My tube amps sound better the longer they're on..

[leadfootdriver]

When I power my amps up, they sound pinched an nasally. The longer I play them, the more natural and detailed the sound gets. The highs are pleasing, the lows are warm... U get it..

They're must be something about the whole amp getting warm; caps and resistors, wiring that effects this and not just the tubes. I was hoping someone could explain this.

[Justin Thomas]

Darn right there is. Sometimes I leave mine in the car all day with the Windows up to accelerate the process. (I mostly play heads - no "what about your speakers?" please!

Justin

[Chuck H]

Many things in your amps change between cold and warmed up. This could well be what you're hearing. I won't mention speakers, but I will mention ears. Listener fatigue, even at low levels can have a profound affect on perception. I'll guess it's a combination of both. One way to tell would be to do like Justin and leave the amp in a hot car (or similar, sunny window. hot day, etc.) Then see if the process goes faster than a couple of hours. If it doesn't then listener fatigue is probably part of the equation. Most guitar amps warm up just fine idling or cranked because there's not a profound difference in current for many designs. So you could also pay attention next time you're playing louder than average. If the process happens a little faster on those days then, again, listener fatigue could be part of it.

I mention this because as a designer I have done A LOT of listening at volume. There only so much you can take before you can't trust what you hear to be accurately considered. Many times I've thought I was on or off the mark during listening tests when I knock off for the day. Then the next day things are different without any other changes but time between the tests. I've noticed this is most likely to happen with long listening/testing sessions.

[m1989jmp]

When I power my amps up, they sound pinched an nasally. The longer I play them, the more natural and detailed the sound gets. The highs are pleasing, the lows are warm... U get it..

They're must be something about the whole amp getting warm; caps and resistors, wiring that effects this and not just the tubes. I was hoping someone could explain this.

Umm... bias current rising as the tubes heat up?

[leadfootdriver]

FTR, I have big amps that I play at home at low volumes, so I wonder if that has something to do with what I'm experiencing.

I know all about the Loudness Curves and how our ears hear things differently at louder volumes. When playing loud, the amp sounds and feels totally different than in the house..

So that said, last weekend I did a test where I recorded a riff after power up. I played for an hour and then recorded the same riff on another track to compare them. You can hear the difference no question. The warmed up take is even slightly louder.

[stokes]

Pinched and nasally? That sounds like a problem.A tube amp does get better as things start cooking,power tubes mostly.How long does it take before the "pinched and nasally" thing stops? It should be almost instantly.Once the tubes voltages are applied it should sound normal,not pinched and nasally.It will get better as things start to cook.How old are the tubes?What kind of amp?

[Chuck H]

...last weekend I did a test where I recorded a riff after power up. I played for an hour and then recorded the same riff on another track to compare them. You can hear the difference no question. The warmed up take is even slightly louder.

I'll be the first to point out that a good player has better tone using the same amp as a mediocre player. I don't suppose an hour into practice you were a little hotter than when you first started

[Enzo]

Here is a theory (more or less what Chuck said):
You start out, and after a while your ears get used to the level, and you turn up some. Your ears get more middle-y the lower the volume. Hence, at first your sound is more to the middle, and as you get louder, your end responses widen out.

[eschertron]

There are many psychological factors that are in play here.
One sure-fire way to eliminate all of them is to record some material directly onto disk (tape?) and then with all levels consistent, record a pass through the amp at first turn on and then after letting it sit and idle for a few hours. If you think it needs to be "played through" to really warm up, go for it but resist the temptation to tweak a knob during the session Be sure to record a pass of exactly the same material used for the initial 'control' pass.
Another test that can be performed if done this way onto a DAW, is to time-align the two passes, invert phase on one, and mix them together. any changes in the amp can then be really highlighted.

edit: I personally have never been able to do this because I can't resist the urge to change the amp's controls even when I've told myself NOT to.

[R.G.]

Folks, this is simple. It's well known that the girls all get prettier at closing time. Well, the amps sound better too.

[catalin gramada]

Do you like vintage ?

[J M Fahey]

Tone improves with time

[tubeswell]

Besides your ear fatigue, heat increases resistance and causes bias shift, so the way the circuit functions changes slightly with increasing heat.

If you get a 1959 plexi superlead really pumping, you'll notice that the amp sounds supremely awesome as the quad of EL34s light up cherry red (just before you smell that smokey smell) LoL