This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Friday, May 11, 2018

KMA Fuzzly Bear

For Fuzz Friday, here's an interesting take on the Bosstone fuzz with a few value changes, extra diodes, and a voltage sag control. Schematic and discussion here. I did add a bit of a mod to this–the resistor marked "0-10k" limits the minimum setting of the drive pot. Stock, lug 1 goes directly to ground. But IMO, it's a bit better to have that limiter there, otherwise it's just another way to mute the pedal. So adjust that to taste.


16 comments:

  1. Nice compact layout! I'm the guy who drew up the strip board at the link and settled on 4.7k as a min. resistor, letting me get usable tones at lowest gain. Of course, experiment. One guy who built it reported getting octave type sounds with his neck pickup, low gain and high sag.

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    1. Oh that's cool. Don't think I've gotten octave out of my Boss Tone before.

      I actually referenced your stripboard layout in drawing this one up and liked the min resistor addition. I'm generally not a fan of gain controls that can just turn off the effect. Thanks for chiming in!

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  2. I built this one, but it sounds bad...Probably something I have goofed up somewhere, or a bad component. I used 5089's for transistors. I'll go back over it sometime later and see what I messed up.

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  3. built this again, from scratch. same result. Used BC109 and 2n3904 this time.

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    1. The really weird thing is there is a tiny (I mean TINY) sweet spot in the sag control that will send some signal thru...Like if the sag control was a 5K instead of a 50k...I actually took the sag pot out and jumped a small resistor (1k-4.7k) in there and could get some sound out. Still sounded bad, but at least it sounded like something. lol. I dunno...If I get some time I might do Alex's vero layout, but I'm trying to get my hammond skx to run thru my leslie 147 atm, so...I should really just get a life :;

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    2. Q2 needs to be a PNP transistor. Probably why its not working.

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    3. any PNP? I'll see if I have any. Any suggestions? Obviously, I know nothing about electronics....But I can solder like a beast.

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    4. I am so embarrassed. I thought 3904 was close enough to 3906...But the 04 is NPN and the 06 is PNP....Guess what I found when I dumped out my whole bin of transistors...3906's. Tag it as verified. Apparently I have an extra one already made up if someone needs it. Thanks for the heads up, Dave.

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    5. Haha it happens to the best of us. Thanks for verifying Peter!

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    6. Hopefully my dumb-assed-ness will save someone else some heartache. Thanks again for the help today, and all of your great layouts!

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  4. Great Fuzz. But I use B150K as Sag

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  5. Built it, the only thing that came trough the amp was a very weak signal very distorted, changed the diodes and the transistors and again the same result.

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  6. Mine works nicely but I feel it sounds a bit thin. At least it's not as fat sounding as in the demo videos, so I'm wondering what hfe values you guys used...? I have a BC109C and a 2N3906. The BC has quite high hfe (around 480) and the 2n3906 has something around 150 I think. And I've used a 220n input cap instead of the 330n, but calculating the cut-off frequency of the HP-filter it forms with the 150k to GND, the 220n should be totally sufficient (4.8Hz with 220n vs 3.4Hz with 330n).
    Also the sag-control doesn't change too much in the sound.
    So maybe it's just about the transistor hfes?
    Thanks for the layout btw! Great stuff.

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  7. Hello. First of all great site. This will be my first build using your shemes. I was not able to find the image for this one on the image transfer library. Could you tell me how it should be scalled to fit the desired size? Thak you very much.

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