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Hardware Instruments => MatrixBrute => MatrixBrute - Tips & Tricks => Topic started by: 11ish on October 11, 2017, 07:50:36 pm

Title: Expression Pedal inputs as additional CV ins?
Post by: 11ish on October 11, 2017, 07:50:36 pm

Hello everyone,

is it safe to use the exp. pedal inputs for CV signals from a modular synth if voltage is kept within a certain range? According to german forum site I came across a while ago, it should be between 0V and +3,3V… Is this okay or will it cause any problems?

Thanks!

Title: Re: Expression Pedal inputs as additional CV ins?
Post by: DrJustice on October 12, 2017, 12:08:40 am

I just measured the reference voltage, it's 3.3V, which is consistent with the manual, page 53:
"Expression: Tip = Pot center tap ; Ring = 3.3V ; Sleeve = Gnd".

So 0V to +3.3V is correct. You could hook up a simple voltage divider if you want/have to use a +10V standard modular signal.

Edit: I see a diode near the expression jacks. Those could be for either polarity or overvoltage protection.

Title: Re: Expression Pedal inputs as additional CV ins?
Post by: joeman on October 12, 2017, 07:37:52 am

Is there anyone that knows for sure (at Arturia or similar) and can chime in on whether we can send the Expression pedal inputs CV that is negative polarity and/or +/- 5v (or 10v) etc without damaging it or requiring any attenuation or polarity adjustment etc?

It would be awesome.

Title: Re: Expression Pedal inputs as additional CV ins?
Post by: 11ish on October 12, 2017, 01:46:23 pm

Thanks DrJustice! I guess I'll give it a try then with correct attenuation.

Title: Re: Expression Pedal inputs as additional CV ins?
Post by: PES on October 14, 2017, 08:33:45 pm

I’ve used the exp inputs as CV inputs, but it’s some time ago now. I definitely went beyon 3 volts, and also used negative voltages (LFO) from a Mono Lancet.

I have no idea if it is safe or if I were lucky, but no damage done. Negative voltages translate to 0 voltage, so for an LFO the negative period is “off”.

Also ran audio signals into them, and it responded quickly to those (there’s some filtering meaning it’s not quite as fast as the audio - but it’s fast).

Title: Re: Expression Pedal inputs as additional CV ins?
Post by: charloctave on May 30, 2021, 12:38:59 pm

I have made a special cable with a mono jack on one side and a TRS jack in the other that houses a couple of resistors to make a voltage divider bridge. It works perfectly and I use it to control different parameters of the MxB with my theremin.
an exemple with the LFO rate from the left antenna:
https://youtu.be/ALkpPKxDPsA