This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Monday, August 22, 2016

Earthquaker Devices Grey Channel

This is the 400th layout on the blog. Kinda hard to believe I've drawn up that many. O_O

The cool dudes from Akron cooked up the Grey Channel, a dual overdrive based on the classic grey spec DOD 250. The 250/Distortion + circuit is one of my favorites and it turns out it's one of EQD's favorites as well:

It is based around a classic hard-clipping gray box overdrive (subtle hint, huh), one of my all-time favorites. Coincidentally, this is the very same pedal that got me started building pedals and launched EQD. It is two channels of a simple hard clipping overdrive that leaves the character of the guitar and amp intact. The Gray Channel retains the classic warm overdrive sound and expands upon it with several clipping options and bigger bass response. Each channel has 3 clipping modes. The Green channel- “Si” (Silicon clipping diodes), “Ge” (Germanium clipping diodes) and “N” (no clipping diodes). The “Si” mode will be bright/loud/fuzzy and has a natural tube type break up. “Ge” mode is a little looser with more lows and warmth and less output. “N” mode acts as a clean boost until you hit roughly 1 o’clock on the gain, at which point it’ll start to saturate the op amp into a biting, loud distortion. Phew! Still with me? Cool, onto the modes of the Red channel. Here, you’ve got “LED” (LED clipping diodes), “FET” (Mosfet clipping diodes) and “N” (again, no clipping diodes). “LED” mode is the loudest, cleanest and most touch sensitive/least compressed. “Mos” mode is the most compressed with a tighter crunch; the biggest hesher of the group. And finally, the “N” mode is the same clean to crazy loud op amp distortion set-up as the Green channel. With a couple of switch clicks you can go from your bypassed tone to warm break up to over-the-top gnarly grind and any/every combination in between.

Using the above info from the EQD product description, I've come up with a work-a-like to the Grey Channel. Using the Grey Spec 250 schematic as a base, I drew up 2 of them using a single 1458 IC (a dual version of the 741), increasing the value of the input capacitor to 22n (feel free to adjust that to taste) for extra bass response and including the various clipping options outlined above. I also changed the value of the gain pots from C500k to B1M, which is a fairly common mod to 250/Disto + circuit.




You can wire two separate on/off footswitches if you want, but if you want to wire it like the original with a master on/off and then channel selection, wire it like this:


Connect X to X and Y to Y. If you want to use a bi-color LED in place of D2-3 you'll need to wire it like this.

42 comments:

  1. Anybody can insert pot of tone in layout.

    ReplyDelete
  2. Congrats on the 400th layout ² and this is great! I was trying to find a excuse to make me one DOD250 (wich I love), and now this! Thanks heaps

    ReplyDelete
  3. Felicitaciones! Gran trabajo...

    ReplyDelete
  4. Thanks for all the layouts you have turned loose on us etchers! 400 is no small drop in the bucket.. you almost filled that bucket!

    Cody

    ReplyDelete
  5. Congrats on 400 layouts. This is a great site!

    Being familiar with your ninja-like skills I'm guessing one of those volume pots is upside down.

    ReplyDelete
    Replies
    1. Oh. Yeah, volume pot on the left needs to be flipped. I'll fix it. *facepalm

      Delete
  6. yaayyy, congrats for the 400th layout!
    that DOD 250 section sounds amazing, perhaps I should build that as a single pedal

    ReplyDelete
  7. Build it and sounds amazing. It's verified! Congrats for the 400th layout.

    ReplyDelete
    Replies
    1. Aw you beat me to it! I etched it up last night but haven't populated it. Thanks for verifying!

      Delete
  8. Hello!!! I want to do it but how is the wiring to use a bicolor led? And the spdt swich is 3 pins?

    ReplyDelete
    Replies
    1. There's a link at the very end of the post on how to wire it with a bicolor led, and check the General Layout Notes for switch info.

      Delete
    2. OK, thanks, since the cell phone did not see the link, now I have another question, in 1, 2, 3, 4, 5, 6, where is X, Y, in A, In B, out A, and out B?
      Sorry for the ignorance I am very new in this and I am gradually learning.

      Delete
    3. Not entirely sure what you're asking regarding 1-6, but the connections for X and Y are written in the post below the footswitch wiring diagram. The in and outs from the switches go to the corresponding in/outs on the board. If this is your first or one of your first builds, you might want to go with something a little simpler and less complicated. Just so you get a feel for it before moving onto something like this where a lot more can go wrong, just because of the amount of off board wiring.

      Delete
  9. Hello, again, maybe not explain me well, my English is very bad, specifically my duca is the following, in one of the photos there is a 3pdt with two leds and each pin of the 3pdt are assigned a wire, The photo that is 3pdt with the led bi color the other pins do not have any wire drawn, and in that case I do not know what is the input, output, y, x, etc.
    http://fotos.subefotos.com/dffc16520fdc738ca31518872ad68398o.jpg

    ReplyDelete
    Replies
    1. Ah, all you need to do is replace the middle column of the channel select switch with the column that's used in the bi-color LED diagram.

      Delete
  10. Great!!! Many thanks for the info and for the patience haha.
    greetings from Argentina.

    ReplyDelete
  11. Hi all,
    Where has the image gone for the bi-color LED wiring?
    I can only see the separate LED wiring image.

    Cheers
    Elbee

    ReplyDelete
  12. Great layout! I prefer it with 100k lin pots for the gain, and changed the 47k resistors in the gain stage for 4.7k.

    ReplyDelete
    Replies
    1. Hi Michael, 100k Lin for gains or volumes? And what is the difference in terms of sound?

      Delete
  13. Hello! the IC 1458 can be LM or MC? They are the same? Which one is recommended?

    ReplyDelete
  14. They're pretty much the same. I think I used a LM1458 in my build.

    ReplyDelete
    Replies
    1. Thank you! Before buying I wanted to be sure

      Delete
  15. Thanks for all these layouts I've been really busy since I discovered this site this is the like the 8th one and the first I can't figure out. I wired them with separate switches and the b side seems to be fine but the a side makes a loud squeal when I turn up the gain or volume past a certain point.

    ReplyDelete
  16. Oh i want a tone knob so much( Could't you give me a tip where to place a tone potentiometer on this circuit?

    ReplyDelete
    Replies
    1. Check this out:

      http://www.muzique.com/lab/swtc.htm

      Delete
  17. this looks awesome, putting it on my short list to build \m/

    ReplyDelete
  18. This comment has been removed by the author.

    ReplyDelete
  19. What about conecting the gains tô Vb insthead of ground? like the height Knob of EQD white light

    ReplyDelete
  20. Build it and love the sound of the Fets, and the germanium. I think I may socket the LEDs, they don't sound much different from the clipping bypass. Any suggestions? I'm also thinking of modding one side to the specs of the MXR distortion + if possible. The tough choice there would be choosing which side! Wish i had socket-ed the diodes from the get go.

    ReplyDelete
  21. I found the Germaniums way too quiet so I put four in total in series which helped with the volume drop issue.

    ReplyDelete
    Replies
    1. Hi J, so you put two diodes in parallel and then another parallel of diodes in series?

      Delete
  22. Hi there, building this right now. Do you think I can use 1N270 as replacement for the 1N34A diodes? Or, maybe, 1N60P? Thank you! Regards

    ReplyDelete
  23. Hi! Congratulations for this amazing build.
    I've just tested the pedal and I think I have some problems:
    - I have very low volume in both channels (to make it sound good I have to set the volume at 3 o'clock at least)
    - I also have really low gain until 4 o'clock and then it's already too much gain...

    I couldn't find any mistakes on my build so what can I do? Any suggestions? Please help :)
    Many thanks in advance.
    Cheers!

    ReplyDelete
  24. The original circuit, the DOD 250, have a 4,7k resistor before pin 3 of Gain, and this pot is C500k insted of BM1. Maybe this could help.

    ReplyDelete
    Replies
    1. Thanks Skizoide!
      I will try this mods and let you know!

      Delete
  25. Ok. Tell us if it solved the problem.

    ReplyDelete
    Replies
    1. Sorry for the late answer.
      I tried the mods you suggested (but with a 250K pot instead of 500K) and now it works great!
      Great pedal, thank you so much ;)

      Delete
  26. The clipping switchs have different pinouts between the perfboard and the transfer images.

    ReplyDelete