Hi,

Those pdf's are the only ones I have. The thing is: the ONLY difference between the API pre in that pdf and your Harrison pre is the op-amp. Everything else is exactly the same, every resistor etc.

So, if you'd like to try, you can just get an API2520 discrete op-amp or similar (ML2520 etc.) and substitute the old monolith op-amp. It will sound a little better. But old 5534's also sound really good. The 32/24 series Harrison pres are absolutely superb sounding pres, no question about it.

Hey I was wonderin if it would be possible to send me larger pdf's or whatever of the mic pre compared to an API mic pre schematics you posted. As you know I have been trying to get my 32 series up and running for over a year now, finally at the point I can do a little tracking through it. Really dig it, a huge improvement over my Jim Williams modded soundcraft. To be honest, I wasnt expecting much from the pre amps, no one ever mentions them, but wow! I am totally digging them, they all have 5534's.