Thanksgiving Week Madness - Gnat (Buzzaround) + Super 64 (Superbolt) in one

coltonius

Well-known member
As a teacher, this year has been incredibly busy for me. I've scarcely had time to build anything since school began back in August/September. It was such a relief to finally finish this build which I had planned out literally months ago!

Right side = Burns Buzzaround
Left side = JHS Superbolt

Enclosure by Monarch Enclosures (find them on Instagram or Etsy)

They both sound great individually and make for a really sweet 'lead' tone when stacked. Settings are really amp dependent.

Gnat:
I like to run the Balance (Bias) around 9-10 with the Timbre and Sustain around 1 or 2. The transistors were sourced from Small Bear from their pre-measured section, and they make for a relatively smooth sounding Buzzy. It's not entirely smooth, mind, just smoother than some of the others I have by Function F(x), Monsterpiece, and Collector Effectors. Yes I have a problem. Shut up. If I do this build again, I'll likely do a 'socket and swap' to see if I can't coax some more gating and raunch out of the circuit.

Superbolt:
Another circuit I have an addiction to. I have a V2 by JHS but find the form factor somewhat limiting for what you get.. Using the 'original' as a guideline I found in a different Superbolt build (told you..) that the 120k low gain resistor didn't affect much change between the High/Low settings. It's obviously a very marked and distinct change on the JHS version, so I tweaked resistors until I landed on 39k for that build. For this build I installed a 33k minimum resistor and a 100k trimmer using PedalPCB's adaptor so I could dial it in more precisely.. And indeed I found the ideal low gain setting to be around 39k.

Without further ado.. The photos:

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BONUS! I also had time to build some Rotoclones (based on the PTD Rotobone) for a handful of people this week. Enjoy some handmade sonic farts!
- 11 position X and Y input/output capacitors
- GeSi option (CV7007, 2N404, etc... whatever fit best)
- "standard" Bosstone tones all the way up to blown out lower octave / horn and bone tones!

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Awesome wild stuff, great builds.
Now what's a Rotobone... I just googled it and found Paul Trombetta pedals if that's the ones. What is it based on and lots of switchable caps obviously.
Any links to a schematic?
 
Awesome wild stuff, great builds.
Now what's a Rotobone... I just googled it and found Paul Trombetta pedals if that's the ones. What is it based on and lots of switchable caps obviously.
Any links to a schematic?
I've never played an original Trombetta Rotobone, only a Mini Bone- but someone asked me to take a crack at it because they didn't want to pay $1,000 to buy an original.. It was meant to be a one-off deal but I keep getting requests to make more! You can find details on the distilled version (Mini Bone / Bone Machine) in PedalPCB's Trumpeter build doc. Essentially, it's a mega tricked out Jordan Bosstone.

The two rotaries are for Input / Output capacitors, which affect so much more than the circuit's EQ. Tweaking the values can induce oscillation and lower octaves (trombone / horn tones), which can be further tweaked by the Mood (Bias) knob. The original Rotobone uses 6 positions but I chose to use 11 since I don't know the exact values (the original circuit is gooped).

The far-left toggle is called "GeSi" because it switches Q2 from Silicon (stock) to Germanium (for a warmer / different sound). I've found the best results from Ge trannies with an HFE of about 170-190 and relatively low leakage.

The toggle next to it sets the range of the Mood (Bias) knob from high to low, just like in the Trumpeter build doc!
 
Excellent, thanks! Now the input cap selector is obviously C 1 different values from 10nF up to large ones 1 uF andmore? Similar with output cap C 4 I guess?
What silicon PNP did you end up using for Q 2?
Cheers again!
 
Excellent, thanks! Now the input cap selector is obviously C 1 different values from 10nF up to large ones 1 uF andmore? Similar with output cap C 4 I guess?
What silicon PNP did you end up using for Q 2?
Cheers again!
The Input rotary (Y) starts at 4n7 and incrementally works up to 1uf, while the Output rotary (X) starts at 10n and works up to 2.2uf. I stuck to the "usual" incremental values (10n, 22n, 33n, etc..) and avoided any wacky values (12n, 39n, etc...) to make things as simple as possible.

For Q2 I used a 2N2907a!
 
Thanks for your great Information! Do you have a wiring diagram, especially for the GeSi switch, so I could add it to a build using the Trumpeter pcb? I‘ve got some AC 128s I‘d like to use.
 
Thanks for your great Information! Do you have a wiring diagram, especially for the GeSi switch, so I could add it to a build using the Trumpeter pcb? I‘ve got some AC 128s I‘d like to use.
Sorry for the delayed response.. The Collectors of both Q2 options (Ge and Si) are wired to ground. The Base and Emitters are then wired to a DPDT on/on toggle. For example:

1 4
2 5
3 6

Lug 1 = Silicon Base
Lug 2 = Base on the PCB
Lug 3 = Germanium Base

Lug 4 = Silicon Emitter
Lug 5 = Emitter on PCB
Lug 6 = Germanium Emitter
 
Hi @coltonius.

First...all three builds look very cool and I'm definitely inspired!

I just had someone ask me to put together a Mini-Bone/Trumpeter with options to fiddle with various components (such as the input and output capacitors as you have done here). Can you please confirm if I have this correct: the first rotary switch chooses options for C1 on the Trumpeter schematic and the second rotary switch replaces the SPDT (on/off/on) so that you can choose more than the two caps (C6 and C7) on the Trumpeter schematic?

Any other changes (aside from the Si/Ge switch) that you did (or that you might recommend now that you've got some of these builds under your belt)?
 
Hi @coltonius.

First...all three builds look very cool and I'm definitely inspired!

I just had someone ask me to put together a Mini-Bone/Trumpeter with options to fiddle with various components (such as the input and output capacitors as you have done here). Can you please confirm if I have this correct: the first rotary switch chooses options for C1 on the Trumpeter schematic and the second rotary switch replaces the SPDT (on/off/on) so that you can choose more than the two caps (C6 and C7) on the Trumpeter schematic?

Any other changes (aside from the Si/Ge switch) that you did (or that you might recommend now that you've got some of these builds under your belt)?
It sounds like you've done it right with the caps!

- C1 = Y rotary
- Jumper lugs 1 and 2 of the Bone knob, use C5 as the X rotary
- I also included a "high / low gain" toggle by wiring the Emitter of Q1 to a toggle that switches between ground and a 4.7k resistor to ground. (This is a completely made up guess, I have no idea how Trombetta does it on his own builds.. However it sounds pretty damn good!)
 
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Thanks @coltonius, I appreciate the response.

So it sounds like you used the X rotary to select cap options in place of C4 and C5 on the Trumpeter schematic...does that mean you left the on/off/on switch in place to choose between C6, C7, and no cap at all?
 
Thanks @coltonius, I appreciate the response.

So it sounds like you used the X rotary to select cap options in place of C4 and C5 on the Trumpeter schematic...does that mean you left the on/off/on switch in place to choose between C6, C7, and no cap at all?
I left off the toggle and those caps. It's pretty much worthless in its stock form anyway.. On my Mini Bone builds where I've included it, I've always opted for larger values so I can actually hear a difference. Just don't ask what those values are or you'll make me a liar! It's been so long that I've forgotten.
 
I left off the toggle and those caps. It's pretty much worthless in its stock form anyway.. On my Mini Bone builds where I've included it, I've always opted for larger values so I can actually hear a difference. Just don't ask what those values are or you'll make me a liar! It's been so long that I've forgotten.

:ROFLMAO: That's funny...I'll let you save face and avoid asking...;)

Huge thanks for sharing the other details though. I'm pretty sure I'll build a stock Trumpeter at some point but, for now, this is a huge help for me in terms of trying to put together a DIY "Rotobone" for a friend.
 
The Input rotary (Y) starts at 4n7 and incrementally works up to 1uf, while the Output rotary (X) starts at 10n and works up to 2.2uf. I stuck to the "usual" incremental values (10n, 22n, 33n, etc..) and avoided any wacky values (12n, 39n, etc...) to make things as simple as possible.

For Q2 I used a 2N2907a!
Rotary 1 is for C1 and rotary 2 is for C6,C7. Is this correct?
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Rotary 1 is for C1 and rotary 2 is for C6,C7. Is this correct?
View attachment 39019
No, I deleted C6 and C7 since they're largely useless. Rotary 1 is C1, just like you said. Rotary 2 takes the place of C4/C5/Bone knob.

Bonus: I've also implemented a High/Low Gain toggle by placing a 4.7k resistor between the Q1 emitter and ground. Stock (Emitter > Ground) is high gain. Emitter > 4.7k > Ground is low gain.
 
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