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. 






38 comments:

  1. 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. They were measured from an original

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    2. 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. can I use some ac128 or oc44 on this?

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    1. 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. 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. Awesome, thanks Javi! :o)

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

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

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

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

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  4. Great little circuit. Looks very interesting.

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

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

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

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  9. Thank you Mark now i understand that!

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  11. 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. 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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  12. 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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  13. 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. 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. 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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  14. 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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  15. Built it with OC1075 trannys and worked like a charm, great sounding Fuzz.

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

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

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  19. 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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  20. 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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