Seems like the best "upgrade" for tube amps.... to leave the amps on for a few hours before playing. I've noticed recently that when I turn on my Joule amps and let them run for hours, it makes a huge difference in the dynamics and high end sweetness. It gets hot in our house, but it's worth it. Is there a technical reason for this?
I have noticed the same thing with my tube amps, both my flea-powered 46 SE amps and my 50W PP amps. After 2 hours or so, I can hear greater detail and the soundstage has more of a see-through transparency. It's not a night-and-day kind of thing, but the music consistently sounds better a couple hours into a listening session.

I don't know any technical reason for this but it may have something to do with the heating of the transformer cores. A year or two ago I replaced the power transformers in my 46 amps with tranformers rated for higher current, and I notice the "warm up" differences much more now than I did with the old transformers.
Any real good system needs to warm up for an hour or two before sounding best. I deal with it by playing digital...then I switch to analog.
Are you saying let em warm without playing any music helps your tubes sound better or???
"12-16-14: Jriggy
Are you saying let em warm without playing any music helps your tubes sound better or???"

All components need to be warmed up for best SQ, not just tubes. Also, it doesn't matter if you play music, or not. Just as long as the components get warm.
Yes, it is true. Electronics do need some time to stabilize. This is especially true for tube gear which uses filament to heat up the electronics so after some time, they sound better.

Happy Listening.
Agreed. Tubes take some time to reach their best sound. I always find that music sounds better after the amps have been on at least 90 minutes or so.

Not day and night, but just more involving and enveloping.
You should turn your rig on and listen to it IMMEDIATELY before it gets too warmed up, and then turn it off after a few minutes and go away. It doesn't necessarily sound better, but this forces you to get out more.
Hmmmmm suppose you don't believe in foreplay either.
Service people that worked on tube equipment (TVs) back in the day have suggested letting tubes warm up before putting signal through them. Supposedly this helps protect and extend tube life. I wait at least 20 minutes after turning tube amps on before playing music. Independent of that, things do sound better to me about an hour into a listening session.
Isn’t it true that speaker cones also are designed to operate best at a certain thermal equilibrium point? Most often I let my whole system warm up prior to a listening session. Does sound better after an hour.
If I don't worm-up before lifting weights or swimming, I'll get sore or can get injury.
Worming up is illegal in my state
'Is there a technical reason for this?'
Technically, I call them "operating temperature". as all products (human & car included) were engineering, designed and tuned at such degree to its best.
If I let tube guitar amps warm up (for 30 minutes?) before using them I would make a lot of people stand around. My experience recently with a quad of kt120s was that running music through them as soon they were ready (30 seconds or so) caused the tubes to last about 7,000 hours, which was more than I expected.
Hi Wolf-Garcia, WOW, 7,000 hours !! What kind of amp are you using them in ?
That's good to hear about KT-120s. I have been using my pair for over a year so maybe I have a few more years to go. Mine are run pretty conservatively----500v and 65ma---so that should help.

By the way, I don't see any point in waiting very long before playing music through the amps. I usually let mine warm up a couple minutes (while I am sorting through LPs) but that's it.
Interestingly, a few hours of warm up applies to solid state gear as well. In fact the manufacturer of my solid state preamp recommends at least two days of warm up before listening, then leave it on continuously, turn it off and you will start over! I believe that these warm up periods involve the electrons finding their shortest signal path as well as transistors or tubes reaching their optimum temperature.
Jolida 502p, and I run it a lot.
With solid state gear if you want it to really sound right it probably has to be left on all the time- especially preamps.

Our amps seem to get to 99% of where they are going in about an hour- two hours they are totally there. In the old days it took more like three. I credit component improvements for the shorter time these days.
I have a Van Alstine Synergy 450 which has 12 separate power supplies,
Frank made the statement there were at their best within 10 minutes.
I was dubious but he was correct.
Well Frank at Van Alstine also says all caps, wire, parts etc... sound the same as long as they meet spec. I was close to buying some gear from him until he went off on that subject. I quickly realized while he is a great designer, he does not understand some other things that impact sound quality. Like worm up!
Grannyring, Frank has brought to market some very
interesting designs and appararently he has a good
following, you don't see too much of his gear for sale on
the used market very often. But I would have to disagree
with his statement that all parts sound the same as long as
they meet specs. When I owned an Audible Illusions preamp
and had some of the caps in the signal path upgraded to
Mundorf caps, the end result was nothing short of
spectacular, the improvement was dramatic.

As far as warmup times this does vary from one manufacturer
to the other depending on design. For example if you look at
the Odyssey Stratos, many people for the price love it but
the biggest complaint is that this amp takes forever to warm
up and sound its best. No wonder the power switch is located
on the rear of the amp.
Grannyring, that's why I sais I WAS dubious.
My ears know 10 minutes is all it takes on my AVA 450 .
FWIW, I never met anyone I agreed with on everything.
QuickSilver, VTL or Manley poweramps operate in 5...10min according to the measurements I've done in the past with analysing bias and transient responses via oscilloscope.
If I play same record first in 10m and then play it again in half-our, it might seem to sound different and so is CD. If I turn off the poweramp no matter tube or SS and turn back-on and after the settle time play the same, it will sound different again(actually that's the case of the most of improvement I've experienced).
Frank is a wonderful designer and like many skilled designers they simply don't have the desire or curiosity to try and experiment with "boutique" parts assuming they are a rip off sold to unsuspecting novices like me:)

I have owned one of his amps and heard his latest top model. Very good sounding for sure. He knows his stuff and I just wish he was more open minded to learn and give due diligence to "boutique" parts.

I have heard the same distain for upgraded parts, wire, tweaks etc.. from other very gifted designers. I suppose it is hard for them to find the time or passion to fully dive Into this world. I understand. So much to learn and experiment with and it is so hard to be expert in all things.

Schubert, yes your comment was understood and my comments are not all all intended to poke at you. I would also be dubious of that statement and may still be :)
The human brains goal is to provide a stasis, both psychical and mental.
If you make a design at first to keep costs at a minimum, you will not only believe that is the correct course, but if you are highly invested in that belief the brain will not let you hear any difference. Not saying Frank or anyone did this.

The main reason not to lie is soon you will believe you own lies.
Interesting thought and one that causes me to reflect on my own beliefs and biases on all things audio. Thanks much.
Not original to me, just my words.
Brain research has exploded in last few years.
It is possible that Frank feels that there is no substitute
for good engineering, even expensive parts. Case in point I
purchased a cheap chinese preamp, called Modwright to have it
upgraded. He asked me what would you have me do to it if your
not happy with the sound in general, I did read between the
lines at that juncture and let it go. But there are good
products out there that do benefit from upgrades.
Someone once said something along these lines: The sound quality of a given component is 75% due to the circuit design, i.e. the engineering, 75% due to component part selection, and 50% due to build quality.

I like this not just because it's funny but also because it reflects the truth that a given person can focus intently on just one of these aspects and can improve sound quality significantly and then conclude that this is the most important factor. For example, a designer might spend lots of time trying different operating points with his tube circuit, or a modder might spend lots of time trying different capacitors, or a builder could try different layouts and different chassis materials. Each one will find that some variations are better than others and there may be even be a "best." But this experience does not mean that this one approach (circuit design vs. component swapping vs. build quality) is the only or even the best road to good sound. They are all obviously very important, and none of them greatly outweighs the others in my opinion.

From the other posters' comments, it seems Frank Van Alstine is mostly in the circuit design camp, but I am sure that even he would acknowledge that component quality and build quality play some role in the sonics.
First you do the circuit design.

Next is to see how much it is affected by materials. Some areas in the circuit will be sensitive and other areas nearly immune.

3rd to to sort out what the best materials/parts are and install them.

4th- the 3 most important things in audio: listen, listen, listen.
Salectric, well said and spot on. It requires one to have an open mind and the desire to persue all these important aspects of a build and the resulting sound.

Atma, also well said as usual.