Wednesday, 7 October 2020

Roland AD-50 Double Beat w. mods by Mark Hammer

 Mark Hammer tweaked one of the coolest yet most forgotten circuits a few years ago. Roland AD-50 Double Beat was a Fuzz Wah from the 70's with a fuzz with three tone settings and a "so-so" wah. He added three more tonestings for more versatility.

I built the stock Double Beat a while ago and found the normal setting sounding really good, one of the best fuzz sounds around while setting 2 and 3 sounded iether very thin or dark and dull so those settings is modified for this layout as well.

Also the stock Sustain control goes from fuzzy to very fuzzy so I added a Pre Gain control before the circuit since it cleans up really good. Original had 2SC1000 transistors which is obsoslete but really liked the sound of metal can 2N2222's in this circuit.

Tone settings is as follows: 

  1. Normal Fuzz. Sounds killer!
  2. Treble Boost. Original had 250pF cap which made it sounding very thin. Cap value is increased a bit to make this setting a bit more usable.
  3. Treble Cut. Dark and muffled with original cap values. They are slightly reduced in this layout.
  4. 2-pole Low Pass Filter. Similar in sound to setting 1 but a bit smoother.
  5. Crossover Distortion. Same eq as setting 1 but has a quite rough "sandpaper grit" feel to it
  6.  Scoop. Similar to scoop mode in a Superfuzz.
 




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24 comments:

  1. ZZOYD9 October 2020 at 22:50

    This comment has been removed by the author.

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  2. ZZOYD10 October 2020 at 19:25

    Nice Fuzz, pre gain -very helpful pot! Used 2n2222a hfe 270-290, but changed Q1,Q2 to 3904 hfe=150-170. This is realy enough for it! Used only 4 tones.. Try silicon Or led Diodes like Germanium. Germanium diodes-excelent sound!

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    1. fuzzhead10 October 2020 at 22:07

      I agree....I feel my 250hfe 2N2222's is a bit much, will try something with lower hfe.

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    2. ZZOYD10 October 2020 at 22:39

      where did you dig our old soviet schemes? That pedals was all so terrible!Poltava fuzz, VEnta =)

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    3. fuzzhead11 October 2020 at 05:46

      lol...they might be but at least they are offering something different and you can mod them to something good....
      Most of the schematics is found at Soviet Guitars forum but make sure to use goodle transalte f you don't know russian....
      http://sovietguitars.com/e107_plugins/forum/forum_viewtopic.php?103421

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    4. ZZOYD11 October 2020 at 22:06

      I'm from Ukraine =), so i speak russian!

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  3. ZZOYD20 October 2020 at 20:59

    i BUILT THIS ONE,& named it Ronald Reagan Fuzz! https://imgur.com/a/w8m08oR

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    1. fuzzhead21 October 2020 at 16:52

      Cool! Which of the four rotary setting is in the box?

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    2. ZZOYD23 October 2020 at 14:27

      ge, si diodes, standart out, mid scoop

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  4. Kimonostereo13 March 2021 at 05:50

    Out of curiosity, has this veroboard layout been verified? Unless I'm reading it wrong, it looks like switch position 3 is going through D2 and D1 of switch position 5. Was this intentional? I don't see this on Mark Hammer's original schematic.

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    1. fuzzhead13 March 2021 at 05:59

      Yes, it is verified. Not sure if you read it correctly since switch position passes through afixed low pass filter and switch position 5 is fed through D1 and D2 followed by 220k.
      Here is the schematic:
      https://www.diystompboxes.com/smfforum/index.php?PHPSESSID=r2affeppbf6vpbmta75dte2740&topic=124665.msg1183714#msg1183714

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    2. Kimonostereo13 March 2021 at 20:32

      Oops! Sorry! Thats what I get for viewing this on my phone! Thank you for sharing your layout! It's given me some options for my build. I've noticed some diagrams use a 50kA for the Sustain. Did you find the 10k worked better? I've also noticed that unity gain seems to be at about 9am on the knob, so lots of volume on tap!

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    3. fuzzhead14 March 2021 at 07:13

      Yeah, the earlier units had 50k for the fuzz pot, it was reduced to 10k later on. 10kB gives a slightly better sweep but I would still recommend a 10kC.
      It is very loud for sure, so there is lots of room for experimenting with different passive filters and diodes between Q3 and the rotary.
      I guess even lossy tonestack like big muff would work without hurting the output too much...

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  5. KG21 March 2021 at 00:30

    I built it today : thank you for another great layout!
    The pedal works quite fine, but I have a quite low output level. I have read above that the output volume should be massive, so something is wrong with my build : should i look at Q3 values? Is it Q3 responsible for the output volume?
    Also, to allow more bass to pass through, should i up the 100nF cap to 150 or 220nF?

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    1. fuzzhead21 March 2021 at 06:50

      For more low end you you can encrease 100nF caps as well as 10nF cap. .
      Yes, it is possible that your volume issue derives from Q3, it should boost the signal quite a bit. You could try to follow the signal with an audio probe. Start at the top leg of 10nF and the the right leg of the horizontal 100nF cap.

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    2. KG21 March 2021 at 17:15

      This comment has been removed by the author.

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    3. fuzzhead21 March 2021 at 20:31

      Are you using metal can 2N2222As or plastic PN2222s?. They have opposite pinouts and the layout reflects the metal can transistors.

      How is the signal at the collector of Q3?

      If the volume drop happens after the 100nF I suspect you might have ground bleedthrough between it and the rotary switch but I'm not sure....

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    4. KG21 March 2021 at 21:00

      Thank you, FuzzHead.
      I have tried audioprobing the circuit : this thing can sound loud and tasty!
      - When I will have fixed the loudness issue, I don't even think that I'll need to change any capacitor, it's gorgeous the way it is already :)
      - I think Q3 works fine, because when running my audio probe at the Q3 emitter, I hear the loud & warm signal. The 10nF and 100nF caps sounds loud as well.
      - If I put my audio probe on the right side of the lines A, C, G, it sounds loud, too (warm & fuzzy sound).
      - If I put my audio probe on the right side of the lines B,D,E,F,I,J, it sounds quiet, way below unity gain.

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    5. KG21 March 2021 at 21:16

      Urgh, I accidentally erased my reply...

      - I am using plastic (TO92)2N2222A. I tried to plug them turned 180°, and, to my surprised, it didn't change the sound much.

      - At the Emittor or Q3, the sound is loud, warm and fuzzy.
      At the Collector of Q3, the sound is loud, harsh and gated.

      - This is my impression, too : it seems that the volume is loud at the transistors, but it is getting dropped afterwards in the circuit. I think some of it goes to ground, but i can't figure out where and how... :(

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  6. KG27 March 2021 at 17:45

    Hi,
    In the end, I have added a LPB daughterboard, and this thing sounds excellent :)

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  7. Ian4 September 2021 at 19:11

    Best fuzz pedal ever - nice one Anders. Position 6 is amazing!!!

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  8. Tom17 February 2024 at 08:37

    I see why you like this one so much Anders. Definitely no volume issue with the one I built. I like the crossover position. Thanks.

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  9. Ben Spinks22 February 2024 at 20:49

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