Pass Labs XA100 - Manual (Page 8)

8 XA100 Owner’s Manual
Speaker cables should be firmly tightened down at the speaker
output terminals, but not with a wrench. Output terminals will not
withstand the levels of torque that may be easily applied by wrench.
Hand tightening without excessive force is plenty. Cleaning contact
surfaces with one of the commercially available electronic contact
cleaners should be part of your annual system maintenance.
The XA100 has a single large power transformer, under actual
conditions in the amplifier, it supplies but a fraction of its rated
power. This very conservative rating contributes to exceptional
voltage regulation figures and low noise figures at the loudspeaker.
The XA100 has a significant number of power supply filter
capacitors. These caps are used to create the unregulated output stage
rails at plus and minus 30 volts at 7 amps. RC filtering is used to
passively remove ripple from the supply rails.
All the power transistors in the product are hyper-matched parts,
with gate voltages matched to 0.5% and all devices taken from the
same manufacturing lot codes (made on the same wafer).
So how long will this hardware last? It is our experience that, barring
abuse or the odd failure of a component, the first things to go will
be the power supply capacitors, and from experience, they will last
15 to 30 years. Fortunately they die gracefully and are easily replaced
by a good technician. After that, the longevity will depend upon the
number of operating thermal cycles, but we can say that we have
had amplifiers operating in the field in excess of 20 years with no
particular mortality, and we don’t have good information beyond
that. More to the point, you should not worry about it. This is a
conservatively built industrial design, not a frail tube circuit run on
the brink of catastrophic failure. If it breaks, we will simply get it
fixed, so sleep well.
Fun Hardware Facts