Effect of cold on tubes/valves

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Effect of cold on tubes/valves

Postby jeffl » Wed Dec 07, 2005 7:36 pm

If your tube amp is sitting in a cold car all day (say 0 degrees F.), are the tubes subject to damage from normal jostling in the vehicle when you begin to drive down the road..? And, once you get the amp inside, can you turn it on and warm it up when the tubes are still cold to the touch,or should you let the room warm it up to room temp.first...?
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RE: Effect of cold on tubes/valves

Postby ricochet » Wed Dec 07, 2005 8:08 pm

Won't hurt the tubes. I don't worry about warmup/cooldown myself, but if you bring one in from the cold and it's humid enough inside for it to form condensation, it'd be best to let it warm up and dry off.

It is possible for the electrolytic capacitors in any electronic equipment to feeze. But it's got to get really cold for that to happen, like cold enough for the coolant in your car to be in danger of freezing. I normally just have my amp out in the car long enough to carry it from home to the office and back, 1/2 hour or so at most, and don't worry about that stuff.

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RE: Effect of cold on tubes/valves

Postby randy101 » Wed Dec 07, 2005 8:41 pm

I thought that I was the only one who snuck his guitar and amp into work.
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RE: Effect of cold on tubes/valves

Postby jeffl » Wed Dec 07, 2005 8:55 pm

I didn't know Rico ever took his home from the office..I thought he kept one rig there. Myself, the rehearsals with the current band are in town,and I live 18 miles out,so on rehearsal days, my rig sits in the car for 10 hours before I head out to practice that nite. It does seem like tubes don't need much time to reach room temp when setting up for a gig though...faster than I would've thought. And,BTW, I usually let my amp warm up for 15 to 20 minutes even if it's not cold. I've been told the amp plays better if it warms up for a while.
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RE: Effect of cold on tubes/valves

Postby ricochet » Wed Dec 07, 2005 8:58 pm

I don't think it makes much difference. The freezing temperatures of electrolytics ought to be available online. I'll look around a little. Other than that, there's nothing in an amp that cold can seriously harm.

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RE: Effect of cold on tubes/valves

Postby randy101 » Wed Dec 07, 2005 9:05 pm

That condensation on the tubes would make me feel squeamish. Maybe its just me. I would worry more about my guitar.
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RE: Effect of cold on tubes/valves

Postby ricochet » Wed Dec 07, 2005 9:44 pm

I'm not worried about condensation on the tubes. It's the wiring under the chassis that'll cause problems if it's wet. There are terminals that may be at 425V in close proximity to grounded or somewhat negative terminals on the tube sockets.

As for electrolytic capacitors' freezing points, I've found a bunch of charts showing their characteristics down to -55 C or so. Most of 'em these days seem to have electrolytes based on glycerol or glycol solutions. I found this interesting quote on http://extremetemperatureelectronics.com/

At low temperatures, the most difficulty arises with components that rely on movement of ions or on chemical processes. These include electrolytic capacitors, some types of ceramic capacitors, and batteries. At low temperatures such activity "freezes out." Electrolytic capacitors typically lose capacitance rapidly upon cooling, and at cryogenic temperatures (below about −150°C) may have perhaps 10% of their room-temperature capacitance.

Obviously your amp is going to sound better after it warms up if it gets down to -150 C.

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RE: Effect of cold on tubes/valves

Postby trguitar » Wed Dec 07, 2005 11:48 pm

A vetran of cold climates, I can tell you there will be condensation when brought indoors and one tiny drop of water in the wrong spot could be very bad. I always let my gear ger to room temp before I plug in in the winter. Oh, and by the way, I know it might be unavoidable but I have read never leave your guitar in a place where you wouldn't stay. This is to say they like the same temperature and humidity that we do. My friend brought in his acoustic to work for me to look at so I could fix it up for him, he said "It's in the truck." and it was -20 that night. I set him straight on that one quick. lol A new saddle, some new bridge pins, strings and a neck adjustment and he was off and running. He has bought 3 new guitars since, can you say GAS boys and girls?
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RE: Effect of cold on tubes/valves

Postby bluejay » Thu Dec 08, 2005 8:23 pm

On the guitar front, I accidentally and stupidly left my Marin DMX acoustic in the car overnight after a house party last Friday night and the temps went down around zero. I was careful about bringing it in and letting it warm up while in the case (I think there is some great insulation advantage to it being an expanded foam-type of padded case), then just opening the case and letting it sit without touching it until it was close to room temp. Of course I bought the DMX, which is all high-tech materials except for internal bracing, because I wanted a guitar that I wasn't worried about dragging around (like I always was with my '68 Gibson acoustic). As far as I can see, none the worse for wear, but I'm still kicking myself for forgetting about it. All I did was take less than a minute to pull the truck into the driveway when I got home so it wouldn't be violating winter parking rules and leave me paying a $25 ticket, and ziiiiiipppp, spaced on grabbing the guitar out of the backseat on the way back past the car.
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RE: Effect of cold on tubes/valves

Postby blues power » Thu Dec 08, 2005 9:31 pm

[updated:LAST EDITED ON Dec-08-05 AT 04:33 PM (EST)]i know what you mean but i dont think it would cuse too much of a prob. common scense would say let them adjust to ambient tempuraters before you move it in or outside.

in the old days all the aircraft electronics were tubes and the fighter planes were not heated in WW 2. so i never heard of a prob
and they were subject to extreme temps and vibrations. i read up on history from the era every day and havent come acrost anything liek this.
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RE: Effect of cold on tubes/valves

Postby ricochet » Fri Dec 09, 2005 2:16 am

Yes, modern day tube amp advisors who suggest risk to tubes from not properly cooling them down before moving them seem to be unaware that all mobile radio equipment used to have tubes in it, and they were exposed to often rather severe vibration and jarring while hot, along with extremes of ambient temperatures, with no special warmup or cooldown procedures. The old tube manuals contain no such precautions, and no specs for minimum operating temperatures, only for maximum tube envelope temperatures in the case of rectifiers and power tubes.

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RE: Effect of cold on tubes/valves

Postby maxx england » Fri Dec 09, 2005 10:12 am

Can't add anything except I knew someone who damaged a Fender Twin by not making sure the valves were fully seated after a bumpy journey.
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RE: Effect of cold on tubes/valves

Postby ricochet » Fri Dec 09, 2005 2:37 pm

Hmmm, wonder what got damaged in it? Tube amps will usually run safely with any of the tubes unplugged completely. (Won't usually work properly like that, but won't burn anything up.) Did he get arcing in a socket or something like that?

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RE: Effect of cold on tubes/valves

Postby maxx england » Fri Dec 09, 2005 3:08 pm

I know nothing, technologically, I'm still bashing rocks together.
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RE: Effect of cold on tubes/valves

Postby ricochet » Fri Dec 09, 2005 3:24 pm

Ah, drumming then? ;)

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