post by KSS » Mon Feb 03, 2020 5:26 pm

Synthbuilder wrote:
Sun Feb 02, 2020 5:09 am
I've not tried changing the range on the Yarns, but if you can change it, I'm guessing the upper limit is set by the 12V supply, which after the polarity protection circuits and op-amp limitations cannot be much more than 8.5V.
I've not measured the outputs of the regular CV outputs. I'm guessing it's 0 to +5V but I will look into that perhaps today.
Tony
Thank you, Tony. Do let us know if you get the chance to check those other CV outputs.

Is there any MIDI2CV module or device which *accurately* replicates the ARP typical duophonic action? Something one could use with a digital style KBD to accurately replicate the old ARP KBD gate and trigger characteristics. (given that the contacts of the newer KBDs like Fatar are not ewell suited to resistor string designs.)

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Synthbuilder
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Re: Poly CV control

Post by Synthbuilder » Tue Feb 04, 2020 4:27 am

KSS wrote:
Mon Feb 03, 2020 5:26 pm
Do let us know if you get the chance to check those other CV outputs.
0V to 5V. This was from the velocity outputs but I presume the others are similar.

Tony

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oozitron
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Re: Poly CV control

Post by oozitron » Thu Feb 27, 2020 1:53 pm

I second the recommendation for Yarns:
Four voices of CV & Gate
Several modes (Mono/Poly) and things like four different MIDI channels running the four mono parts
MIDI pitch bend is injected into the CV (and you can set the range in half-steps)
MIDI mod wheel engages an on-board LFO and is injected into the CV
Portamento is in-line with the CV (mono & poly) and legato mode too
BONUS: it runs fine on +/- 15 volts!!! (a real man's power supply :hihi: )

Also, it has a MIDI Out that will carry voices 5~8 to a second Yarns if you make an eight voice :goo:
Also also, it has an arpeggiator and a simple sequencer on board, syncs to MIDI Clock or the internal one.

Here's what I did with mine:
oakleyheim.jpg
Tony's ASV modules are perfect for this. Sounds amazing and is hours of fun; my favorite synth now!

Drew
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kindredlost
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Re: Poly CV control

Post by kindredlost » Fri Feb 28, 2020 11:17 am

Thats an incredible four voice Drew. :tu:

I see the pared down input panel “Oozitronics” ha! Was there any less soldering and wiring when eliminating the modulation jacks? My guess is “yesbutmaybenot”.

Any of your awesome tracks you would like to share so we can hear this beast would be more than welcome- hint, hint :razz:

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oozitron
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Re: Poly CV control

Post by oozitron » Fri Feb 28, 2020 8:33 pm

Thanks Kindredlost!

I left out the patch points for two reasons:
1) This was designed for polyphonic playing, not as part of my modular. I just didn't see myself using them; it's enough to have to make every knob adjustment *four* times! Adding 4x patch cables would just be too much.
2) Cost. Eighty 1/4" jacks is expensive :eek:

The socket board is connected to the main PCB by 3 ribbon cables. I just had to put in about 10 little link wires to connect the normalled paths.

One small change I made was the LFO > VCOs modulation. Instead of going to both VCOs, mine only goes to VCO2. Just a touch of it for warbly detuning, or a lot for Sync patches. Four voices of "rolling sync" (with each voice's LFO a bit different) sounds really amazing.

I still need to add a stereo mixer. I'm also going to add a Master VCF knob (by the Yarns).

And I recorded some noodling last night. Need to edit it down a bit...

Drew
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