30 May 2013

Pedal Effects: The Wah effect


Note: this entry was already published in my old Spanish version of this blog, around July / 2011. I am just revisiting it here for its possible interest.
The Wah is one of the very few pedal effects which effect can be regulated dynamically in real time while working and therefore, is a nice tool to add our personality to our riffs.
It isn't a fool-proof pedal and, gets some time to get something of interest from it but, it worth the try.

But, what do we know about Wah?.

What a Wah does

A Wah is a Filter type of pedal. Basically, it is a band-pass filter that reduces the gain of those frequencies over and below a certain band of frequencies, generating a peak of gain in the center of that band.

Imagine that you get a parametric equalizer and you put at max the center frequency control and, you go steps down symmetrically with frequencies at right and left, until you leave some kind of triangle.
The center position will have a big bump in the corresponding frequency, while those frequencies under zero will be clearly rolled off (highs and lows).

More or less, this is what happens in a Wah but, with a bell shape, instead of a triangular shape and, with the particularity that this bell shape can be "transported" right and left with the help of the rocket of the pedal.

When the note we are playing in our guitar resonates with the center frequency selected in the Wah is, where we get that typical Wah sound.
Guitar Wahs usually move in a range of frequencies between 400  Hz and 2,2 KHz, but not all Wahs sound the same. Why?.

Behind that range, the width of that peak band is limited. That width is known as Q in Equalizers and, that's why you will see some wahs having a Q-Control knob. Small Q values give you notch frequencies while higher Q values will distribute the peak to frequencies closer to the notch frequency (resonance peak).
Other wahs can have just some Q presets and a switch to choose one of them but, usually most of wahs work with a single Q that gives it's own signature sound.

This pedal was born with the goal to emulate a muted trumpet, during the golden years of Jazz and Swing bands, maybe to fire out the trumpeter and leave the guitarist to do all the job.

Classic Wahs

Three are the models that created trend in Wah world: the Vox Wah, the Cry Baby and the Clyde McCoy Wah by Thomas Organ.
All them were born between 1966 and 1968.

The circuit of those were very basic. A couple of transistors, one inductor, a few resistors and caps... that's all. From those components, the "Magical part" was always the Inductor.

First Vox Wahs very produced in Italy and, they used Fasel inductors, because they were really cheap.

As often happens with musical gear, that cheap components produced some kind of asymmetrical clipping, with even harmonics, that sounded very musical. Since they were cheap components, they were noisy and, they were very prone to catch RF noise and, even to dial a Radio Station!.
Paradoxically, they are the most wanted nowadays.
Those first units had a warm and vocal voice, quite well human. Something that disappeared when they switched to new inductors (even of the same brand). That is the Wah sound I can remember and, the one that seems so difficult to achieve in modern Wahs.
There are a lot of mods around but, probably, no one like Roger Mayer, that was continuously enhancing Jimi Hendrix' pedal effects (among other well known guitarists) better knows this effect.
Roger Mayer sells the Red Lion kit, that you can throw in any basic Cry Baby and, that should incorporate all those modifications that he did for Hendrix.

Wah voices

Well, it seems that in the whole electric guitar world, a sonic war remains, with two well defined sides: British and American sounds.
As always, the explanation it's gave by the big Ocean that divides Europe and America. Each side used those components available at lower cost in their respective Continent, which produced two very distinctive voices.

Morley pedals are a good representative of the American Inductor.
They sound more aggressive, less vocal but, second to none.
It's Steve Vai' sound, by example.

In pedals with both inductors, this is usually identified as the "Red" inductor.

The Fasel Inductor is the voice of Jimi Hendrix Wah, by example.
In pedals with both inductors, it's usually identified as the "Yellow" one.

As everything in music, it's just a matter of taste to use the more adequate to each particular situation.

Some models of Wahs incorporate both inductors and, allow you to choose the American or British voice with a switch.
The Vox Big Bad Wah (Satriani) has both voices, as well as the MXR Custom Audio Wah, among others.
Other discussion level would be how much that voices sound as the originals.

Appart from that Inductor, that produces the foundational voice of the Wah, there are other characteristics that give to each wah model their own entity.
The Sweeping Range, is that ramp witch which each pedal sweeps the available range of notch frequencies.
Some pedals have a shorter or longer ranges, some work very stepped between frequency changes, some work very linearly along the range, some work in a logarithmic way.
At the end, the rocket of your wah is moving a pot inside the case to select the notch frequency. The own characteristics of such a pot (taper) would determine how the effect will behave. A linear pot will produce a linear sweep, while a logarithmic pot will produce a logarithmic sweep, by example.
Well, we can discuss over other components but, those two are the one with higher impact in a Wah.

If you are thinking on to buy a wah, forget Cliches.
Many people ends buying a Dunlop Cry Baby or a Vox 847, just because those are the two more often recommended in forums (for people that even never tried both!).
The truth is that, most of the people having such pedals and that really use them, ended applying some extra mod to them, to make them more useful (we will talk below about some of their issues).
Being one of the few personal expression tools available, the best you can do is to try absolutely every Wah model you can (forget Brand and Model, just try it!) and, to choose the one with the more convincing sound and sweep range (who cares about which inductor it has, which Q or which sweep range!) and, be sure it's compatible with the rest of your pedal board.
If it happens that your election was the expensivest wah then, bad luck.
If it happens that your election was the cheapest wah around and that when you say in forums "I am using the Shitdelux Wah" nobody seems interested, what's wrong?. Works for you?. Go ahead!.

In my particular case, the Wah type that I like more is the Clyde type and, from those I was trying, the Real McCoy RMC4 Picture Wah gives me the closer sound and closer sweeping range. It's also a fuzz friendly wah, what helps in a pedal board loading a vintage fuzz.

Switching and effect control systems

The typical way to switch on and off the effect is a pedal switch at the end of the rocket. By pushing hard the pedal, you actuate on the switch, switching on or off the effect (something that occurs in the higher frequency range of the wah sweeping).

The typical effect regulation control was an specially designed pot, which shaft is enclosed in a teeth gear, linked to your pedal's rocket.
Your rockets closes or opens the pot, moving the notch frequency to lows or highs.

This pair of mechanical systems are the natural option in most of wahs but, they have some drawbacks.
Usually, the pot is the piece that usually goes wrong first and, you will end changing it during your pedal's wah at least once.
Also, that switch, after lots of switching looses its smoothness.

That made some of the makers to look for more creative ways to switch on/off the effect and to regulate it.
Morley released some Wahs that were regulated with the help of quiet photo-resistors. It has also some models, like the Bad Horsie 2, that switch on the effect as soon as we step on the rocket (in the low frequencies range), without needed to push any switch and, as soon as we release the rocket, this goes back to its original position (up), switching the effect off.

Roger Mayer's Vision Wah is using a photo-resistor regulation system, also. It switches on and off in a similar way as any traditional wah but, instead of using an electro-mechanic pedal switch, is using a quiet electro-magnetic switch.

Whitout any doubt, the most curious system from all is the one by Z.Vex. His Probe Wah uses some kind of copper platform that works in a way similar to the antenna of a Theremin so, you regulate the effect depending on how close your foot is of that plate, without any physical contact.

The Wah in effects chain

Even that there are no fixed rules in Music, the Wah it's often placed in two very different spots in the chain: before or after gain pedals (fuzz, distortion, overdrive). Results are very different in one and the other way.
I like it more before gain pedals. After, the effect sounds very exaggerated.

Additionally, since the Wah corresponds to a very old design, many of Vintage Wahs and historical-correct clones or reissues of those have impedance issues and, can be true tone-suckers. Therefore, a typical mod for such pedals is to correct the impedance levels, with the help of some buffer.

Nowadays, there are good Boutique Wahs, that are very close to the original ones in sound but, that incorporate some enhancements that make that wahs to better suit any pedal board. Wahs with an internal buffer are usually known as fuzz-friendly and, allow you to put the wah before the fuzz, without affecting the tone of your loved vintage fuzz. Examples are the Real McCoy ones or the Fulltone's Clyde.

Sure, more modern Wahs designed from scratch got rid of that kind of issues, from the beginning.

In case of vintage Wahs, their natural place is to be the very first pedal in your effects chain (if you don't have also a vintage germanium fuzz). In other position, they can sound weak, thin and harsh.


Lazybones' Wah.
The notch frequency varies automatically following the envelope of the input signal. By example, the picking strength regulates to where the notch frequency moves to.
The Mu-Tron III by Musitronics was the first Auto-Wah (or Envelope-Follower Filter) available to the public, around 1972.
It was followed by Doctor-Q, Zipper, Bass Balls and Y Triggered Filter by Electro-Harmonix.

While the typical Wah seems more associated to Rock, the Auto-Wah is more often associated to Funky.


When I'm ok of my meniscus torn, I will try to do a comparison between several Wahs.
(note: that comparison was previously published in this English version here: 3 Wah comparison )

In the meanwhile you can hear how the Real McCoy RMC4 Picture Wah sounds in this video. I am sorry, but my knee doesn't allows me a better demo.

1 comment:

  1. This is a very good and clear explanation of the workings of wah, envelope, tone, frequency and pedals associated with said. Great job on this friends. Very well written for beginners comprehension and advanced consideration. Nicely done.


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