Ampeg v4b in 15 degree temp

[megafiddle]

I needed to search around a bit, but I found a low temperature rating for a 6L6:

Link Removed

Operating environmental conditions : -70 to +60 C

The temperature difference between the heated and unheated parts of the tube will not necessarily be any greater in colder environments.

A tungsten heater has a certain amount of self regulation because of the positive temperature coefficient. So I would expect the heater to run at a fixed temperature independant of the ambient temperature. But with a heater at 1600 F (for example), the temperature difference in the tube is still pretty similar for a weather change of 15 F to 75 F,
1585 F vs 1525 F.

The plate and screen do not run at a fixed temperature for a given power dissipation. Instead, they will have a certain temperature rise above ambient. If the ambient temperature is 60 F lower, the plate and screen will also be 60 F lower. So the difference between the plate and screen, and the cooler parts of the tube will not change as much with ambient changes. The heater does contribute to the plate and screen's environment.

-

 

[B-string]

I needed to search around a bit, but I found a low temperature rating for a 6L6:

Link Removed

Operating environmental conditions : -70 to +60 C

The temperature difference between the heated and unheated parts of the tube will not necessarily be any greater in colder environments.

A tungsten heater has a certain amount of self regulation because of the positive temperature coefficient. So I would expect the heater to run at a fixed temperature independant of the ambient temperature. But with a heater at 1600 F (for example), the temperature difference in the tube is still pretty similar for a weather change of 15 F to 75 F,
1585 F vs 1525 F.

The plate and screen do not run at a fixed temperature for a given power dissipation. Instead, they will have a certain temperature rise above ambient. If the ambient temperature is 60 F lower, the plate and screen will also be 60 F lower. So the difference between the plate and screen, and the cooler parts of the tube will not change as much with ambient changes. The heater does contribute to the plate and screen's environment.

-

This just reminded me for some reason of the old radio hacker days. With the old metal 6L6 they used to fit a tin can around the metal 6L6's and seal the base so they could fill it with water. Doing this could increase the output power greatly (by the standards of those days anyway).

 

[nashvillebill]

Vacuum tubes were used in missiles as well as high-altitude bombers. 15 degree temperatures are not a problem!

 

[comet9]

Update..amp worked fine. Warmed it up about 20 minutes..no problem,sounded great but I don't think it was even 15 degrees. The extreme cold hurt the turn out but we got paid. One for the books.

 

[JimmyM]

Update..amp worked fine. Warmed it up about 20 minutes..no problem,sounded great but I don't think it was even 15 degrees. The extreme cold hurt the turn out but we got paid. One for the books.

Turnout schurnout...just pay me

Glad it went well.

 

[BassmanPaul]

People make all together too much about a tube amps frailties. Cold glass is warmed by the tubes heater. The colder it is the longer it takes to warmup is all. Just about the only thing to be careful of is water hitting the tubes when at operating temperature. Never once in all the years I used tube amps did one fail 'cos the ambient temperature was too cold.

 

[Luckydog]

I hate playing in cold temps. Much prefer excessive heat than bitter cold. Good on ya that you made out ok.