- Feb 21, 2008
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That's pretty much the deal. The more complete the vacuum is, the less easily the tube will break up and the gassier it is, the easier it will break up. Some tubes, in general, are known as harder tubes (like a 6L6), whereas others (like an EL34) are classified as softer....and, obviously even tubes of the same type vary in the same sense.I thought it was how they were produced: Hard Vacuum, Medium Vacuum, or Soft Vacuum. That is...how much air was pulled out of the tube during manufacture. Each might yield a different sound. IDK for sure, just guessing.
They are talking about a different kind of tube. The valves in a guitar amp are not special function, they are plain old garden variety receiving tubes.
The hardness and softness is as Blind Lemon said, a matter of current draw. Have a squizz at this:
How Vacuum Tubes Work
It's a good primer on valves.
Is this what Danzego is reffering to? (2nd section from top, blue font)
"Figure 3 (Inside a miniature tube) shows a typical modern vacuum tube. It is a glass bulb with wires passing through its bottom, and connecting to the various electrodes inside. Before the bulb is sealed, a powerful vacuum pump sucks all the air and gases out. This requires special pumps which can make very "hard" vacuums. To make a good tube, the pump must make a vacuum with no more than a millionth of the air pressure at sea level (one microTorr, in official technical jargon). The "harder" the vacuum, the better the tube will work and the longer it will last. Making an extremely hard vacuum in a tube is a lengthy process, so most modern tubes compromise at a level of vacuum that is adequate for the tube's application."
No, that's the deal. Here's another word on it, from Sweetwater.com:Great link. Thanks, Splat.
I guess we can all agree that the "harder" the tube is the higher the clean headroom?
In other words, "softer" tubes distort at lower volumes?
Or am I totally confused here?
Jayzus wept, that quote from Sweetwater is just nonsense. No wonder this going around as fact.No, that's the deal. Here's another word on it, from Sweetwater.com:
Glossary: SOFT/HARD VACUUM | Sweetwater.com
Terms used to describe the intensity of the vacuous space within a vacuum tube's glass envelope. A hard vacuum denotes a more complete vacuum is created in the tube manufacturing process. Hard vacuum tubes - like the 6L6 and 6550 - have a higher saturation threshold and therefore distort less easily then soft vacuum tubes. Soft vacuum tubes - such as the EL34 or 6CA7 - have a less intense vacuum (sometimes called a gassy vacuum), saturate more easily and therefore break up [distort] more quickly.
btw, the excerpt you posted from that other guy's article is what I was talking about.