Here is one good example how you can install TAISTO Electronics EQ units to your own bass guitar and extend your bass sound range.
Below you can see B-2EQ1 2-band EQ kit for bass guitars. Optionally you can also add volume pots, switches and knobs.
New TAISTO B-2EQ1 2-band eq unit was installed customer's own handmade 4-string Stingray style bass guitar. Bass had one pickup and 3 controls
The pickup used in this customer's bass was Multicoil pickup with Stingray style covers made by Rautia Pickups. The eq unit was covered with copper tape. The pickup and eq unit delivered great sound with serial and parallel modes.
Here is example of wiring schematic for B-2EQ1 unit with volume potentiometer and push/pull switch for serial/parallel pickup switching. In this bass guitar boost switch was not installed - boost related wires were soldered together for normal gain level.
Pickup and EQ unit delivered great sound range with all controls: Bass, Treble, Volume and Serial/Parallel pickup coil switching