Monday, 17 February 2014

ZVex Machine w/ mods

I was cleaning up my layout folders and noticed that i had not posted this one up. It's a slightly modified Machine. First of all, the second driver stage has a gain control now, per the Madbean "Macheen" schematic. Also, i found that using Si diodes and a smaller value for the Limit pot made this design sleekier and way more usable. Already verified.


Posted by at 11:00
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14 comments:

  1. Greg5 March 2014 at 03:54

    Great compact layout for a great effect! This really does work as advertized. It does great things in front of a heavy fuzz. It emphasizes how useful the SHO circuit is too...

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  2. Andy Miller24 March 2014 at 14:26

    shoudn't D4 and D5 be arranged head-to-toe instead of both the same polarity?

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    1. IvIark24 March 2014 at 14:30

      Yes they should, Miro will no doubt update it when he sees your post

      Delete
  3. Andy Miller27 March 2014 at 00:17

    Hmmm... . the Limit pot wasn't doing anything, and I was suspicious of those diodes, so I looked up a schematic and asked the question and corrected that polarity on my build. . . but the Limit pot still doesn't do anything audible. The effect seems to do pretty much what I expect it to otherwise, as far as I can tell from the demo videos out there. But it's a bit of an odd one - hard to tell how the gain stages interact from listening. It definitely makes a fuzz sound weirder and angrier when you've got some gain and volume going. Not sure what's going on with the limit control.

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    1. mirosol27 March 2014 at 09:07

      I'm posting the corrected diodes right now.

      The Limit control sort of lifts the diodes off the signal path when turned clockwise.
      +m

      Delete
  4. Unknown5 April 2014 at 23:22

    My build works perfect apart from a piercing "beep" sound when the pedal is turned on, and it gets louder & higher pitched the more the gain knobs are turned clockwise. Tried using a probe to find the issue, but I can't seem to isolate where the noise is coming from. Do you have any ideas what might be happening?

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  5. ξεναγός νεκρόπολης23 October 2016 at 21:10

    just build this one.works ok(?), but i have a problem with the 5k lin pots. till 95% of the sweep they do nothing,and the gain comes in at the last 5%.any ideas?

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  6. Travis23 October 2016 at 21:14

    Try reverse log. You may have some 5K reverse logs laying around if you build SHOs

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    1. ξεναγός νεκρόπολης23 October 2016 at 21:29

      thanks travis for the quick respond!
      nope...unfortunately i don't..all my pots are linear.i guess i have to unbox it and try to "make" a reverse log from an other value...my dog eat my notebook where i had my notes for that...ahh!!i had to write them down again anyway...boring..

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  7. ξεναγός νεκρόπολης23 October 2016 at 21:17

    and from gate of q1, there is a missing 10k to ground

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    1. AlexS24 October 2016 at 04:49

      10M?

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    2. mirosol24 October 2016 at 08:09

      Ah. So there is. A 10M, but still. I'll do a redraw at some point. Due to defective disk controller, i lost all my files. Including backup disk, so i dont' have source files for any of my layouts anymore. So don'e expect a quick repost...
      +m

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    3. ξεναγός νεκρόπολης24 October 2016 at 09:54

      yeah AlexS! that was what i wanted to say! it was too late and after 14 hours in my lab i was a bit dizzy.anyway.i made it work by just soldering a 5k resistor at lugs 1 & 3 of both gain pots. i know now they're 2,5k but they work much much better than when they was 5k lin. i believe that even a 1k would work just fine..

      it's funny though that this schem(machine) is in every diy effects block with 5k lin pots, and in the comments people say exactly the same thing!that it works better with a rev log!

      anyway. an easy fix just for now, is to move the cut at the right of the gate of q1 one hole under the 22k. And from that spot take a 10M to ground

      Delete

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