Jweilers1 is not correct, old Fender amps are not like newer or modern tube amps. They are based on very old circuits that were licensed from companies like Western Electric etc. They were not Fender’s own circuit design. When you aren’t playing them for more than 10-15 mins put them in standby mode or in the case of a vintage Champ etc, turn it off! It doesn’t need an hour to stabilize, it needs 5 mins. A Champ, that many famous recordings were made with, is simple one half of a table radio in a box, it is not voodoo like many will make you believe. Families turned their radio on, listened to their shows then turned the radio off, they didn’t leave it on, nor did they warm the radio up for an hour. When you meet a great guitar amp tech you will learn the difference between the voodoo we read in our audio hobby versus what really makes a difference in a circuit. Also, ask a good guitar amp tech what kind of power cable you should use, he should have some $2,500 units on the shelf that sound better, LOL!!!
