VP25

Single-stage 70's-style mic preamp

The VP25 preamp is essentially an exact recreation of the legendary preamp circuit found in the vintage API consoles of the mid to late '70's. The 528/536 input modules have precisely this same exact circuit. The only exception being the change to the larger 2503 output transformer. The rest of the circuit is slightly different than the ever popular 312 schematic or what is found on the 312 cards themselves. You will find a few more components in the audio path like coupling capacitors on both sides of the discrete opamp. The use of series and loading resistors, along with a few decoupling capacitors is also faithfully implemented.

http://capi-gear.com/catalog/product_info.php?cPath=22_117_55_57&products_id=454