Monday, 15 February 2021

Dunwich Amplification Cthulhu Fuzz - 1 knob silicon version

 Time for some doom. Recently traced by evilarsen and an odd fella who likes fuzz. Layout is verified.



 
 
 

 






28 comments:

  1. got another request for you! I saw this nice easy phaser, link at the bottom. I guess the single opamps could be replaced with a quad like lm348, which is 4 741 in the same 14 pin package. Might be interesting to try...would you do a layout of it!? Thanks in advance.
    https://electronicmusik.wordpress.com/2011/03/12/diy-vintage-phaser-pedal-1977-build-you-own/#comments

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  2. Thanks for another one-knobber fuzz. Always looking out for the best and I really like it. Sits somewhere between a meatheat and ritual in my opinion and I think I like it better than both after a quick test--time will tell. A few subs for me: 910 instead of 845 resistor, 680pf instead of 820pf and 2n4123 at 93hfe for Q4. Keep up the good work!

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  3. Am I mistaken in thinking Q4 should be 2N5088? Great work on an awesome layout, excited to build.

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    1. No, triple checked and triple checked again the label on Q4 as I thought it was 2n5088 as well with a misprint but no...the transistor clearly says 2N5008.
      Socketed a 2N5088 just for fun and it works but sounds a bit more te´trebly and and harsh.

      For comparison: one knob germanium version have a low gain PNP ge at Q4 and 3-knob hybrid version have a 2N2219A in that spot.

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    2. Interesting, I will try Si NPN at hFe around 70-90 then. Thank you for your thorough research!

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    3. Some of the Silicon versions are 2n5088 and some are 2n5008. I believe Magic was using a 2n5008 in his builds but all of my builds used a 2n5088. Yes most likely a bit more edge and harshness when you use a Q with larger hFe vs the lower hFe models that were found in different variants.

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  4. I've got another oversized layout for you when you got time, Boss DF-2 Distortion Feedbacker. I haven't seen a vero layout for this anywhere yet, I presume due to the size.

    https://www.pedalpcb.com/docs/Backfeeder.pdf

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    1. wow, thats a biggie...I'll take a look in a couple of weeks to see if is doable.

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  5. This is fairly correct, Q2 is sometimes 2n3904 in the NPN Silicon versions. Sometimes the volume control is a log pot, sometimes is a linear pot. Not a huge difference IMO.

    Interesting it took this long for someone to trace it and put it up. Its been out there for quite a number of years. Technically the first versions were called the Pyramid Fuzz but I only built maybe 4 of those before the art and name were changed. I think the very first unit was originally built for Dave in Slomatics on turret board before most of the later units were PCB.

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  6. Thanks, I thought I read 2N3904 on Q2 on a fuzz throne's pic but I was not sure. And yes, we used pics from the fuzz pyramid's pcb to trace this.

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    1. Not much difference between 2n3904 or 2n2222(a) (metal or plastic variants) in the sound I got on the pedal outside of lot to lot variations in hFe so anyone building it likely is fine either way.

      All things considered YAFF so the typical approaches work well enough.

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    2. Oh man, thanks for stopping by and give us insight about your circuits! Mucho appreciated!Big fan of your fuzzes. Played Cthulhu, Volt Thrower and Fuzz throne in the past and they were all top notch!

      I realize that you might not want to shed too much light on your designs but I'm in the end of the process of tracing Hybrid 3 knob Cthulhu, Fuzz Throne and I'm starting on Volt Thrower.

      Got schematics drawn up and I somehow got your emails attached with your posts...mind if I post them to you? I totally understand if you want at least some privacy regarding your designs and let us do some more work.;-)

      Cheers
      /
      Anders

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    3. I can't exactly stop people from tracing stuff but I will leave the hard work up to you folks.
      I am basically retired from building but Magic Pedals carries on the legacy of building all my Dunwich designs. So out of respect for Magic I can't help you with the traces since he still designs and builds them.

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    4. Cool beans!
      Don't mind workin'. :-)

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  7. Great sounding fuzz. swapped Q4 for a Russian NPN diggin it! Fuzzhead you have done amazing work, thanks for your efforts. Dunwich pedals are what got me started building pedals years ago!

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  8. How are Q2 & Q3 working? It still produces sound if I remove either of them. Missing Q2 sounds duller, but removing Q3 sounds the same.

    It sounds great though, thanks to all involved.

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    1. I don't know how Q2 & Q3 works, they "just" paired. As you, missing Q2 sounds badder but missing Q3 sound good but less gain. We think Q3 could be optional, on some version of hybrid Cthulhu Q2 is an NPN germanium and there's no Q3. Depending taste of owner with some slots we have a many possibility's fuzz.

      Cheers

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    2. I can test today with Q1: 2N2219A, Q2: 2N1306, Q3: Nothing, Q4: 2N2219A. Sound really great.

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  9. Q2 and Q3 were more to mess with people. Q3 is probably not "on" very much because the base emitter junction forward voltage for Q2 is likely 0.6-0.7V and that voltage is fixed for the circuit. Most likely that is not large enough to meet VGS(th) for Q3,

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  10. mine has a choked sound not at all similar to the original one, who works which transistor did you use? the sound improves a little by drastically decreasing the resistance from 27k with a 2k it improves but it is always choked

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  11. If i wanted to make this have a little more low end, would you think i should start with the 15nf caps and the 100k resistor?

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    1. I think it is enough to raise the 15nF caps (which is 30nF since they are parallel).

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  12. many thanks, ill mess around with it!

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  13. I couldn't get this one to work. It sounded weak and splattered a lot. After reading the comments here I took the step to pull out the BS170 (q3) and Boom, or should I say DOOM, the beast roared.

    Great sounding fuzz. This fella was boxed up and on my board quick sharp.

    Nice one!

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  14. How would this sound on bass and would it be wise to change the 15nf parallel to say two 470nf?

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  15. Built this today. It's a badass one knobber for sure. I used a germanium MP11 for Q4 and I'm really happy with the sound. Very crushing.

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  16. I'm a bit late to the party on this one, but just finished building this tonight. It was gating really bad and the volume was very low, like others have mentioned on here I pulled out the BS170 and it roared to life. Great, simple, one-knob doom machine, I'll be boxing a keeping this one for sure!

    ...Oh I didn't have a 5088 or a 5008, so I used a 2n304 instead. It did the trick!

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