Foxx Guitar Synth Wah

[pinkjimiphoton]

i'm watching it too bro, hope we don't end up in a bidding war. i will conceed in that case.

just thought it interesting...i think it's the guy that posted here asking about how to re-wire the battery snap.

i downloaded your layout, i gotta find a BOM... i may try and build one...while the eyes aren't bugged out.

it WOULD be cool to add to the collection, tho, huh?

[digi2t]

i downloaded your layout, i gotta find a BOM

If you downloaded my layout, you should have the BOM. It's on the layout. You are talking about this one?



You'll need the schematic for the wiring though, it's a real Medusa. It's in my Gallery.

If you need me to roll you a custom Vactrol, just say the word. The layout was designed around it. Or, you can use two VTL5C3's, wiring the LED's together in series. I've tried that, and it works as well, though my Vactrol has more... WHONK, to it.

[pinkjimiphoton]

i am BRIAN dead i think...

yah, i got it on my desktop...thanks for the tips bro!!

[digi2t]

I should warn you right now, for the most part, great circuit. But...

Since the LFO is part of a quad opamp, it's prone to ticking in some modes. Especially bad in HI mode (think Ludwig Fuzz Percussion!). I've thought about a redraw, to divorce the LFO section from all this, but since I use the envelope and wah aspect of it for 99.9% of the time, I didn't bother.

Wouldn't surprise me if the original is plagued by the same problem. I'm not sure if  a resistor/cap reserve on the +9 pins of the IC's would help either. I have to try it I guess.

[pinkjimiphoton]

diggit, thanks for the heads-up...maybe separating the grounds with a cap would work?
seems to me, i'd probably use it the same way you do anyways, lol!!

great minds and all...

well, not quite, but you know what i mean. 

if it's got yoy....

[digi2t]

MAJOR UPDATE!!!

After having had the opportunity of exploring an original Foxx Guitar Synth in the flesh, I discovered an error in the wiring for the Arpeggio Hi/Lo function. This was partly due to the, um... vagueness  , of the original schematic. The error pertains to what is called "flange" in the schematic, but is more accurately an arpeggio function. In reality, there is no flanging going on here, but rather, a sort of arpeggio "cascade of notes" effect. This section of the effect is meant to be used with the LFO engaged, or else it does not do anything. Quite cool actually. Very cool to be honest. Blew my mind when I heard it.

Here is the updated schematic;



In the original unit, the rotary selector switch is a DP5T. In Arpeggio mode, the second deck handles routing the signal either through a 22K resistor for HI, or a 100K for LO. In my unit, I have the J.C. Maillet resonance pot mod, so the Hi/Lo selection deck is not required, since I can sweep through the Hi/Lo range with the pot.

If you're using the original resistor setup, then use a DP5T, and use the second deck to switch between resistors. If you're going with the resonance pot and 12K resistor, then you can use a SP4T, and bring the "Flange Hi" and "Flange Lo" wires from the board to a single pole on the rotary switch. Then you can use the resonance pot to dial in the arpeggio range. Personally, I like this better, it's more flexible. If you're going original, use the DP5T, and use the 22K and 100K resistors, with their connected ends going to the B.P. line (imagine the 200K pot replaced by a stright line).

Just an added bonus, I used a DP4T anyway, using the second deck to power my LED's for the mode indication.

I also added the 0.1uF cap on the pedal pot, which is on the original, but at the time of first drawing, I only had pictures to go on and I couldn't make out what value it was. It's a lame attempt to detick the circuit in Arpeggio mode on the original, so I also added a 1uF electro cap on the pedal pot to ground. On mine, the 1uF does an excellent job of deticking the circuit in all modes. It's dead quiet now.

The vero remains unchanged. I just need to update the wiring, since it adds an important dimension to this pedal. Here is a short video demo of the Arpeggio function.

Vero and schematic are in the Gallery as well. I can now stick a fork in this one, it's DONE!! 

[petey twofinger]

always wanted to at least hear one of these . never cease to amaze sir . hats off !

[pinkjimiphoton]

props dino!!

i still haven't got to it yet, trying to give poor gineen a break for a little while, actually cleaned up the dining room...

i have to build a superfuzz for my bud mike out in AZ, (i bought 50 828's off fleabay) but this is definitely on the list of must have stuff.

still gotta get the stuff together for cousin ludvig, too...ayyyy

[akestromer]

Ok, (hopefully) resurrecting a very old topic.
I started building this to try to eventually make my own version of the Frogg Compusound. I have a strong suspicion it was based on this.

Pretty much all of it works great.
But I can't figure out the Flanger/Arpeggio mode.
I hooked it up like this (I tried writing it down but this is probably easier to understand):



(and that goes to the switch that's connected to the output (15µF +side) I should say)

It sounds good, but I'm getting very low output. What am I doing wrong?

And thank you so much for sharing this! It's been a lot of fun to build!!