Tube amp warm up

Hey, I've got a question! I bought a 2 year old tube amp that hadn't been used for almost three months. It took a number of hours to sound it's best but now sounds superb after 10-15 min of being turned on. Wonder what the technical reasons are for it not sounding its best after being 'on the shelf' for 3 months?

Probably the capacitors needed to be "reformed" by use. That is the reason people slowly bring up voltage using a variac for equipment that has been sitting for years.

Larry,
What does 'reformed' mean? Also, have you ever heard that the more use transformers get, the better they sound? I seem to remember hearing or reading that many years ago but it doesn't make any sense to me.

A lot of warmup character has to do with the tubes themselves, as well as filter capacitors.

As most of you might know, we don't have any transformers in our amps, and our MP-1 MkIII is entirely regulated, yet the warmup character on any of these is the same as almost any other tube amplifier or preamp, so my belief is that it is 90% the tubes.

Most of the transistor stuff I've had over the years needed to be on for about a week to warm up properly.

As the charge builds on the plates of the capacitor, they actually move a bit in relationship to one another. But, for something sitting around for a few months, that is not the issue.

Still, capacitors take a very long time to come up to song, some types and brands more than others. I know a designer who uses Blackgate brand capacitors, but has put in alternatives for customers who do not want to keep their amps powered up all the time. He told me that his amps sound thin and dry if the Blackgates are not kept charged all the time.

My amp has a lot of Blackgates in them, but I cannot see myself leaving the amp on all the time. For me, it is more a safety concern than life-of-tube issue -- the designer insists that the tubes will last longer being left on all the time rather than being subjected to harsh turn-on conditions.