Keep it dry and covered all the time unless you're using it. Warm it up on cool days, fine for the rest of the day. 35-40 kinda a lower limit, with older valve amps. SS they can get pretty cool. 20 degrees is cool.
I'd think 5 under a small heating pad, or a 1-2 min hair blower take the frost off. Someone will chime in and, say.. "I was on the Island of ICE COLD" and it was 50 below. No problem plug it in and let er rip... LOL Be careful... That stuff worked in Korea, freezing cold...Flip the switch and the PA work, at 10 below..
Regards
I'd think 5 under a small heating pad, or a 1-2 min hair blower take the frost off. Someone will chime in and, say.. "I was on the Island of ICE COLD" and it was 50 below. No problem plug it in and let er rip... LOL Be careful... That stuff worked in Korea, freezing cold...Flip the switch and the PA work, at 10 below..
Regards