Mad Professor - Stone Grey Distortion

soundclone · Post by **soundclone** » 24 Jul 2011, 13:52

i have build this pedal,nice distortion. But i think too much treble. any body can help me to reduce treble?

HEAD · Post by **HEAD** » 24 Jul 2011, 14:12

Yeah, it should definitely got another name: Stone Deaf Distortion, as it is realy able to perforate your ears with it's treble content.
Try to increase the caps in the inverter stage or play with the high cut values of the tone pot.

guycapuano · Post by **guycapuano** » 24 Jul 2011, 17:11

Hows it sound used666?

grrrunge · Post by **grrrunge** » 24 Oct 2011, 20:52

RnFR wrote:2n2 input cap- no wonder this thing is all mids!

Why exactly is that? Doesn't the 1M/2n2 filter just make a cutoff at around 72hz?

kabi · Post by **kabi** » 02 Nov 2011, 14:25

hi all, thanks for your great work on this one

Here's my built, did it for a friend who also added his artwork

The small font text didn't stuck well here and there and i also got some paper residues in some places that i was unable to remove. Guess i'll have to experiment with various photo papers/labels a bit to achieve a better result. Oh well, i consider this to be a great built overall (took some extra time on the wiring) and a nice distortion box as well, works perfectly and sounds exactly like it should as far as i'm concerned

grrrunge · Post by **grrrunge** » 16 Nov 2011, 15:57

Allright, so I built mine today using HBO's vero, and I was less than impressed with the sound of the circuit.
It was extremely treble-heavy, and cut a good bit off my low-end. The controls for tone and drive were acting up ridiculous as well.

I've been toying around with it all afternoon, and did the following changes:
Drive pot: 1M linear instead of 1M log
Tone pot: 10K linear instead of 50K log
C7: 0,1uF instead of 2,2nF
R12: added a switch to switch betwen a 4K7 and a 7K5 resistor

It's still not as dark sounding as the demo on ProGuitarShop's youtube channel. Anyone's got ideas to mellow it out a bit?

roseblood11 · Post by **roseblood11** » 16 Nov 2011, 16:54

How did you try the pedal? In a band context or in the bedroom?

The original pedal isn't dark sounding at all. I had it at hand when I retraced it and I compared it to my build side by side.
It cuts a bit of bass, that's why I put a 4n7 in paralell (switchable). But it cuts through any mix very well, and I think that it was designed to do exactly that. 100nF for C7 is a lot. I tried values up to 47nF when I had the circuit on the breadboard, and even that was way too muddy to my ears.

And a linear gain pot works better? Almost unbelievable. I used a linear first, because I didn't have an audio taper one. Gain was almost at max at 10 o'clock, with almost no audible change above that.

HBO made a vero layout? Can't find it, could you please post the link?

grrrunge · Post by **grrrunge** » 16 Nov 2011, 17:34

roseblood11 wrote:How did you try the pedal? In a band context or in the bedroom?

The original pedal isn't dark sounding at all. I had it at hand when I retraced it and I compared it to my build side by side.
It cuts a bit of bass, that's why I put a 4n7 in paralell (switchable). But it cuts through any mix very well, and I think that it was designed to do exactly that. 100nF for C7 is a lot. I tried values up to 47nF when I had the circuit on the breadboard, and even that was way too muddy to my ears.

I've just been building today, so i tested it on my VHT SP-6 and my small Kustom workbench-amp. I'm not one of those bedroom-players though

I just thought i had an idea about how it was supposed to sound with my gear, when i heard the clips of it on youtube, and i was terribly wrong.

roseblood11 wrote:And a linear gain pot works better? Almost unbelievable. I used a linear first, because I didn't have an audio taper one. Gain was almost at max at 10 o'clock, with almost no audible change above that.

Yep - linear gave me a smooth transition all the way from "crunch" to "balls out"

The tone pot only had action on the first quarter of a turn, so i changed it for a 10K linear - smooth transition and effective range again

Since my last post, i've swapped C12 for a 33nF, and i'm fiddling with higher values for C9 as well. I'm missing a bit of chunk-chunk in my palm mutes

Maybe i did something totally wrong? I'll post some pic's of my build in a couple of minutes...

roseblood11 wrote:HBO made a vero layout? Can't find it, could you please post the link?

It wasn't HBO, who made the layout, I used yours

Sorry for the confusion - i've just been building quite a few of HBO's layouts lately, so i thought this one was his as well.

grrrunge · Post by **grrrunge** » 16 Nov 2011, 18:33

I think i'm gonna stop tweaking for today

It's meatier, chunkier, and more like i want it to be. I'll box it up, and try it at rehearsals before i mod it any further...

I've ended up with the following changes to the vero:

C7: 22nF
C9: 68nF
C12: 33nF
R12: 4K7/7K5 switch
Drive: 1M lin
Tone: 10K lin

grrrunge · Post by **grrrunge** » 16 Nov 2011, 19:12

Pic's as promised:

J0K3RX · Post by **J0K3RX** » 03 Dec 2011, 02:17

Anybody see this mod on the original? Sounds real good... I was wondering where it's attaching to the circuit? Any ideas?

MoonWatcher · Post by **MoonWatcher** » 03 Dec 2011, 22:09

HEAD wrote:Yeah, it should definitely got another name: Stone Deaf Distortion, as it is realy able to perforate your ears with it's treble content.
Try to increase the caps in the inverter stage or play with the high cut values of the tone pot.

+1 on increasing the caps in the inverters' loops. Check out the Blackstone Mosfet (Appliances?) pedal. Sorry for butchering the name, but the last inverter stage has a really big cap in the loop - 470pF if I'm remembering it right. The only caveat is that if the gain is dropped low, the inverter designs tend to sound muffled.

And obviously something as simple as increasing the input cap would help a lot. I honestly would not go below 15nF. There is too much distortion in the design. Lots of people might realize that even 22nF is too small.

If you put a reasonably large resistor in series with the output (probably a minimum size of 150K or so), you can typically put any type of tone circuit after the inverters that you might want. I would think that if this is a proper distortion that it might work well with a Big Muff type of tone control, just with the high pass and low pass filters tweaked to taste. That way, not only would you kill the excessive treble, but you could blend in more bass, too.

geiristudio · Post by **geiristudio** » 10 Jan 2012, 18:11

I don't have a TL051 but I have TL072 and TL082. I've built the circuit with them and it doesn't work. Do I need to have the TL051 ?

HEAD · Post by **HEAD** » 10 Jan 2012, 18:27

What you need is a single operational amplifier. TL0X2 are both dual opa. So they both won't work. Try a TL0X1 or several other single opa.

J0K3RX · Post by **J0K3RX** » 10 Jan 2012, 18:32

geiristudio wrote:I don't have a TL051 but I have TL072 and TL082. I've built the circuit with them and it doesn't work. Do I need to have the TL051 ?

TL051 is single channel, the TL072 is dual channel....

EDIT: Head beat me to it...

geiristudio · Post by **geiristudio** » 11 Jan 2012, 00:19

Duh, stupid me! I'm ordering some TL051 right now! Can't wait to finish this one!

Btw, which other opamps can be used instead of TL051 ?

HEAD · Post by **HEAD** » 11 Jan 2012, 00:20

geiristudio wrote: Btw, which other opamps can be used instead of TL051 ?

... that's a joke, isn't it?

2 posts above yours should give you a first guess.

roseblood11 · Post by **roseblood11** » 11 Jan 2012, 00:26

opa134 or ca3130 work very well

Seiche · Post by **Seiche** » 11 Jan 2012, 12:42

geiristudio wrote: Btw, which other opamps can be used instead of TL051 ?

TL0X1 means you can use the TL051, TL061, TL071, TL081.

roseblood11 · Post by **roseblood11** » 11 Jan 2012, 14:57

BJF often uses CA3130 opamps (with mosfet inputs) in his more expensive pedals. I think that he replaced it with a tl051 here because it's a few cents cheaper.

Mad Professor - Stone Grey Distortion [traced]