"ShredMaster" - very cool edited version here !

[MartyMart]

http://aronnelson.com/gallery/album03/ShedMaster_OD

I wanted to get those "SHRED" tones without all the Eq options, which
also means less "Knobs" !!
Here's an edited schemo, which offers the "tone" and "Dirt" in an easy
to build version.
I built it on vero a few weeks ago and it sounds great !!
Not a ton of low end, but that's how I like my "OD/DIST" boxes....
I just added one extra 1N4148 for asymetrical clipping, but you can just
use two, as per the original.
Adjust the caps as shown to taste, also the 0.001 roll of cap, after the diodes,  is optional.
PLEASE NOTE:
The gain pot should be wired as lugs 1-2-3 from left to right on the
schem, I wired mine 3-2-1 at first and yup, it was reversed !!

If anyone spots that I've made a total "hash" of it, or something could be
improved, PLEASE let me know !!

Enjoy,
Marty.

[MartyMart]

Listening/comparing to a few other builds for "tone" etc, here's what I've
found :
It responds quite well to "pick" dynamics and offers a nice "gutsy bright"
sound, not too far from the "YJM 308" and "Liquid drive"
I dont like the "harshness" at full tilt, but between zero drive and 3/4
drive it's fantastic
A great circuit for blues/rock use, with a nice "mid" hump, great infront
of a valve amp, "TS" style !

Marty.

[WGTP]

Good job.  Looks alot like what has been on my breadboard for several months.  It started out as a Blues Breaker.  Main differences are that I made the first stage into a TS/ and used LED's instead of SI's after the second stage.

I'm sure you already know this, but raising C5 to 100 or 220pF might help the harshness at max gain.  I'm using 220pF with a 470K resistor instead of 680K.  

[MartyMart]

Good job.  Looks alot like what has been on my breadboard for several months.  It started out as a Blues Breaker.  Main differences are that I made the first stage into a TS/ and used LED's instead of SI's after the second stage.

I'm sure you already know this, but raising C5 to 100 or 220pF might help the harshness at max gain.  I'm using 220pF with a 470K resistor instead of 680K.  

AHA ! thanks, staring me in the face but I could'nt see it !!
I'll make that a 200 or so and see how it goes
It's a great noise for the parts count BTW  :shock:

Marty.

[John G]

Marty,
If you are happy with the treble level at low to mid gain levels then it may be more advantageous to leave C5 alone and up the value of C2. This will have thw effect of shaving of more treble as the gain is advanced. A value up to 1nF should do. I do believe that the harshness you are hearing at hi gain settings is the second op-amp clipping, all pedals using this circuit topology seem to exhibit this trait. My way of getting around this problem is to put the diodes in the feedback loop of the second op-amp, or taking the gain of this op-amp down (maybe half) and changing the output cap / resistor to 1uF/1K ohm feeding the diodes to preserve the same clipping threshold.
Just my thoughts,
John G

[MartyMart]

Thanks John, after reading WGTP's comments I was thinking to reduce
the 680k, so could also increase C2 a little.
Wouldn't  using the diodes in the second half of the op-amp's feedback
loop make the "tone" a bit too close to a "TS" type circuit ?
I like the sound at the moment, just that "harsh" end thats a problem..

Marty.

[John G]

Marty,
Yes the sound may change, I just though it was worth trying. Don't forget if you lower the gain of the second op-amp then reducing the output resistor will drive the diodes harder giving the same distortion.
Cheers,
John G

[StephenGiles]

After 300 miles of driving back from South Devon and then delivering my 94 year old mother in law back to her kennel, and downloading half of Cream's last night concert, an impressive one here Marty!
Stephen

[MartyMart]

Marty,
Yes the sound may change, I just though it was worth trying. Don't forget if you lower the gain of the second op-amp then reducing the output resistor will drive the diodes harder giving the same distortion.
Cheers,
John G

I see, so perhaps a relationship of 470k and a 4k7 - 6k8 output resistor would do it ....

Cheers,
Marty.

[WGTP]

John is right.  C2 will have more effect the higher the gain and C5 effects it all.  As in all things, Balance is important.  I think the 1N/100K combo will roll thinks off around 1.6KHz.  2N at 800Hz.   The higher the gain the more roll off.  Also, the .001uf by the diodes is rolling off highs.  I guess you end up with a 3rd order lo pass filter.

I may be wrong, but using smaller resisters should result in less Noise???