Stone Grey Distortion (4049)

[Frank_NH]

Hi all,

Though I'd upload this layout for the Stone Grey Distortion which uses the ubiquitous CD4049UBE CMOS chip rather than the 4069.  Why - well, because I have a boatload of 4049s I got off of eBay and I had to use them for something!

This is also a little different from the Mad Professor SGD layout on the main page is a few other ways:

* It uses two red LEDs as clipping diodes, and they sound great in this circuit.  And it's always fun to see these light up while you play, something you could potentially highlight in your build (you know, glowing cat's eyes and all that).
* I found the tone control to be a bit lame, so I put in Jack Orman's SWTC2 which now gives it a much wider range of tone sweep.  At the same time, I increased the Volume pot to A100K.
* There's no reverse polarity diode on the board - you can put one in series with the +9V input if you want.
* I reduced the Gain pot to A500K.  The max distortion is pretty good to my ears, but feel free to increase it to the original A1M.
* I used a TL071 for the op amp but feel free to use your favorite chip.

I was jamming on mine tonight and it sounds great.  My vero is a slightly different version than that shown below (as I improved my layout to reduce the width), so it should be considered unverified.  However, it's only a little different, and I think the layout should be good to go, but let me know if you find a mistake.

Have fun!

[Muadzin]

I do like this dirtbox, it's my main distortion. Next to a Big Muff. I'm curious as to the pots, what benefits does the increase of the volume pot to 100K bring (more volume?), or the decrease of the gain pot to 500K?

[Frank_NH]

I decreased the gain pot because at 1M it seemed to max out the distortion at about 50-70% or so.  It seems pretty gainy to me at 500K. However, if you want that little bit extra ooomph, go ahead and use 1M.  I increased the volume pot to 100K because that's the value used in the SWTC2 (http://www.muzique.com/lab/swtc.htm).  It doesn't seem to affect the output versus the original 50K. (For more information about selecting volume pot values, look here: http://www.diystompboxes.com/smfforum/index.php?topic=102644.0).

[Hozy31]

The layout is now verified. Built it today along with the Idiot Blowerbox (obviously to use with my bass unlike this one). Its a good distortion and pretty loud. Used your suggestions Frank and the gain pot is perfect at 500k. Cheers for the layout.

[Frank_NH]

Hey, thanks for verifying the layout Hozy31!  Mine is in the "to-be-boxed" queue, just behind the Shredmaster .

By the way, I realized that with a simple change you can add a polarity protection diode to the layout as shown below.  All you have to do is desolder the 100 ohm resistor and add the diode as shown (a 1N5817 should work well or a 1N4001).

[Hozy31]

Cheers Frank.

[motterpaul]

Hey Frank...

No transistors?  The original has two FETs. I didn't really dig into it to see what the function is for them. I also ordered the parts ($7) so I will build both versions and be able to compare them.

EDIT: it looks like the FETs are used as clipping diodes, and not transistors. So I didn't need to bother to order them.

[Frank_NH]

Yes - this version uses LEDs as clipping diodes.  The schematic is on FSB here:

Topic:
http://www.freestompboxes.org/viewtopic.php?f=7&t=13342&p=257724&hilit=+stone+grey#p193074

Schematic:
http://www.freestompboxes.org/download/file.php?id=18241

[motterpaul]

I just built this. Works great but way too much treble for my gear. I have tone full CCW and it is close but not very defined. Should I try different caps for 22n?

[Travis]

I'd be looking at the 2n2 input cap first....

[motterpaul]

Actually, I was just thinking the same thing. That's the one that controls how much low end you start out with. I do need more low.

[mug]

Build the board today (using the other layout), just one quick question: the cd4069ube-chip looks like this:

So there is this round symbol on the one and a cut on the other side - which one corresponds to the "o" that indicates orientation?
Thanks!

[motterpaul]

the U cut is the "top" - not the hole.

[mug]

Thanks!