Of course I built the ubiquitous CMoy
. It was a big improvement over various built-in headphone amps (e.g. in a TV) and added headphone capability to where it did not exist (e.g. to a Playstation).
Encouraged, I built the PPA project
with a Young-Jung power supply
. The enclosures for both the amplifier and its power supply are from modushop
On first power-on the amp oscillated at 12 MHz when connected to headphones. The oscillation was inaudible but clearly visible on a scope. A quick look at head-fi.org
showed that PPA instability is not a new problem. I reduced the value of R11 (see PPA's schematic
), which eliminated the oscillation and improved the sound. I replaced the recommended OPA627 with LME49710.
PPA is positioned as a high-end DIY headphone amp, and it is in this project that I felt how subjective "high-end" is. PPA is a nice amp, but a true high-end device like Musical Fidelity X-CANv8 simply blows it away.