Wahs and Neck Pickups

[Paul Marossy]

I have been pondering about this one for a while. Why is it that with a wah pedal that you get a strong wah effect using the bridge pickup but it almost disappears when using the neck pickup?! (speaking of humbucking pickups) Is it because there is just less harmonic content on the neck pickup than on the bridge pickup? It doesn't seem like there is that huge of a difference between those two positions to my ears...

[Ge_Whiz]

Well, the harmonic content from the bridge pickup IS significantly greater than from the neck pickup on any guitar. It also depends on what note pitch you are playing, where and how you play it, and the wah frequency sweep. Finally, many guitars, especially those with humbuckers, have a more powerful bridge pickup in a deliberate attempt to incite distortion and thus further increase the harmonics.

[Paul Marossy]

Well, the harmonic content from the bridge pickup IS significantly greater than from the neck pickup on any guitar.

Yes, but why is that? Does it have something to do with the strings being near their "fixed end point" vs. the string vibrating more towards the midpoint of the string? I guess that is the physics part of the equation.

It also depends on what note pitch you are playing, where and how you play it, and the wah frequency sweep.

Those are all fairly obvious. I wonder if a preamped guitar signal would respond differently? I have used a preamped guitar with my wahs before, but it was usually always with the neck pickup on.

Finally, many guitars, especially those with humbuckers, have a more powerful bridge pickup in a deliberate attempt to incite distortion and thus further increase the harmonics.

This I know. I guess the harmonics generated then would be partially controlled by how "hot" the pickup is.

[Jaicen_solo]

FWIW, a bridge pickup will inherently produce fewer harmonics when compared to a neck pickup solely due to it's position beneath the strings.
What you'll usually find, is that a neck pickup is more harmonically complex than a bridge pickup for a given output. HOWEVER, because the bridge pickup is close to the bridge (well, duh!) you'll find that the strings aren't able to vibrate as far as those over the neck, which means you get proportionally more higher harmonics, and fewer lower harmonics. When adjusted for the same output, a bridge pickup will this sound brighter. It is the attenuation of frequencies in the mid-high range which gives wah's their dramatic sweep and vocal qualities. That's why they often sound better on bridge pickups.

That said, slash always used the neck pickup for his solo's, so what do I know?!

[1wahfreak]

I was just going to ask this same question. I just built a wah using the GGG modable wah and a Stuart C inductor. Everything sounds great on the neck PU on the clean channel but when switched to the bridge using distortion it loses that awesome quacky quality. Even if I introduce a little overdrive to the neck PU it starts to lose something. What is the difference between a Halo type wah and the newer "bad horsie" type wahs that seem to cater to the high gain players?

[Paul Marossy]

What you'll usually find, is that a neck pickup is more harmonically complex than a bridge pickup for a given output.

So then, more harmonics is not necessarily equal to harmonically complex?

HOWEVER, because the bridge pickup is close to the bridge (well, duh!) you'll find that the strings aren't able to vibrate as far as those over the neck, which means you get proportionally more higher harmonics, and fewer lower harmonics.

Ah, this is the key point. That explains a lot right there. I never was too keen on the physics of a vibrating guitar string...

When adjusted for the same output, a bridge pickup will this sound brighter. It is the attenuation of frequencies in the mid-high range which gives wah's their dramatic sweep and vocal qualities. That's why they often sound better on bridge pickups.

And a neck pickup seems to abound in the lows to the beginning of the mid-highs. So, it's kind of like the neck pickup just misses those frequencies. I get it now.

That said, slash always used the neck pickup for his solo's, so what do I know?!

Interesting, I didn't know that.

[Paul Marossy]

What is the difference between a Halo type wah and the newer "bad horsie" type wahs that seem to cater to the high gain players?

That's easy. The classic wah, such as a CryBaby, uses an inductor. The Morley Bad Horsie type pedals are not inductor based. Some people prefer the sound of a non-inductor based wah. I generally don't like those types of circuits except for the Colorsound inductorless wah (Twin-T circuit).

[1wahfreak]

Thanks Paul, so what happens to the high gain signal when it's passed through the inductor vs the inductor less wah? Supposedly Joe Satriani uses stock cry baby's for his high gain stuff but it certainly doesn't sound muddy or as lifeless as mine does.

[Paul Marossy]

Thanks Paul, so what happens to the high gain signal when it's passed through the inductor vs the inductor less wah? Supposedly Joe Satriani uses stock cry baby's for his high gain stuff but it certainly doesn't sound muddy or as lifeless as mine does.

That's a good question. I would think that it all depends on how the circuit is designed and the sweep frequency that it's designed around. To me, an inductor based wah just sounds more fat and complex. Other factors to consider are that Satriani generally uses (or used to use) Marshall amps and speaker cabs with Ibanez guitars equipped with DiMarzio FRED and PAF Pro pickups. One guy will also sound different from another with the exact same equipment because of technique and personal preferences as far as amp EQ, etc. is concerned.

Anyhow, I never really noticed how much Joe uses a wah until recently (after I became a wah freaque). 

[Jaicen_solo]

Actually, i'm not sure I believe all this inductor mojo. In a crybaby circuit, the inductor isn't actually in the 'signal' path as such. It provides a high impedance path to ground to high frequencies. Different inductances alter the range of the frequency sweep. However, if you wanted, it's possible to alter the capacitor in parallel with the inductor, which I think is much easier. This will give a similar effect.

As for modern wah's, I believe they have a slightly narrower sweep more concentrated in the upper mid frequencies, to compensate for the scooped mid's often used in high gain amps.
Anyway, check out geofex for the technology of wah's, great read!

[Paul Marossy]

As for modern wah's, I believe they have a slightly narrower sweep more concentrated in the upper mid frequencies, to compensate for the scooped mid's often used in high gain amps.

Maybe so. Marshalls are often used for a scooped mid sound, maybe there's a correlation there as far as Satriani is concerned?

[Penguin]

actually the morley bad horsie is an inductor and is not a twin t design.  if you look at the b horsie you will notice that its really close to the old clyde wah's.  don't take my word for it. though look on the site morley has the schematics up.

[Paul Marossy]

actually the morley bad horsie is an inductor and is not a twin t design.  if you look at the b horsie you will notice that its really close to the old clyde wah's.  don't take my word for it. though look on the site morley has the schematics up.

Hmm, that's new to me. I thought all of their wah pedals were non-inductor types...
Well, there you have it - the inductor wah is once again on top.

BTW, I just added a 4.7uF cap across the power supply on my Maestro Boomerang clone. I'll test it out later to see if that gets rid of the shriek at full treble. 

[Penguin]

http://morleypedals.com/vai-1es.pdf



yeah i am a big vai fan otherwise i probally wouldn't have guessed that.  i would have never bought a morley unless i didn't like the tone.  and well i am a bit biased when it comes to the vai gear.   but yeah i did a whole thing on my old site on how to remove all the crap out of that wah.  i ended up just making my own doublesided pcb board for it with all my tweaks and mods.

ed

[Paul Marossy]

Well, I'll be. There's a 500mH inductor clearly shown on that schematic. I'm sure that some people would have a problem with those opamps in there, though. 

Anyhow, I am also a fan of Vai - not as much as some of my other guitar heros, but I really like most of the stuff on "The Ultra Zone" and I thought "Passion and Warfare" had some stuff on it that really pushed the envelope. Like "Ballerina 24/12" and "Alien Water Kiss", for example. And then there were albums like "Sex and Religion" that I thought ws terrible...