Replacing Tubes, Service And Preventive Maintenance - Hughes & Kettner EDITION TUBE Bedienungsanleitung

Volume pedals, wah-wahs and the like evoke a slightly
different sound and elicit a different response when you plug
them into the EDITION TUBE's front panel input rather than the
effects loop. Both can sound hip, so which option you choose
is a matter of personal preference.
4.0 REPLACING TUBES, SERVICE AND
PREVENTIVE MAINTENANCE
Your EDITION TUBE features factory-equipped EL84 and 12AX7A
tubes. They are first burned in and then checked for their
electrical and mechanical properties (microphonics), selected
and matched, and then given a final audio and response test
once they have been installed in a EDITION TUBE. One of the
most important steps in the testing process is power tube
matching, i.e. selecting and pairing tubes with identical
characteristics.
WHEN SHOULD YOU REPLACE TUBES?
The tubes in your EDITION TUBE are of exceptionally high
quality and will last extremely long. If you do encounter a
problem, first check whether one of the following situations
apply:
• Is the defect a problem caused by a faulty or worn-out tube,
or is there actually a peripheral problem, for instance a
defective speaker cable that caused damage to the tube? If
this is the case, unless you correct the defect first, the problem
will recur once you have installed a new tube.
• Did the AC power supply fluctuate during operation?
Whereas digital equipment often malfunctions when the
power supply dips below a minimum value, all-tube amps tend
to malfunction when the power level rises above a certain
value. Generators and faulty high-power circuits often cause
these power fluctuations.
• Did a fuse trip although there was no plausible cause?
Aging fuses, particle ionization in the tube or spark-over due to
power spikes may cause this type of problem. In this case,
replacing a tube will not solve the problem.
• Old tubes begin to show signs of wear after they have been
in operation for a very long time: increased microphonics and
noise, treble loss, weak power output, muddy sound, etc. are
all indicators of pending tube failure. Power amp tubes wear
out faster than preamp tubes. If you encounter these
problems, replace the tubes. Not only do old tubes sound bad,
they also have a tendency to fail altogether.
NOTE: We recommend you refrain from exchanging tubes
solely for sound experimentation purposes. Improper use runs
the risk of damaging your amp and will not be covered under
warranty. Besides, we tested every conceivable tube option
and installed the tube types
that deliver the best possible performance.
KEEP THE FOLLOWING IN MIND WHEN YOU ARE READY TO
REPLACE TUBES:
• We recommend only qualified service personnel replace
tubes.
• Before removing the chassis, ensure the mains cord is
unplugged from the wall socket! Wait at least 2 minutes for
the amp to power down.