VOX847 Axis Wah Modifications

Axis Wah Mods

A Great Sounding Wah…On A Budget
Over the years, the wah pedal has become one of the most popular and influential of all guitar effects. Many famous guitar players have used this piece of equipment in their songs…who can forget the opening of “VooDoo Chile (Slight Return)” or the awesome wah pedal parts of “Machine Gun” both by Jimi Hendrix. All of these famous guitarists have created a huge demand for the wah pedal…but unfortuntely all is not well in the world of mass produced wah pedals. The sound of these pedals tends to be…not so great. But fear not, ye tone seekers, for there is a remedy to your wah pedal ailments…and it won’t break your bank account, either!

A couple of years ago I exposed the guts of the famous Vox Clyde McCoy wah pedal for all to see, and even built a clone of the wonderful pedal, but the problem is that it required the purchase of a replica Halo inductor and a replica of the ICAR-taper wah pot, which can end up being quite pricey. As a result, I’ve been working on modifying a Vox V847, that I just received a few days ago, into an excellent sounding pedal…minus the new inductor and wah pot! That’s right! For this project we’re using the original Vox inductor and the original Vox wah pot! You can even use the original wah pedal circuit board for this project too…but I etched a new one just so I would have a fresh start, and a fresh look. I’ll include the PCB and Layout files for the replacement board if you decide to take that route.

There are really only two major changes being made to the pedal…the addition of true bypass switching and the addition of an output buffer circuit board, which allows the wah pedal to work in series before a fuzz pedal. The other changes are all quick and simple resistor and transistor changes, which can be made quickly and easily by using a desoldering braid.

True Bypass Switching
Okay, so the first thing we need to do is to install the DPDT switch for true bypass. If you have a Vox V847 wah, then follow this diagram, and if you have a new Dunlop Crybaby, then you will need to follow the directions on this page since the operation for the Crybaby is a little more complicated with the PCB-mounted jacks. For the Crybaby, I would recommend that you follow the second set of intructions…”Eliminating Input Buffer.” The input buffer will no longer be needed with true bypass switching. Both of those great true bypass conversions are located on Stuart Castledine’s website, so be sure and check it out! Make a note that if you wire the bypass switches as shown in those great diagrams, then you may omit the 1M resistor in the input of the circuit that’s shown in the schematic that’s shown down the page a little.

Adding an Output Buffer
The second operation that we’ll perform is adding the output buffer circuit to the wah pedal. This step is optional, but I would certainly add it if you plan to use a fuzz pedal (like a Fuzz Face) in series after the wah pedal. A common problem is that the wah pedal simply won’t wah when put in series before a fuzz pedal. Unfortunately, this is the way it sounds the best to most people. This problem can be solved by adding an output buffer to the Axis Wah, which won’t alter the tone of the pedal. This is a simple JFET buffer that’s based on the Wah Wah project at Tonepad, and can be added to any wah pedal that doesn’t have an output buffer, namely the Vox V847s and the Dunlop Crybabys. The input impedance of this buffer is set by the 1M resistor from the Gate of the JFET to ground. Since this buffer can give a slight vme boost, so a 100K trimpot is on the output of the buffer to act as a volume pot so you can keep the volume of the wah pedal at the same level as when it’s off. The PCB and Layout for the output buffer are in the “Project Files” section at the bottom of this page.

Resistor Changeups

  • First, if you’re using the true bypass wiring instructions on Stuart’s website, then you can just forget about the 1M input pulldown resistor, but if you’re wiring the switch like this, then you’ll need to solder the 1M resistor to the solder side of the circuit board, from the input end of the input resistor to ground. This resistor will prevent a loud “pop” when the pedal is switched on and off.
  • Next we’ll replace the 68K input resistor with a 47K resistor. This will give a little volume boost to go along with the true bypass switching.
  • To enhance the mids of the pedal, and to smooth out the bass to treble transition, we’ll replace the 1K5 resistor on the base of Q1 with a 2K2 resistor.
  • The next resistor to change is the 470 (or 390 or 510) resistor on the emitter of Q1. Using a lower value will increase the gain of the pedal, and it will also enhance bass response, which is sometimes a problem with some pickup configurations. For this change I chose a 330 resistor, which isn’t too big and it isn’t too small. Using one that’s too small could result in distortion, which we don’t want.
  • The final resistor change that we’ll make to the circuit is the “Q” resistor…the 33K resistor that parallels the inductor. To help give the wah pedal a more vocal quality, I’ve chosen a 47K resistor, which isn’t quite as drastic as the 68K that some people use. It’s very nice sounding and certainly an improvement over the original 33K.
Changing the Transistors
The transistors that come in the Vox V847 and Dunlop Crybaby pedals are the high gain, general purpose MPSA18. I personally think that these transistors are way too high gain to make a good sounding wah pedal. The toe-down position is quite ear-piercing and unpleasent. To help make a more mellow wah pedal, I’ve chosen to use a pair of nice BC109C transistors that I ordered from Steve Daniels of Small Bear Electronics a while back. For Q1 I chose a unit with a gain of 400, and for Q2 I chose one with a gain of 388. The end result was a very nice, a bit more mellow sounding wah that’s not as ear-piercing when toe-down, and the heel-down is still nice and fat…the bass response actually made the springs in my Twin Amp’s tube shields rattle!Below is a schematic of the Axis Wah with all modifications mentioned above.
Axis Wah Schematic

Vox V847 Wah Schematic Blocks




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Silverbird SH-9

Seymour Duncan Silverbird SH-9 Humbucker

At first glance, the Silverbird might make people think it’s the old Iommi model that the Duncan company makes that is currently known as the El Diablo.  Preceding the Iommi by a solid decade, the Silverbird provides a little of the DNA for what followed.  Mostly when it comes to the bobbins and the magnets.

The bobbins are Tele bobbins, which might have someone thinking they are too big.  Fret not (ha! a pun!), I had no issue fitting them into a humbucker cavity.  It is also generally found with it’s own fitted pickup mounting ring, but a trem-spaced ring should also do the job.

What looks like big thick rails are actually the magnets.  The Silverbird has a pair of Alnico 2 magnets, right out there to grab a hold of that energy firsthand.

If you’re looking for a hard-to-find Duncan pickup, it doesn’t get much better than this.  Even so, the Silverbird is almost as scarce as any hands-on evaluations.

That’s right.  Of the guitar gear curiosities that some send me to check out, the Seymour Duncan SH-9 Silverbird humbucker is one.

Generally speaking, the pickups that follow in the same basic design of the Silverbird are known for having a pretty heavy and dark character.  So I’m not sure what to expect.  Still, not to be too terribly confused for a trained monkey, I install the Silverbird into my main test guitar.  It has 4-con lead wire, so I go with the typical (for me) series/split/parallel wiring.  And away we go.

Seymour Duncan Silverbird
Seymour Duncan Silverbird

The lion’s share of the SH-9 models that you can find on the internet seem to be 9BJ.  That means Maricela (MJ) Juarez made it/them.  It also means there’s a metric ton of mojo going on, because 1) MJ made it, and 2) it was made during what some are starting to consider the Duncan company’s Golden Age of everything always sounding good.

You know, it’s a pretty interesting pickup.  A big bold low end that stays firm (is that a JLo reference?) and doesn’t get muddy.  The mids are pretty even, with a bit of a grunt in the low mids and a bit of a snarl in the high mids.  And the highs are chirpy and airy while retaining a bit of the A2 sweetness.

For dirty amp settings, the Silverbird can go vintage “brown” and it can do prog metal.  Slight adjustments to the pickup height reveal a little more of a shift that I see in some humbuckers in this class.  I’m still have a little shock over how much articulation there is in the punchy lows, which gives riffing a rhythm work plenty of authority thanks to the natural compression of the pickup.

The Silverbird has a little more push to it than a vintage style option, so clean amp settings might require a of a rolloff on the volume (at the guitar or at the amp).  On split and parallel options, it blended really well with a P.A.F. style neck humbucker.  By itself in series mode, you’ll easily get a usable crunchy clean.

This bad boy is so few and far between that I really can’t find a usable video.  But you know I have specs:

Series – 14.29 K
Inductance – 5.608 H
Split N – 7.188 K
Split S – 7.109 K
Parallel – 3.565 K
Magnet – Alnico 2 bars

This pickup does show up for sale online from time to time, albeit not often.  For what it’s worth, my experience would suggest going for the real deal original SH-9 with the 80s era sticker on the baseplate.  In the event you find someone that doesn’t know what they have, the DCR specs clearly give it away.

The SH-9 is more of a mystery.

It was initially called the Silverbird, and this pickup was supposed to go in an obscure guitar. Unfortunately I was unable to discover which guitar. I spoke with some guys at the R&D department of Seymour Duncan and one thing that stands out in all stories is that this humbucker was comprised of two Tele bobbins and had two Alnico II bars as pole pieces. The Silverbird was quite hot for the day, but with pickups like the Alternative 8, the Blackout series, the Parallel Axis Trembucker II and the visually similar but tonally different El Diablo, the Silverbird can be considered a medium hot pickup by todays standards.

I’m saddened by the cancellation of this pickup, because it looked quite cool and I suppose the tone is awesome too. However, I do have a hard time figuring out exactly how this pickup would sound. Some say the SH-9 sounded bold, articulate and bit fat. Others say it was very clear with lots of treble. All I know is that I’d love to see the SH-9 in one of my guitars! I could wait for it to pop up on eBay, but why wait? The Custom Shop can make almost any pickup you can dream of!

This leaves just one more question: why were these pickups renamed in the chase of the SH-7, and discontinued in the case of the SH-9? In case of the SH-7 Seymourizer, I suppose they renamed the pickup to streamline the line-up. I guess it was convenient to make matched sets because the market kind of demands it. So many humbuckers in the Seymour Duncan lineup come as a set: the ’59, the Jazz, the Invader, the Distortion, the Pearly Gates, the Alnico II Pro, etc etc. And of course the JB is available with its friend the Jazz as the Hot Rodded Humbucker set.

Scott Miller says: “I think the main reason this one was discontinued is that it was too big for a lot of guitars. It was built with two Tele Hot Stack bobbins, and there is no way that pickup could ever fit into any humbucker mounting ring (and we did not provide one that would fit). And, in a lot of cases, the mounting ring was a moot point because the pickup wouldn’t even fit physically into the route. Size is definitely the issue on this one.”

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Sabbath RangeMaster

One of the earliest treble boosters was the Dallas Rangemaster. Unlike most of today’s clones, the original Rangemaster was not a pedal, but a box meant to be placed on top of the amplifier. The circuit makes use of a single OC71 or OC44 germanium transistor.

The Rangemaster has also been used extensively by Brian May, Tony Iommi, Marc Bolan, and Rory Gallagher. Tony Iommi’s Rangemaster was modified to be full-range.

There are a gazillion treble boosters out there now so plenty to choose from. I have no idea on the specific mods done to Tony’s Rangemaster but those early Sabbath albums are full of some of my favourite guitar tones of all time

.01 uF for the input cap – that seems to be Sabbath-Sound tonewise

Create full range blend pot in a Rangemaster type circuit, like in the Easy Face schematic: LINK. The input wire goes to the 100k lin pot. Use 4n7 for the treble cap and something like 1uF or even 2.2uF (.01 uF) for the bassy cap and you’re done! You can now dial in anything from the standard treble boost to a mid boost, full boost and even bass boost.

Iommi wasn’t a huge effects guy in the early days, but he did use a couple of key items to achieve his signature tone. In addition to cranking the mids and high-end on his Laney amps, he also hit the front of them with a Rangemaster treble booster for more overdrive and punch. The result was a fat, fuzz-like tone that is often mistaken for a Big Muff or some other pedal. It is, in fact, just a treble booster and a big-ass tube amp set on “destroy”. Modern guitarists also tend to forget that Iommi’s sound was not a high-gain one. Even with the Rangemaster, his tone was quite clean by modern metal standards.




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Axis Fuzz

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Electronics Projects For Musicians

Even if you don’t know an ohm from a volt, Craig Anderton’s revised and expanded book shows you how to build 27 accessories that enhance your sound and broaden your musical horizons. If you’re an old hand at musical electronics, you’ll really appreciate that all of the processors, from tube sound fuzz to phase shifter are compatible and work together without creating noise, signal loss, bandwidth compression or any of the other problems common to interconnecting effects from different manufacturers. There’s even a complete chapter on how to modify and combine effects to produce your own custom pedal board. Low cost project kits available from PAiA help make even your first exposure to electronics a pleasant, hassle-free experience and thanks to CD bound into the book, you know just how the device will sound before you even start.



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A.I.=How the Enlightenment Ends

How the Enlightenment Ends

Philosophically, intellectually—in every way—human society is unprepared for the rise of artificial intelligence.

Henry A. Kissinger
June 2018

https://www.theatlantic.com/magazine/archive/2018/06/henry-kissinger-a i-could-mean-the-end-of-human-history/559124/

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Rossler Kaos Attraktor Schematic




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XMACHINA is a Probability Auto Generative Drum Machine Engine with 4 BPM sync LFOs autopanning each sound while modulating “seed” factors that plays drum samples plus has built in CR78/MFB502 type Drum Synth that also transmits 4 channels of generated MIDI patterns for driving hardware at same time from the “Probabilty” Engine… XMACHINA also directly writes multichannel MIDI data compositions into DAW

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TripleSloth Schematic

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xn+1= 1 – axn2 + bxn,
(a and b are parameters)

Michel Henon, an astronomer at the observatory in Nice, France, was born in Paris in 1931. Curious about the degradation of celestial orbits, he began to model the orbits of stars around the centers of their galaxies.
Henon considered gravitational centers as a three dimensional object (as opposed to a point in space) and carefully studied the orbits of the stars. To simplify the task of trying to track a three dimensional orbit, he considered, instead, the intersection of a plane with these orbits. Initially, the intersection points appeared to be completely random in their location, moving from one edge of the plane to the next. However, after a few dozen points were plotted, a closed, egg-shaped curve began to appear. This mapping was, apparently, the cross section of a torus (i.e., a doughnut).
Henon (along with one of his graduate students) continued to study this mapping and continued plotting the points for a system with increased energy levels. Once the newer mappings were made, though, the continuous curve began fading and random points began to appear proportionally to the energy. Over the years, Henon tried many ways to predict the upcoming points of his high-energy graph until finally, he decided to abandon classical methods and use difference equations.
Applying a formula to force the data into the shape of a crescent moon, Henon found some interesting results. The formula was fairly simple. Take the old y and multiply it by 0.3 (b). Then subtract 1.4 (a) times the old x squared. Finally add one to the whole equation. This yields this system:
xnew= y – 1.4×2 + 1
ynew= 0.3x

Although, at first, it seems like an ordinary curve, closer inspection reveals distinct curves, one thicker than the other. If we magnify the picture, we see that each of these curves is also made up of two similar curves. This happens for every possible magnification of the curve.

In astronomy, Michel Hénon was a leading figure in the field of stellar dynamics, galactic dynamics, and the evolution of the rings of Saturn. In mathematics, he is known for the so-called Hénon maps and attractor, which is one of the most studied chaotic systems.
In the late 1960s and early 70s, he worked on the star clusters and by using Monte Carlo methods, he developed numerical techniques to follow the dynamics of globular clusters. His probabilistic method proved to be much faster than usual N-body methods.
He published a two volume book on restricted three-body problem.

He died on April 2013 in Nice.
http://adsabs.harvard.edu/cgi-bin/nph-a … &version=1
https://www.youtube.com/playlist?list=P … 6-akNgLG7-_

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