matta I found this GREAT simplified video on how a tube works, courtesy of Tube Depot (www.tubedepot.com) Hope you enjoy! Matt
Bob-Dubery Me can like to be dof. I have watched that twice now I still don't understand what all the dinguses do. The plate and the cathode - no probs. The control grid - no probs. But what's that other grid do? Not the beam forming plate but the grid between the control grid and the beam forming plate?
Gearhead Not all grids were there at the start. First, you had no grids - rectifier tube. Then, you got one - triode. Still one of the best designs. The other grids are not about the basic function anymore, they try to solve issues that guitarists don't want to know like parasitic capacitance and Miller effect and all that crap. If you understand the triode, you can understand how amps work and even repair them. If you want to design them and use tetrodes and penthodes in the power stage, well, you copy Fender like everyone else did. Or copy other people's Fender copies like all the boutique guys did. I regret most of the hours I spent trying to understand what electrons might do once flying through a vacuum. Should have practiced playing.
Bob-Dubery Wizard wrote If I remember correctly - rectifier tube works like a diode; triode like a transistor That's the long an the short of it. I'm in the category that Gearhead describes - I understand how a triode works. I never got my tiny little mind around pentodes. Not that I'm planning to build an amp this weekend.
Karel-Mars Only thing you need to know about penthodes (also called beam tetrodes in USA) is that they sound better (and are louder!) in guitar amps than triodes. (they have a funky 3rd order distortion that everybody likes - esp. in combination with push-pull) That is in the power amp side of things. Triodes generally sound better in the pre-amp section. VOX AC30 sound is penthodes in push-pull. Marshalls also use penthodes. The only amps that use triodes in the output stage were built before WWII - they sound groovy for jazz.
proze Thanks for the vid!! Awesome to see! Karel Mars wroteThe only amps that use triodes in the output stage were built before WWII - they sound groovy for jazz. The Blackstar HT5 uses a triode in the output stage, a 12BH7.
aja zappa wrote For an encore: How does YouTube work? hehe smartass! ? http://www.howstuffworks.com/youtube.htm
Gearhead In case anyone wants to dig deeper, this is an excellent tutorial: http://www.audioxpress.com/resource/audioclass/index.htm
Tamago The closest semiconductor equivalent to a tube is a FET. They are similar in many ways, except the latter doesn't need the high DC voltages.
