Modding a DOD DFX94 -- looping and triggering?

[notnews32]

Hey All,

I'm sure most of you are familiar with the DOD DFX94, or at least one of it's DOD cousin delays.

I'd like to make looping (and messing with the loops) and triggering easier. I'm imagining a mod similar to the "looper stomp" mod people do to the DL4 that involves augmenting its rotary switch (which is also the mode selector switch on the DFX94) with stomp switches that select positions on the rotary switch, effectively bypassing the rotary switch when engaged.

The DOD DFX94 has one mode for loop recording, and another mode for triggering the loops. You have to record the loop in one mode, then turn the rotary switch to trigger mode to play the loops back. I'd like to wire the pedal with two switches if possible, one to enter loop mode and bypass the rotary switch (where I would record a loop), then stomp another switch to trigger the loop... this stomp would ideally both enter the trigger mode (a position on the rotary switch) and also trigger the loop (stomping on the main/bypass footswitch). THOUGH, since the "entering the trigger mode" stomp would need to be non-momentary (I think), and the triggering of the loop itself would be momentary (right?), I'm guessing that one stomp can't do both of those things I'd like it to... so maybe I'd need three stomps, where the mode-selector stomps would be non-momentary and the trigger stomp would just remain as the main/bypass stomp already there.

Either way, if I wanted to return to whatever mode the mode selector rotary switch was on, I would click the looper or trigger stomp, which would return full functionality to the rotary switch and whatever position the rotary was on before I stomped the looper switch would be active (i.e. a delay setting).

On top of all of that, the DFX94 has this very cool feature where you can mess with the loops you recorded. By turning the time knob you can speed up or slow down the recorded loop. If there was any way to externally control this knob by replacing it with a passive expression pedal output maybe?, that would be great. OR maybe if there's room in the enclosure I could just move the knob to the side of the pedal and replace it with a larger roller knob I could move with my foot.

Sorry for the wall of text... hopefully I've written this post coherently and in the correct subforum, and someone out there is familiar with this pedal and/or the DL4 mods and could help me with this! For whoever can help me work through this mod I'll make it worth your while by throwing you a pedal or something when it's all done.

Thanks!

[lordgalvar]

I am actually modding one right now, but got way sidetracked with the mods (which ended up turning into something else). Dandolin and I were trying to figure/find ways to make cv controlled delay and I started with the FX94 (because of price and the bad switch). I figured a way but when I got it all wired up, which should have worked in theory, it went all haywire and lofi...kinda stuck inbetween bypass and not-bypassed. It didn't really work. This little project got me into building stuff like crazy.

Anyway, the idea was to jumper the two modes with a momentary switch (which I pretty much found out wasn't going to work because it looked like it was reading the value of a detented pot to select mode to me...it only had three terminals/lugs) and to make a gate/relay bypass to replace the bad bypass switch for remote swtiching...I didn't really have my design down yet and when I got the bypass working I used it on something else.

Maybe use a multimeter to read the values the pot or switch or whatever it is is throwing out and then replicate the difference with a momentary switch. Like if value 1 is 100k ohms and value two is 120k ohms (I don't know what they are), jump off two wires with a resistor or something that adds the 20k ohm difference. Might work? I doubt it though. If the other modes don't matter, replace the whole thing with a momentary DPDT or something with the right values to tell the computer what mode it is in.

CV control of the time knob would be somewhat easy but you should just rehouse it at that point and replace the switch and stuff. Use a switching jack and just run wires between the jack, board and pot. I don't know what value it is off the top of my head, so I couldn't suggest an exp pedal to use.

Anyway, now that I have some working stuff I might revisit it...I will post more when I bust it out...(might be a little bit)

[notnews32]

thanks for taking the time to reply

it'd be nice to access the delay settings.. if I could maintain that circuitry and functionality I'd prefer that over losing it all together in lieu of a sole-looper. I'm really torn with exactly how I want this pedal to function.. lots to think about. If you start to consider this project again, definitely shoot me a PM.. I'd love to work through it with someone, Ive got some cool ideas.

based on how crowded the enclosure is already, I'm thinking no matter what I do I'm gonna rehouse it.

just curious.. working on anything cool these days?

[Faldoe]

Why would you want two separate switches when the DL-4 Loop Mode mod with one switch would do that?

Sounds like some cool stuff. And yeah, there is zero room in that enclosure for anything else. Def needs a rehouse.

Damn, I might need to find another in the future, lol. Enjoy.

[lordgalvar]

thanks for taking the time to reply

it'd be nice to access the delay settings.. if I could maintain that circuitry and functionality I'd prefer that over losing it all together in lieu of a sole-looper. I'm really torn with exactly how I want this pedal to function.. lots to think about. If you start to consider this project again, definitely shoot me a PM.. I'd love to work through it with someone, Ive got some cool ideas.

based on how crowded the enclosure is already, I'm thinking no matter what I do I'm gonna rehouse it.

just curious.. working on anything cool these days?

So the FX94 was stuck way back in the closet, but I dug it out. Will get started with it in again sometime soon. The plan was to set it up with a bypass switch (to get rid of that junky one), a momentary switch to jump between recording and playback modes, and a cv mode to play the sample back via trigger in (which would essentially be another bypass switch, but it wasn't working...making me think that there is a minimum time for the switch to be engaged for it to sample/playback...which I think was my problem...I was running like a 5-10ms trig signal into my relay and it was too quick to hear anything...so I may have to make something that is a set length to take the trigger and play or just make an LFO with a lower speed instead of the cv trig in... probably shouldn't listen to me ramble, I'm an idiot )

I think partially I am coming at it from a noise/glitch making broken sound side of things...but I shall see where it goes.

As for other stuff, I have finally sourced all the parts for the floppy disk delay, but this morning I was mowing the lawn and at the grocery store (which is alway bad because my mind wanders...) and I thought of something cooler to do on the way with the same parts.

Then my friend, who's sister is like managed/produced by some famous people, is trying to talk me into making some pedals for her to sell at shows as like a "signature" model or something. He wants me to make a toob screamer but I told him no and if he wants that to build it himself. Funny thing is that she is an acoustic act (no looper or anything...just got her first pedal this week...a tuner)? I had this idea for a reverb (seeing as she mostly is mic'd into PAs) but he said he wanted something more bloosy....but he is trying to get me to start a company or something because he thinks there are millions in the "pedal biz" which makes me laugh (but I think he just wants cool friends with interesting jobs...and I am an ex-plumber turned house-spouse).

Eh, rambling. Thatnks for asking, sorry for the randomness haha.
tl;dr -> same old dumb ideas that probably wont work. But will mess with the FX94 (I really should have marked that molex connector )

Is there a DL4 loop mod for the FX94?

[lordgalvar]

Yea, should be doing tile work but I'm not. The rotary switch is a 20k pot with detents. So whatever values it reads resistance wise for the modes you want to switch between are what we are going to have to replicate in theory. Like have the 20k momenarily bypassed by a switch that sends a certain resistance value back and when you press it it goes to playback and let go it defaults to where the pot was set at. At least that is my best guess. Probably could make a exp pedal cycle through the modes if you wanted haha.

[notnews32]

...
The plan was to set it up with a bypass switch (to get rid of that junky one), a momentary switch to jump between recording and playback modes, and a cv mode to play the sample back via trigger in (which would essentially be another bypass switch, but it wasn't working...making me think that there is a minimum time for the switch to be engaged for it to sample/playback...which I think was my problem...I was running like a 5-10ms trig signal into my relay and it was too quick to hear anything...so I may have to make something that is a set length to take the trigger and play or just make an LFO with a lower speed instead of the cv trig in...
...

By minimum time for switch to be engaged, you mean like a setting built into the pedal so that scrolling past a delay setting to the looper setting for eg wouldn't make the pedal turn those passed-by delay settings on... and then when the switch rests on the looper setting for a certain amount of time the pedal activates that setting? That makes sense if you think about it.. there would be a lot going on in the pedal when someone was scrolling from one side of the dial to the other if there wasn't a minimum time requirement that needed to be satisfied before the setting was active.

..but what do you mean when you say that the 5-10ms trigger was too quick to hear anything? Too quick to activate a setting?

If by "make something that is a set length to take the trigger" you mean make a device that accepts that trigger length and therefore engages a setting, that sounds much more difficult than figuring out what the minimum time requirement for setting engagement is and changing your trigger length to that.. right?

I could be way off with everything and I'm sorry if that's the case... I'm just starting to dive deeply into audio circuits (I've built up a few circuits so far and do a lot of reading) but as of now digital circuits are a bit out of my grasp. I appreciate your stream-of-consciousness responses.. so feel free to gush!

[lordgalvar]

Sorry for rambling man.

I didn't have it wired up with a stomp switch when I was messing with it. I had the switch (for activate/bypass) setup as a relay at the time that was triggering off of the trigger out of a Korg Volca beats which is a very short signal and therefore a very short relay switch. The effect really did nothing and was kind of stuck, so I ordered some momentary and latching switches to replace it with something that works (because it is being rehoused too). The idea was to play samples back randomly when in the playback mode because the pedal was already on but the samples only play when the switch is tapped. So the switch would be activated by an outside CV source. Anyway, it didn't work, so...ignore all that 5ms-10ms stuff. I don't know what went wrong but may revisit it later. I think it was just too quick for the computer to switch to playback and back (because the switch was held down for less than is probably humanly possible via the relay). Yea, all of that isn't worth your time, so sorry about the confusion (was just mentioning the background of my messing with this pedal).

To switch between the sample and playback mode on the detented pot, my idea was to use a 3PDT (i.e. bypass switch) to route the three lugs/holes where the pot was on the board to either the original dentented pot or another pot of the the same value. This, in theory, would create the ability to switch modes via stomp switch. I don't know if the effect uses all three lugs of the pot, which is why I am using the 3PDT for the moment but if it doesn't an LED indicator could be added. Sadly I do not have the proper pot sitting around (keeping parts around is the worst part of all this). Furthermore, this would allow you to switch between any two modes with the stomp of a switch. Even better if I can find a dentent pot that is exactly the same.

I'll draw some pictures and try to get a pot in somehow (or drive over to ratshack...but I don't want to do that because I already have a cellphone and trying to talk them out of a sale sucks). I will look on Amazon or something.

[notnews32]

dude ramble on.. everything I can read only helps

I think I understand how using a 3PDT switch could allow switching between the looping and sampling modes, and you'd still be able to use the OG stomp switch to trigger the looping and the sampling.. but could you explain why you'd need another identical pot to do this?

Ideally it would be nice to switch from a delay mode to the sampling mode by stomping a switch (sw1 = any delay setting to sampling setting), then stomping a different switch to go from sampling mode to looping mode (sw 2 = sampling to looping), then pressing sw1 again to go back to whatever delay setting the detent/settings pot was on. In my mind this would require 2 switches and only the one pot. How is your second pot being used? I imagine sw1 as a gate to all of the settings on the detent pot (if it's engaged, then the signal goes to the sampler, if not then it's bypassed and the setting on the detent pot gets the signal), and sw2 as a back-and-forth between sampling and looping that would switch between the two either if sw1 is pressed or if s1 is bypassed and the detent pot is on the looping or sampling setting. Does that make any sense?

Sorry if it feels like you're holding my hand thru this... trying to wrap my head around it

[lordgalvar]

I think I was talking about trig and sample mode. I hadn't looked at the case in a long time (I just have the pcb out had to google img search the case so I didn't have to dig through a box).

The way I understand the pot being use to switch is like this:

signal -> pot -> resulting value = current mode
so lets say 20k ohms is sample and 17k ohms is trigger (don't know for certain)
signal -> pot 1 @ 20kohm -> sample mode/ then switch is pressed which results in signal -> pot 2 @ 17k ohm -> trigger mode

could be done to switch between any two modes (the second pot just tells the computer which mode to be in by the reistance value).

You could do that switching between three modes but it would require the 2 switches plus 2 extra pots (or their equivelent resistence value... for both sides as far as I can tell) (or some kind of mux thing...but the switches would probably be easier.

I got it wired up and it works but sometimes gets stuck in a mode....but I was switching between looping and another mode (but when going back to looping, it didn't work). I am going to mess with it more and see what's going on.

Also, you have to be very careful taking it apart. The wire connections are very weak and kind of a mess. Takes a minute to find out where they go if you didn't write it down. Anyway, going to get some notes together...check back soon.

[lordgalvar]

Roland EV-5 expression pedal does work a little but has very little range. Moog EP-3 doesn't really work at all. The delay pot is a 5k ohm...and the values of both expression pedals are way higher.

LDR does work though and is kind of fun (but does not get as glittery sounding as when sweeping the pot).

Momentary stomp switch SPST does work for the bypass.

So far I have rewired all of the offboard wiring, replaced the bypass switch, tested the mode switch, tested expression pedals, and tested LDR delay control.

Next: various mods that were planned. clean up wiring. build it a new home.

Update: got cv switching working...I think the fx94 had a grounding issue before so that's good.

[notnews32]

sounds like you're making serious progress.. damn

thanks for walking me thru your thought process. I think I understand everything you typed out... I wouldn't be able to recreate it though on my own bench.

If you're willing to type up some instructions or give me some kind of guideline that I can go by and then ping you if I have any questions, that would be great... I have a few things lying around (working things that sound cool, not broken things or things that sound shitty) that I don't use that I could throw you for the trouble.

[notnews32]

I play with this pedal and can tell that it has so much potential.. I'm just not at the point with my DIY circuit skills to be able to open it up and hack it the way I want to.

I'm open mine up tonight and take a few notes and mess around with it... I think I'll be able to replace the bypass switch at least.

BTW... where is your expression pedal wired into? As a replacement for the 5K delay pot? Wouldn't any 5K exp pedal do the trick here or am I missing something?

[lordgalvar]

There just isn't a 5k expression pedal on the market that I know of is all. You could probably make one with an old wah enclosure or something (or justwire it to a pot off board). The work around is to use a vactrol for the exp pedal which is next.

I'll post notes and photos when I am all done...just got a few more things to try and clean up.

Some test sounds:
[youtube]http://www.youtube.com/watch?v=SGX-7pyQMUg[/youtube]

Same kinda deal (skip to minute 5 for the best stuff):
[youtube]http://www.youtube.com/watch?v=icqyRRdDbq0[/youtube]

Man, I do this to learn and because I enjoy it. Don't worry about it! Thanks, bud!