Using PRO2 sequencer/arpeggiator w/ external synths

[fernando]

Hi all
Is it possible to control external modular synths through the PRO2 CV/gate outs? I mean, does it send CV/Gates corresponding to the sequenced or arpeggiated notes?
Thanks

Fernando (new to the list)

[Jonas Sjöström]

Hi Fernando, yes it does! I'm using the Pro 2 to control my TTSH (ARP2600 clone) via cv/gate from the pro 2 to the TTSH, works perfectly. But you have to keep in mind that the pro 2 send by default 0-10volt via cv and most eurorack needs 0-5v so you need to adjust the cv scale in the global settings to offset cv out from the pro 2 so it sends 0-5volts. It is described in the manual starting on page 76 it is fairly straight forward. you use DC in the mod slots and send minus value to the cv out that you use to control the modular stuff to get 0-5volts.

It is also described here: http://forum.davesmithinstruments.com/index.php/topic,69.0.html

//jonas

[BobTheDog]

Hi Guys,

Just to elaborate on what Jonas has said in case there is any confusion (maybe mine!).

Gates usually trigger in the 2.5V to 5V range though some can be higher, What Jonas says about using scale is correct for gates but might need some adjustment depending on what you are plugging it into.

For Pitch CV though you might have a range from -10V to 10V depending on the module so you should not use scaling, but you may need to use the DC offset and the coarse tuning on your module.

[Jonas Sjöström]

The 10volt gate is no issue for the external stuff, the 10volt gate from the pro 2 will do for any Gates. But it is the pitch CV that needs to be altered most likely because most manufacturers have a cv-range of 5volts = 5 octaves but the Pro 2 has a 10 octave range with it's cv and playing mid C on the pro 2 then will play the highest pitch on the external sound generator i.e. VCO. that is why you need to scale/offset the CV volt out from the pro 2.

[BobTheDog]

Most manufacturers  do NOT have a 0-5V range, that is just incorrect.

You do not want to scale the pitch CV as there is a standard of 1V per octave whatever the voltage range is.

[Jonas Sjöström]

Good god!!

Fernando, all you need to know is found here

The Pro 2 is extremely flexible when it comes to Control Voltages, and it can be configured to properly interact with virtually all Eurorack modules.

The Pro 2's CV outputs have a range of 0 to 10v. Since the range is 0-10v, Middle C is sent from the CV output at 5v. This allows the CV out to track over a 10 octave range, from 0 to 10v.

There is no standard input voltage range for Eurorack modules. Some modules/external synths have a 10v input range, while others have a 5v input range. Using the "DC Offset" parameter in the Modulation Matrix, you can configure the Pro 2 as necessary to work correctly with your specific module.

You can also assign the keyboard/sequencer of the Pro 2 to transmit CV data at 1v/octave by assigning "note number" to modulate "CV out (1-4)" with an "Amount" of "127" in the Mod Matrix.

 

For example:

If the Pro 2 sends CV at 1v/octave to an oscillator that has a maximum input range of 5v, sending Middle C from the Pro 2 will result in the oscillator playing at its highest frequency.

There are a couple ways to correct for this offset. First, you could use an external attenuator. Or, by applying a negative DC offset to the CV output via the Modulation Matrix the Pro 2 can compensate for the voltage difference completely internally. Here's how you would configure the Pro 2 to control an external oscillator which has a 5v input range from the Mod Matrix:

 

Mod Slot 1: Note Number --> 127 --> CV out 1 (This will set the CV output to scale at 1v/octave when a note is played)

Mod Slot 2: DC --> -64 --> CV out 1 (The DC offset of -64 will apply a -5v offset to the CV)

 

The external oscillator with a 5v range in our example will now track at the same octave as the Pro 2's internal oscillators.

You can adjust the DC offset for other maximum voltages as well.

In general:

DC offset value of -16 would equal a -1.25v offset to the CV output
DC offset value of -32 would equal a -2.5v offset to the CV output
DC offset value of -48 would equal a -3.75v offset to the CV output
And so on...

 

You can also make incremental adjustments to the DC offset to fit your specific application.

[BobTheDog]

And where there does it say you should scale the pitch cv voltage?

[fernando]

Thank you so much for the prompt exhaustive replies. So, it will send both CV and GATE outs according to the sequencer or arpeggiator notes, am I right? I am going to buy a Pro-2 to control my Moog (vintage) modular, model 55 and model 15...
And I understand that I'll have to make some offset adjustments!

[BobTheDog]

I'm not sure about the Arpeggiator but the sequencer is fine.

I would try out the arp for you but my back is bad and I can't risk messing around with patch cables

[fernando]

Thanks again Bob, and many wishes for your back!

[smalls]

I literally just signed up to ask this exact question. Happy to see it's already being discussed.