Capsize Preamp for use with Acoustic

[DadTheTinkerFairy]

I built a Capsize preamp to experiment using with my acoustic. It has a Fishman magnetic sound hole pickup, not piezo. It is a pretty low output pickup so I was looking for something to clean boost and add a bit of tone shaping. I also added a buffer/inverter for an XLR balanced output. It works great, however, the tone is very dark.
It looks to me that C3 and C5 are the main culprits. Am I correct, if I remove both of them if that would brighten things up? Maybe reduce the size of C14 as well?
Or suggest a circuit that would work better for this. Thanks.

 

[DadTheTinkerFairy]

I decided to socket C3, C5, and C14 to experiment. Turns out C3 and C5 don’t have nearly the effect I I thought they do. They mostly serve to reduce the noise floor and only slightly reduce presence treble frequencies. I may just reduce these from 3.3nf to 2.2nf.

The big culprit turned out to be that I accidentally installed a 100nf for C14 instead of 1nf. After some more experimenting, I will probably end up reducing this to 470pf or 560pf as the 1nf does still cut some treble.

 

[Ginsly]

I can’t speak to this circuit, but @Robert has both a K&K Pure Preamp and Fire-Eye Red-Eye in the works- both of which are suited for acoustic instruments. Watch out for them!

 

[DadTheTinkerFairy]

I can’t speak to this circuit, but @Robert has both a K&K Pure Preamp and Fire-Eye Red-Eye in the works- both of which are suited for acoustic instruments. Watch out for them!

Thanks! We definitely more attention to acoustic gear in the DIY community. The available acoustic preamps are stupidly expensive for what they are, no reason we can’t build them ourselves.

 

[DadTheTinkerFairy]

I’m going to experiment with the jfet bias as well. I set them to 4.5v but saw another thread that they should be set to 5.875 for Q1 and 6.345v for Q2.