There certainly CAN be a difference in quality between different inductors and different circuit paths. Poorly-designed or cheaply manufactured components can create unneccessary resistance, which can lead to signal attenuation, esp. at high freqs, or can become capacitive in ways that exceed the intent, which will cause frequency anamolies and phase-distortion. So people who say that the components can make a difference in the sound are technically correct. End of factual analysis.
BUT, as a matter of personal opinion, I am inclined to side with Joe on this one-- this is an electric guitar pedal. This is super-primitive, soviet-era technology that was for the most part invented in garages by potheads with parts from radio shack.
"Vintage" electric guitar, and the whole signal path through the amp including the speakers, was designed for volume, not for fidelity. The signal path and audio integrity of electric guitar is terrible. Noisy, severly bandwidth-limited, crude, you name it. From the speakers to the cables to the amplification cicuitry, it is DIY-style improvisational technology, and not the audiophile-kind, either.
I'll bet that the original designers of these pedals never conducted any kind of significant testing on the components they used, beyond experimenting with different nominal inductor values (not different chemical formulations). I bet at most they went to radio shack or You-Do-It electronics and bought a few different sizes of parts and when they found one they liked, they wrote down the specs and ordered them in bulk. If the manufacturer and composition of the first factory run happened to be the same as the first prototype, that was probably only because the wah-pedal company, like Radio Shack, was buying from the cheapest supplier.
I doubt very seriously whether many of the guitar gods of myth and legend were sitting conducting double-blind listening tests of different years, makes and models of wah pedals, like a wine connesuier, or a modern-day gear nerd lovingly caressing some "authentic" crappy old leaky, dime-store capacitor from a vintage Fender Bassman.
The placebo effect is real, and there is real "magic" in certain types of gear for certain types of players. I will give away one of my most jealously-guarded studio secrets by way of illustration:
I have a bunch of old guitars. Some of them are valuable "vintage" instruments, some of them are simply old. New clients almost invariably go for the flashier "vintage" ones-- the mid-60s SG, or the burnished old strat, or whatever.
Now, we all know that guitar players get bored. they get tempermental and irritable, and ideas that seemed to them two hours ago like the apex of western art seem like tired old casio keyboard riffs after tuning up and setting up and making the same mistake 12 times in a row. They complain about the sound, they say they're not getting the tone they're after, they want to change brands of string, they think the problem is the wrong brand of tuning gears, they want to switch to doing rap metal or free-form jazz, whatever.
Here's what I do: "You know," I say, "The Les Paul (or whatever they're playing) certainly seems like the obvious choice for this kind of music, but I almost wonder if... nah. You're probably not ready for 'El Diablo'. You wouldn't be into it."
"What? What do you mean I wouldn't be into it? What's El Diablo? I'm ready, BELIEVE ME, I am READY for El Diablo."
"You think so?"
"Are you kidding? I know so! Just lemme try it, El Diablo is exactly what I'm missing! What is it?"
"Wait here. Let me go into the BACK ROOM. That's where we keep...
El Diablo."
I make a dramatic show of getting up on a chair to remove a hidden key from above the door and suspiciously, furtively, unlock a supply closet, and jump in, pulling the door shut behind me so no one can see what secrets lie within. A few tense moments later, I emerge with...
El Diablo. El Diablo gleams sensuously in the dim light of the tracking room. The deep, bloody patina glow of her red-and-black sunburst finish is offset by the crackled, textured, but still-brilliant old chrome of her hardware. The age-mellowed, bone-colored bindings speak of dignity and consequence. The strings resonate with a subtle, ominous, flamenco twang as my fingers shift across them to present the voluptuous curves of her naked painted body to the budding talent before me.
"THIS," I say, "is El Diablo." (sharp intake of breath from the awed recipient). I continue:
"I couldn't even begin to guess how much this would be worth today (true). I doubt you could even find one for sale anywhere-- maybe once a year or so one comes up on eBay or someplace, I wouldn't know (true). Very, VERY few people alive right now have ever played a guitar like this (still true). It took a LOT of legwork, time and effort to get this, and I expect you to be very careful with it (sort of true). I don't usually bring it out for clients (true). Now give it a shot and see how you like her."
Usually, but not always, he LOVES her. He wants to marry her. He makes love to her with his fingers. He swears that it is exactly what was missing, that the sound is so much fuller, richer, sweeter. Better. And you know what, it IS better. The MAGIC is there, that wasn't there before. It is the magic of a creative spirit in the presence of something special, something magic, creating something magic. It was the magic that was in his very first guitar until he learned enough to be embarrassed by it and think it inadequate.
Of course, as you've probably guessed, El Diablo is nothing more than some obscure old yard-sale rehab or flea-market bargain or whatever. Two of my "El Diablos" are funny-shaped old Fenders (bought pre-Nirvana, who drove up the prices for those), Two are ancient archtops of unknown manufacture, one is a weird old single-coil, single-pickup Les Paul of some sort, one is a very antique-looking old yamaha with the name painted over and some modifications done by yours truly that I have been known to exaggerate and say is "custom."
Of course, I don't actually use the term "El Diablo" (not usually anyway, maybe if the guy is high). And I wouldn't try to pull something like that on somebody who was obviously very knowledgeable about old guitars (those people almost always bring their own, anyway, though). And I almost always reveal the man behind the curtain after the perfrormance is done.
In fairness, every guitar I own is one of the best I have ever played-- that's why I own them. From the vintage firebird to the $120 Ibanez knockoff, every one of these guitars is there for a reason, and does something that none of the other do as well. Every one is immaculately set up, plays like a dream, has no or very little hum and no buzzy frets or off-intonation. Every one stays in tune, even with vigourous playing and tremelo bar work, if there is a tremelo bar. i put a lot of work into shielding the body cavities, filing the nuts and saddles to exactly the right height, re-habbing sketchy solder joints, replacing hardware that causes breakage or tuning problems, replacng bad frets, adjusting pickup height and pitch, etc and so on.
I have replaced a lot of elctronics and a lot of hardware and spent a lot of late nights with calipers and sandpapre and files and a soldering iron. I've spent a lot of time shopping for these guitars.
Many (rather most, or almost all) off-the shelf guitars come poorly set-up, with bad fret jobs and variable wood quality and poor sheilding of the electrical components and action that is improperly matched to string gague and pickup height (even expensive ones from big brand names).
Given all this, it is almost safe to say that for many guitar players, I could pull up any of my guitars at random and say, "I bet this is the best guitar you've ever played" and be right (and I'm not really even a guitar player--just a guy who loves good sounds and good instruments).
But the point is, what made "El Diablo" work for Guitar Johnny was NOT the guitar itself, but the magic of a special instrument.
Some really outstanding players can pick up some crappy old POS guitar, badly set up with rusted old strings and plug into a cheap solid-state amp without even looking at the knob settings and create the voice of God. Others can be given a glorious instrument and a magnificent amplifier and a full rack of expensive effects and hours to tune up and dial up their sound and produce something that sounds like soggy limp ass hairs.
The magic is in the fingers, the technique, and the spirit of the player, not in the circuits or the type of glue or composition of the tone capacitor. This is true for all instruments, but it is especially true of electric guitar, which is, let's face it, about the crappiest, most obnoxious, offensive, and annoying instrument on God's green earth. And those are exactly the qualities that make it so compelling when it's done right-- like the wracked-out old voice of damaged bluesman, the crackly, hummy, fizzy, lo-fi noise of an electric guitar is what makes it so real and so compelling.
That's my feelings anyway, not fact.
Cheers.