TUBE AMP BASICS
Solid state amplifiers are really not much different from your standard household
electronics; you just plug them in and go. Tube amps, however, are significantly
different. Let’s try to answer some common questions about proper tube amp use.
1.
Can you really die from messing around with the guts of tube amp?
Yes, you can. Tube amps carry significant voltage, even when turned off.
DO NOT mess with the insides of a tube amp unless you are a trained tech.
2.
OK, question 1 scared me. Can I safely change my own tubes?
Yes, you can. The dangerous voltages are only a problem if you start
messing with wires and transformers. It is perfectly safe to change your
own tubes.
3.
How often should I change tubes?
There is no set timeline for changing tubes. If you play ever day, a good rule
of thumb is to replace your power tubes once a year and your preamp tubes
every other year. However, it is entirely possible for tubes, particularly
preamp tubes, to last decades.
Here are some signs that you need to change your tubes:
●
Excessive noise like squealing, humming, or hiss
●
Little or no high end/treble
●
Muddy low end or loss of clarity; amp sounds “muddy”
●
Mysterious fluctuations in the amp’s overall volume
●
Amp doesn’t work!
4.
What the heck is “biasing” and do I need to do it?
“Biasing” is a technical term that has to do with things like “voltage applied
to the grid” and “moving the operating point into a more linear range.” If
you didn’t understand that, then don’t attempt this yourself!
Fixed-bias amps, like your new JCA5012C, allow you to “plug and play”
matched power tubes of the same type/model without needing a bias
adjustment. Switching tube types, will probably require modification to the
amp’s circuitry and this type of “tweaking” will void your warranty.
