Balanced Volume Pedal?

[progmr]

Good morning:
I am wondering if it is possible to construct a volume pedal with balanced jacks in and out?  I run several guitars through a 4 channel DI box into a mixer.  I would like to be able to control the main outs from the mixer via pedal before it his the PA.  I have an existing cheap volume pedal but of course it accepts only 1/4" unbalanced.

Thank You

[Mike Burgundy]

Make it an active one and it's easy.
You could leave the active bit in the signal chain in it's own box, or inside the mixer, and use a regular cheap volume pedal as the controller. Stick a DC voltage on the volume pedal that controls an LED/LDR combo, or (MOS)FET, and you have your remote. For good symmetry, it's easiest to do the volume thing on an unbalanced signal, wether you use the remote version or the actual pot in the signal chain.
Converting from balanced to unbalanced is easy: just set up an opamp using BOTH + and - inputs for the respective signals. Creating a balanced signal needs an inverting opamp stage at 1:1 amplification.
See different mic preamps and DI schems for ideas.
hih

[progmr]

Thanks Mike,

The issue is that the main out coming into the pedal is already balanced, I would prefer to not convert back to unbalanced, then back to balanced after the volume pedal.  I guess in short is it possible to build/modify a volume pedal to accept balanced XLR type connections.

[Gladmarr]

Progmr;

You could just use dual ganged potentiometers.  That way you can control the "hot" and "cold" side of the balanced signal.  For most volume pedals that should be as simple as switching out the existing pot in the pedal.  If you are running stereo to the main PA, that could get more complicated, as you'll have to hook up two dual ganged pots to your pedal.  The issue is mechanically setting all that up.  And, eventually you'll run into problems when the post start to wear out.

[progmr]

Thank you Mike! I believe that should work

[Mike Burgundy]

be advised that dual gang pots are either not very well matched, not made for many revolutions, or both. Try it though, if it works, great!
It is not a bad thing at all to switch back to unbalanced, process the sound with whatever you want, then switch to balanced again.
It's what all (and I mean ALL, I am not aware of any product processing in true balanced configuration for the entire chain) the pro gear does, studio included.