This week on the Breadboard: The Baya Azul (Mad Professor Blueberry Bass OD) V1.5

[Chuck D. Bones]

I just can't get enough of Bjorn Juhl's pedals. There are two versions of the Blueberry pedal. V1.0 has the input feeding into U1. V1.5 has a JFET booster in front of U1. I breadboarded V1.5 with a few minor mods. I rewired the NATURE control as a BASS control and added a TREBLE control. I fiddled a few component values. The trace of V1.5 shows an A1M DRIVE pot. This is way too large and there is nothing going on above noon with A1M. I first went down to A250K and then eventually A100K. The R12, R13, C10, C11 feedback network controls the gain at high DRIVE settings. Going beyond 250K has no effect. I selected Q1 and adjusted R4 to get approx 5.5V at Q1-D. I selected Q2 and adjusted R17 to get approx 5.5V at Q2-D. For the TREBLE control, I increased C12 to 33nF and inserted an A50K pot in series with C12. Sounds really good playing a bass thru this into a clean amp, nice edge of breakup tone. Plenty of range on the BASS knob and just enough range on the TREBLE knob. Almost clean with DRIVE at zero. If you have high output pickups, then you might want to omit R6 & C4.


Knobs (L-R): VOLUME - BASS - TREBLE - DRIVE


I used BF244A, same as Mad Professor. Selected 2N5952, 2SK30A-Y & 2SK117-GR should also work. Mind the pinout!