PPA v2 Amplifier Board
PPAv2 is similar to PPAv1, except with a custom discrete output stage, plus a few other enhancements.
Specs:
- 6.3 in. × 3.925 in. board size (Eurocard size, 160mm
× 100mm)
- Isolated power rails reduce rail-modulated
crosstalk.
- Differential-drive topology gives the simplicities of virtual
ground without the crosstalk problems that normally go with that.
- The signal channels use the Jung multiloop topology for
low distortion.
- Compatible with most FET-input op-amps.
- Discrete diamond buffer output stage, with adjustable bias, to
let you trade portability for sound quality.
- Room for thousands of microfarads of
rail capacitance, even with low-density
audiophile caps. At the same time, differential drive means the
qualities of the rail capacitor bank don’t affect the sound of
the amp as much as in other topologies.
- Reverse power supply voltage protection.
- Quiescent power draw ranges from about 40mA on a minimal
feature set to about 120mA when maxed out.
- Enhanced JFET cascodes for
biasing the op-amps into
class A.
- Optional bass
boost.
- Board-mounted ALPS RK27 (a.k.a. "Blue Velvet") potentiometers
for volume control and bass boost adjustment.
- Resistors on 0.100" × 0.300" spacing allow the board
to be set up for easy
experimentation.
- A companion NiMH battery board
allows for portable amplifiers.
- Optional power LED turn-off circuit for indicating that the batteries need to be recharged.
