Vox wah wah mods

[abbey road d enfer]

The Expandora has an input impedance of 100k, which lets the wah breathe.

 

[Spencerleehorton]

The axis fuzz has a 220R and 1nf connected the Q2 base which isn’t on this version so I’ll put them in and see if when the fuzz is full up it doesn’t go crazy!!

 

[Spencerleehorton]

Here is the axis fuzz schematic with the other parts in red that I haven’t put in.

 

[dai h.]

you know that is reminiscent of the Octavio/a (which I think is from Helios) :

 

[Spencerleehorton]

I have put in the parts in red off the schematic I posted and it has calmed the squealing/oscillation a bit but the B50k I have for the volume pot even when the effect is off has a very high pitched squeal I can here when it’s over half way?
So will change this for the stated C50k, it’s a much better sounding fuzz but somewhere between the arbiter fuzz face and this axis fuzz I think would be the best of both worlds.
The arbiter fuzz face lacks some definition and top end but has lovely sustain, the axis fuzz has a bit to much top end but nice definition

 

[Spencerleehorton]

For the other wah I need a new 100k hot potz 2 pot, there is a point near the heal point in the hot potz 2 which is in it that just makes this horrible scream!!
I also need another for the univibe in the wah enclosure I’ve built from mad bean the harbinger two.
I’m assuming the Dunlop hot potz 2 are the best ones to use?

 

[dai h.]

I have put in the parts in red off the schematic I posted and it has calmed the squealing/oscillation a bit but the B50k I have for the volume pot even when the effect is off has a very high pitched squeal I can here when it’s over half way?
So will change this for the stated C50k, it’s a much better sounding fuzz but somewhere between the arbiter fuzz face and this axis fuzz I think would be the best of both worlds.
The arbiter fuzz face lacks some definition and top end but has lovely sustain, the axis fuzz has a bit to much top end but nice definition

not sure what's going on with the squealing but I would think the schematic is correct (i.e. a log pot for volume) there. FWIW re: the C taper I mentioned earlier is for the Fuzz control on a Fuzz Face.

re: the network in red, the Dunlop Octavio has 4n7 instead of 1n:



and Dunlop Band of Gypsys (similar but without the octave up part I gather) has 560R and 4n7 (plus some LPF looking stuff on the end) :


(sorry, I didn't quite understand what you meant by "Harbinger Two" before, but I guess it's appearly this (Univibe in Crybaby housing project)?) :

https://www.madbeanpedals.com/projects/_folders/FilterMod/pdf/HarbingerTwo.pdf

(according to the document) he's using that wah pot (Hot Potz 2), and I'm not sure what that's supposed to be (if it's supposed to be a "W" (half audio/half reverse audio) as on some EQ sliders and EQ controls or??). Whatever provides useful control and something that doesn't have a large "dead area"(nothing apparently happening)? I know that there are different tapers, different percentages from mid rotation to one end, and lesser or greater number of sections on the track (for log tapers), but how to decide specifically I don't know (sorry!). Also, if you need some odd taper (or combo as on a dual pot) and also (preferrably) have it last many cycles (million rotations or whatever), then I think it's even harder to find (but an actual engineer (not me) might work out a different way to accomplish the goal).

 

[Spencerleehorton]

Ok well I have some new information about the fuzz side of Hendrix.


This west coast fuzz apparently is what Randy Hansen (Hendrix soundalike) uses and apparently is much closer than either the axis fuzz and fuzz face!!

Going to make a pcb and see what it’s like!!

I will resume my fuzz face thread and explore this new to me fuzz.

As per the harbinger two speed control, the pot I have at the minute just seems to go from really fast to really slow, so I definitely think the pot is shot, I do have another one I can try.

 

[dai h.]

Cool. Saw the discussions at the metroamp forum. Curious to hear what you think of it. Was kind of impressed how Randy got those special-effects sort of Hendrix sounds with his gear. Pick scratching with a Fuzz Face sounds like a jet engine to me.

Might also try asking at Aron's Stompbox Forum (as Gus suggested). It's a pretty friendly forum with a lot of knowledgeable people (not that there aren't nice and knowledgeable people here, but it's more guitar effects-centric there). And also freestompboxes.

(news in the wah world: apparently Vox came out with something supposedly closer to the old V846 (looks like the old layout plus some additional parts). The author of this page speculates some of the extra parts are to help keep radio out, compensate for the higher gain of newer transistors (perhaps CDIL Continental Devices India BC108 or 9?) , plus a anti-pop (switching noise) ground reference for the input:

https://alltubepreamp.blog.fc2.com/blog-category-22.html

 

[Spencerleehorton]

Well I’m quite far down this Hendrix gear rabbbit hole now so I will explore all avenues!!!

I’m going to make the pcb for the west coast fuzz and I have all the parts minus the transistors that I have found and will order.

Like I said earlier in the thread. So far my favourite distortion is the expandora, it’s not close to Jimi but has best sustain and clear tone with loads of feedback.
when I think of Jimis sound it all about having loads of feedback and being out of control but then being able to dial it back and get that crunchy clean sound when you lower the guitar volume.

 

[dai h.]

when I think of Jimis sound it all about having loads of feedback and being out of control but then being able to dial it back and get that crunchy clean sound when you lower the guitar volume.

Maybe that was the Fuzz Face (that is, going through the FF but with guitar pot turned down)?

not sure if they are still on the web but I recall somebody uploading solo'ed guitar tracks from Jimi some years ago. Were interesting to hear the distortion (haven't listened in a while but my memory was the impression was that the sound wasn't particularly distorted).

also, some guys on Youtube do the Hendrix stuff quite well (here is one (IMO)) :

https://www.youtube.com/@TheVibratory/videos

 

[CJ]

i have a vintage Randy Hansen poster in my work dungeon if that's worth anything,

you need one of those original inductors from Italy for that wah wah,

 

[Spencerleehorton]

i have a vintage Randy Hansen poster in my work dungeon if that's worth anything,

you need one of those original inductors from Italy for that wah wah,

Yeah shame someone can’t wind me one or get me the correct core info!!!
I know they were wound at 530mh at about 13 ohm

 

[dai h.]

I took the cover off on a Dunlop red Fasel (I had 544.4mH and 13.4 ohms written down for this--I think it changes with temp.? The windings look kind of messy.) :



I also have a note from UK-based guy Stewart Castledine:

https://wah-wah.co.uk/wahs.html

(re: his Halo (inductor) copy.."1100 turns of 0.1mm came out as 535mH 89 ohms DCR" vs. (his original 1967 Halo).."500mH 83 ohms DCR")

(my RM9090A kit inductor) :

424.4mH (63.7 ohms) and (it has a tap) 309.2mH (55.9 ohms)
(sort of suspected not enough winds was causing a bit of thinness to the sound)

There are some good posts by Gus (who if I understood correctly thought some of the inductor mojo was a bit overblown(?)) on wah workings here:

http://www.diystompboxes.com/smfforum/index.php?topic=88660.0

 

[CJ]

I always wanted to try a 24 pos gold point rotary switch because the tapers on this pots leave something to be desired,

It is hard to A\B those inductors unless you want to plop down 1000 to 2500 to do some research.

People never give the frequency and voltage for those inductance tests so it is impossible to get an exact match.

And DCR changes after you get the wire on the core for some strange reason that I have yet to pinpoint.

 

[dai h.]

IIRC mine were 1kHz 0.6Vrms (handheld LCR meter)--I didn't know if I was actually supposed to use a lower freq.

FWIW, an old Roger Mayer interview (gone but still in wayback machine) :

https://web.archive.org/web/20060208063320/http://www.musicgearsource.com/rogermayer.html

 

[Spencerleehorton]

From what I’ve read about the inductors, it’s the cheap core material that was used which is the key to the sound?

 

[Spencerleehorton]

I’ve ordered a castledine ICAR pot to see what they are like.
Will try some bc109b in the wah aswell.

 

[dai h.]

(did a quick search of harmony central and apprently another thing disappeared from the web (not available in wayback machine), so for posterity/informational purposes) :

From Roger Mayer: "The use of silicon transistors in the basic fuzz face circuit as in the later models only made the radio and oscillation problems worse and highlighted the problems of the basically unstable configuration and that is why I developed the Axis Fuzz which was a much better silicon design.

The Classic Fuzz we produce today uses germanium AC128 transistors which I think provide the best route for those who require an authentic link to the past and the following should give you some insight into the complexities involved with making the best from a basically bad electronic minimal parts circuit which of course the Fuzz Face was. There were no frills in the electronic configuration and the whole design was price driven and only worked well with a lot of selection and tweaking and the chances of finding a good one then or now was slim to non existent.

Jimi's fuzz faces were modified by me mostly for studio use but also for stage. The early fuzz faces due to their simple minimal parts design suffer from many problems due to the facts that the AC128 transistors used had a very large range of gain or hfe from 20 to over 600. These transistors were first selected in pairs by me to optimise the character of distortion produced. There are a large number of combinations of 1st stage gain and 2nd stage gain that produce different results. In addition to the complexity of selection of the transistors when a pair has been decided upon the 1st stage collector resistor must be optimised in conjunction with the 2nd stage collector current to make the circuit work well. This is the reason that no two fuzz faces are the same and we used to buy about twenty to find one really great one. I specialized in performing a technical analysis of the components of the best one and taking this process many steps further. The input and output network were also modified to provide pre and post equalisation control".

source:
http://reviews.harmony-central.com/reviews/Effects/product/Roger+Mayer+Electronics/Classic+Fuzz/10/1

This is from luthier (I think he invented the guitars with the funky "wavy frets")/writer Paul Guy who relates his experience with Fuzz Faces and wahs working at a music store in 60s (the part about the wahs needing selection is interesting--I think I overlooked that before) :

<[email protected]> wrote:
> Can anyone e-mail me the spec's on their Fulltone 69 fuzz so I can
> modify my reissue Dallas Arbiter Fuzz Face to sound better?
> I have one of the Face mod's by Roger Meyer that Jimi Hendrix
> supposedly used (for trade).

There's no "supposedly" about it... it is well documented that Jimi used
his Octavia pedals and that Roger Mayer fixed up Jimi's Fuzz Faces,
wah-wahs and UniVibe (as well as his guitars and amps - which were not
modified, just fixed up to work the way Jimi liked them).

I just wrote an interview with Roger for the Swedish guitar mag ("FUZZ")
I write for, and in it he tells how he selected and/or re-biased Jimi's
Fuzz Faces. The "Classic Fuzz" Roger builds today is made exactly to the
specs he used on Jimi's boxes, with the transistors individually tested
and biased. (This isn't just Mayer's marketing, I've seen him doing it,
he's a good friend of mine.)

As I wrote in a post on a thread about ToneBenders a while back, you
have to remember that fuzzboxes in the 60's were very much pot luck.
The tolerance spread on the transistors was absolutely huge - the
average germanium transistor had a specified gain factor of "from 50 to
200", or something like that. This is not a problem if the transistors
are individually tested and biased , but unfortunately these things were
mass-produced to as low a price as possible (I remember the Fuzz Face
cost seven pounds ten shillings in England). When all the boxes are put
together with the exact same value components you wind up with wildly
different results, the bias resistors need matching to the gain of the
transistors.

I worked at a music shop in the West End of London in 66/67. We were
selling Fuzz Faces by the carton and being the junior I got all the crap
jobs like "Put batteries in those Fuzz Faces they just delivered". When
I wanted to buy one I went through a dozen and checked them out. I
thought half of them sounded like crap, but there were two really good
ones. I still have the one I bought.

Vox and Cry Baby wah-wahs were just as bad, you had to check a few
out to find one that sounded good. This had more to do with the
tolerance spread of the capacitors - they were using plus/minus 20%
caps, which in reality could be plus/minus 30 or 40%. As the frequency
of the filter is (partly) dependent on the cap values those old wah-wahs
had quite a range of centre frequencies...

Paul

--
Paul Guy Guitars (Handmade - Custom Shop - Repairs)
Katarina Bangata 65, 116 42 Stockholm , Sweden
My homepage: http://home3.swipnet.se/~w-37192

(this is the source but apparently you can no longer browse usenet (or archives) through google without having an account and logging in) :
http://groups.google.co.jp/group/al...read/thread/37370379ef91866e/8fa204990016c2c2

 

[Spencerleehorton]

Those castledine wah wahs sound very good and have 4 trimmers to tweak to taste, vol I can see written on one, i would think one would be the Q and not sure about the other two? also seem to have 3 electrolytic caps in there? One of them will have to be the 4uf but I’ve got no idea what the others are or where they are within the circuit?
Also in some schematics the first resistor and 10nf cap are reversed?