Mad Bean Pedals Bumblebee, Quick Start Manual

6 

The 

BumbleBee

 is a re-creation of the Baldwin Burns Buzzaround; a very rare and somewhat legendary fuzz monster. 

The Bumblebee stands apart from the Fuzz Face and Tonebender. It's not as nearly as bassy as the FF and it is capable 
of getting even more fuzz saturation than the TB (IMO). At the same time, it can be tamed quite well into some classic 
(and controlled) fuzz tones. And, the interaction with the guitar volume is absolutely excellent for dialing fuzz up and down 
on the fly. 

2015 Version 



New layout with voltage inverter incorporated onto the PCB.



Added output volume control.



Axial caps option no longer available due to the newly added parts.



Changed the Balance pot value from 5kB to 10kB for more range.



Added optional 1M pull-down resistor.

_________________________________________________________________________________________________ 

Controls 

Sustain

 – The overall fuzz amount from least to greatest. 

Balance

 – A variable bias control for Q3.  

Timbre

 – A simple tone control/capacitor blend. 

Vol

 - Output volume. 

_________________________________________________________________________________________________ 

Notes 

The 

BumbleBee

 is a 

positive ground

 effect. However, it is wired as a negative ground circuit due to the voltage inverter 

circuitry now included on the 2015 PCB. So, there is nothing special or different needed to build this circuit. 

The NKT213 is listed for the stock version of the 

BumbleBee

. These are the transistors used in the original Buzzaround. 

Unfortunately, they are very rare these days and almost impossible to find. However, you can use any matched 
Tonbender set of PNP transistors in place of the NKT213s. The OC75 is a very good replacement and offers an incredible 
fuzz tone. These are available as a matched set from smallbear. 

You can use the fancy round transistor sockets or inline sockets for Q1-Q3. The two pads in the middle are connected. 
Note that the little tab is for the emitter. 

The controls on this fuzz circuit are highly interactive. They are unusual in that the Sustain and Timbre are voltage 
dividers (the Vol control is as well but this is normal). This means when you turn them all the way down, it actually kills the 
signal. So, it takes a bit getting used to because, as guitar players, we are not accustomed to having three knobs that kill 
our riffs. We like knobs that make our riffs louder and crunchier, not puny and quiet. And, the Bumblebee certainly does 
that, too. To understand how it works think of it like this:  



The Sustain pot controls how much output signal from Q1/Q2 goes to Q3. Low settings means small signal and
vice-versa. The more signal, the more saturation. I tend to keep this under half-way up. After that it gets very
unruly!



The Balance pot varies the bias point on Q3. At low settings little or no voltage gets through to the Q3 collector so
the overall output is low (or off). When it's turned up, the output swings upward (IOW louder) as Q3 is brought into
bias. It is essentially acts as a clamp on the Sustain pot in that allows you to dial down the output volume without
reducing the total fuzz you get from the Sustain control.



The Timbre control is essentially a low cut in reverse. At low settings the low end frequencies flatten out. As it is
turned up more bass (and more volume) gets through to the output.



The most important thing to remember - every control you turn up makes this thing a lot louder and fuzzier. So,
the added volume control will help a lot to balance out different settings.