Friday, 29 January 2016

Electra 600D

I recently acquired an Solec DO-131 St. Dist. + O. D. (horrendous name) as a defunct unit and fixed it up. I found the sound very pleasing and versatile. Apparently this taiwanese pedal has been sold originally as Electra 600D, then as Omnifex 700D(?) and as Solec name monster among others. As topology goes, i found this rather interesting as well. Dist+/OD250 style gain stage, followed by switchable hard clipping and a Big Muff style tone stack. Loud and versatile dirt design. The tone control and clippers are easily made to suit one's taste. This is why i thought this was worth a post... Couldn't find other demos, but for Omnifex.



21 comments:

  1. Very nice layout Miro! This does look pretty versatile

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    1. Something peculiar with the original though. The level control affects lows :) Louder the better. Circuit may sound thin when not cranked :)
      +m

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  2. Just built this and the sounds is gating/clipping very hard. I did not have a C100k so I went with an A100k .When dialing Depht around 50% I get a more or less good sound for a few seconds, then it's back to terrible-clip-land. Dialing Depht and/or Tone to 100% I hear like gain building up, the some humming then silence. As if something gets overcharged. Really strange behaviour.

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    1. I'll check it, but the log instead of reverse log isn't a good sub.


      Found it. There's a cut missing from depth 2 row. There needs to be a cut right off the 3k3 top joint - Before the 470k. Under the link.

      I'll add it as soon as i'm back at my desk...
      +m

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    2. Fixed. Try adding that cut and see what happens.

      Also, if you don't have any reverse log pots, try wiring the depth (gain) in reverse. Just take the lug 3 wire to lug 1. Now the turn will control the gain level as it should, but in reverse - max gain in ccw and minimum gain in cw.
      +m

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  3. You can mark this verified. Sounds really nice and it might be even worth getting a c100k for this :) And thanks for the tip with the pot, but I already did that rewiring thing earlier on.

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  4. Good to see you back in business, Miro :) I've spotted an error maybe though in this one: the 470k resistor from the input buffer's tranny's base goes to +9V in your layout, but to the reference voltage in the schematic I've found (http://www.mudpods.com/Electra_600D.html). The reference voltage would make more sense to me, as on the schematic, but since your layout is already verified, I'm not sure...

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    1. You're correct. Letters dedfining the voltage lines and switching are rather annoying. Vref does make more sense, but as for buffer fuctionality.. Not sure if that makes that much difference. The forward bias voltage will work, but it's not "correct" when taken from supply.

      Either way. Fixed. Gladly, an easy fix. If Thorsten wants to try the fixed layout, just take the said 470k's bottom lead two rows up.
      +m

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    2. I'll try that tomorrow. Nothing against that thing sounding even better than it is now.

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    3. ok, just tried this out and...nope. Moving that resistor up is a very bad idea. You'll end up with sort-of a tremolo on speed :D

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    4. Hmmm. Wonder if there's something fishy going on in your build. Gavin below apparently build one with "correct" bias voltage fot input buffer. And like i stated, that should not affect the sound at all as it (the 470k resistor in question) only contributes to the behaviour of the input buffer.
      +m

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    5. Nah its fine. I did not realize you've moved the cut to the right towards the IC in the latest layout so my resistor was in the wrong place when I had those issues. I've socketed the resistor so it was a short fix :)

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  6. Debugging/modifying would be much easier with a schematic. Does anybody have one?

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    1. http://www.mudpods.com/Electra_600D.html

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    2. Google/duck duck go. And Csaba posted a link above in his comment earlier...
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  7. I built this at the weekend and its working. I do find that one of the switch settings does reduces volume but its still great. I noticed the 470k post earlier an changed that, no difference at all in anything.

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    1. This comment has been removed by the author.

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    2. Switch behaviour is on par with the original. It adds clipping diodes shunt to ground, so volume drop is imminent. That also shifts the distortion texture more to the distortion way. One could try replacing the 1N4148s with yellow LEDs. That way the drop would be less and distortion texture would be more raw, yet crunchy.
      +m

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    3. I've tried several diodes like different LED's, OA61 or 1N34 but the 4148's have the most fuzzy tone. The others were too near to the overdrive tone. So far the 5088 with 4148 gives the biggest difference between the two modes, even if you loose some volume.

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