Tuesday, 4 March 2014

Shin's Music Dumbloid Standard

Latest $600 TGP favourite and as expected it's money for old rope.  The Screamerloid is probably the correct name, and by some strange coincidence that sounds like painful hemorrhoids.  Thanks to Eisy on FSB for the schematic.

Out of the 231 overdrive layouts currently on this blog there is a pretty high proportion that are extremely close to the Tubescreamer (some are basically identical) and this is definitely one that is very close.  But I also think there is enough differences to make this an interesting build, and there's no doubt this has quite a few fans so something must be working right here.  95% of it is a Tubescreamer, but the notable differences is there are no clipping diodes in the feedback loop of the first opamp stage, there is a single LED being used for aymmetrical clipping in the feedback loop of the second stage, and the Accent control is an added control for the second opamp stage which will alter the frequency response, and I think possibly the gain of the stage too.  Those changes are enough to make this unlikely to sound just like a Tubescreamer even if the topology is extremely close in many other areas, and so this is one that I will definitely be building just to see how those sort of  changes make this differ from what I would have expected from this circuit.

Still not worth anything like $600 though :o)

Expected cringeworthy marketing spiel:

One of the most iconic and sought after amps in history… in a pedal!  All D*mble amps are different in tone but the main characteristics that set these amps apart are the open uncompressed cleans and the evenly compressed overdrive.  These pedals are very limited.  Shin’s music in Tokyo Japan is the builder and he knows tone.  This does not sound like a pedal…it sounds and reacts like an amp.  Many pedals claim this feat but few can back it up…The Dumbloid does!







36 comments:

  1. The original has a Jazz/Rock switch, it looks like. Maybe that's what the other $585 gets you.

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    1. No the Special has the Jazz/Rock switch, this is the Standard. It's apparently a switched cap to ground from Volume 3 so if anyone wants to experiment and let us know what you find that will be great. It makes a low pass filter and something like a 220n will give a corner frequency of around 723hz which may be a good starting point to experiment.

      I'll add a layout for that version when we can get a confirmed value from the original.

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  2. Wow... Do these really cost 500USD? And for that money they really only put some stickers on the boxes for the pots, etc.?

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  3. Built one. Noticed that i didn't have any OPA2134s at hand, so i tried on a few others. AD712 works well sounds good.

    The sound has definitely nothing too much to do with a TS. So in a sense it's very nice adaptation and probably very much worth a build. But for the love of ... 460 euros for a pedal that looks like a cheap DIY custom?!? Seems i'm charging way too little for my builds :P
    +m

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    1. So my component swaps are AD712 for the opamp, BC549Cs for the buffer transistors and 20K lin for the accent.

      Sorry Mark, i tagged this one already :)
      +m

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    2. Awesome thanks matey! :o)

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    3. I'll take some of my description back :) It's not completely different from TSs. It is a way louder and the mid-honk isn't as horrible. So i would say it sounds like a mash of TS9, SD1 and Hotcake. Nevertheless, 460€.
      +m

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    4. Mirosol said "So my component swaps are AD712 for the opamp, BC549Cs for the buffer transistors and 20K lin for the accent."

      Oh-uuuu....that means I have everything I need to build it in stock!

      Thanks Miro!

      G

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  4. ........ $666.48 Canadian!

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    1. Sickest thing is that it looks way worse than most of the builds by this blog's readers...
      +m

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  5. I built this one today.i used 100% of the correct transistors (BC548B's) and chip (OPA2134). I don't like it at all so it'll never get boxed and that's after modding to make it better, but thanks for posting it anyway.

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    1. Would you please elaborate a bit more on that?....

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    2. Sure. since it only has one clipping diode (red led) it's dirt is mostly opamp distortion, and it's after the tone and accent controls, which IMO, makes it even worse. it has a fizzy decay on all of the distorted tones which I don't like at all.

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    3. Try a 220p cap or similar between pins 6 and 7 mate, and maybe increase the 82p. That may get rid of enough of the fizz.

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    4. AD712 seems to clip quite nicely... I don't think the fizzy decay changes with the tamer cap. It's characteristic to some opamps to clip horribly.

      John, if you have any, try AD712 on it to see if that changes the decay texture...
      +m

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    5. i'm running a 100p where the 82p is and it didn't help at all so I think that miro is correct. usually an OP2134 is a very nice sounding opamp but not in this one. unfortunately, i'm out of AD712's at the moment, but I have a ton of other dual opamps.

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    6. Try on the usual suspects TL082, TL062, NE5532, JRC4558, JRC4580, LM1458.. I bet one of those should saturate nicely. TL072 sounds horrible when it saturates :)
      +m

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    7. okay, so far I've tried the following:
      OPA2134 (the stock chip)
      OPA2604 (about the same)
      LFR442
      LM833N
      NE5532
      TL062
      TL072 (IMO, just as good or better than the OPA2134)
      and my favorite is the lowly LM1458! it actually sounds pretty nice now. some of the others were terrible.

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    8. Just as i thought :) Adding to my earlier comment - TL072 *usually* sounds horrible when it clips.

      Harnessing opamp saturation/clipping in a design is much harder than one would think. The ugly decay is usually masked by hard clipping on most designs that use this method, but on this one - i believe the opamp should be just right, of you'll end up with broken sounding decay. Can't really say why the OPA2134 doesn't sound broken on the original. Could be just one manufactured batch that works correctly on this circuit.

      Also. I've been following the FSB thread and one should probably swap the 150K resistor from supply Q1 base with a 470K to get higher input impedance :)

      I'm sticking with AD712 as it seems to work :)
      +m

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    9. I tried a JRC4562D in it and so far, I like that one the best now.

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    10. I have about 30-40 different dual opamp chips and I have found the best sounding one for me. it's a MC33172N which is basically a dual LM741. the fizzy decay is hardly there at all and completely gone if I turn the accent down a little. sounds great now and it's getting boxed tomorrow.

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  6. This looks interesting, will have to make one!
    I have an OPA2107AP I can try until I find the proper ICs... from the valvette custom drive LOL
    But if the 2107 sounds good it is staying

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    1. For me it didn't work at all. Rails get too hot and it sounds closer to digital fuzz than any overdrive :) But socket it so you can try anything in there.
      +m

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    2. ah ok... thanks Mirosol - I cannot believe how the real pedal looks... all slapped together... :facepalm: $600 on ebay
      double :facepalm:

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    3. WOW!
      This thing makes a KLON look like a punk. The tone variations with the accent and tone knobs are extreme. No I would not pay $600 for it but that's a mute point huh? Thanks for this build lvlark!!

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  7. finished my REV2 but added the 'special switch to it. it sounds great now with the MC33741 chip.

    pics:

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/Dumbloid/DUMBLOID-01.jpg

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/Dumbloid/DUMBLOID-02.jpg

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    1. Ha ha great job John, that looks wicked! :o)

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    2. Great work once again! Yours looks way better than the original :)
      +m

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    3. thanks guys. I just used a plain/natural 1290NS enclosure (it's the same size as a 1590B) and scuffed the upper part for a 'brushed' look. then I used my p-touch instead of a Dymo for the control lettering using photoshop to make them from the original pedal, so mine are smooth and glossy and aren't 'raised' like a Dymo label.

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  8. oops. I meant the MC33172N chip

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    Replies
    1. did you end up with any other mods than the chip and the switch?

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    2. Cool, thanks. Now I just have to find one of those chips. I have a couple of LM1458s and TL072s on their way, so that'll have to do for now. The 1458 is also basically a dual 741 if I'm not mistaken though.

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  9. Built it. Used all the stock components. I kind of like the fizzy decay. It almost has a fuzz-like quality to it. I can see how many say it is very amp-like.

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  10. It is mentioned 17 cuts on the board,but I see only 16,I am a rather novice,can you explain me this!Thanks already!

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    1. there's 16 cuts, not 17. it was probably not changed at some point while the layout was being made.

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