Adding a tube to a pedal?

[Wixomwhat]

if you added a tube to a pedal somehow what part would the tube be replacing?

just curious

[R.G.]

The battery  clip.

See "The only way to get real tube sound in a stomp box" at GEO.

[Hal]

the transistor.  Transistors and tubes both act as amplefiers (or switches).  Differently, but kinda with the same theory.  One smaller voltage (current) controls another.

[ExpAnonColin]

The battery clip.

Ok, that one took me a minute, but excellent joke

-Colin

[R.G.]

OK, I'm calmer now. I'll try to answer with a straight face.

if you added a tube to a pedal somehow what part would the tube be replacing?

At a conceptual level, any amplifier (transistor, FET or opamp) or switch (transistor, FET, opamp, or logic inverter) or diode, in the sense that a tube can be made to do the same function if you take note of its special needs. A tube can amplify at gains of one to maybe a hundred. A tube can switch from on to off. A tube can be made to act as a diode by opening the grid lead.

At a practical level, you can't really do this. Not in the sense that it's impossible, but it's not practical from an effort or economic sense.

A tube has special needs for power supply and impedance levels that make subbing a tube for some other part impractical at best and a Quixotic crusade at worst. The special needs of the tube so overwhelm the rest of the circuit that you're really redesigning the entire thing to fit the tube's needs.

There are places where only a tube will do (as in a lot of musical industry advertising copy 8-)  ) for some reason. In those places, it's best to start with what the tube does and design around its needs.

Replacing a part in an existing design is not a particularly useful exercise except for being able to claim that there's a tube in there.

[Wixomwhat]

Thanks for all the info RG!

[chrishopkins]

There are places where only a tube will do (as in a lot of musical industry advertising copy  ) for some reason. In those places, it's best to start with what the tube does and design around its needs.

Yeah - I've got a Marshall VS100 - the amp sounds exactly the same whether the 12AX7 is in the circuit or not.  I read somewhere that the valve is either a placebo or is being used as a diode.