I built this from the GEOFEX layout. The mighty roar of this pedal demanded more than than puny plastic standoffs could hold. Wussy adhesive backing would not be enough. I chose to go with 440 allen bolts and aluminum standoffs to secure the PCB to the enclosure.

There are four tubes: 12ax7, two 12ab5 and a 5y3-gt rectifier. I’m not the tube expert, but it looks like the 12ax7 is used as an input preamp. The two 12ab5 tubes are set up in a push pull configuration.From what I’ve read it sounds like the two 12ab5s put out about 9w max. The amp is pretty quiet, good for mellow practice.

Here’s a few pictures.

I think I can save my build by either bending the IC pins over so the chips are upside down, or soldering the chips to the copper side of the board.

The Distort-o-matic VI for example, uses a very off the wall concept. The input signal is imposed on a 40k carrier wave. The carrier is a square wave generated by a 555. This signal is then fed to a high frequency transducer. The device has a high frequency receiver to pick up the signal from the transducer. The high frequency signal is filtered to leave the original input signal. Who thought of this? And what was going through their mind at time? This is so nutty!

Not sure what it will sound like. Figure you have to built it and find out. This is where we get to the hit and miss quality of the Stompboxology projects. Stay tuned for some sound samples…

I ordered all the parts to build this thing a long time ago and never got around to building it till now. Joe had the idea that we should explore the 555 and find some new things to do with it. So I dug the Stompbox Cookbook and found the Distort-o-matic VI. I etched up two boards and drilled them.

This hasn’t been tested. It was made more of an exercise.

To make up for the reduced output I modified the output buffer. This also made for a better effect in my opinion. I feel the trem sounds better when unity gains falls in the middle of the trem sweep.

Here’s a few notes. Part numbers follow the original schematic from Stompboxology.

R14 was 470K. Make this 309K (or there about). Lowers the input gain
and clears up a lot of nasty distortion that shows up when the input
is high.

R16 was 3K3. Just remove this, or replace it with something really
large ~1M. This increases the gain at the output. Which makes up for
the gain lost by the first change and gives it a little extra gain for
a better tremolo effect.

R25 was 25K. Make this 100K. This decreases the lower end of the rate.
I like the slow tremolo sound. I’d almost like to make this a little
larger. But it might require a weird size pot 120K, 150K, 200K etc.
You can fiddle with C15 also, but this tinkers with the fast rate
which I like.

I had an idea to build another with a switchable rate cap for super
fast audio rate modulation and regular low frequency modulation. The
HF modulation might give a weird sort of “ring moddy” tone.

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Shocktave Build

This worked right after I found a small solder bridge grounding the input cap. The PCB layout I posted has some very small traces that are very close to the ground plane. I thought this was going to be a nightmare to solder. It was actually not too hard. I found careful application of small amounts of solder worked well.

I had to sub a 2n5089 for a 2n5088. Since I only 4 2n5089s on hand. I picked the Q1 as the substitute.

My first impression was wow this is so distorted I’m not even sure that it’s working. After some testing I notice there is a very nice octave that comes out at times. Seems playing single notes around the 12th fret really brings out the octave, go figure. The octave sounds very nice under the right conditions.

Chords throw everything out the window. Playing a chord seems to make the sound explode into a barrage of noise, and not very musical noise at that.

Could be good for something. The mix is useful. Turning it down you can mix the octave to a pleasing level. Turning the mix all the way up produces a random arpeggiated note sort of distortion. This has some potential, but is hard to control. Q4 and 5 form an oscillator that is driven by the input signal. I wonder if  there were a control control the frequency of the oscillator if some more interesting sounds would come out.

The oscillator portion of the circuit stumps me. I don’t understand how this works and have not been able to find anything similar for reference.

I had built a BSIAB II while back that had all of the transistors in a row. This made for a fun layout. It also made it convenient to use a single 15 peg milmax header as a socket for all the transistors. This worked out well, so I thought I’d try the same idea here. It works out especially nice since all the transistors are the same and face the same way. Hard to put the wrong one in the wrong place or backwards. Not that I would ever do that.

I’m sorry the values are hard to read to in the layout. I’m a beginner with Eagle. If anyone knows how to arrange the values are part names individually please post a comment and let me know.