I designed and tested an opamp adapter to replace the HA1452W preamp chip, which appears to be a pair of externally compensated opamps.
It works just fine. There's a spot on the belly for an smd power bypass cap and two spots for small caps to filter ultrasonics out of the feedback loop, which may be needed to prevent oscillation depending on what opamp you use.
I have a bunch more boards. I can provide a complete kit with an lme49720 (aka lm4562), pin strips, a socket, smd 0.1uf cap and a pair of 22pf through-hole caps for $15, or w/o the chip for less.
It works just fine. There's a spot on the belly for an smd power bypass cap and two spots for small caps to filter ultrasonics out of the feedback loop, which may be needed to prevent oscillation depending on what opamp you use.
I have a bunch more boards. I can provide a complete kit with an lme49720 (aka lm4562), pin strips, a socket, smd 0.1uf cap and a pair of 22pf through-hole caps for $15, or w/o the chip for less.
