Craig Anderton Octave Doubler Fuzz

[Freppo]

I haven't built this one yet.. so i'm a bit unsure about the pot numberings.
But other then that it should work. I've gone over the layout several times.
I  left it stock, except I added C10, a mod suggested by Mark Hammer.
He also suggest trying other diodes (like 1N4148) in the octave section (D3 & D4)

This one requires a bipolar powersupply or a negative voltage inverter like this one.

Cheers
/ Fredrik

[Freppo]

Here's another layout of Mark Hammer's modified version of the Octave Doubling Fuzz



It uses a quad IC insted of two dual IC's and a single supply/Vref.

Here's what Mark wrote:
"The mods are as follows:
1) A transistor input buffer "borrowed" from any number of Boss pedals.  Anderton uses a non-inverting op-amp for the first stage in the original, which has a high input impedance.  I borrowed that op-amp to use for another function (see below) with the negative side-effect of having a lower input impedance in that first op-amp in the fuzz stage.  The transistor input buffer attempts to compensate for that.
2) The original provided for feedback-cap switching in the first (fuzz) stage.  Personally, it never did anything for me, so I picked a compromise value of 33pf.
3) The original has a fixed gain for the fuzz section.  I made the gain variable and skipped the input Drive control.  Note that treble content declines as gain is increased.  At max gain there is a rolloff starting around 4.8khz.
4) The octave-generating circuit remains the same, but the modded version introduces it a different way.  Here, I've used a sort of pan control that goes between the octave and an inverted octave tone.  When centred, they cancel each other out, yielding a sort of combination level/phase control.  Use a linear pot for this to know where the centre is.
5) The original uses a "cancel" switch to completely kill the fuzz signal.  I preferred to have variable control and replaced the switch with a pot.
6) The original has a gain of around 15 for the fuzz and 22 for the octave signals in the output stage.  With the use of a variable fuzz-level pot I set the two signals for fixed gain of 10, although you can up it if that's not enough for you by increasing the 100k resistor to 150k or higher. Note that with 100k, the 150pf cap gives a rolloff starting around 10.6khz.  If you make the resistor higher, you'll need to make the cap a bit smaller to retain the same rolloff."


/ Fredrik

[Freppo]

Ok, so I built Mark Hammers modified Octave Doubling Fuzz
It works kinda (sounds fuzzy), but no octave effect and weak output.
Sound a bit muffled aswell.. Probably some fault with the layout,
..or the schematic.. I'm pretty sure I got my built right, but Mark wrote:
"I haven't built it yet, but I see not reason why it shouldn't work"...
So the schematic isn't confirmed which may be the problem..

So I think I'll scrap this one :/

/ Fredrik