PBA Pre-biased Opamps
Pre-biased Opamp, PBA, is a tweaker's dream come true!
The PBA board is a direct replacement for a dual opamp in a DIP8 package. It provides two channels of pure low-distortion Class A voltage amplification. The PBA is offered pre-populated with a great sounding low-noise JFET dual audio opamp, or as a bare board that can fit any dual SOIC8 opamp with a standard pinout.
As more and more new so called "Audio Opamps" hit the market, they show vanishingly low distortion figures. However, this exciting performance is achieved through the use of heavy negative feedback, and the measurements done at full output voltage swing. What remains unchanged, is the push-pull output stage, operating very close to pure Class B, that guarantees low quiescent current of the entire chip, but produces about 98% of total distortion figures of the opamp. Unfortunately, these crossover distortions are most noticeable at very low voltage amplitudes, where most of the RIAA stages, headphone amps, and line stages operate.
The technique of forcing an opamp output stage into a pure Class A operation had been known for decades, and used by numerous venerable audio designers to drastically reduce opamp distortions. Generally, it requires a current source that pulls small DC current from the opamp output to the negative rail.
Save your board space and time by using a PBA for a greatly improved sound quality.
Enjoy the great sound!