The PPA headphone amplifier
This is my first attempt at building a PPA headphone amplifier. If you ask me, this turned out pretty good... ;-)
The enclosure measures app. 100x170 mm. and is designed to fit eurocard-sized PCB's. The amp is a bit larger than the others I've built, but still compact. The locking Neutrik output jack is mandatory to avoid short-circuiting the output if the headphones are accidentally (un)plugging the headphones while music is playing.
Note the way the colour of the LED changes depending on the angle and the material it is shining on (compare with the picture above).
Rear panel. Nothing elaborate here, just one input, a power switch and the DC-socket. Power is supplied from a "wall-wart"-type DC power supply salvaged from an old modem.
The image below clearly shows how the amp is designed with separate channels for left, right and ground. The circuit and PCB-layout is designed to give the best possible sound quality - the good looks are just a bonus :-) This amp is built on a version 1.0 PCB. The current layout is slightly different.
The transparent lid gives a nice view of the internals, even if it isn't very practical for daily use. Every fingerprint and speck of dust shows and it scratches very easily.
A good example of my excellent phtography skills, don't you think? ;-)
This is by far the best sounding headamp I have built (and also by far the most expensive). The sonic differences compared to the META or the MINT are simply astonishing. Because I mainly have "bright" headphones, I prefer the OPA627 opamp to the default AD8610. I am still surprised that exchanging opamps can have such a profound impact on the sonic signature of an amp.
© Uffe Nisbeth 2003-2004 Last update: Sept. 28, 2004