Hi!
I'm trying to make a preamp for my bass!
I admit i am kind of a beginner, but i couldn't find any schematics that would satisfy my needs.
The idea of the preamp that when i'm playing a song i don't really have time to set the tone knob to the desired value, so this provides me the option to set the pots before playing, and when the filter is needed, i just have to turn a switch and i have the right cutoff.

In TINA-TI everything seems good , but i did not built it yet, but i hope everything will work as it works in the simulation.

The pot in the 1st opamp's feedback loop is a trimmer, to set it for the pickups output.
In the filter section the the pots set the cut off point for the lopass and hipass filters, the switches are 2 circuit type that turn of/on the filters, and connects the the parallel resistor in the feedback loop of the second opamp thus giving a recovery for the filters.
If both switches turned of, it will give a bandpass filter with level boost.
The last pot is to control the output volume.

I would appreciate any feedback, is you find any errors or unnecessary components, wrong values, etc.

 

I'd change VF4 to about 50K. That will stop the next (output) cable from affecting the highpass frequency.