Thursday, 14 March 2019

Anta Fuzz

First post of the new year. This comes from a request posted in the forum. Not much I could find about this other than it's a Fuzz Face derivative made in the 70's in the USSR.


47 comments:

  1. Welcome back, Zach! Thanks for the post.

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  2. Yeah second that welcome back ✌

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  3. Just what the doctor ordered, a simple quick build for boredom!

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    2. All ready for testing and then I realise it's MINUS 9 volts and I don't have the pre-requisite power supply or the IC to build an inverter... D'oh!

      Oh well, I've been meaning to build a voltage inverter and need to order some other parts anyway. :D

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    3. You could use a 9V battery...

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    4. For a negative voltage?

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    5. Black battery wire to 9v and red battery wire to ring lug of (stereo) input jack.

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  4. Any suggestions for a KT349 replacement? I couldn't find any for sale and precious little information about its specifications.

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    1. From what I found theirs 3 different versions of those transistors. Since this is a Fuzz Face derivative you should be able to throw any PNP transistors you’d use for a Si Fuzz Face without issue.

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    2. actually, it may be a challenge: http://www.5v.ru/ds/trnz/kt349.htm
      if you look at the table there are three version of these. Most important column is h21–≠ i believe. Markings on originals are usually just colored dots.

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    3. If you look at the gains for each of the transistors you’ll see KT349A 20-80hfe, KT349B 40-160hfe, and KT349C 120-330hfe. This is similar to what you’d expect from other transistors commonly used in fuzzfaces like BC108. The letter designates it’s gain ranges when they were sorted by the factory (low, medium, high) while those without a letter were unsorted and could be within any of the ranges.

      Again, since this is a fuzz face based circuit I would expect that any pair that would would throw into a regular fuzz face to he fine here. So expect the differences you’d find if you put a high gain set vs a low gain vs “grail” pair.

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    4. Under challenge I mean its not clear what exact transistor modification was used. Originals become unobtanium because of golden-covered legs - most of them were recycled...

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    5. the original transistors are still available on eBay. really the transistor type shouldn't matter all that much being that this is a fuzz face derivative, but the gains will have an impact.

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    6. i have two BC108A?
      do you think it will works?

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    7. Only if you reverse the polarity of the circuit. To build it as is you need PNP transistors.

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  5. Could you reverse polarity of caps and put npn w/out problem? Use whatever npns you want?

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  6. That will work.

    With that output cap I imagine it has a ton on low end.

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    1. I’d try it out. I like 100nf output caps like in the Fulltone ‘69 personally.

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  7. So you would lower the output cap? What would be a reasonable cap value?

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  8. yyyeeeeaaah
    glad that the blog lives!

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  9. just found a demo of original for curious people https://youtu.be/AUBY1q8pJfM?t=67

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  10. Zach, there is a typo: both 470K should be 47k

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  11. and input cap should be 100n instead of 1u

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  12. was able to run it with 2n2907a transistors (hfe ~300) with some small issues:
    1. it mutes if guitar volume knob at 10 - should to reduce volume;
    2. at fuzz knob at max there are some high frequencies go thru. No taming caps were used.
    will try to find less gainy tr

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  13. Here I thought everybody had run away! I'll have to try this if you can get hold of the parts!

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  14. 10u cap positive pole should be in G row.

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    1. no, why? but 10u should not be connected to q2 collector for sure - it goes thru 30k. will update my build, thanks

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  15. would still like to see a true vibrato like the vb-2 or malekko vibrato

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    2. forum->requests is your friend. vb-2 was refused by IvIark 5 years ago. Malekko vibrato is hacked small clone.

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  16. You can tag it, Zach. YAFF. Switched to 2n2145 with hfe around 160 for both (rotated at 180 degrees).
    Thanks for keeping blog alive!

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  17. sorry for flooding, but i've a got original kt349a by chance. with a stupid low hfe at 42-46 this thing sounds best! good cleanup, good articulation on the bridge. At full gain it sounds differ than FF, more on the distortion side. So, its alert for owners of very low gain GE or SI transistors. This circuit is for you. I'm not a big fan of soviet stompboxes, but this one will complement Inta Wah pedal from the same series.

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    1. Slav, did you finally remplaced 470k resistors to 47k?

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    2. yes, I did. All works fine in my build. Didn't notice that Zach omitted it. You can check schematics following link to the forum.

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  19. https://tagboardeffects.blogspot.com/2012/02/offboard-wiring.html - i have a printed copy of this on my workbench

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  20. Would a 2N3906 work for this?

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  21. it's sounds better if you remove the 6.8k resistor, even though the resistors should be 47k, not 470k,

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  22. Build with 2n2907 and works...
    Too much low noise, but noise desappears with knobs at Max, there sounds decent...

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  23. Why has this 47k not 470k resistors not been corrected?

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    2. Is 47k
      Look:

      http://guitar-fx-layouts.42897.x6.nabble.com/Anta-Fuzz-circa-1974-td45854.html

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  24. My build drops volume, any suggestion to solve the problem? thanks

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