The below circuit is from the Fishman Loudbox Mini acoustic guitar amplifier, the tone controls portion. The low and mid are fixed frequency peaking EQ and the High is a shelf. I understand the low and mid but can't figure out the high:
Low:
f = 1/(2 PI sqrt(R14 R15 C11 C12)) = 53 Hz
Mid:
f = 1/(2 PI sqrt(R16 R17 C13 C14)) = 766 Hz
(I'm reasonably sure this is right since Fishman has told me the Mid to be 750 hz).
High:
I thought it was f = 1/(2 PI C15 R18) = 4200 Hz, but that seems too low (maybe not). Is U2A involved with the High, or is that an output buffer?
Thanks.
Low:
f = 1/(2 PI sqrt(R14 R15 C11 C12)) = 53 Hz
Mid:
f = 1/(2 PI sqrt(R16 R17 C13 C14)) = 766 Hz
(I'm reasonably sure this is right since Fishman has told me the Mid to be 750 hz).
High:
I thought it was f = 1/(2 PI C15 R18) = 4200 Hz, but that seems too low (maybe not). Is U2A involved with the High, or is that an output buffer?
Thanks.
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