What do you see as the downside of tubes?


I have decided on getting a tube amp and it will be the integrated Mastersound 300B driving a pair of Living Voice Avatars, so at least that decision has been taken.

My main question is what you see as downsides of having a tube amp. As I've decided on getting an integrated tube it's really about what the downsides are I might want to know about beforehand.

The ones I'm aware are the following.

-The tubes need to be replaced and in the case of a 300B this will be somewhat costly.

-Bias is another issue but I'm not sure how big an issue. Do you plug in your meter every so often or just when you roll tubes or replace a dead one? The meter as such isn't gonna be a big issue as I don't think it's that expensive.

-Heat won't be a big issue as we have no kids nor a nosy dog that could get burned. Hope my electricity bill isn't gonna go through the roof, but then again, I can't quite imagine that.

I'd appreciate if you could add whatever your experiences are regarding this question are as I'd like to know more before I buy it.

Thanks
krauti
Mapman-I sure it has to do with the flow of electrons in solid state junctions of pnp or npn materials vs the flow in a vacuum from cathode to plate thru the grid(s) in your output tube; somehow harmonically there is a difference that can be heard.
I sure Ralph will expand on your question as well if he sees it;thats the best I can do.
Actually, Carver showed that an amp could be *modeled*, but even in his tests the modeling did not match the actual behavior of a tube amp.

Mapman, here are some primary differences.
1) Tubes are often much more linear than transistors. Triodes are the most linear form of amplification known. This results in far less need or no need at all for feedback to reduce distortion.

2) tubes produce mainly lower-ordered harmonics, transistors tend to produce higher ordered harmonics, especially odd-ordered. This can be easily seen in the overload characteristics of the amplifiers where these behaviors are exaggerated. Anyone who has run an amplifier into clipping and observed the output with an oscilloscope knows what I am talking about

3) tubes tend to high impedance while transistors tend to low impedance. In addition, there are capacitive effects in transistors that are magnified at higher currents. The effect of this is that both transistors and tubes will sound better (lower distortion, smoother sound, greater transparency) when driving higher impedances.
Atmasphere...As I recall (and it was a long time ago) after "modeling" Carver inserted networks to match what was modeled. Listening tests by a gang of golden ears were unable to distinguish the modeled amp from the real thing.

May I submit that a D/A conversion (digital amp) can be much more linear than any analog component (eg: tube).

Clipping characteristics are of academic interest. I don't operate my amps into clipping.
Eldartford-Was the modeling used by carver the t that he started to add in his amp names?
Atmasphere,

Are those things inherent in all tubes versus all transistors, or just more common in practice?

Also, if inherent, technically what is different that accounts for these differences?