I got off into thinking about what to look for in a tube amp to head off disasters - that is, to prevent the normal wear-outs from becoming expensive failures.
Let me preface this with: I know full well that it's not always possible to prevent or predict failures, and not always possible to stop them when they happen. But there are some things that are indicative of problems, and some things that need taken care of immediately.
I'm just thinking these over.
The model for this is that there is an incarnation of Maxwell's Demon sitting inside the amp, checking over and over for any problem you've told him/her/it to watch, and reliably squawking when one of these conditions is noted.
Some things I've thought of already:
- power tube overcurrents of sustained duration
- loss of the bias supply in fixed bias amps
- B+ levels too high or low
- B+ with too much ripple ( this indicates either overcurrent, poor function on primary filter caps, or loss of a rectifier in a full wave setup)
- temperatures too high; likely targets are surfaces of the power transformer, output transformer (+choke??), air temp in the top of the cabinet; others?
- AC input power too high - too many watts going into the box
What else?
Let me preface this with: I know full well that it's not always possible to prevent or predict failures, and not always possible to stop them when they happen. But there are some things that are indicative of problems, and some things that need taken care of immediately.
I'm just thinking these over.
The model for this is that there is an incarnation of Maxwell's Demon sitting inside the amp, checking over and over for any problem you've told him/her/it to watch, and reliably squawking when one of these conditions is noted.
Some things I've thought of already:
- power tube overcurrents of sustained duration
- loss of the bias supply in fixed bias amps
- B+ levels too high or low
- B+ with too much ripple ( this indicates either overcurrent, poor function on primary filter caps, or loss of a rectifier in a full wave setup)
- temperatures too high; likely targets are surfaces of the power transformer, output transformer (+choke??), air temp in the top of the cabinet; others?
- AC input power too high - too many watts going into the box
What else?
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