Vox wah wah mods

[abbey road d enfer]

The resistor is 10K not 1K as previously stated.

The FuzzFace response varies enormously with the impedance of the source it is connected to. E.g. when connected directly to a guitar, the pick-up inductance combines into a low-pass filter resulting in aggressive distortion of low strings and moderate crunch on treble strings, which is not always desirable.
Inserting a pedal, which has a constant ohmic impedance provides a more balanced effect. Now, if the output impedance of such pedal is very small (like a buffered output) the input capacitor in the FF creates a high-pass filter, which in turn alters the response in the opposite direction, making it very trebly.
Varying the output impedance of said pedal, via a potentiometer or switched resistors, provides a range of tonal variations.
Is there an optimal value? It depends on personal preferences, each one his own...

BTW, Brian May's sound is the result of using a treble booster with the same characteristic response vs. source impedance, so his Rangemaster combines input low-pass due to the pick-up inductance and high-pass due to the input capacitor, for a resulting midrangey band-pass.

 

[Newmarket]

Fuzz Face type circuits need to be fed from a high impedance source to sound as expected.

 

[abbey road d enfer]

Fuzz Face type circuits need to be fed from a high impedance source to sound as expected.

Exactly! That's why some are disappointed when driving it from a pedal with too low an output Z, or a wireless receiver.

 

[JerryPbury]

Exactly! That's why some are disappointed when driving it from a pedal with too low an output Z, or a wireless receiver.

I put a 10k resistor on the output of my wha and it works perfect into the Fuzz Face. I also put the Wah first in the effects and the Fuzz Face next. If I’m not using a Wah I’ll use a Fuzz Face that has a 10k on the input. Boosters or overdrives come later in the chain. I always follow the Fuzz Face with a tuner. Seems to get along better with the other effects.

 

[GeorgeToledo]

The Hendrix-esque sound people often aim for with fuzz+wah is usually achieved with guitar into fuzz, wah after fuzz, which can skip the “problem” of the fuzz receiving low impedance.

 

[JerryPbury]

The Hendrix-esque sound people often aim for with fuzz+wah is usually achieved with guitar into fuzz, wah after fuzz, which can skip the “problem” of the fuzz receiving low impedance.

Plenty of pics on the internet show otherwise. Hendrix put the wah first and then the FF.

 

[GeorgeToledo]

Plenty of pics on the internet show otherwise. Hendrix put the wah first and then the FF.

Oh, hmm…ok. Thanks for the correction. Looking at pics now.

For some reason (being a dope!?), I thought I heard some recordings that sounded like wah was happening after some of the other effects sometimes, but the pictures do tell the story.

 

[GeorgeToledo]

Relatedly…If anyone happens to have info/photos regarding the order Eddie Hazel would usually hook things up, I’d be really curious to see it.

 

[Whoops]

Plenty of pics on the internet show otherwise. Hendrix put the wah first and then the FF.

It seems so, but it’s strange as in stock form I never liked the sound of a Wah into a Fuzz, but I really like the opposite, Fuzz first in the signal chain. Passive pickups straight into a Fuzz (with no buffers in between) it’s my preferred fuzz sound.
Actually a Fuzz face into a Wah sounds more Hendrix to me than the opposite. It’s strange.

Photos don’t lie and also Roger Mayer confirmed that a Wah was first in the chain, at least in Woodstock





From Roger Mayer:
“Which effects did Jimi use at Woodstock?
“A Vox wah pedal, silicon Fuzz Face and Uni-Vibe, in that order. He didn’t use an Octavia.”

https://www.musicradar.com/news/fx-...-wah-wah-but-making-it-talk-is-something-else

Now if he also used that order or reversed it in the studio or not I don’t know. Also as Mayer was working with him at the time modifying his gear, it’s possible the Wah or the Fuzz were modified and not stock.
It seems at least the Wahs were modified according to Roger Mayer

“Jimi used the Vox wahs and the Italian Jen ones, but he used the Vox wahs in America because the Italian ones weren’t sold there. I’d modify them occasionally by changing the sweep capacitor [value], or I’d insert a buffer to enhance the harmonics coming through.”

 

[GeorgeToledo]

Apparently on the earliest records the wah sounding stuff was done at the console.

 

[abbey road d enfer]

“Jimi used the Vox wahs and the Italian Jen ones, but he used the Vox wahs in America because the Italian ones weren’t sold there. I’d modify them occasionally by changing the sweep capacitor [value], or I’d insert a buffer to enhance the harmonics coming through.”

Which leaves us with the big question "did he insert buffers in the input or the output of the Wah?"
Seems to me like a buffer at the input wouldn't do much because the input impedance is high enough (>68k) to be almost insensitive to the actual source Z. Remember the output Z of a Strat is n0k worst case. Actually, with the volume cranked up, it's much less.
However, the Dunlop wah (CryBaby) features an input buffer, with the rest of the circuit very similar to the Vox. I'm not sure the buffer makes a noticeable difference. Well, it may with humbuckers.
A buffer at the output would decrease the output Z in a way that is accepted as detrimental to the FF.
The mystery remains.

 

[ccaudle]

A buffer at the output would decrease the output Z in a way that is accepted as detrimental to the FF.

As you pointed out previously the inductance of the pickups causes a modified frequency response at the FF, so perhaps a buffer with a resistor to make a moderate but constant output impedance?

 

[abbey road d enfer]

As you pointed out previously the inductance of the pickups causes a modified frequency response at the FF, so perhaps a buffer with a resistor to make a moderate but constant output impedance?

The actual output impedance of the Vox Wah (and the CryBaby as well) varies enormously with frequency (and the position of the frequency pot), from about 20k under 300Hz, to 100-300kohm at the resonant frequency to about 200-1000 ohms at 2.5kHz.
The result is that the amplitude of the peak is considerably reduced when the Wah is loaded with the low input Z of the FF. It looks legit that adding a buffer would compensate that. The counterpart being that the FF is not too happy about seeing a low source Z.
So yes, of course, a buffer with a high input impedance and medium output Z seems to answer both constraints.
There is a business to make selling a box with two TS jacks, a buffer and a potentiometer in series.

 

[JerryPbury]

As I wrote before, put a 10k resistor on the output of your wha pedal. That’s what was done on Hendrix wha (See picture 9), makes a big difference. I run the volume all the way up and the fuzz knob half way on the fuzz face. He got most of his distortion and sustain from cranking his amps, not from the fuzz face being cranked.

 

[abbey road d enfer]

Here is the output Z of the Wah, simulated in LTspice.

It's quite different than the Electrosmash simulation
https://www.electrosmash.com/vox-v847-analysis
I wonder why...

 

[abbey road d enfer]

As I wrote before, put a 10k resistor on the output of your wha pedal.

You can't make much money just adding a resistor.

 

[abbey road d enfer]

He got most of his distortion and sustain from cranking his amps, not from the fuzz face being cranked.

+1

 

[mr coffee]

Hey Jerry,
Your 10K may well sound better in series with the output going into a fuzz face, but if the picture shown is to be believed, it appears to be showing 1K (brown-black-red).

 

[JerryPbury]

Hey Jerry,
Your 10K may well sound better in series with the output going into a fuzz face, but if the picture shown is to be believed, it appears to be showing 1K (brown-black-red).

It’s been awhile. But there is an article by the guy that did the original mod that should clear it up.

 

[Spencerleehorton]

Yes that resistor is 1k as I originally stated, tried it in the wah and didn’t really make any difference so I put in an output buffer but I didn’t have the 2N5457 so I’ve used a J201.
Going to revisit some of the mods and inductors as I seem to be getting this weird clunk when I heel down which isn’t a nice sound?
Also ordered a new psu for my Hendrix setup, so really want guitar into vox wah, fuzz face, Octavia then univibe.
Still got to make the BOG axis fuzz but that will be done by end of the week.