Author Topic: DEFX Atomic Duck/Q2/Tresonator build - Funk-a-duck/MS-20 Filter Clone combo  (Read 280 times)

itisjanuary

Purchased a number of PCB's from deadendfx, and these two in particular caught my interest. I used MS-20 Filter clones in my Synthtech/MOTM system 20 years ago, and love the idea of putting some together with the funk-a-duck. I intend to house them together running off of the same power supply (haven't decided between open-frame 18v or an external...) and likely in a Hammond 515 or SCEM series enclosure. I'm seriously tempted to stack a few Q2's/tresonators in here, but don't know the power consumption of these units to help select the proper power supply. Anyone have the data?

I love the idea of the tresonator foot-deal modulation but would want the rest of the controls more at hand (rather than at foot), so I'm brainstorming on how to accomplish a cord-connected pedal accomplishing the task of sweeping the B100K dual gang pot. I suppose I could build a cable to extend to a foot pedal with the appropriate pot, but I worry that the cord length might introduce something negative to the system (haven't researched this yet). I'd rather use a regular CV pedal, but haven't figured out a graceful way to make this work. This is still in brainstorming stage, and any suggestions are greatly appreciated.

ElectricDruid

If you want the controls more at hand, I'd suggest putting the Tresonator PCB and all its controls into a normal enclosure, and then you'd just wire up your foot pedal as a CV pedal. The Tresonator can cope with 0-10V CV, so you could either put a 9V battery inside the foot pedal, or you could use a TRS lead to supply the foot pedal pot with 10V from the main box.
That way, there's no signal wires going back and forth, only CV, and you have more space for controls in the main enclosure.

itisjanuary

That's along the lines of what I'm thinking, but I was scratching my head about how to put that foot pedal into the circuit ala the treadle.

To quote the build document:

>In a nutshell, it's a Frostwave Resonator, with all the normal Resonator controls on the sides. At the
>front end, we find four, 3 position switches, which allow for CV to be fed to the parameter of choice via
>the treadle. The center position is OFF, and one side is + to - sweep, and the opposite position is - to +
>sweep. In other words, you can have any parameter(s) you choose sweep up, while having another
>parameter(s) sweep down. The dual gang pot is wired as such, to handle one going up, while the other
>goes down. The red/green LED's indicated which parameter has been chosen for treadle control, red for
>+ (up), and green for - (down).

So the 100K dual gang pot that is the treadle(the foot pedal expression) sends out both sweep up and sweep down signals (probably not the right lingo here) simultaneously, which can then be routed internally to each of four modulation points for independent configuration. Correct me if I'm wrong, but if I wired in a jack and switch to bypass this dual-gang pot, I'd be one conductor short with a standard TRS cable (ground, cv to pedal, modulation back to Tresonator) to carry the other output of the dual-gang pot). This could be accomplished with a dual-TRS setup, but I'd rather not make something that won't interface with anything else.

While your suggestion to just use a CV pedal is ideal, is there a way that I could replace the 100K dual-gang pot with a simple circuit to take a CV in and output two opposite sweeps like the potentiometer would? I know it's possible, but I'm just getting started in electrical engineering and haven't built the foundation to know this yet.

>The side controls can also be used in conjunction with the treadle, setting limits to a particular
>parameter being controlled. For example, if you wish to have the treadle sweep the complete range for
>a selected frequency or resonance, then turn the control pot for that control to maximum. If only half of
>the range is desired, then set the control to halfway, and so on.
>As you can see, it allows for almost infinite configuration of CV control, all under your foot.

This modification is sweet. I can't wait.
« Last Edit: February 07, 2021, 02:53:48 PM by itisjanuary »

ElectricDruid

That's along the lines of what I'm thinking, but I was scratching my head about how to put that foot pedal into the circuit ala the treadle.

To quote the build document:

>In a nutshell, it's a Frostwave Resonator, with all the normal Resonator controls on the sides. At the
>front end, we find four, 3 position switches, which allow for CV to be fed to the parameter of choice via
>the treadle. The center position is OFF, and one side is + to - sweep, and the opposite position is - to +
>sweep. In other words, you can have any parameter(s) you choose sweep up, while having another
>parameter(s) sweep down. The dual gang pot is wired as such, to handle one going up, while the other
>goes down. The red/green LED's indicated which parameter has been chosen for treadle control, red for
>+ (up), and green for - (down).

So the 100K dual gang pot that is the treadle(the foot pedal expression) sends out both sweep up and sweep down signals (probably not the right lingo here) simultaneously, which can then be routed internally to each of four modulation points for independent configuration. Correct me if I'm wrong, but if I wired in a jack and switch to bypass this dual-gang pot, I'd be one conductor short with a standard TRS cable (ground, cv to pedal, modulation back to Tresonator) to carry the other output of the dual-gang pot). This could be accomplished with a dual-TRS setup, but I'd rather not make something that won't interface with anything else.

I agree. I think you need to think of it more like a modular synth module and less like an effects pedal, and then you'll see solutions. After all, you must have done stuff like this with your modular - CV control of various parameters.

Quote
While your suggestion to just use a CV pedal is ideal, is there a way that I could replace the 100K dual-gang pot with a simple circuit to take a CV in and output two opposite sweeps like the potentiometer would? I know it's possible, but I'm just getting started in electrical engineering and haven't built the foundation to know this yet.

Yeah, that's a simple enough task. An inverting op-amp would turn a 0 to +10V CV into a 0 to -10V CV. If you use an inverting mixer (so add one extra input to your inverting op-amp) you can add a 10V offset, and now you have 10V to 0V.

Quote
>The side controls can also be used in conjunction with the treadle, setting limits to a particular
>parameter being controlled. For example, if you wish to have the treadle sweep the complete range for
>a selected frequency or resonance, then turn the control pot for that control to maximum. If only half of
>the range is desired, then set the control to halfway, and so on.
>As you can see, it allows for almost infinite configuration of CV control, all under your foot.

This modification is sweet. I can't wait.
That would be a "CV amount" control on a synth module. Again, you must have seen stuff like that.

itisjanuary

Seen it, yes. Soldered it up from dummy-proof instructions, yes. Figured it out and done it myself, no. I was also a teenager while synth-ing and didn't have the time or discipling to do what I'm starting now. My modding went as far as replacing capacitors in a NOS Roland System 100m keyboard and soldering a lead off the CV summer circuit for a pitch-bend wheel.

Thanks for the lead. I'll do some experimenting and studying. I'll breadboard up the circuit when the parts come in and start playing around with options.