G2 analog CV/Gate Output Mod

[3phase]

Hi, just wanted to mention the realisation of a CV/Gate output mod for my G2. After working for quite a while with DC enabled outputs my demand grew to have a wider cv range and also to be able to trigger older synths that require more than the 3,5v the G2 gives out max.. It also has pissed me off that i needed 2 valuable G2 outputs just for one simple CV/gate combo.. With a little extra electronics i was able to do that with a single channel now..and more..but i am still working on that. I decided to keep the G2 internal Mod simple.
Just 4 extra mini jacks for standard analog synth interfacing. And all the extra tricks from an external box.. that interfaces with the dedicated CV outputs.

This little mod gives me 2 cv outputs that give a 7 octave range, with internally adjustable offset, and 2 gate out, internally adjustable from 5v to 10 volt .

Using the Outputs C and D of the G2 for that.. So that Outputs cant be used for Audio when being used as CV control channels.

Also the gate goes high as soon a voltage higher than 0V is generated on the output channel..so CV and Gate are not independent from each other, but a neat little trick to control on external monophonic synth voice with just one G2 output.

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[dorremifasol]

This is awesome. Thanks for showing!

I'd really love to implement this solution in my G2. I'm very curious about your gate output solution.
If I understood well, a circuit raises the gate output as soon as anything other than 0 is sent thought a CV output. Does that mean that it can only work with sounds that don't have a decay after being released? I mean, the CV output should be 0 to make the gate output be 0 as well.

[3phase]

thats the drawback..works only on notes without release phase..which you have on monophon analog synth sequencing and basslines quite often.. or you use as before one channel for the pitch and the other for gate.. the extra gate outputs are anyway good for me since i needed higher gate voltages to trigger an arp.

I am working on a solution to multiplex the cv outs.. but only have 5 cv outs with a 1 ms refresh rate working yet..on a board thats to big to fit inside the g2..current draw with under 20 mA probably still ok.. so might become an internal solution at one point. But i think a can double or tripple that with better circuit design.. or, what would be better, do that 5 with a single channel.. However..since such solutions need dc interfacing with the g2 i ve put 2 simple real dc outputs on my g2 now. The solution with the removed caps was a bit to limited, could´nt trigger the arp for example. Thats the better solution.. have a basic DC 2 channel out..and do the demultiplexing with an external box that is still in development.

The electronics for the demultiplexing would anyway only fit inside the G2 with a professional manufactured circuit board.. I am thinking about that..but the market for such a mod would be probably to little..

In any case thats just step one.. i got too much fun with the g2 as sequencer for real analogs already.


The other way around is probably interesting too. It already has a gate and cv input in form of the footswitch/pedal jack..

[blue hell]

Nice build :-)

[Jack_Hertz]

Very nice! Would this be cheaper / easier / better then using a Kenton MIDI to CV box?

[varice]

Nice work

What external synths are you controlling?

[varice]

[3phase]

yep..good idea pitch change as trigger.. However for the cv gate output for the g2 thats too much hassle for me since i want the direct ports on the g2 universal plain dc out.. the two extra gate jacks are mainly for clocking.. they give me the running status while the out above delivers clock ticks.. since the offset internally is variable i ve set it in a way where the actual gate triggering is happening within the negativ voltage range what allows the main cv output to deliver clean 0-5 v clock pulses ..but the whole setup can be used as pseudo gate for short sounds too. and the whole thing is prepared to get two extra holes and become a 5 cv out plus that pseudo gate / running status jack on a single audio channel..so just channel D for cv control


So as mentioned before..that is just the interim state or interface to the de-multiplexing device im just building that shall give me 5 independent cv outs and a clock with running status on a single G2 output... so 7 jacks..on two channels = 14 jacks..
Since i dont want to drill that many holes into my g2 i will realize that in an external box with own power supply.. An internal solution would be thinkable too..but big question than..

how much extra current draw can the internal power supply take?
Since the power transformer gets already quite warm on the expanded g2 that might be quite limited..

Any ideas or suggestions how much extra current one might be able to steal from a g2 power supply? Is the power supply of the G2x bigger than the one for the standard g2? If not the internal supply might take a little extra load. However.. for now i keep any extra circuit outside of the G2

And the synths this is supposed to sequence is mainly an arp avatar and an oberheim sem module.. booth actually capable for duophonic osc control.. so with filter and gate each in need for 4 cv´s.. So my project is not as over sized as it looks on the first hand.. i prepare for 5 cv´s to have an spare option cv and to allow me if it gets tight with the process timing to reduce to 4..

and the extra clocking outputs are just to use the short timing intervals in between the cv transmissions to smuggle some extra info.. I ve use for din sync output of a g2.. i tried that allready.. ther are fun things to do when the G2 controls the clocking of an 808. However that clocking ports might be left out too when theymake to much problems.. main goal is to achieve 4 independent cv out on one g2 audio output with a timing resolution of max 1 ms.. but targeting 0,5 ms .. should be better than what midi can do..

Thats actually another reason that i split the project in 2 stages.. so i still keep the high resolution single CV per audio output version when needed and the extra box with multiplexing related timing and resolution flaws for standard operation with cv hungry synth modules. i ill see how that goes during the winter..

[varice]

[Oli]

Nice work!