Tube Primer

[rbilleaud]

I know this is going to be a rather basic question for those of you out there who are old hands at this stuff, but here goes. I have a deep and abiding love for music and a 15 year old daughter who has a science project to do. I have always been enamored with the idea of building my own tube amplifier to replace my little Peavey Audition so I thought now would be the perfect opportunity to build one and at the same time give my daughter a science project she can really get into. I have a pretty good understanding of basic electronics - enough to know how not to electrocute myself, and how to use a multimeter. I understand the principles of how vacuum tubes operate. I figure I can handle the construction of a simple P1 design. Where I have trouble is understanding the differences between tubes, for example, what makes a 6v6 different from a EL84, and how does that affect the sound. Is there anywhere I can look to find a good primer on this without going into all of the heavy mathmatics that are too complicated for my old mind to comprehend? I'd appreciate any advice you can supply.

[soundmasterg]

Pete Millet's site has a lot of free books on it that you can view or download that may help with this.

The basic idea is that every tube is made differently, and the dimensions between parts inside the tubes are differnt, as is the amount of vacuum inside the tubes, and the sizes, shape, and metallurgy of each part. So one tube may have a larger plate and another has a smaller and shorter one. Another tube may have large spacing between the grid and plate and cathode, while another may have very close parts placement. These type of things affect the voltages each tube can handle, the gain and amplification factor of each tube, and most importantly to the sound, the capacitance of a given tube type. There is nothing out there that I know of that will say X tube sounds like it does when compared to Y tube because of such and such though.

Here is Pete Millet's site: http://www.pmillett.com/

Greg

[Enzo]

Consider a small kit. A Champ clone would be a fine basic project. You could make one from scratch, but the kit will come with a chassis , all the parts, and most everything covered. That way you won't get half way through it and realize you now need to order some small thing. Or get all the parts in and then realize, oops, we have no wire to connect things together with.

[Old Tele man]

...something like this? http://music-electronics-forum.com/s...light=Tele+man

[Chuck H]

I don't know of any way to determine the tone of a tube from the data sheets. A tube designer MAY be able to get an inkling of a clue. But maybe not. You have stumbled on one of the most discussed topics at any tube amp forum. 'Which tubes sound good?'. Of course different tube "types" (el84, 6V6, etc.) have characteristic qualities. But have four people describe the difference and you'll walk away with four different pictures in your mind. All I can suggest is that you consider what amps you like the sound of. Or if your not sure then consider which players tone you like and research their gear. Once you know the amp/s in question you can find out what tube "type" you want to start with. Then you'll need to do more research to find out which brand and/or make of that tube type may sound good for what you want. There is also the consideration of operating class. As in "class A" or "class AB1". The same tube will sound different when operated either way. Also, and I'm not trying to make this complicated, the voltage the tube operates at will have an effect on it's tone. This is really pretty simple because once you identify an amp you might like to build, the operating parameters and tube types are there in the design. Then you just need to find out what "brand" of tube to get. Unless you get a complete kit. In which case the tubes will likely come with it. And if there is an option on tubes for a kit, I'm sure whoever sells it would be glad to offer help in choosing based on experience with their product.

Chuck