Saturday, 10 September 2016

Earthquaker Devices Grey Channel

A dual overdrive based on the classic grey spec DOD 250.
The schematic didn't come from the original EQD pedal.
David has recreated the circuit on his website (Perf & PCB Effects Layouts).
You can find his original and verified layout here.


25 comments:

  1. Verified! Pretty cool sounding pedal. Cheers Alex.

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  2. yep, the germanium option is pretty awesome I think. (1n34a from tayda works well in this)

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  3. Very nice to have so many different clipping options in one pedal, they all offer something unique too. I added a switch to run channel B into channel A for even more options, the germanium side pushing the MOSFET side is an epecially nice crunchy distortion.

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  4. Anyone tried this as a bass overdrive? I'm keen. If not I guess it's mod time 🤘

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    1. Did you have any success adapting it to bass?

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  5. Quick question: I understand the basic layout conventions, including the board, components, cuts, and links, but there's one symbol I don't get: in the link on the far right, there is another symbol about halfway down the line, like a small circle that interrupts it (repeated on the link to its left). What does this indicate?

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  6. Another Quick Question: In the Channel Ftsw, the center pole you said +9v, but in other site I saw GROUND. The other contacs are exactly the same, but this one is ground. It's wrong?

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    1. It would differ depending on whether you use a common cathode bicolor LED or a common anode bicolor LED. No difference in the audio part of the circuit

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  7. Hi all.
    Don't know if I'm missing something but I can't find spst on off on switches anywhere (I'm in the UK).
    Is it definitely spst and not spdt?

    Cheers

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  8. Is a CLR required on the red/green channel footswitch? Would it be one for each positive leg?

    Cheers
    Liam

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  9. Hello and thanks for all the amazing work that you do.. I have a problem with my build.. it has very little gain and after a research I did I think that the 47k resistor before the gain 3 should be a 4.7k.. is that correct? I haven't test it yet, but will do soon and I'll report back..

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  10. Someone over in the comments section over here tried it with 4.7k resistors:
    http://effectslayouts.blogspot.co.uk/2016/08/earthquaker-devices-grey-channel.html

    Might be worth socketing these 2 resistors and finding the value that works best for your tastes

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    1. Thanks! I tried it already huge difference.There is so much more gain, but the 1m lin pot acts very weird it is like an on off switch, (no gain at all until 4 o'clock and after that too much gain)because the resistance is huge.I'll try something like a 100k or a rev log pot

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    2. Guys I have the same problem... Has someone tried different pots for the gains? Suggestions?

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    3. I switched the resistors to 4,7k and used c100k pots, made a biiiig difference!

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  11. Hi! Many thanks Alex for this build.
    I've just tested the pedal and 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!

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  12. Hey everyone!
    During last weekend I completed this build, great layout!
    I too ended up changing some values, cause the first run did not perform well in my opinion, at least quite different from the demos. I wired up the pedal as a two single effects in one enclosure (using the usual "Dual offboard" by Mark), for both channels I needed to crank the volume knob to get a decent sound and the gain too seemed "strange".
    So, I swapped the following:
    -Both 470K resistors connected to Gain3 reduced to 4K7.
    -Both volume pots to B100K.
    -Both gain pots to C500K.
    I searched online and I found some schematisc for the DOD250 with these values... I'm not saying this is the way to go, but for me worked better, for sure now the volume is finally acting as expected (unity around 10 o'clock).
    I also followed some comments of the original DOD250 layout posted by Mark back in 2010, they mentioned these values and I trusted 'em.
    https://tagboardeffects.blogspot.com/2010/07/dod-250.html
    Thanks!

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