THAT 1512/1646 mic preamp

This board is for a mic preamp using the THAT corp chips 1512 (or 1510) mic amp and 1646 line driver.

The implementation is straight from the THAT datasheet, but with the addition of an optional DC servo to allow DC coupling of the audio path between the two chips.

There is an error in the silkscreen on this board - D5 is shown with the wrong polarity. It should be installed with the stripe/line side towards R1. The bare board image is corrected but actual stock have the wrong polarity shown until I get more made.

This board allows building with either a coupling capacitor in the audio path between the 1512 preamp and the 1646 line driver, or a direct DC link with a DC servo to eliminate the DC offset. I used a OPA1641 for the DC servo (it must be an opamp that itself has low DC offset)

full documentation coming - in the meantime ask me if you have questions

email me at parenthetical at this domain