Do tubes lose resolution as it ages?

[flargosa]

Do tubes lose resolution as it ages, or does it sound consistent after burn-in until it dies?

 

[leadbelly]

Yes they slowly pixellate.

 

[DF96]

No they don't lose 'resolution' (whatever that is).

No they don't stay consistent from 'burn in' (whatever that is) to 'death'. However, a good circuit will maintain its performance over a wide range of valve parameters so you should not hear any change.

 

[flargosa]

However, a good circuit will maintain its performance over a wide range of valve parameters so you should not hear any change.

What do you mean by good circuit? How do you know the circuit is good? Do you look at the schematics and determine if the design is good? So I assume you guys use the tube till it breaks?

 

[famousmockingbird]

In my experience tubes hold a decent transconductance right about until they die. They don't linearly 'deteriorate'.

 

[v4lve lover]

in most tubes cathode activity is not the limiting factor to lifetime, rather the tube elements de-gass during use which increases grid current and hence causes output tubes to run away in fixed bias arrangement.

 

[DF96]

What do you mean by good circuit?

Various things, including the performance being insensitive to valve parameters.

How do you know the circuit is good? Do you look at the schematics and determine if the design is good?

Knowledge, experience plus a calculator.

There are several common ageing/failure mechanisms in valves:
1. open circuit heater
2. gas
3. loss of emission