When i first read about Parker's "Fly" and "Superfly" guitars in Guitar Player back in 1993 (before they were in production), i was fascinated by the idea of having electric and acoustic sounds on one guitar, and being able to blend between them.
A number of years later, i finally got a Fly Classic, and was finally able to get the sounds i'd been hearing in my head for years. Then i started playing sevens and got my Petrucci 7 with the piezo option. (Thanks, Donnie!) But actually using the piezos in a live context the way i wanted to would have required an extra hand or two in order to blend seamlessly from one sound to the other while playing.
I started looking around for a stereo blend pedal... one that would allow me to go from 100% magnetic to 100% piezo with both at full volume in the middle of the pedal's travel. Much to my amazement, nobody made one. Fishman made a "PowerBlend" pedal for a while, which was essentially a Morley volume pedal with an acoustic buffer/preamp circuit and a pass-through for the electric signal. It didn't really "blend" at all. (Apologies to Blendtec.)
I emailed just about every company that made volume pedals... Morley, Ernie Ball (who also happen to make a lot of guitars with magnetic and piezo pickups), Visual Sound, even a bunch of boutique pedal makers. Nobody made what i was looking for.
For a while, i used a convoluted workaround of using a stereo expression pedal (a BOSS FV-300L) that allowed me to simultaneously control the volume of my GT-6 and Yamaha AG-Stomp in opposite directions with custom settings that made the volume pedal only work in half of its travel on each device. It was big and kludgy, but it worked. But i wanted something simple. Something passive. Something i could use on its own or in different rig setups.
So i made my own.
I wanted it to be passive, and as simple as possible. I bought an empty wah pedal shell, a 500k blend pot and a 25k blend pot (i wasn't sure which would work best), and a bunch of jacks. I wired it all up and started testing, experimenting, troubleshooting and tweaking.
What you see here is my second prototype. I use a stereo cable coming out of my guitars, and that goes into the right side of the pedal. The signal is split to the two halves of the blend pot, and then output to a pair of mono jacks on the left side. Simple. Effective. It ain't pretty, but it works. (Any others i make will look a lot more finished. This one is just the raw aluminum shell, which i actually think looks kinda cool.)
In the first prototype, i encountered an issue with a feature in the GraphTech AcoustiPhonic preamp design that makes it work in an undesirable way with a pot placed directly after it in the signal chain. The AcoustiPhonic uses a stereo switching jack and a tiny amount of DC voltage on the piezo side of the preamp's output to detect whether you have a stereo or mono cable inserted. If it's a mono cable (which it detects by the piezo output being shorted to ground), then it automatically jumps the piezo signal to the tip contact, summing it with the magnetic signal so you get both signals going down one wire.
This is a GREAT feature, but a volume pot works by shorting the signal to ground through a variable resistor (the pot), and this would cause a loud POP as the preamp tripped into mono mode. If i reversed the pot wiring so the output was on the wiper contact, the automatic stereo/mono switching was avoided, but the DC voltage on the piezo signal would cause an audible hiss of pink noise when the pot was moved.
I worked around this issue by placing another active device in the chain before the pot. In my particular case, i used my Tech21 Acoustic DI box, which has a sort of "effects loop" configuration. The piezo signal goes into the blend pedal (which essentially acts as a splitter) and then out of the top of the pedal, it goes to the Acoustic DI input, and the 1/4" output from the DI goes back into the blend pedal and to the piezo side of the pot, then to the blend pedal output which goes back to the DI's "Input to XLR" jack. The XLR output then goes to the PA. The "send" on the blend pedal uses a switched jack, so if nothing's plugged into it, it bypasses the loop.
(I've suggested to the excellent and helpful people at GraphTech that perhaps in a future revision to the AcoustiPhonic preamp that they put a DIP switch on the board to allow the end user to disable the automatic stereo/mono switching, for those like me who always run in a stereo configuration, or for those who might want to use a non-switching barrel-type output jack.)
In the heel position, i get 100% piezo (or as close as the pot will get me). In the toe position, it's all magnetic. In the middle, there is a very slight detent, which you can just barely feel through your foot, and both signals are at full volume there. With the tension on the treadle set just right, it's a little easier to locate, and you can quickly find it and the pedal will stay there.
This is exactly what i've been looking for. It enables me to blend smoothly and seamlessly from one sound to the other, or to add a bit of one sound to the other, without interrupting my playing.
If anyone is interested in something like this, i am considering building them to order, now that i've worked out some of the kinks. I've tested it with my GraphTech GHOST-equipped guitar and my Music Man JP7 with piezos. I don't see why it wouldn't work with Parkers, Godins, or other Fishman, L.R. Baggs or RMC-equipped guitars as well.
This will take a stereo output (say, from a chorus or delay pedal) and allow you to dynamically blend it between two separate amps or signal chains, correct?
Also, you need a sweet logo and finish on it... raw aluminum looks badass (I scratch-built a RAT pedal using a similarly unpainted enclosure), but I think it's screaming for some sort of two-tone finish and sweet decals... I know, minor niggles (and much more expensive and difficult to produce) but, the 'pedal nerd' in me is speaking.