Silicon Buzzaround

[mac]

This is my silicon version of the Burns Buzzaround.
A bit more complicated to bias than a silicon Tone Bender 3Knob because Sustain and Balance controls change bias.
I used MPSA42 transistors, cheap and low hfe, 130 to 150.
The modifications are,

- Added R11 to feed the base. It should be between 100k to 150k if hfe is as noted above.
- Decreased R7 from 27K (24k) to 4k7.
- Changed Sustain pot to 250kA, but 100kA can be used too. Since silicons have higher Vbe, I had to include R10 to keep the base above gnd. It sounds bad below 33k to 47k. Can be omitted.
* R7, R11 and R10 are critical at low values of Sustain and Balance pots.
- Silicon transistor, silicon diode
- Used the TB 3K tone control to have the same volume when you go from high to low,
changed C6 to 4n7, and included an optional cap C7 to tame highs.
- Added a Volume pot since the Balance pot is more like a Texture pot, but can be omitted.

The schematic,


Yes, that thing that looks like a pot is a Spice symbol that works as a pot

A sound clip,
Guitar to breaboard to clean Laney LC30II HH
Mic to Dell Mini
4 riffs at different settings,
- Sustain 2, Balance 2
- Sustain 2, Balance 5
- Sustain 6, Balance 2
- Sustain 6, Balance 5
Tone at 5
https://drive.google.com/file/d/1eS8eyCtvNb9sW4TPFWR3NJVCuDyrbkkP/view?usp=drive_link

mac

[digi2t]

Wow! Interesting.

I'll try to breadboard this when I have some time. I would like to a/b this with the Buzzicon. Samples sound cool.

[Gus]

Looks interesting

[Kipper4]

Yerrrrrr nice Mac.
Thanks add to list.

[bifbangpow]

I just finished building a buzzaround clone from a kit because i couldn't find a buzzaround circuit board layout. 
I freaking love the way yours sounds though. Wow. Great mods!

[mac]

I tried BD237 of similar gain but much higher internal capacitance.
Like TB 3k it can get ear-piercing at max Sustain and Tone after 5-6. BD237s tame highs better than MPSA42, 2N2222/18 or 2N2369.
C2 could be decreased or removed with these transistors.

mac

[bmsiddall]

*bump*. Mac, are you able to repost the schematic? I'm obviously a latecomer to this thread 

[mac]

mac

[GibsonGM]

Thanks, Mac - do you have a new sound clip by any chance?

[mac]

Thanks, Mac - do you have a new sound clip by any chance?

No new one, but the old one well hidden in usb drive :-)

mac

[mac]

I could modify the first post --> updated links to schematic and sound clip.

mac

[GibsonGM]

I'd like to hear it if you can re-link, but no worries if not! 

[mac]

I'd like to hear it if you can re-link, but no worries if not! 

https://drive.google.com/file/d/1eS8eyCtvNb9sW4TPFWR3NJVCuDyrbkkP/view?usp=drive_link

Now we can modify old posts and re-link missing images and sound clips 

mac

[GibsonGM]

Thanks Mac, that was cool!  It reminds me of the better parts of a Fender Blender, in a way   

[antonis]

Nice job, Marcelo..!!

P.S.
I'd try to connect R5 lower leg to Q2 Emitter and tweak its value..
(about 6k8 to preserve Q1 particular gain, lower to get a bit higher gain and higher to get a bit lower gain..)

[mac]

P.S.
I'd try to connect R5 lower leg to Q2 Emitter and tweak its value..
(about 6k8 to preserve Q1 particular gain, lower to get a bit higher gain and higher to get a bit lower gain..)

Reminds me of my post on B to E resistors in power darlingtons, and Vox VBM1 too.

mac

[bmsiddall]

Many thanks!