ROLAND: BeeBaa AF-100, Point to Point and Vero Layout (Modded)

This is a bare-bones Roland BeeBaa.  I built the full version and found that all I really used was the scooped fuzz sound - so this is just that.  Nothing but unadulterated vintage Japanese fuzz....    

I think this works best with low-gain transistors.  I made a version using weird KT315 Soviet BCE transistors, and it sounds mean.   If you want to take the simplicity a step further, just drop the Sustain control and run at full tilt all the time - you'll have a one-knob Japanese fuzz.  

There are also two great variations on the BeeBaa over on Dirtbox Layouts, which are well worth a look. The Stoner Bee and the Pink Goat.  Genuinely great layouts there - check it out if you haven't found Ander's site before (which seems unlikely).  

ROLAND BEEBAA AF-100 - MODDED VERO LAYOUT

AKA The Balmoral Electric Bee

Version 2, which is slightly more sensible in terms of spacing.

Now, if you want to mod it even more;

• Decrease the input cap to 100n to reduce bass - or you could get creative and sweep or switch between two caps for a thin-to-fat setting

• Reduce the 4.7n caps to increase treble - 1n on Q3 as an example 

• Bypass the notch filter completely by taking a feed from the 1u cap on the output of Q3 - which will be insanely loud by the way

• Remove a 10u cap to reduce gain (Q1 or Q2)

• Adjust the notch to your liking - use values from a Univox Super Fuzz as an example

ROLAND BEEBAA AF-100 - MODDED POINT-TO-POINT LAYOUT

ON THE SCOPE / FFT

Input signal: 440hz sine wave, approx 130mv TRMS

KT315 Soviet-era transistors

A distinct octave effect can be seen, and there's a lot of high-frequency content.  

Note:  The version on the analyser below has a 1nf capacitor instead of a 4.7nf capacitor on the last transistor before the output, resulting in higher frequencies.

The stripped-back BeeBaa has a lot of output, and an additional tone control could easily be added before the volume pot.

As a reference, this is roughly the difference between a 4.7n cap and the 1n cap on Q3 in LTspice (1n = more high-frequency content, which I tend to prefer)

This is it on LTspice, which is pretty similar to the scope results - always nice when the match (the light blue one is the output, the others are straight out of Q1, Q2 and Q3)

BRIDGED-T NOTCH FILTER

This is the notch filter produced in the modded Roland Bee Baa.  As mentioned above, this includes the response of Q1, Q2 and Q3, and then the notch in light blue.

SOVIET BEEBAA

Modified Roland BeeBaa with KT315 Soviet-era transistors (note: 1nf on last transistor). This was built using a slightly different layout to the one posted above, as the Soviet transistors are BCE, instead of CBE.  

I probably should have cleaned the edges of the vero up a bit more...  this was something I threw together without breadboarding, so I wasn't sure exactly how it would sound.  In the end, I'm very happy with it - just wish it was a neater build, but hey..   

SOVIET BEEBAA VERO LAYOUT

ROLAND BEEBAA AF-100 SCHEMATIC  

The stripped-down version removes the following;

- boost section and switching

- one filter option

- tone control