Double expression from my SP-1 Mission!!!

paranoid

Fractal Fanatic
Ok member Morbid got me thinking the other day in this post.
http://forum.fractalaudio.com/threads/diy-wah-vol-expression-pedal.109094/
Well here it is and it works like a charm with my mfc, and I am hoping it will also work with the AX-8 that I am waiting for invite on, as are many others.
The whole reason and purpose for this mod is to have 2 ext controllers operated by one control pedal to save room, and to save cpu( by not having to use mixer block or volume blocks to make this happen) I have rewired the SP-1 so that the switch now switches the variable pot connections between the 2 trs jacks, instead of the pot on 1 trs and the switch on the other. So now this is 2 expression outputs but only one works at a time, when you switch the toe switch the 1st trs jack is left at toe down and the second is variable, and after the switch is pressed again the 2nd trs is held at toe down and the 1st one is variable again(much like the expression pedal on the pod hd500). I am now already thinking about modifying my other SP-1 to have this feature but with the switch at the heel. then I would use one for volume and wah, and the other for things like the formant or delay mix, things that you want to start from the heel.
Now I am not an engineer and do not know much about electronics( I am a heavy diesel truck mechanic by day and a guitar nut by night!) so don't laugh, don't tell me how bad my wire connections look, Because I already know! But I am posting pictures here and maybe some crafts men that are good at this stuff can improve upon it.

Ok I started with an SP-1 which was already modified to have the jacks on the right side so wires would not be on the out side on my mfc rig( so when mine doesn't look like yours this is why). The only additional supplies needed a few small pieces of wire. every thing else is already there. so here are the pictures!

This is my board

This is the SP-1

this is the before

the after!!!!
 
Ok, Please forgive my ignorance if I am just missing something here. I am asking this because as soon as my parts arrive I will be modding my EP-1 to turn it into an SP-1 and I am intending on setting it up as a volume/wah so that when you press the switch it activates the wah, and leaves the volume in full on position or bypassed, and then you press the switch again it activates the volume and leaves the wah in full off position or bypassed.
So I am confused as to how your method is any different than method 2 explained in this video.
 
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Did you watch all of Chris's video? with a standard SP-1 in stock form it is 1 expression pedal and 1 remote switch. so to use as 2 expression pedals with the axe fx you have to set the modifiers for both of the effects you want to control the same, this makes the sp-1 control them both at the same time. then you must use some other kinda blocks in the grid to bypass one or the other of the effects you have the expression set to so they do not both function at the same time(I can use input or output volume with this mod, no volume block). with the mod I have preformed these extra blocks are not needed. the switch in the sp-1 does this inside the pedal. with this mod though you will not be able to use the toe switch as an external switch, it will only be usable as a double expression pedal.
 
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Did you watch all of Chris's video? with a standard SP-1 in stock form it is 1 expression pedal and 1 remote switch. so to use as 2 expression pedals with the axe fx you have to set the modifiers for both of the effects you want to control the same, this makes the sp-1 control them both at the same time. then you must use some other kinda blocks in the grid to bypass one or the other of the effects you have the expression set to so they do not both function at the same time(I can use input or output volume with this mod, no volume block). with the mod I have preformed these extra blocks are not needed. the switch in the sp-1 does this inside the pedal. with this mod though you will not be able to use the toe switch as an external switch, it will only be usable as a double expression pedal.
Gotcha! OK makes total sense now. You're essentially eliminating the need for a volume block.
 
And additional modifiers. Also if you want to control other things like reverb mix and delay time for a song part in the original form you have to bypass the effect( or us multiple blocks to work around this) to switch the pedals use, with this mod it goes to the toe down setting, that can be set were you want it in the modifier page.
 
Just ran into this, and happen to have a spare SP-1, which is great because they don;t make the SP-2 anymore. I saved the pictures to do the conversion if my SP-2 goes out on me. Thanks!
 
Just ran into this, and happen to have a spare SP-1, which is great because they don;t make the SP-2 anymore. I saved the pictures to do the conversion if my SP-2 goes out on me. Thanks!
If you can not make out the wiring in the photo let me know. If you pm me an email I can send you a simple drawing I made of the wiring.
 
This is great. I have an old Dunlop Wah that I want to convert for my Ultra, for this specific reason. It will work with the Ultra, correct?
 
It should. Pretty sure the Ultra uses the same expression pedal polarity as the Axe II.

Polarity should be:

Pot lug 1 (ccw) to TRS ring contact
Pot lug 2 (wiper) to TRS tip contact
Pot lug 3 (cw) to TRS sleeve contact

In the pictures above, the green wire is pot lug 1, red wire is pot lug 2, and black wire is pot lug 3.

The mod is to wire both TRS output jacks in parallel to the pot, but the two tip contacts go to the two throws of one of the poles on the switch. That pole is then connected to the middle wiper lug of the pot. The other switch pole is connected to a ring TRS contact and its two throws are connected crisscrossed to opposite throws on the other pole (white wires). The switch flip-flops the connections of the two output jack tip connections between the pot wiper and the ring connector. The result is one output get's it output from the position of the pedal while the other is hard wired to full up (toe down position). Clicking the switch swaps which output is the pedal controlled one.

This approach works ok when the two expression outputs are connected to the same device, but it should not be used to connect each expression output to different devices, since the outputs are not fully independent of each other. That would require a dual gang pot like the one used in some of the newer Mission expression pedals with dual outputs.
 
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@mr_fender great job explaining all that. I made it work but never could have explained it correctly. I am sure you are correct about running it with 2 different devices(never tried), but it works really well with my AX-8, and MFC, one at a time that is.
 
Thank You for this. I am another Dunlop Wah owner looking to convert for the Ultra. Is the pot in the Dunlop suitable or no? Is there a parts list available? I'm good with a soldering iron and mechanics of it all, just not the electrical details. Thanks
 
Sorry I did not know photo bucket dumped all our photo serving. I will try to get some photos back up some time. Just battled Irma here in FL so will have to take care off some other things first, like get power and fix the 4'x 2' hole in the roof. then I will see about finding the card those pictures are on and find a new photo server.
 
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