Ambient temperature and tubes

[whitelabrat]

I'm thinking of building an remote power amp that will reside in the Garage, next to my listening room. Would I get into trouble starting up an amp from zero Celsius or less? Does anyone have experience with the reasonable limits of ambient temperature?

I understand that most components such as capacitors are rated for use well below freezing, but the tubes do need to be warm.

[ratza]

They will widthstand for sure. Tubes are almost void inside and they're not sensitive at all at low temperatures.

[kevinkr]

Originally Posted by whitelabrat

I'm thinking of building an remote power amp that will reside in the Garage, next to my listening room. Would I get into trouble starting up an amp from zero Celsius or less? Does anyone have experience with the reasonable limits of ambient temperature?

I understand that most components such as capacitors are rated for use well below freezing, but the tubes do need to be warm.

Actually you do need to be careful of electrolytic types - most commercial types are not rated for operation at freezing and below. Film caps have no such limitation.

A bigger concern IMO is the possibility of condensation forming on components when there are significant changes in temperature and humidity over a short time period when the amplifier is not on. Cold and dry conditions followed by a rapid increase in temperature and humidity will result in condensation in all the wrong places without care. As an example all of the transformers I stored in the open in my dry garage rusted over time due to condensation and I finally had to move them indoors.

Take a look at some of the techniques the military used to ruggedize electronics for outdoor use during WWII, you may want to "mildly" implement some of those features. (Conductive surfaces and anything that can rust needs to be protected - including transformer lams. The chassis probably should be reasonably hermetic, but provisions for cooling components need to be considered. Use chassis mounted power resistors.

Something else - if you plan to use mercury vapor rectifiers in the PSU you must allow for much more warm up time in cold weather in order to allow the mercury to fully vaporize before applying plate voltage to them.

None of this is insurmountable and won't even add much cost or complexity if accounted for from the beginning.

[PigletsDad]

I have found polystyrene capacitors to fail on temperature cycling - it was over a bigger range, in the lab, but the other film types that we used were all fine.

Electrolytics certainly fall in performance at low temperature - the ESR goes way up.