R2R inspired Vintage Wah. (Cocked Wah with selectable expression out)

[HuckleberryThin]

I wanted to challenge myself with a R2R Vintage Wah style build. On eBay I found a seller (detrick fx) with a classic board layout with matched transistors, carbon comp resistors, and period style caps. I chose to use a modern Yellow Fasel since I found one cheap. I also used the “Black Bear” 100k pot from Small Bear.

I fit the parts and board in a 1590C tall boy and used a Mad Bean Pedals to learn more about the wiring for 3PDTs. Excellent resource! I also referenced old photos of vintage Italian Jen wahs since some of them used the Fasel style inductor.

The cocked Wah works as you think, but the expression needs to be 100k as well and I only have a 25k pedal that doesn’t play well. That means another project. I may swap out the black bear pot for a CTS 100K and use that as the expression pot.

My wiring isn’t the neatest thing, but I was tickled that the pedal worked first go. If anyone has any input or other ideas I’d like to hear them.

 

[~Tu3ePh0x~78~]

If you use an expression pedal, does it then have the range and sound like a Wah pedal? And to add an expression jack, does it wire to where the treadle pot assembly would wire to the board? May wish to get with you on the schematic/wiring (outboard device) Thanks!! Dean

 

[HuckleberryThin]

If you use an expression pedal, does it then have the range and sound like a Wah pedal? And to add an expression jack, does it wire to where the treadle pot assembly would wire to the board? May wish to get with you on the schematic/wiring (outboard device) Thanks!! Dean

The expression pedal uses the same pot as you would normally use on a classic wah, so it feels the same. With that stated the wah kits available are kinda meh and I haven't fully completed mine as I'm waiting to find a used one locally for cheap. (The kits use a funny treadle rack that don't match up with any pot that I have.) You could buy a new rack and drill it out to fit the kit, but I honestly can't be bothered to go that far .

Now with an off the shelf expression pedal that uses a 25k pot it may not work depending on how it's wired. Some expression controllers swap the tip and ring. I have a paint audio mini foot pedal that has two jacks for the different schemes, so when I use that the throw of the pedal is backwards. Heel up=full treble. Toe down=all bass end. This has a use but it is very different than any wah, but I don't notice it having more range or less.

I'll attach some photos and a hand drawn true bypass wiring layout I did, but don't follow the cliff style jack wiring as it grounded out the circuit and didn't allow the expression to be use. The blue and yellow wires from the wah board go to the (on-on) switch and then out to the pot and TRS jack.

Also the 10k pot for the cocked setting will be backwards from how you would think it would work. (Turned down all treble end turned up all bass end) You could probably swap it out with a reverse 10k pot and it'll work like you'd expect.

I hope this helps.