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Saturday, 8 February 2014

Monolith Fuzz Oracle

This is a nice aggressive sounding fuzz.  The switch on the original is a push pull on the Color pot and so you can either do the same and get a 250K switched pot, or alternatively just use a DPDT 2 position toggle.

Info from Monolith Fuzz about the original:

The Oracle Fuzz is my original twist on the fuzztone "in my head"... Imagine an Italian made Vox Tonebender (2 transistor MK 1.5 circuit) with all of it's lovely midrange-heavy goodness mixed with the throaty low "huumphh" of an early Big Muff, and you're getting warm. 






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40 comments:

  1. Andrea Giovanetti8 February 2014 at 16:01

    An OC76 usually have the Hfe from 30 to 70/80, the Hfe is a little high for OC75 too

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    1. IvIark8 February 2014 at 16:10

      They were measured from an original

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    2. IvIark8 February 2014 at 16:15

      Not that you have to get exactly that level of gain of course, and you could try any other type of germanium transistor too. I have some Russian GT402's and whilst they don't get up to 300hfe, there were some around 200 which may still be good in this.

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  2. Afonso8 February 2014 at 18:56

    can I use some ac128 or oc44 on this?

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    1. IvIark8 February 2014 at 19:05

      You can try any PNP germanium transistor. I'd recommend socketing them so you can audition a few different ones so you can choose your favourite combination

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  3. JaviCAP8 February 2014 at 18:58

    Tag it, Mark :P Sounds great with a 2N404 110hfe as q1 and a 2BS187-7 205 hfe as q2. Will have to check with different hfe's as I think that I have some very high gain germaniums (about 350) at any place.

    Colour is not very sensitive, Density is a great control, lots of different sounds as you turn the knob.

    Surely this one will get boxed (1590A, of course)

    J.

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    1. IvIark8 February 2014 at 19:05

      Awesome, thanks Javi! :o)

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    2. JaviCAP8 February 2014 at 19:32

      Just to note, that Q1 is fliped 180 degrees, collector shoud be up :)

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    3. IvIark8 February 2014 at 19:34

      It shouldn't mate. They're PNP so its emitter to supply

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    4. IvIark8 February 2014 at 19:37

      Here's the schematic mate http://i76.photobucket.com/albums/j6/IvIark_2006/Layouts/Schematics/Monolith-Oracle-Schematic.gif~original

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    5. JaviCAP8 February 2014 at 19:44

      Sorry, I was reading wrong the schemtics, it's Ok as it appears

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    6. JaviCAP8 February 2014 at 19:55

      Yeah, I still have problems when dealing with PNP :P I still remember my PNP trannies exploding on the Soul Bender :P

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    7. JaviCAP9 February 2014 at 00:34

      I've tried the highest hfe germanium that I have, an AC184, rated 295. The result is even better than before.

      Sadly, I'm afraid that so high gain trannies are not common at all. Have never seen an OC75 over 120hfe, so don't know where the builder could find a lot to build this model.

      Well, now we know were we can use this rare high gain germaniums. Truly is a great fuzz, you won't regret if you build it!

      J.

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    8. IvIark9 February 2014 at 11:40

      Thanks for the info, I'll have to keep a look out for something high gain

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  4. Doron Barness8 February 2014 at 19:52

    Great little circuit. Looks very interesting.

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  5. tom k8 February 2014 at 22:34

    Cute fuzz face design.

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  6. Travis8 February 2014 at 22:36

    This seems cool to me for two reasons.

    It gives me something to do with some really high gain germs I have, and I like the was the PNPs are flipped in a positive ground circuit like the Fuzz Factory

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  7. Travis8 February 2014 at 22:37

    negative ground*

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  8. johnk9 February 2014 at 07:16

    IME, the gain works better with reverse log 1 meg pot.

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  9. Alex9 February 2014 at 11:03

    Hi John.
    Sorry for the unrelated question but would it be possible to get a layout for you Fat-Tone Junior?
    Thanks

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  10. boratto11 February 2014 at 10:21

    a silly quetion, what is the 3rd pot on the pedal at the video?

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    1. IvIark11 February 2014 at 10:37

      There's 3 pots, Density, Color and Output (volume pot)

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  11. boratto11 February 2014 at 11:00

    Thank you Mark now i understand that!

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  12. boratto24 March 2014 at 02:59

    This comment has been removed by the author.

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  13. Unknown13 April 2014 at 09:55

    hi, i built it & it sounds fine. Vol & Color work ok. But DENSITY only works at the last quarter of the 1M-Pot. Had same problem with Meathead de luxe. Anyone got an idea how to fix it?

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    1. IvIark13 April 2014 at 11:54

      The taper of a reverse log pot would increase the resistance much sooner in the pot's rotation so I'd suggest trying that instead

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  14. Manasu14 April 2014 at 18:57

    Could someone explain the pot wiring?
    I don't get the "density" and "color" explanation on the left, while I cant figure what's "color 2".

    Seems like a sick pedal.

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  15. Gnarly Head10 July 2014 at 21:40

    I just built this pedal in a 1590B enclosure. Cramped, but everything fit. I used a pair of TK3055 germanium PNPs, measuring around 300hfe each.

    When I plug the pedal in using my 1 Spot, there is a LOUD annoying hiss. At the lowest output setting, the hiss is unbearable. There's plenty of nice fuzz when I play, but this hiss makes the pedal unusable...

    Now, seeing as I built it in a 1590B, I had no room to put a battery. But, on a whim, I clipped a battery into the circuit with the bottom off, and voila! No hiss. Just fuzz. Plug the 1 Spot back in, hiss city. I'm gonna wire up a 9V snap to a 2.1mm barrel connector so I can run an external battery for now, but I'd like a more permanent solution and be able to run this off my power supply (I really hate batteries).

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    1. johnk10 July 2014 at 21:55

      you might try adding a 10R resistor in series to the 9V with a 100uf like this to see if it helps:

      http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/Monolith/9V_filter.png

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    2. Gnarly Head10 July 2014 at 22:29

      Thanks! I'll try that out. I gotta wait till tomorrow to hit the parts store so I can grab a 100uf cap. I'm also gonna try out the pedal with a bunch of other power supplies tomorrow at the music shop I work at, see if anything sounds better. I also noticed that my 1 Spot started humming (used to be whisper quiet).

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  16. poppy25 March 2015 at 14:05

    It's a bit silly to ask but is this one wired as a positive ground effect like a PNP fuzzface for example?

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  17. Unknown17 May 2015 at 12:09

    Built it with OC1075 trannys and worked like a charm, great sounding Fuzz.

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  18. Hozy316 June 2015 at 18:57

    Built this using OC602s and its really good but sound fizzles out pretty fast on the higher strings i presume its because these only have an hfe of 20 to 30. These were my only Ge PNPs i had left. However, could be that i had no B250ks so used a B220k instead. Will buy some others Ge PNPs and buy the appropriate pot and check the difference. May post back soonish with results.

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    1. Zach6 June 2015 at 19:15

      those gains are way too low for this. i'm not sure about anyone else's build, but i found that as long as you've got at least 80hfe it should sound good. currently both q1 & q2 have gains of approx 100hfe. i've also had them a set in there that was about 100hfe for q1 and about 300hfe for q2 like the original. that sounded good, but the lower gain set is a little darker and warmer, which is more of what i like.

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  19. Unknown4 January 2016 at 13:27

    What does the 47pF capacitor at the Density Pot? More Noise? ;)

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  20. Unknown25 March 2017 at 03:27

    This comment has been removed by the author.

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    1. Unknown25 March 2017 at 03:29

      what is correct 4.7pf or 47pf, turret board layout from has 4.7pf and yours has 47pf

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  21. Mulekicker30 November 2017 at 13:25

    Built this yesterday. Sounds killer. I used a 1kc for density and 2 Japanese 2sb176's. HFE's were 136 and 167. Gonna order a higher gain tranny from small bear for q2 and see what happens but it sounds really good as is.

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  22. Squirrels15 August 2019 at 00:12

    I’ve had a love/hate relationship with this little bastard for years. Between different transistors with different gains and building and rebuilding I love how heavy it gets and works with my OR15 but the noise always made me scrap it. For whatever reason I never tried a battery in it until recently and wouldn’t you know, the noise is gone. I built a Huminator and now even with a One Spot, no noise. I also just realized that it works just as well behind a buffer too. I got my hands on an OC42 (112 hFe) and a black glass OC42 (245 hFe) and it’s one of the heaviest fuzzes I’ve built. The best part about this fuzz is that it sounds great with lower gain transistors too.

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