Stingray 3EQ Preamp

[subnormalwater]

Hi everyone, I built this preamp by following this thread: https://www.talkbass.com/threads/diy-stingray-3eq-preamp.883257/

I'm using it as a stompbox.

I used a TL072 instead of a TL062, B250k potentiometers since I ran out of B50k and 2.2uF on the biasing side.

I found that this preamp is eating a lot of treble, even at 100% treble I still can hear some loss of clarity compared to directly plugging the bass on the amp and it doesn't feel the same amount of boost I can get out from mid and bass.

I tried swapping some op-amps I have around and I found that the NE5532P sounded the best but still loss of definition

Is it due to my 250k pots or did I mess up something?

These are my readings (NE5532P):

1: 4.04V
2: 4.04V - these two are not quite stable, not sure if it's my probe 
3: 3.61V then slowly drops
4: 0
5: 4.01V then slowly drops
6: 4.14V
7: 4.30V
8: 9.11V

[anotherjim]

The front end doesn't look suitable for passive pickups to me. Was it originally designed for use onboard a bass with active pickups?
My feeling is that, to avoid dulling a passive guitar, it needs a high impedance buffer stage in front.

[subnormalwater]

It's the onboard preamp of a Musicman Stingray, to be honest I don't know if it has active or passive pickups. I'm going to try this preamp with a buffer, thanks for the suggest

EDIT:

You're a genius! I placed it right after a buffer (klon buffer diy - really simple) and works like a charm 

[Rob Strand]

Was it originally designed for use onboard a bass with active pickups?

The Musicman uses passive pickups. It's a humbucker.

You might want to chuck out or trim the 2n2 at the input.
You can play with the front end  high-pass filter.  If you pull it out is can be a bit boomy.

Personally I would have went for the 2-band Musicman; it's got some funky pots though.
Not that the 3-band is "bad" it has half decent frequencies.

[subnormalwater]

Hey Rob 

I wanted to build a 2EQ but as you said it uses some weird pots.. I'm happy how it turned out leaving mids flat and using only bass and treble

[Rob Strand]

I wanted to build a 2EQ but as you said it uses some weird pots.. I'm happy how it turned out leaving mids flat and using only bass and treble

Yeah bit of a pain.

I would have gone with a straight 2-band, like the "South Beach" one as opposed to the a three-band with the mids set flat.    Anyway nothing wrong with that 3-band.