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Saturday, 19 January 2013

Runoffgroove Mockman

From ROG: This project has returned from beyond the grave for a tune-up. Compressed, harsh, and '80s sounding are fitting descriptions of its sonic character. Yes, it is a niche sound which is quite the opposite of some JFET-based distortions developed by the 'groove, however we feel it is a great time capsule of an era fondly remembered by many. Whether you are looking for a simple weekend project or willing to play a cover of an '80s hard rock anthem, the Mockman will suit your needs.

 During the '80s, countless artists recorded directly to console using a Rockman amp. The Mockman sounds uncannily reminiscent of this sound as it is based on the Scholz Rockman's distortion section. Distortion is created by overdriving the op-amps, similar to the Sansamp units, but with strong equalization in each stage: a high-frequency emphasis combined with an aggressive low-frequency cut.

 In this revision, the optional LEDs were completely removed, the high-end has been tamed to reduce hiss and some harshness, and gain was increased for additional sustain. Also, switch at the output sets the amount of bass for a biting '80s sound (Classic) or a heavier '90s sound (Modern).

 The original op-amp was an RC1458, however you are encouraged to audition any dual opamp, as this component is an integral part of the sound. The JRC4558 opamp works quite well. Some faster/better op-amps like TL072 and NE5532 produce a slightly brighter sound. Modern rail-to-rail opamps like TLC2262 and TLC2272 sound a bit louder and better defined. In particular, our favorite op-amps were the JRC4558 and TLC2262.

 The output filter capacitor can be set initially to 470pF, then tuned according to your preference and the op-amp in use.

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32 comments:

  1. Madferret19 January 2013 at 15:19

    Hell yes you can tag this! It's a full on 'hair metal' style distortion, high gain with a nice EQ balance. It's times like this a wish I still had long hair so I could put a power headband on or shave it into a mullet and rock the f*ck out!

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    Replies
    1. Madferret19 January 2013 at 15:19

      OK, no mullet but you get the idea.

      Delete
    2. IvIark19 January 2013 at 15:27

      Excellent, thanks for verifying mate

      Delete
    3. Madferret19 January 2013 at 15:31

      It really is a pleasure mate. This won't be everyone's cup of tea but this is exactly what I want from a distortion as opposed to a Fuzz. It's badass!

      Delete
    4. motterpaul20 July 2014 at 23:44

      This comment has been removed by the author.

      Delete
    5. JaviCAP21 July 2014 at 00:28

      No, it seems an understanding problem, not a grounding one :) You can't find any path to ground on the lower row, because is not connected to ground.

      The only pin of the IC that is connected to ground is Pin 4. Your voltages are a real mess, and have no sense at all, so you have something really wrong on your board. In the schematics that you tell, the volume lug connected to ground is 1, as in all volume knobs, unles you want a volume knob that works counter clock wise.

      If that's your first vero, check the cuts, component location, solder bridges between rows.

      Voltages should be something like

      4-5v
      4-5v
      4-5v
      0v
      4-5v
      4-5v
      4-5v
      9v

      J.

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    6. motterpaul21 July 2014 at 01:30

      THank You. I figured that out and found a bad cut in row 3 (ground) at the top, I now have new voltages I will post now.

      000
      000
      4.68
      000
      4.68
      000
      000
      9.47

      Now, I get a sound, but it start out way distorted and then fades out, I tried reducing the pot - no help. It sounds like a capacitor problem since it fades out the more I play it, and within about 20 seconds have no more sound.

      Delete
    7. JaviCAP21 July 2014 at 02:15

      I had a similar problem with the Univox Superfuzz, and finally happened to be a resistor from emitter to ground, that should be 1k8...but I soldered 1M8 instead :P

      If you find no dodgy caps, check resistor values, just to be sure.

      Anyway, 0 volts on Pin 1, 2, 6 and 7 is not normal, so check this area first, as there's something wrong there.

      J.

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    8. JaviCAP21 July 2014 at 02:18

      By the way, there are no cuts on row 3 (ground)

      Delete
    9. motterpaul21 July 2014 at 03:31

      This comment has been removed by the author.

      Delete
    10. motterpaul21 July 2014 at 07:23

      Darn .... I rebuilt this thing from scratch and it still has the same problems. I don't seem to get voltage to the IC. I am thinking maybe I have the outside grounding wrong (on the guitar in & effects out) - any tips there?

      Delete
    11. motterpaul21 July 2014 at 07:36

      Maybe it is the switch I don't get. I have a STDP (single pole double throw) - so it has two positions, but three lug on the bottom. I assume it goes in pairs, so I would wire up 1 & 3 for sw 1 and sw 2 --- but I am not sure. Any help here?

      Also - should I ground everything to the board? Sorry but this is the first project I have done here - and not having any joy.

      Delete
    12. motterpaul21 July 2014 at 22:06

      I JUST got this working. I should have known when the voltages were not right that it was related to the input voltage. It turned out I had a 22k resisitor where I should have had a 100 ohm.

      So - two things when you start to build these - it is probably a good idea to set out all your parts ahead of time so you have them accounted for. Then, print out a copy of the schematic and check off each part as you add it to the circuit.

      To troubleshoot it, it is easy to check caps (the value is printed on them), resistors, for us newbies, are a little harder. The "Electronics Asst App" is invaluable. It shows you all the right codes for caps & res. for any value.

      To trouble shoot, it is also easy to see the circuit, but I fixed my build when I opened up that app and started checking all my resistor values.

      Delete
  2. mah6219 January 2013 at 15:42

    Damn, 10 minutes from my second tag of the day. Well done mate! I had a rock man in the 80's, used to plug it into my portastudio and I thought I was George Martin. Very nice indeed, Miro!

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  3. mirosol19 January 2013 at 15:57

    Guys! That means that we are 4 tags away from the fact that Mark has to write another notification! How cool is that!
    +m

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  4. Unknown30 June 2013 at 13:35

    I built this one and it sounds ok. Would help if it had a tone stack of some sort. Any suggestions and how to put it with this circuit?

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  5. Jumbled Opinion17 December 2013 at 21:24

    Forgive the newb-style comment, but I assume the SPST switch will be a normally-open switch, correct?

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    Replies
    1. mirosol17 December 2013 at 21:37

      No. It is latching on-on or on-off switch. Something like this will work fine:
      http://www.taydaelectronics.com/electromechanical/switches-key-pad/toggle-switch/mini-toggle-switch-spdt-on-on.html
      Just leave the pin 3 unconnected.

      Normally-open usually refers to momentary switch.
      +m

      Delete
  6. Hozy314 April 2015 at 17:21

    Needed a break from building Fuzzes so built this and DeArmond square wave today. This is an excellent sounding pedal. Built today using a TL072 and its a loud pedal with a great heavy sound with an added brightness. Definitely recommend this one.

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  7. mbndvm5 November 2017 at 01:00

    Where do you all get the variable capacitor for Cx? I can't seem to find one. Thanks in advance.

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    Replies
    1. mirosol5 November 2017 at 07:06

      If you mean the output cap in this layout - nowhere. The variable caps only come in very small value range and mainly meant for radio purposes. In this case, you might want to socket the cap or wire it's connections to a breadboard and try on the values to see what works for you.
      +m

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    2. mbndvm5 November 2017 at 14:13

      Ah, ok, it's not a trimmer Capacitor then. Thank you. I am new at electronics, so it was a bit confusing. This explains, why in the PCB diagram, CX appears like a ceramic, because it is. Many thanks!!

      Delete
  8. jtbeau1423 March 2019 at 03:15

    The modern switch doesn't appear to make a noticeable difference on my pedal... Could it be because I subbed the 10nf near the 22k resistor with a 22nf? I couldn't find a 10nf so assumed itd be close enough.

    The pedal sounds good but its not as highly distorted as I'd thought itd be; it sounds like a pushed marshall, but not a PUSHED marshall...

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    1. jtbeau1424 March 2019 at 19:31

      So after trying to install the led mod to this circuit i found a small solder bridge. After cleaning it up the circuit has GOBS of gain now; to the point where it squeals at high settings! I have a feeling this is because of my 22nf substitution as a higher value there would be increasing gain a bit (i didnt think by THIS much though).

      This is an awesome tone however, and sounds very close to the sound of my Marshall plexi build pushed with a tubescreamer. Incredibly tube like to say the least! This circuit deserves my praise, it sounds phenominal!

      Delete
  9. Gino15 May 2020 at 09:59

    hi to all!
    i've built this and it's work...but there is a "noise like a ground hum" anyone have solved this??
    thanks in advance

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    Replies
    1. Elijah-Baley16 May 2020 at 08:52

      I think nobody had this problem with this circuit. Has your PSU this kind problem with other pedals?
      Check your 100uF, position and orientation. And then an overall check up.
      I tried it on breadboard and probably I'm going to build it on a protoboard to fit it in a 1590A.

      I found it sounds fine and gainy, I tried to replace the 1M on the left with a pot (keeping a minum resistorm too) to have a gain control. It works.

      Just a little issue: the sustain is good, but did somebody notice an unnatural decay of the note? It becomes clean a bit abruptly.
      The thing gets worst a bit with my less gain setting.

      Delete
    2. Samz Asylum6 February 2023 at 23:22

      Elijah-Baley can you provide pictures of how you did your gain control please?

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    3. Elijah-Baley7 February 2023 at 09:17

      Actually, I used another layout, but the trick is really easy.
      You have to replace the first 1M resistor to the left with a small resistor (22k-47k) and remove the jumper on the left.
      The lug 3 of the Gain pot goes in the second stripe, the lug 1 & 2 on the fourth stripe. The Gain pot is a 1M linear.
      I got no issue once I built the board.

      Delete
    4. Samz Asylum8 February 2023 at 19:08

      Thanks! I'll give it a try.

      Delete
  10. Gino1 June 2020 at 16:06

    thanks for your answer!!
    i run with 9 volt battery and i've cheched the 100 uf and for me is ok.
    I looked at everything but in my opinion everything is ok.

    look forward to some more answers

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  11. Jeremy9 September 2020 at 09:48

    Just finished this build and the results are fantastic. I tried a TL062, TL072 and the original RC1458 IC, and the original is by FAAAAR the best to my ears. The TLs had a unpleasant high end emphasis to them, and the RC1458 is smooth and sounds most natural. And the most like I remember the 80s. :). Thanks to the original poster

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