Saturday, 1 April 2017

21st Century Big Muff

Mictester's version of the Big Muff.
You can find the original FSB thread and schematic here.
I've used the updated schematic on page 2.

14 comments:

  1. Needed something to build today, so gave this a go. Tag it verified! This is one badass muff variant. Really great pedal. Transistor pin outs are the wrong way round which didn't take long to figure out thankfully. Mine seems to take a few seconds to fire up but when it does WOW! Thanks as always Alex and all those great guys on FSB.

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    1. Good Lord Gavin! That was quick! Do you mean the transistors Emitters and Collectors should be inverted?

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    2. Yes, Emmitters and collectors should be inverted. I couldn't resist as i do like a good big muff.

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    3. I'm not sure. That would connect the 6K8 resistors to the Emitters instead of the Collectors. Have you checked the pinout of your transistors?

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    4. Sorry, my mistake i seemed to have them the same orientation as the layout. Think i'm starting to loose it.

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  2. What's up with the 4 gain lugs going to 9v. I have never seen that before. Does that make the distortion better or does it make it have more gain. Would this be a high gain pedal.

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    1. The switch changes the resistors used to connect the transistors' collectors to the 9 volt supply.


      This is what the designer of the circuit said on the forum post :

      "I revisited this circuit over the last few days. It occurred to me that one of the biggest changes that you can make to the clippers in a Big Muff if to vary the collector resistors (try 4k7 or 5k6 all you "low gain" freaks and prepare to be pleasantly surprised!). I had a supply of 100k dual log pots (used in my mixers), and decided to try making the collector resistors for the clippers variable. My first attempt tried using a single pot (I'm cheap like that) but it wasn't terribly good. Going for the dual pot, wired as two variable resistors is amazing - it goes from less than the usual Big Muff tones right up to an uncontrollable screaming monster!"


      And yeah, it would be a pretty high gain pedal. It's a big muff, after all.

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    2. Thanks for the info got it now.

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  3. This comment has been removed by the author.

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  4. There ist never enough muff, got to try it.another one for the list!

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  5. Thanks Alex! Since I requested this, I'll have to try building your layout. As you mentioned in the post, there's a nice FSB thread on this muff variant - definitely a cool take on a well-known circuit.

    As for the transistor dual pot gain control, I would probably consider using a DPDT switch to flip between a low gain mode and the standard mode with fixed resistors (standard mode has collector resistances of 12K for Q1 and 22K for Q2, according to an older schematic in the thread). The switch would be wired where the Gains 1 and Gains 4 control wires are on the layout.

    "There ist never enough muff..." Comment of the day :)

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  6. What would happen if a 500k dual pot was used for Gains instead of 100k pot? (Asking because I happen to have a 500kA pot collecting dust.) Also, are there any recordings yet?

    Thanks for all you do. Love the sight!

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    1. You would need to add a 56K resistor across lugs 1 & 3 and another one across lugs 4 & 6.

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  7. So.. 50k (layout) or 100k (as it seems here in the comments) for gains?! :D

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