Paramix Expression mod?

[Anonymous]

Just ordered a Paramix board — SO glad my days of trying to do one myself are over.

BUT… is there a way to mod it so that an expression jack can control the wet or dry levels?

[Cybercow]

Michael – there sure is. You can choose between two different jacks . . . .

This one above is isolated from the chassis and all three pins have pass-thru switching. Just connect the wet control to the pins not seen in this photo to the PCB, and connect the pins that are shown to the actual Wet pot.

Or you can use a jack like this . . . .

This jack does NOT isolate the ground from chassis, but that’s OK because P3 (the “Wet” pot) has lug #1 connected to ground. Use a DMM to sort out the switching to pass control of the P3 connections on the PCB to the expression pedal. So when the expression pedal is inserted, it breaks the connection of lugs #2 & #3 of the pot from the PCB. With no expression pedal plugged in, the “Wet” pot will behave as normal.

Just be sure the expression pedal you use has a 100K pot in it.

[Anonymous]

Thank you!

Just one follow-up. I assume I have to match the 100K pot no matter which jack I use? Not sure I want to be swapping pots in my Boss FV500H expression pedal (which I think uses a 10k pot for expression)

[Cybercow]

Michael – best to stick with the values in the BOM & schematic to assure proper operation.

[theurbaner]

HI ! I’m adding a question related to this topic.

I’m planning on building a Paramix with an expression pedal as mentionned above. If I understand well, the expression pedal will replace the wet knob but won’t affect the dry.

Is it possible to make it a unique knob (and therefore expression pedal) with Dry/Wet control ? Like in the Buff N Blend in fact but with the extra options of the Paramix (phase switcher…)

Thanks in advance,

[Cybercow]

theurbaner – yes, one could use a long-shafted dual-gang A100K pot on an expression pedal to simultaneously control the “WET” and “DRY” controls. Just need to be sure to wire one of gangs reversed from the other so one goes up while the other goes down.

In addition, R12 could also be replaced with an A100K pot to act as a master volume.

[theurbaner]

Of course ! So obvious it didn’t cross my mind… Thank you Cybercow.

[wilkie1]

You may want to use a true “Blend” pot that uses a MN taper instead of A taper.  That will provide a more natural change in volume with less overall loss of volume at the center detent.  It is recommended that you “unload” the pot by not connecting the grounds.  That will eliminate any loss of tone.Google pot tapers for more info.

[theurbaner]

Ok, thanks wilkie1 for the tip. I just ordered a MN taper dual gang ! 🙂

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