[Mark & Mary Ann Weiss]

Phase-Linear D-500 Power Amplifier - Rare! Upgraded!

It took a long time to decide to part with my venerable Phase Linear D-500.
It has served me well for almost 30 years. It has been my pride and joy, the
centerpiece of my sound system for nearly three decades.. But now that I am
upgrading the video side of my theater, I am forced to decide which
components I really need to keep, and which I must part with.

http://cgi.ebay.com/ws/eBayISAPI.dll...m=230104272694



Two years ago, I used my 30+ years of engineering design knowledge to trace
the cause of these design problems and make corrections to the wiring layout
that would eliminate the problems.
The input ground was moved from the speaker ground, to a common "star
topology" ground, eliminating all crosstalk.
The AC, DC and audio signal wires were rerouted through separate sections of
the chassis, so that AC line noise would no longer bleed into the audio
input wiring, or into the DC power wires.
The original 13,000 microfarad power supply capacitors were replaced with a
very expensive custom made capacitor from Phillips, of 45,000 microfarads
each.
Additional polypropylene capacitors were added to shunt high frequencies
from polluting the DC power pool.
A second 25 amp bridge rectifier was added to the power supply and parallel
wiring added to the capacitor bank to double the current delivery ability of
the power supply and share the inrush current of charging the larger
capacitors.
A shield was added to the driver board PCB where a 5" long unshielded signal
trace was picking up stray electrical fields.
Phase Linear also made a mistake with the resistor value of the charging
resistor on the ballistics circuit of the left power output meter. They were
off by a factor of 10, obviously misreading a 1,000 ohm color code and
putting a 10,000-ohm resistor in instead. This was corrected, so both meters
now respond with equal ballistics.

Read more about it on the auction site.