Why go passive?

Q & A for building and interfacing your rack gear with Ground Control Pro and GCX-based systems.
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valdoltra
Posts: 13
Joined: Tue Feb 28, 2012 1:46 am

Why go passive?

Post by valdoltra » Tue Oct 15, 2019 6:16 am

Why do exp pedals need to be passive? I have Behringer FCV100 (manual here https://media.americanmusical.com/ItemF ... manual.pdf). Should I be able to use it and how (TRS only on CV output or TRS -TS/TR on input and ouput).

Are there limitations regarding potentiometers?

Cheers,
Vladimir

JohnClark
Posts: 7401
Joined: Tue May 05, 2009 2:33 pm
Location: The Lab

Re: Why go passive?

Post by JohnClark » Tue Oct 15, 2019 10:38 am

If you are referring to using a pedal on a Ground Control Pro then yes, you need a passive pedal with a potentiometer 25K or more.

The FCV100 might work with when set to CV Mode, but it looks like the Tip and Ring are reversed from how they should be for the Ground Control Pro Pedal jacks.

I hope that helps!
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valdoltra
Posts: 13
Joined: Tue Feb 28, 2012 1:46 am

Re: Why go passive?

Post by valdoltra » Wed Oct 16, 2019 2:45 am

I will try with various options. But just for curiosity satisfaction; why do they need to be passive?

Thanks!

JohnClark
Posts: 7401
Joined: Tue May 05, 2009 2:33 pm
Location: The Lab

Re: Why go passive?

Post by JohnClark » Wed Oct 16, 2019 11:24 am

The expression pedal ports are designed such that they are putting 5V across a potentiometer and reading the voltage on the wiper. This is using the potentiometer in the pedal as a Voltage Divider. An active circuit intended for audio will likely produce wild results and could potentially be unhappy with 5V signal level.
The CV mode on your FCV100 does in-fact switch to a passive circuit that simply connects a 50K potentiometer on the TRS "Output 2" jack. So if you can get it connected, and can endure its somewhat sharp angle in the heel down position ;) , it should work fine for this setup in CV mode.

Let us know how it goes!
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