speaker cabinet, or the speaker cabinet itself. Is the
STDBY
switch in the
up
position? Is there a speaker cabinet plugged into the
MAIN
speaker output? Have
you tried a different speaker cable? Most speaker cabinets make the electrical
connection to the speakers via quick connect tabs that can sometimes fall off.
Check to make sure each speaker in the cabinet has two secure wired
connections to it and there are no dangling, disconnected wires inside the speaker
cabinet. If you have another amplifier, use it to test the speaker cabinet.
If you determine the problem is with the amplifier and not with the instrument,
instrument cable, speaker cabinet, or speaker cable, your amp will need to be
seen by a qualified repair technician.
There is unwanted noise coming from the speaker or the amp suddenly
sounds bad.
In the vast majority of cases,
this will be caused by a failing vacuum tube.
See
the section above on replacing tubes. If the problem persists despite replacing
tubes, your amp will need to be seen by a qualified repair technician.
Frequently Asked Questions
Do I need to bias my amp when changing power tubes?
Because the Dusky Electronics D
₂
O Amplifier's power section is cathode biased,
which is selfadjusting, no adjustments need to be made when changing power
tubes—even for tubes of different types. See the section above on power tube
rolling.
Is there a special
power on
procedure I should follow?
The short answer is “no.” If that satisfies you, you can move on.
Most users of tube guitar and bass amplifiers will be familiar with lore regarding
power on and power off procedures along the lines of “turn on the power first,
wait 30 seconds, then turn on the standby.”
The conventional wisdom behind this procedure is that applying full power to the
tubes before their heaters have had a chance to warm up can lead to cathode
stripping, where material is literally pulled off of the tube's cathode and pulled to
the tube's plate, damaging the tube. While this is a real phenomenon that affects
large radio transmission tubes that operate at kilovolt and megavolt potentials,
there is no evidence that this phenomenon occurs at the smaller scale of
receiving tubes used by audio amplifiers.