DD-7 expression, tap, feedback momentary, other stuff...

[Invisible Man]

Trying to re-house a DD-7. I'd like to wire a tap tempo switch up--no biggie. Just wire it to the EXP jack (there's room).

But I'd also like to have control over the feedback/regen. I won't have EXP access, so is it possible to just jumper a momentary switch between to of the lugs on the feedback pot? Which lugs? Does it matter what kind of switch?

To be clear: the end goal is to have momentary control over maxing out the repeats, and to have on-board tap tempo. Doable?

[Nocentelli]

I've not seen a schematic for the DD7, but I have my doubts that the feedback pot is a simple voltage divider like you would find in a PT2399 based digital delay. Since you can assign the expression pedal to control any of the parameters, it would seem more likely that there is digital control of feedback and the pot is more likely to be a digital rotary encoder.

[Invisible Man]

How can I figure out whether it's a digital encoder or just a pot? I have gut shots ready to go...

[crochambeau]

How can I figure out whether it's a digital encoder or just a pot? I have gut shots ready to go...

Encoders will often have detents so it feels like a many position rotary switch and/or rotate without a stop. Gutshot will help, I'm guessing it's a pot, but your approach will be decidedly different if it's not.

Regarding your question if shorting out legs of the pot will work, I'd grab an alligator cable and test before committing any solder.

I have no experience tinkering with one of these, so...

[Invisible Man]

That all makes sense to me. The "mode" selector has detents, though that's just a rotary selector switch. The other three controls are continuous, so I figured they're just regular mini-pots.

All four pots are labeled as 50k, which (to me, at least) rules them out as encoders. The plan is to rehouse the pedal in a larger enclosure--one where I can use three stomp switches (bypass, feedback, tap), and also to de-solder the pots from their flying daughterboard. I'd like to give myself more room, and bigger knobs. I can't hardly get my fingers in there on the Boss pedals with four knobs. I am a giant, and I like big things.

[crochambeau]

Agreed, 50K probably rules out an encoder, unless someone was really unwise in the part number naming department.

Sounds like a fun project.

[Invisible Man]

I'll do some poking around, and I'll report back. Taking a perfectly functional pedal and wrecking it has kinda become a thing that I do (to cheap ones, anyway).

[Dr. Sherman Sticks M.D.]

was looking into this last night on my own accord. think i might try this if i can get my hands on a DD5 or 7 for a decent price.

this might be relevant to the momentary feedback.
http://www.diystompboxes.com/smfforum/i ... c=110714.0

[Dr. Sherman Sticks M.D.]

found some more stuff.
https://www.youtube.com/watch?v=9NQFI_zCI2c
http://www.thegearpage.net/board/index. ... p.1203981/

sounds like if you jump the 2 and 3 lugs on the pot, it will work unless you have the feedback knob all the way down, then the knob still overrides the switch. might not be a big issue, but i think the first link i posted above talks about how to override that.

[Invisible Man]

Yup. That's what I'm looking for. Thank you! This is gonna be a fun and cheap project, I think...I'll post result, pics, and hopefully a video when it's operational.

[Dr. Sherman Sticks M.D.]

anytime! the dd7 has trails right? nm googled it

[Jero]

Taking a perfectly functional pedal and wrecking it has kinda become a thing that I do

nm googled it

Words to live by folks

[Invisible Man]

anytime! the dd7 has trails right? nm googled it

This is part of what could make it extra gnarly. Hold the feedback switch, then bypass the pedal. Let the trails do their thing, and then mash on the feedback stomp at any point during the trails to "bring them back."

[eatyourguitar]

electro harmonix delays have 5v pots wired to a 5v microcontroller with a built in ADC then from there it goes over serial connection to the 3.3v DSP processor that does the delay software. on this pedal it would be easy to add cv input, or expression pedal input. it would also be easy to have it assignable if the manufacturer wanted to add a display. nothing needs to change to have midi or assignable parameters on the expression jack. I am not saying every pot is a dc voltage but rather I would not rule it out until I open the pedal. behringer also uses voltage divider pots on the pedals with no display.