[SilverS]

Hello everyone,
 
I'm starting to dip my feet into the waters of tube amplification, and as with anything new there are many strange things I'm reading that don't make since to me. So to help my self not look like a complete newbie when I post in the future I'd like to go ahead and get it out of the way all at once. So here are my questions to the tube aficionados out there:
 
1) What is Tube Rolling? It sounds fun.
2) What is the function of the tube in a circuit?
3) What are some ways I can get rid of the bell sound I get when put something down on the same table as my preamp?
4) Is it better to have more or less Tubes in a circuit for the best sound quality?
5) Do tubes have a life span?
6) Do tubes really explode?
7) Do bigger/smaller tubes sound better?
8) Is my tube supposed to look all messy inside? (I might have to include a picture of this)
9) I've heard tubes are supposed to glow and heat up? Is it bad that mine don't?
 
I think thats everything, if I think of anything else I'll post it in here.

 

[FallenAngel]

1) Using different tubes in the circuit.  Make sure you use compatible tubes.
2) Generally the tube is used for the voltage amplification, sometimes as current buffer as well, depends on design.
3) Your tube is microphonic, some tubes are, some aren't.
4) Completely depends on design.
5) Yes, as do all components, check the tube datasheet, usually they're good for a few years.  Again, depending on design.
6) Generally tubes do not explode, capacitors do.
7) Completely depends on tube and design.
8) Nothing should be moving inside a tube, look at tube photos.
9) Tube heaters do heat up and glow, most tubes generally don't glow themselves, though lots of designs have lights under a tube to make it seem so.

 

[kboe]

 
 
Tube rolling allows you to use what are essentially the same tubes, but from different manufactures.  The different makes of the tubes have variations is sound qualities that you can use to fine tune the sound of your amp.

 

[wuwhere]

There's a lot of vacuum tube info out there, just use your favorite search engine.
 
1. Tube rolling is fun, however, it can get very expensive, specially if you are looking for tubes that are rare, NOS and out of production for some time. There are plentiful of tubes out there, mostly from military application. Tube rolling is essentially swapping tubes, example, a WE396A = 2C51 = 6N3P = 6N3P-E = 6N3P-EB = 6N3P-DR = 5670. That means all these tubes are pin and voltage compatible. BUT they all may sound different from each other. AND the same tube from the same manufacturer may sound different also depending on when and where they were made.
2. In a power tube amp there are driver tubes, these are the little ones and the bigger tubes, these are the output power tubes that provides the power to your speakers, headphones and IEMs.
3. That's what you call microphonics. There are tube dampers that you can buy. You can also put absorptive footings under your tube amp/preamp.
4. More output tubes means more power. So it just depends on your speaker or headphone's needs.
5. Typically 2000 hours. Some are rated up to 10,000 hours. A tube's life is affected also by their bias. If you high bias them, they run hotter and dies quicker. Some tube amps have an auto-bias circuit so you don't have to worry about biasing them. Some have manual bias, on this you have to manually do it yourself.
6. I've never seen one.
7. Read # 2 above.
8. Yes, point to point wiring. Tube amps have higher voltages that the pcb trace will not handle. Specially the voltages coming output of the transformers.
9. It depends on the tube amp. Some are hotter than others.
 
Hope that helps. I'm sure you will get answers too from others in this forum that have more knowledge and experience than myself.

 

[Uncle Erik]

2.  Tubes are used for amplification.  However, you will sometimes find them used to rectify AC into DC as well as regulate the power.  Quite a few of the higher end tube amps use tubes to rectify the power supply.  You can also rectify power with diodes, but they give you a different sound from tube rectification.

 

[ardgedee]

6) A tube will implode if it breaks. Like incandescent lightbulbs, tubes only contain circuitry and a vacuum. When they break they're sucking in atmosphere rather than blowing anything out. A tube might be able to implode violently enough to shatter and throw glass, but I've never seen it; usually one will POP and there'll be some cracks in the otherwise-intact glass.

 

[ardgedee]

Quote:

8) Is my tube supposed to look all messy inside? (I might have to include a picture of this)
9) I've heard tubes are supposed to glow and heat up? Is it bad that mine don't?

8) Depends on what you mean by messy. The innards are more complex than the simple tungsten wire loop that a lightbulb has, and the insides of various tubes look wildly different, thanks to the immense range of applications tubes have been used for. There is also the getter, usually a metallic coating on the inside of the glass at the top or bottom of the tube, to absorb outgassing from the heated tube elements. It's all normal; if the tube's working, don't worry about it. On the other hand, if the tube looks frosty-white, it's a goner.
 
9) Some are pretty bright and too hot to touch, others barely perceptibly glow at all and might only be as warm as a cup of coffee. If you've read aficionados wax poetic about listening in the dark by the glow of their amplifiers (guitarists as well as home audio), you might be disappointed the first time you see a tube amp in the flesh and working; the tubes are nowhere near lightbulb-bright.
 
The more-or-less thumb-sized 5670 tubes in the Elekit headphone amp on my desk are considerably less bright than the LED pilot lights of various other electronics within eyeshot, nevermind the computer screens. They look even dimmer thanks to the black cage shielding them. I like it that way; the amp runs so cool that I can safely tuck it into a tight little nook among other electronics and even stack some more small audio gear on top of the amp's transformer. This is not ordinarily something you should do with tube electronics; when they run hot they should have plenty of free space around them.