DEFX Lola Phase - adding CV control mods

[sammy-arfie]

Hey all, I have a question about adding the CV mods to the Dead End Lola Phase.

I recently came across the 1978 PAiA magazine article that documents adding the optional jacks to the unit for CV control and output of the LFO.

My issue is I built the DEFX version of the pedal, which has some changes to the CV In circuit to make it work with a standard B1M pot. I bought this version with the intention to build the expression pedal, but I never ended up building one and have since gotten a modular synthesizer I want to use my unit with.

Is there another place on the circuit I could jumper in the CV In jack? What modifications would I need to make to that part of the circuit to make it work?

I feel a bit like a dummy for buying the DEFX version now, so hopefully I can work with what I've got. The idea or populating another one of these boards is a little daunting!

I added the LFO out mod exactly like the PAiA article and it works great. I was having a ton of fun using it to add Vibrato, Filter sweeps, and Pulse Width Mod to my modular system. I might even add another output for the other LFO.


Thanks

Sammy

[ElectricDruid]

Have you got a link to the PAIA article or the schematic for the DEFX version?

C'mon, don't make us do everything for you! We can help, but people are more inclined if you make it easy for them

[sammy-arfie]

Have you got a link to the PAIA article or the schematic for the DEFX version?

C'mon, don't make us do everything for you! We can help, but people are more inclined if you make it easy for them

Of course!

I was hoping to catch one of the Dead End guys, or someone else familiar with the Biphase before picking someone else's brain...

http://www.muzines.co.uk/articles/modifying-the-mu-tron-bi-phase/12300


Original version


DEFX version


Full schem
https://drive.google.com/file/d/1WDIcJKwfED5GuEUQh-Zo87qZaRinuMxV/view

[Mark Hammer]

And just to avoid people looking for something that doesn't exist, the DEFX Lola is a clone of the Mu-Tron Bi-Phase, and not a PAiA product clone.  Additionally, although it did feature PAiA products and was essentially published by them, the magazine was POLYPHONY.

[ElectricDruid]

The DEFX schematic shows the CV pedal input, and I don't see any reason why you can't use it as-is. The connections for the jack look like it's feeding 0-15V to the pedal, so the CV pedal can cover up to that range. In practice, most rocker pedals don't go right to the ends of the pot travel, so it probably does 1V to 14V or something.

Either way, it looks like it'd be pretty safe to plug modular gear into. Since you don't want 15V going out to your modular's outputs, you can add a proper CV input jack separate from the CV pedal input. It'll be the same as the current one, but a mono jack without the extra 15V connection. I'd add another pair of 39K/1M resistors to the +ve input for the new jack.

If someone else would like to have a look at those schematics and sanity-check me, I'd appreciate it. Thanks.

[sammy-arfie]

And just to avoid people looking for something that doesn't exist, the DEFX Lola is a clone of the Mu-Tron Bi-Phase, and not a PAiA product clone.  Additionally, although it did feature PAiA products and was essentially published by them, the magazine was POLYPHONY.

Thanks for clearing that up.

[sammy-arfie]

The DEFX schematic shows the CV pedal input, and I don't see any reason why you can't use it as-is. The connections for the jack look like it's feeding 0-15V to the pedal, so the CV pedal can cover up to that range. In practice, most rocker pedals don't go right to the ends of the pot travel, so it probably does 1V to 14V or something.

Either way, it looks like it'd be pretty safe to plug modular gear into. Since you don't want 15V going out to your modular's outputs, you can add a proper CV input jack separate from the CV pedal input. It'll be the same as the current one, but a mono jack without the extra 15V connection. I'd add another pair of 39K/1M resistors to the +ve input for the new jack.

If someone else would like to have a look at those schematics and sanity-check me, I'd appreciate it. Thanks.

So they offer two versions, one which is exactly like the original biphase and another which has the CV input circuit modified to accept a B1M pot, instead of the Mutron Opto Pot or similar.

The B1M version is the one that I built.

I also don't really see why it shouldn't work....I'm very certain I tapped onto the right pad on my DIN cable, but I will triple check.

Thanks for the input, I really do appreciate it.

The CV output is working brilliantly with my synth. I am testing it with an attenuator just to be safe, but it doesn't seem to cause any issues, even st 100%. Just some sweet Pulse width mod in sync with the phase shifting.