Why no heated gear?

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The original question was

why don't manufacturers add heating elements to equipment to bring it too optimal temperature quicker.

It is ridiculous to think that externally heating a component won't do just that... "bring it to optimal temperature quicker." It matters not whether you think it is extravagant, that was not the original question.

As to the poster who pointed out that his garage won't heat an engine to operating temp.. same answer. Of course it won't, but an engine starting when it is room temp will certainly start easier and be ready drive more quickly than one that is freezing cold. Keeping it in a warm garage will "bring it to optimal temperature quicker."

As to the theory that tubes can't be warmed because they are in a vacuum, well, I'm sorry but that whole post simply makes no sense. If that were true then they would remain cool to the touch when operating. If heat can't get in then it can't get out. The simple truth is that everything inside is physically connected to everything outside through the base. The entire tube, inside and out, will eventually reach the same temp whether heated from within or from outside. Even if there wasn't a physical connection there is radiant heat which does travel through a vacuum as proven by the fact that we are warmed by the sun. Also, bias has nothing to do with "heat potential" between electrodes, in fact, there is no such thing as "heat potential" in a tube. Bias is used to establish the proper operating point for the tube. Too little bias and you increase distortion, too much can also lead to distortion and can overheat the tube.

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Thank you everyone for the input.

I'm with you Herman, that some sort of heating would have a positive effect on the warm up process. I completely agree with all the posters that warm up is the only way to get the gear to sound it's best, my intent was to get a few opinions on "speeding" that process up with some sort of external/internal heating. It is my opinion that if a part becomes heated by normal operation during playback, then prematurely heating that part up to at or near operating temperature would result in quicker warm up times and shorter "cold sound" periods. My listening habits have changed and have become more sporadic and shorter in length. I have many nights where I plan to listen, I turn the gear on hours ahead and then not get a chance to listen. Therefore wasting electricity and putting hours on my NOS tubes. If I could get warmed up sound in about 15 minutes I would be a happy audiophile.

Herman, thanks for helping me to win a bet with myself. When I wrote:

So why can't we just heat the tube with an external heat source like a heat gun or a heated blanket? Because "tubes" are vacuum tubes - the glass envelope encases the internal elements in a vacuum. No gas (atmosphere), no heat transfer can occur from OUTSIDE the envelope. See what you can learn when you don't sleep through High School physics class?

I just knew that you were going to reply the way that you did. OK, you caught me. I am guilty of a gross oversimplification.

The fact is that the glass heats up when a tube is powered because of radiant heat. But it's an inefficient process, and radiant heating from a high temperature source in close proximity is a very different process than "warming" from a low temperature source from several inches away. Do you possibly believe that you can pre-heat a tube to anywhere remotely close to operating temperature? Actually, that is done (sort of) for certain types of specialized lab gear and of course cold cathode tubes, which operate at a much lower temperature. But it wastes a lot of energy and can't be done except in controlled conditions.

And regarding your last statement that there is no such thing as heat potential in a tube. Really? So you believe that the anode and cathode in a typical vacuum tube are EXACTLY the same temperature? Planck's Constant indicates otherwise. So between your opinion and Max Planck, I'll take Max.

"The entire tube, inside and out, will eventually reach the same temp whether heated from within or from outside."

From that unimpeachable source, Wikipedia:

"Vacuum tubes require a large temperature difference between the hot cathode and the cold anode. Because of this, vacuum tubes are inherently power-inefficient; enclosing the tube within a heat-retaining envelope of insulation would allow the entire tube to reach the same temperature, resulting in electron emission from the anode that would counter the normal one-way current. Because the tube requires a vacuum to operate, convection cooling of the anode is not generally possible unless the anode forms a part of the vacuum envelope (in which case the cooling is by conduction through the anode material and then convection outside the vacuum envelope). Thus anode cooling occurs in most tubes through black-body radiation and conduction of heat to the outer glass envelope via the anode mounting frame. Cold cathode tubes do not rely on thermionic emission at the cathode and usually have some form of gas discharge as the operating principle; such tubes are used for lighting (neon lights and neon glow lamps) or as voltage regulators."

Do you possibly believe that you can pre-heat a tube to anywhere remotely close to operating temperature?

uh, did I ever say that?

And regarding your last statement that there is no such thing as heat potential in a tube. Really?

Despite referencing several textbooks as well as the web I find no mention of the phrase "heat potential" when it comes to vacuum tubes.. I make no apologies if I misinterpreted what you meant when you used unconventional terminology.

So you believe that the anode and cathode in a typical vacuum tube are EXACTLY the same temperature?

uh, did I ever say that?

Granted, the cathode is generally heated to increase electron emission. That in no way negates the fact that keeping the tube warm when it is not in use will decrease warm up time.

You all can ignore what the original poster asked and try to nit pick responses, but the fact remains... if it starts out at a warmer temperature it will reach it's operating temperature more quickly. That is crux of the debate, double speak and patting yourself on the back for clever responses "I just knew that you were going to reply the way that you did" doesn't preclude the fact that any of you who dismissed the reality that preheating the equipment has a positive effect were wrong.

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