Boss - PQ-3B Bass Parametric Equalizer
Posted: 12 Aug 2008, 11:04
I already posted it at the workbench; small update!
I have a Boss PQ-3B on my bench right now; want to make it into a guitar parametric EQ instead of the bass version it is now. Could not find any schematics so I tried to trace it.
For most parts the unit is identical to the PQ-4; instead of the low / presence knob the low is made parametric. This is done by adding one more stage (total of 3 stages; low, middle, high). This stages differ from the PQ-4
Stage(s)
High uses 3.3 nF
Middle uses 22 nF
Low uses 120 nF caps as the unmarked cap section
PQ4 schematic
I have a Boss PQ-3B on my bench right now; want to make it into a guitar parametric EQ instead of the bass version it is now. Could not find any schematics so I tried to trace it.
For most parts the unit is identical to the PQ-4; instead of the low / presence knob the low is made parametric. This is done by adding one more stage (total of 3 stages; low, middle, high). This stages differ from the PQ-4
Stage(s)
High uses 3.3 nF
Middle uses 22 nF
Low uses 120 nF caps as the unmarked cap section
PQ4 schematic
Sooo..... if I got everything right, than it should lokk like in the schematic below....
