Sunday, 17 August 2014

Resonant Electronics Acceleron Fuzz

This is a really great sounding fuzz and definitely something different from the norm, so props to Resonant Electronic Design.  You'll notice on the layout there's a cap marked ??? and as you can probably guess the guy who did the trace didn't get the value of that one.  Looking at it though I suspect is may be a 2u2 poly cap because it is next to a 1u poly cap on the board but is physically larger.  I would definitely suggest socketing that one to test, but I think 2u2 is the value I'd try first.  The polarised 1u and 10u caps in this are tantalum and the 470u at the bottom left is rated at 6.3V which should allow you to keep the dimensions down for that one.  The 470u cap in the centre is the main supply filter cap and so will need to be rated sufficiently for the supply you intend to put in it, but if you're using 9V then a 10V cap should be fine as the series reverse polarity protection diode will be shaving around 0.7V off the voltage anyway.  Thanks to skywise for the pics and trace and mmolteratx for the scheme.

Info about the original:
Most guitar players either love or hate fuzz pedals. We found ourselves on the fence. We love the classic tones of Fuzz Faces, Tonebenders, Big Muffs, and other early fuzz designs, but many of them are prone to splatty, overly-compressed sounds when set to anything but the optimal settings. Modern fuzzes can do some amazing tricks and can produce some unique tones, but often they are one-trick-ponies relegated to the bridge of a song, random use during late-night jams.

We wanted to design a fuzz pedal that could do it all and never sound out-of-control or unusable. The task was to create a circuit that could produce vintage fuzz style tones, explosion-esque modern-fuzz-style tones, and everything in between - all without ever getting overly noisy or misbehaving. It took some serious tinkering and an entirely new approach to fuzz circuits, but we did it. This thing will roar, scream, and sing - all at the turn of a knob, and it will never let you down by being unpredictable or unusable.

Just like all of our Field Effects pedals, the Acceleron Fuzz uses a discrete Class A topology and is built with audiophile grade components. This is the fuzz that will replace a pedal board full of other fuzz pedals.








40 comments:

  1. I sense a building frenzy beginning...

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  2. Replies
    1. I thought you would like this one :o)

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  3. Oh man, now I really want to build this just to have it. But I've always had bad luck with vero. Been thinking about only paying for fabbed pcbs... Any vero specific tips for a successful build?

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    1. I know things are easier with a PCB and when the boards are marked up you just can't go wrong, so vero may require a little more thinking about. But when it comes to the actual soldering process I think vero is much easier and more forgiving with the big robust tracks instead of the (sometimes) little pads. Sometimes maybe people try out something complex on vero because they can't find a PCB and if it doesn't work correctly straight away it can put you off. But it's like everything, if you're careful and check things you should have no problems.

      This isn't a particularly big circuit and as it's now verified I don't think it will give you too many problems, but if you do have any issues we will help you solve them. Just carefully check cuts and link along with values and placing before soldering

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    2. Sounds like a good reminder!

      Do you ever run into bad vero boards that don't electrically connect properly on some rows? I built a taptation circuit on some vero from Tayda (layout from diysb), and it just isn't working properly, I've double checked parts and polarity and everything... I have another one to build, so thinking about using my Mammoth vero this time.

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    3. never had that happen, check all your rows with the continuity tester on your multimeter, then you`ll know for sure if the vero is the culprit

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  4. You can verify this one! I used MPSA13's instead of the 14s... It sounds great! Thanks for the layout!

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    1. Awesome, you're a star, thanks for verifying.

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  5. Also I socketed the mystery cap and used a 2u2 electro. And I had to flip the MPSA 13's 180 degrees to get the circuit to work.

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  6. Thanks for the tips! Did you put the 2u2 pos on Sw1?

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    1. Hello Mark. Hope the U.K. is OK.
      Rainy here.
      Would it be difficult to put a pot in place of the on/off/on switch?
      i.e. Can you tell me how?
      jeff

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    2. oooouuu man, liking this one too much! Adding it to the list WOOT
      thanks!

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    3. Resonant effects builder on FSB said
      "I mentioned this in the Manifold drive thread, but finding 5457's with the right characteristics is critical to getting these pedals to sound right. It surprised me initially, because the transistors test virtually identically, but in circuit there are very noticeable differences."
      Any tips on selecting proper 5457s or just socket and try out several?

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    4. Hi Jeff, weather has been crap here for a few weeks now, I think our summer is probably over now :( Omit the Sw1, Sw2 & Sw3 wires, omit the cut between Sw1 & Sw2 and make a small link from the collector of Q5 to the row directly below it. Then use a 100K linear pot, Sw4 to lug 1, Sw5 to lug 2, Sw6 to lug 3. That will sweep between one selection of the switch at one end of the rotation and the other selection at the other end and you will no longer get the centre "off" position. I'm not sure how useful this will be though, it depends how different the upper and lower switch position are to how useful the sweep is going to be.

      Hi Leo, I've no idea so it'll be a case of try what you have and see what you think about the results.

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    5. I have about 50 fairchild 5457's to sort through and I will let my ears decide... LOL
      Thanks again Mark!
      Oh btw... I am in Texas and I think last week we finally started Summer... getting 97ºF - 100º F temps now... blaaaa

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    6. Well it certainly isn't as hot as that now. Hopefully we'll get a little more sun before our 9 month winter starts :o)

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  7. Can someone post voltage from Q1's drain from a working build?

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  8. Just checked the demo for the first time. Joe Walsh riff is very impressive :) Wonder if i've sold all my Walsh solo records already...
    +m

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  9. I just got this one built up today, sounds very good! For the paint-by-numbers folks like myself: the icons for Q2 and Q5 (MPSA14's) are backwards. The pinouts, however, are written correctly so double-check those if you're having trouble. As I mentioned, the sound is great. I haven't tried out a range of 5457's yet to see if there's any difference. On my build the middle switch setting is extremely loud, has anyone else noticed that? Thanks again for the great layout!

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    1. Thanks for the heads up, I had the orientation wrong in my notes that I refer to

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  10. Yikes ....... have you seen the gain of those MPSA14's !!!!

    As a Darlington it's listed in the data-sheet with an Hfe of 10 to 20,000 ......... ouch.

    Popov

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  11. I am a little confused about the DPDT switch numbering, does it go across or top to bottom along each side, I have seen it marked both ways on the internet.

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    1. http://mirosol.kapsi.fi/varasto/boxes_other/pots_switches.png
      +m

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  12. Hello there!!
    I built this pedal. Im getting a signal but im pretty sure I've got the switch wired wrong. The middle position getting some fuzz but with a lot of other unwanted signal. The other positions there is no signal. On the swithch I have I wired it: Thanx so much :)
    1 4
    2 5
    3 6

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  13. Ok, sorry just saw the last post about switches...Any ideas?

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  14. Got this thing going! Didn't read the fuzz to ground and the volume to ground. It is funny every time I have run into problems with these builds I find it is something simple that I have overlooked. BTW a really good sounding fuzz! I want to give a big thanks to u all...

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  15. Hi I made a fuzz according to your scheme but when I turn fuzz knob all the way left to the volume stops working and when I turn it all the way to the right Im not getting the needed drive. Can you please tell me which transistor affects the gain? thanks

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  16. At last got this working. Built with BF244A as i was down to my last two 2N5457s, watching the pinout, and just couldn't get it working. Thought i had a bad solder or something. Finally thought to change to J201s and suddenly working like a dream. Really nice fuzz!

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  17. what is resistors are 1K87, 49R9, 47K5?

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    1. Futurlec has the exact values for these resistors. 20 cents each.
      I was very surprised. I use Tayda. Nothing there. Futurlec has all kinds of wild fractional values.

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    2. I's still go with 1K8, 47R (or 50R) and 47K for those.
      +m

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  18. Can a tantalum cap be used for the ??? 2.2 value and if so, how to orient it.

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    1. Check the schematic. In switch position down, the cap connects from Q5 collector to Q6 gate. There is definitely higher voltage at Q5 collector, so negative up (connects to switch 4).
      +m

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  19. I don't uderstand the offboard wiring about output and DPDT switch, can someone help me?

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