Audio Frequency Detection

[transistance]

how about this bandpass filter? its supposed to allow 60Hz-340Hz. I was playing around with FilterLab. I am not too experienced with multi-stage filters but i think this is a butterworth filter. The only problem is i can not rebuild the circuit, cause i forgot the attenuation values i used. Nonetheless, i think it should work fine with x10-x20 gain preamp.

Ohh and i noticed that i have to be very precise with R values when building multi-stage filters. Correct observation?

Do you think this filter will solve my problem?

COMMENT ON EPE PIC-A-TUNER:
That is some hardcore assembly, i can not follow where they are actually digitally filtering the non-fundamental frequencies.

NOISE REDUCTION:
I'm planning to wrap all my audio carriers with aluminum wire mesh (mosquito screens - i dunno if thats what its called but you kno what i mean). That should help?

NOTE:
I'm using TL084 for opamps and LM386 for preamp.


Thanks in advance,
transistance

 

[transistance]

https://www.schickt.de/data/gimmick/theGIMMICK_sch_0.73.pdf

Here is the schematic of a what seems to be a fairly nice digital guitar tuner. Unfortunately the project owner only has the .hex file shared, I was wondering what the use of that comparator was? can anyone share some ideas? Could I use this circuit up to only a certain node before the comparator to achieve my fundamental frequency filtering? Or is the comparator there to capture the first fundamental of the polyphony?