Discrete 812 - The Preamp



The Discrete 812 preamps are based on the good old API technology . There is only one big op amp same shape as the classic API2520 op amp . The design accept all kind of clones at the same format, sometimes with minor adaptations.

Transformers are Profile 4804 for the outputs and Cinemag CMMI8PC for the symetrical Inputs. The preamp is fully controled by a set of 6 good relays themselves driven by an embeded PIC16F628A microcontroler who also provide memories, midi features and manage panel leds & switches.

The 4 knobs on the panel to set up levels:

  1. Gain = rotative selector 12 positions by step of +/-3dbs ...-Grayhill style...
  2. Level = Attenuator ay the discrete Op Amp inputs ( trimmer or level uses ...)
  3. PAN = panoramic with full cut on the edges for mono uses of the stereo buss .
  4. AUX = the level of the mono buss for monitor use, fx send ( post fader aux...)

The D812 preamps boards can be used independantly of the Discrete 812 mixing desk system with a minimum of DIY work indeed.....

Clic on picture to enlarge