Valves For Dummies...

[synsei]

For those, like myself, who are valve virgins, it would be very helpful if a member who has experience aplenty with valves and valve kit could write a guide for dummies describing the advantages and pitfalls of owning valve equipment. Things like bias setup etc are anathema to me and to some other members I suspect. Also a simplified guide to choosing replacement valves both new and NOS with recommendations etc.

Having heard Mark's (Dingdong's) WAD monoblocs recently I'm absolutely sold on valve amplification but I'm extremely nervous about choosing this route because of my ignorance of the subject and because of some of the horror stories I've read (failing valves taking out amps for instance).

As an example of what I am going on about, here are a few likely queries concerning valves and valve equipment:

What kind of lifetime can one expect from a new valve?
With the previous question in mind, does it make economic sense to buy secondhand valves?
Why do valves have to be matched?
Why are some valves better than others?
Why are valves so expensive?
Could there ever be a situation where valve amplification would not be advisable?
Do transistorised Class A amps exhibit a similar sound profile to valve amps?
Where do well designed Class D amps fit in to all this?
Are the running costs of valve amps prohibitive?
Are Class A/B amps a good compromise?

Over to whomever wishes to take up the baton, and perhaps it could be made a sticky...

[Trickie_Dickie]

Most, if not all, of these questions are like "How long is a piece of string".

Lifetime. It depends on the valve and how its used.
Secondhand valves can be useful, for instance, for testing newly built or refurbished amps.
Matched. Not always needed. Mainly Output valves in push-pull.
Better. See length of string.
Expensive. Because there are enough buyers with money to waste.
valve amplification would not be advisable in your ipod.
Transistor amps. Can do - depends on the design.
Class D. I see no reason against them except efficiency. Valves and efficiency don't go together.
Running cost. Could be a lot higher. Cost of replacement valves, etc.
Class A/B compromise. Depends on design.

Hope this helps a bit. Its down to individual taste, really.