DIY Club Project #3: Booster + Buffer

Here’s a demo for our third DIY project: a combination clean boost and buffer.

The project files are here. For other tips, tricks, and resources, as well as all the info on our first two projects, visit the Tonefiend DIY Club page.

This is a super-useful guitar tool. You’ll learn about how to add more options to your effects via switching. You’ll also discover a) what a buffer is, and b) whether you need to care. (Answer: maybe.)

And this concludes the initial set of DIY Club Projects. Now that we’ve learned some workbench basics, the next few projects will involve poking around inside your guitars, where it’s possible to do some real damage. Until then, keep your soldering irons tinned and your smoke alarms armed!

19 comments to DIY Club Project #3: Booster + Buffer

  • el reclusa

    Hafta admit, as much as I like fuzzes and ODs, this is the one I’ve been really looking forward to…awesome!

    • joe

      Love them fuzzes to death — but this is the sort of gadget that can live permanently on your pedalboard for years. Jeez — I don’t think I’ve had an analog pedalboard without a transparent clean boost in, like, 15 years!

  • Chiller

    Maybe a stupid question, but is the pot you have wired up in the final, boxed version a volume pot like at the output of the fuzz and OD circuits? Schematic V3 doesn’t have any pots in it (other than the trim pot on the boost circuit).

  • Joel

    Would LOVE to try that on my bass…

  • Derick

    I just finished my boost pedal today then A/B compared it to my JHS Mr. Magic. This project makes a better clean boost than the JHS pedal. They are comparable when the buffer on the project pedal is off but when the buffer is on the project pedal provides more sustain and better tone than the Mr. Magic. Great build! It’s going to be on my board for a long time. Thanks!

    • joe

      Oh man, I am delighted to hear that, Derick.

      I’m curious to hear your impressions of playing through a buffer, once you get a chance to check it out. Just for laughs, try it right in front of a Fuzz Face, if you have one. It should totally destroy the sound of that pedal — one example of a “better without buffing” situation.

      • Derick

        The only fuzz I have is my modified project 2 fuzz. The booster/buffer brought more life and tone to that pedal as well as the rest. 

        • joe

          Glad to hear it. You could also try putting both circuits in a larger BB-sized box, with two footswitches. (Hint: It’ll probably sound better if the boost comes after the fuzz.)

  • Alex

    Hello Joe!

    Looking to build this next. Was wondering if there is any particular reason why the boost came before the buffer in the pedal? I was thinking of making the buffer toggle switch independent of whether the footswitch is engaged (i.e. two separate circuits housed in one pedal).

  • Alex


    Ok, so I built the pedal and I have a noob question. How would I know if the buffer is working? What is the best way of testing it? Do I need miles of cable between the guitar and the amp?

    BTW page 6 might have the definitions of source and drain mixed up.  

    • joe

      Actually, that’s a great question! But if you hear sound regardless of how the booster on/off switch is set, it’s probably working fine. (You’ll hear it go silent for a fraction of a sec while switching it on.)

      Do you have a Fuzz Face? The buffer will make it sound awful! :poop:

      • Digital Larry

        To help deal with problems introduced by running a buffer right into a Fuzz Face (or other fuzz pedal where you are running directly into a bipolar transistor’s base, even through a cap) – try a 10k resistor in series with the buffer’s output. You’ll still be buffering the previous stage from any downstream loading, while more accurately simulating a passive pickup’s resistance to the fuzz circuit. My guess is that active pickups were not common when these fuzz circuits were designed.

        Also I noticed in the project notes for the DIY Boost + Buff, on page 6 you equate BJT collector to FET source and BJT emitter to FET drain. This is backwards. It’s actually easier to remember:

        BJT collector = FET drain. Well, a drain is a collector of water right?

        BJT emitter = FET source. A source of sound, or electrons, or good will, emits those things, right?

        Sometimes FETs are drawn with the gate in the middle. I hate that! I prefer the gate to be next to the source.

        The remainder of the connection advice is correct as you indicate that the source should be connected to ground on page 7. And I appreciate your “use your ears” advice for tuning these circuits.

  • joe

    Oh man, I an SO going to try that. And the timing of your comment is perfect, because I have a big DIY Fuzz Face post in the works…details to come. 🙂

  • geeeo

    Hey I tried to make the booster part and it worked. It’s awesome! Then I tried to make another copy of the booster but now instead of boosting the volume, turns it from zero to only just a bit louder than the original sign. What might cause this??

    • joe

      Cool! I’m glad it worked for you. Your current problem is probably a bad solder joint or an incorrect part value. Use the continuity function on a multimeter (the beeper) to verify every connection, especially the ones to the transistor and to ground. Also verify that no wires are touching that shouldn’t be touching.

  • Shizmab Abaye

    I have one of these (I believe, or similar) labeled as the “Pure” pedal. I was testing some other things (delay, filter, etc) using this to buffer the guitar and noticed – it’s not really very pure at all. Then I hooked it to a scope and the smooth clipping is glorious – just not what I would call “Pure”. Cleans up well with volume knob of course.

    • Joe Gore

      I confess I don’t remember see specifically what was in the Pure pedal. But it was my best guess is that’s it’s pretty close, minus the buffer stage. It’s a simple JFET boost which does add relatively subtle harmonic distortion. It also adds some sparkly presence, and the low mids feel clarified (though I’m not sure whether that’s an actual frequency cut, or just a byproduct of more powerful highs.)

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