Memory Man Deluxe - Expression Pedal Mod

[clownfire]

So I've got a garden variety, circa 97, MM Deluxe:

http://www.dolphinmusic.co.uk/shop_i...29bc775059.jpg

and I want to operate the 3 right knobs; blend, feedback and delay (which pardon my electronics ignorance are potentiometers no?) using an expression pedal.

Each of the knobs seems to operate in the same way, there's three poles, voltage in, voltage out A and voltage out B (based on the position of the potentiometer).

Does an expression pedal not do this very thing?

My questions are as follows:

1. Am I crazy?
2. Will this work?
3. Is there any resistance concerns with the Moog MP-2?
4. What pin on the TRS is the input voltage?
5. How could I screw this up and destroy the device if I'm not careful?

thanks in advance for your smarts.

[clownfire]

to be clear it's my intention to use an expression pedal per parameter, replacing knobs with pedals effectively.

[clownfire]

Picture

So to be clear I want to connect ABC with XYZ and I'm not 100% sure how.

where XYZ is a chasis mount TRS jack that will have an MP-2 expression pedal plugged into it.

[uvacom]

I've never heard of the Moog MP-2, but the Moog EP-2 (which is their basic expression pedal) and the Moog MP-201 (which is their much fancier one) generate a control voltage. This typically cannot be implemented in a straightforward way into a pre-existing design. Sometimes FETs or LED/LDRs can be used as voltage-controlled resistances, sometimes not so much.

It sort of sounds like you would like a cheap way to turn your DMM into a MF-104Z Moogerfooger. It would be nice if there were an easy way to do that.

[Mark Hammer]

Get yourself a Tone In Progress "Third Hand".

http://www.music123.com/Tone-in-Prog...75542.Music123

That will let you have the equivalent of expression-pedal control over any parameter on any pedal you want, without having to mod them and jeopardize resale value or functionality.

[52 Bill]

Interesting device.
Electro Harmonix had the very same thing back in the early '70s.

The problem that has not been mentioned here, beyond the instability of running circuit wires out to a pedal, the values of the pots would need to be matched as well.

[guitician]

My guess is that if those controls actually adjust a control voltage, a DC level change, then your idea should work fine. I would use gold contacts too, it would minimize DC drops due to contact resistance.

[uvacom]

My guess is that if those controls actually adjust a control voltage, a DC level change, then your idea should work fine. I would use gold contacts too, it would minimize DC drops due to contact resistance.

Looking at the schematic, I don't think any of them generate a control voltage. The delay time pot is the resistive component in an RC network which determines the time constant for the clock which drives the delay, the feedback pot is directing the output of the delay signal back into the input, and the wet-dry mix is mixing the input signal with the delayed signal.

That pedal that mechanically turns the pot shaft is a neat idea. It's definitely a kludge of the highest degree, but it's also an easy to use, low-tech problem solver.

[clownfire]

Thanks for your thoughts - more questions.

That third hand thing is brilliant. Talk about low tech. However some strongly negative reviews out there specifically about the operation and durability.

As a fall back position, I'm still not 100% on if this should work. I know analog man does a mod on the feedback and blend.

"We can also add expression jacks for Feedback and Blend control using a standard 10K expression pedal like the Boss EV5"

this whole KB thing is confusing... what does that mean? I'm unfamiliar with it as a unit of measurement for resistance. Seems to be used interchangeably with K Ohms.

Also, I definitely got the model number wrong on the expression pedal but frankly I'm not married to it. I'll use whatever expression pedal works based on your suggestions.

The three pots in question are labeled (top to bottom in my pic) 10 KB, 10 KB (<--not labelled but meters the same resistance) and 100 KB.

thanks for your patience in teaching me how electronics in pedals work

[uvacom]

The "B" actually refers to the taper of the pot. In this case they are all linear taper. For the 10K pots, yes, you could wire in a jack for the expression pedal, the tricky part (and it's not TOO bad) is you have to switch out the front panel's pot when you plug in the expression pedal. They make 1/4" jacks with DPDT switches on board, so that is one option. You could do the same thing for the delay time, but you'd have to use a seperate pedal with a 100k pot (it would probably not be too difficult to mod an EV-5 or whatever).

[Mark Hammer]

Interesting device.
Electro Harmonix had the very same thing back in the early '70s.

The problem that has not been mentioned here, beyond the instability of running circuit wires out to a pedal, the values of the pots would need to be matched as well.

I had one of those EHX "Hot Foot" flexible shaft pedals when they first came out, and used it to control the volume output of my compressor. The intended application for it was actually the delay-time pot on a Memory Man, so that you could use it as a sort of first-generation "Whammy" pedal.

There were two principle problems with the Hot Foot (besides size; the HF was BIG):

1) The shaft came out the side, rather than the top, making it difficult to control top-mounted pots on pedals without flipping the pedal over unless the pedal was VERY heavy or well-secured.

2) The mechanism for attaching to the pot shaft was big, prohibitting attachment to pots that were closely spaced.

None of that affected the EHX memory Man since it was big and heavy, and the 3 pots were well-spaced apart.

The TIP version, that I linked to, has the shaft coming out the top, which places less torque where it isn't needed, and occupies less space where the shaft attaches to the pot shaft. This allows you to control a single Boss pedal sitting on the floor.

It's lo-tech, but sometimes lo-tech is not only good enough, but better.