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.

18 comments:

  1. Anybody can insert pot of tone in layout.

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  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

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  3. 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

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  4. 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.

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

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

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

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

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

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    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.

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    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.

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    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.

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  8. 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

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    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.

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

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

    Cheers
    Elbee

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