The ParaLooper is something every effects-using Bass player should have, because it will ‘Bassify’ any bottom sucking, high-passing guitar pedal out there. And, it’s pretty simple to build, too. Instead of just an effect loop pedal, this is actually a little mixer that blends your straight signal with whatever effect (or chain of effects) you plug into the send & return jacks. There are controls for wet/dry balance, overall output level (boost & cut), and a low pass filter (LPF) switch for the clean signal.
The first two audio clips, for the Big Muff and for the Fuzz Factory, have [ 100% Dry-100%Wet-50/50 Dry/Wet ]. The rest are [ 100%Wet-50/50 Dry/Wet ].
Electric Bass
Pedal
in effects loop
I think this pedal works and sounds great. It can also be used in a number of different ways. For example, you can use it as a signal splitter by simply plugging the Send output into a second amp, PA, or mixer/recorder channel. It can also be used just like a two-channel mixer by plugging a second source into the return jack. There is also a low-pass filter (capacitor to ground) on the clean signal that can be switched in for even more low end.
The basis for the ParaLooper is the Bass-Thru, from a Japanese web site that happens to have some other interesting schematics, too.
Here’s a PCB layout that I did:
BassParaLoop layout
BassParaLoop PCB