Originally Posted by human
I'm sorry to post this but I'm totally clueless about tube amp. So I just want to ask how does the tube work and how much is each tube and about how long do I need to change one?
Also, I want to ask what is cabinet or thing like that? Must go through preamp or sth like that? ... I'm totally lost.
Sorry to post this.
The tubes are basically like transistors... only Old School style. they are very inefficient as opposed to transistors, as they give off alot of heat. Tube types vary, and the components inside them vary with type. The most simple tube consists of 3 active parts (called a Triode). The Cathode, grid, and anode(plate). There is a fourth part that is not considered active, as it does nothing but warm the tube up to normal operating temperature (filament). The Cathode contains all the electrons from your guitar's signal. When the tube is at full operating temp, those electrons start to be emitted from the cathode, and are kinda shooting around in the tube. The grid is basically a screen that directs the electrons towards the anode (which is where the output signal comes from). If there were no grid, many of the electrons would leave the tube through the glass, and would never make it to the anode, and the amplifying factor would be much less. The voltage that is applied to the grid determines how much effect the grid has on the amplification. The faster the electrons make it to the anode, the more gain there is. So the gain knob is really a controller for the grid voltage if I understand this correctly. Once the electrons pass the grid, they contacts the Anode. This part has high voltage charges on it to help collect all the electrons for the most possible amplification.
That's basically how a tube works.
The prices for tubes depend on manufacturers, whether or not the tube is new, or New Old Stock (NOS). NOS tubes are tubes that were made years before, and are no longer in production. Some people claim they give off a much better tone then the newer tubes. They are also high in price since they are no longer made. Preamp tubes are normally pretty cheap, compared to power amp tubes... You can expect to pay anywhere from 25 to 50 USD for each poweramp tube, where you can get preamp tubes from 10-25 bucks. Normally your preamp tubes will outlast the poweramp tubes, but there are always exceptions to that rule.
As far as tube life goes, well, you are pretty much at the luck of the draw, and how you play your amp. Tubes last longer played at lower "volumes". They say that playing your amp at high volumes, 2-3 days out of the week will normally let the poweramp tubes last 1-2 years. and preamp tubes 2-5yrs. Lower volumes may get tube lives of 2-4 years for poweramp and 4-10 years for preamp.
Here is the signal chain of a standard tube amp.
Guitar -> (input of amp) -> Preamp -> Tone stack (knobs) -> Postamp (PwrAmp) -> Output to Speakers
Your cabinet is where your speakers are housed. The construction of the cabinet has alot to do with how your sound comes out! The speakers have thier own flavor, or color if you will, of sound. The cabinet can be used to help embellish upon that color, or can destroy it and make it sound terrible. Amp manufacturers have cabinet building down to a science to make the best possible sound come out of that cabinet, So unless you know how to properly design a speaker enclosure (cabinet), i'd just buy something that is distributed by a manufacturer!
I hope this helped... I did learn a thing or two in my thought process of writing this, so if it helped you, it's a win win situation! Rock on!