PPA v1 Amplifier Board
The PPA is ppl's Portable Amplifier. ppl
has been building and advocating Jung multiloop type buffered
headphone amp designs for a long time.
You can think of the PPA as a major extension of the design concepts
that lead to the META42 plus some that
appeared in previous ppl amps and some new ones we've pioneered
for the PPA. By using a larger board than we allowed for the META42,
we have been able to exceed the META42's performance considerably.
We later replaced this design with a newer
version primarily featuring a discrete buffer design, plus other
The pre-made boards are no longer available, but the design files are
published below if you want to go and make your own.
- 6.3 in. × 3.925 in. board size (Eurocard size, 160mm
- Isolated power rails reduce rail-modulated
- 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
- Compatible with most FET-input op-amps.
- One to four
Intersil HA3-5002 buffers per output channel.
- Room for over a thousand mics of
rail capacitance even with low-density
caps like Black Gates, Cerafines, and Silmics. 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 45mA on a minimal
feature set to about 150mA when maxed out.
- Enhanced JFET cascodes for
biasing the op-amps into
- Switchable bass
- Board-mounted ALPS "Blue Velvet" volume control (RK27 series)
- Resistors on 0.100" × 0.300" spacing allow the board
to be set up for easy
- A companion NiMH battery board
allows for portable amplifiers.
power LED turn-off circuit
for indicating that the batteries need to be recharged.
Where to Next?
View the PPA v1 Amplifier Schematic
View the PPA v1 PCB Layout
Download the PPA ExpressPCB Design Files
Part Selection Guide
Step-by-Step Assembly Guide
Bass Boost Calculator
Official PPA Site