My switch is a dpdt, but it's weird because it's wired like a spdt. Each wire is extended to its neighboring pole. Idk why they would do that
Can you explain more about the hardwired bypass, and the parallel path leading to decreased impedance?
I have some BC109b's I can use, and I'll try those cap and resistor changes. I also have a BC549C, would that be better than the low gain version?
Deffo do the "B".
Too much gain in this position gives the wah a bit of a spiky, unpleasant high-end response. This was a 2N2905 in the old Thomas Organs - generally between like 100-300hfe.
A "C" bucket will get ya closer to 400-800hfe. Too close to the mpsa18, which is just...too damned hot, too damned clean.
The BC109b/549b has a nice flavor to it. Ain't the cleanest thing in the world: its the dirt that really makes this thing shine in this position. If you want clean, I'd hand-select a 2N5088 at the lowest end of the gain range. Like 300-400hfe.
The second mpsa18 is less important. Personally, I like to swap both while I'm in there, but the biggest difference comes from Q1.
Note: the buffer uses an MPSA13, a darlington transistor. Honestly: I pull this sometimes and do a jfet buffer to increase the input impedance (it's SUPER easy and doesn't require any mods to the circuit board, it just requires turning the jfet sideways and bending the leads).
The tone-suck in the off position associated with wah pedals is based in reality: these circuits have quite low input impedance. That's not a huge problem in use, and can actually kinda add to the appeal of the circuit, as that will tend to shave off a bit of your high end.
BUT...the issue of leaving the input connected is one of parallel paths.
Impedance is a form of resistance, and the law of parallel resistances is:
1/R Total = (1/R1) + (1/R2) + ect.
Your total resistance (impedance) on a branching path is always going to be *less* than your lowest impedance.
Which means: on vintage wahs that didn't disconnect the input, the low input impedance of the wah pedal would drag down the impedance of the entire circuit. Which would shave off a considerable amount of high-frequency signal content and would lead to a more attenuated signal hitting the amp.
The input buffer *greatly* improved this, and if it's the only pedal in your rig that does this you're not likely to notice a difference. The problem lies in where you start stacking pedals that do this...then you're just stacking additional 1/Rx's. It can load ya down real quick.
That's why I'm a fan of just making it true bypass.
Something else....almost forgot about this:
That second 10nf cap? Swap it out for something a little "better" than a poly film cap. Polypropylene is a good upgrade, polystyrene is better.
Why? The old Italian wahs used polystyrene caps. Call me superstitious. I've never actually done a full comparison, and I doubt my ears would really be able to tell the difference. But its fancy, and I like fancy.
Other mods:
The pot, but only if you're certain that you want a different taper out of the pedal. Doesn't do a whole lot on it's own, and the stock Dunlop HPIIs are A) bulletproof and B) do the job admirably.
Inductor: the red fasel is a finicky bastard. It's fine. You can certainly build a great sounding wah pedal around one. But there's something about it that I just don't particularly like.
Probably because I've pulled the originals apart and seen that those were made with 1408 pot cores, and the "reissues" are toroid core.
Dunlop had used pot cores for quite some time. In the mid-90s they transitioned to toroids. As far as I can tell this was done for cost-saving reasons.
I say that because there's less assembly with a toroid, and it coincided with a drop in DC resistance without an appreciable increase in wire diameter...which makes me think they were able to get away with using much less copper wire per unit.
I could be totally off base here, too. But it fits with much of what Dunlop did post-acquisition of the crybaby from Thomas Organ.
Which is to say, I associate toroids with a bit of a "games over losers, I've got all the money" impulse on Dunlop's part. They're not all bad, the ones Dunlop makes are just extremely inconsistent. And I suspect that the red fasel is really just the black plastic cylinder with tighter manufacturing tolerances and a facelift.
But...then again...the maestro boomerang is well loved by many, and that one used a toroid inductor as well. So...meh.
I do like a good pot core inductor though. I mean, I make them and randomly throw them at people on this forum.
