XVR-1 - Pass Labs

The basic circuitry is a very simple discrete single-ended Class A stage designed tooperated at low gain and feedback levels with high performance and stability. In thediagram above you see the matched JFET input devices. These drive a PNP bipolar gaintransistor which is also a level-shifter. Both gain stages are driver by NPN bipolar currentsources which are in turn regulated by an NPN bipolar voltage reference taking feedbackfrom the first current source.The distortion and noise imposed on a signal running through this circuit is typically .03% at30 volts balanced output from 10 Hz to 20 KHz, and .002% at 3 volts output. The bandwidthis flat from DC to way beyond 100 KHz.33