That "tube sound" and power ratings

Mesch- Agreed! It's a bit of a circus in a classroom ... fun, educational and full of entertaining surprises.

Zd542, Zkzpb8, Charles1dad & Atmasphere - many thanks for keeping this thread moving forward.

Atmasphere writes ...

"you never want to push an SET past about 20% of full power or else the higher ordered distortion products come into play (when this happens, its usually on transients, and because the human ear uses the higher orders as loudness cues, the result is that the SET sounds a lot more dynamic than it has any right to because the loudness cues are occurring on the transients. You read about this 'dynamic' character with SETs all the time, but its an indication that the speaker used is not efficient enough)."

20% of full power (I'm assuming that means average power) is a significant % but not outrageous if the speakers aren't crazy-sensitive. Am I to understand that SET owners go into it knowing they NEED to keep this contract if they want to enjoy their sound? If the "SET sounds a lot more dynamic" as it encroaches on this forbidden region, isn't it reasonable to think that SET owners (or dealers or wannabes) might poke through that limit just a wee bit to enjoy the subtle excitement of the extra dynamics? I need to hear this myself to know, but my guess is that doing such a thing might lead to one of those "wow, I never heard THAT before!" kind of moments.

Underpowered amps of either type certainly wouldn't be the fault of the particular design. Operator error seems like the right diagnosis.

Good question, Hazyj...

First and foremost, I'm not in the "tube vs SS debate"; however, I will unequivocally state that tube amps sound more powerful, watt for watt, and that's all I'm going to say about that.

That's definitely true that in the studio it's processing the signal - but at home, tube amps are often doing the same thing. It is a form of distortion. Not all tube based systems distort this way, but I do see lots of listeners using underpowered amps for the speakers they have.

Tubes are a great way to emotionally get close to the music - I think of tubes as a way to create an illusion that performers are in the room with you - but I never think of this as accurate or neutral - but it can be very involving...

At home distortion is not the name of the game. Seriously. The ability of a tube amp to reproduce a more realistic soundstage (as depicted in your 2nd paragraph) is because they are better at low level detail which comes from the greater linearity that tubes offer. I've always been perplexed by the universal admission by both tube and transistor camps that tubes are inherently lower distortion, but then tubes are always getting docked for being 'distorted' simply because they sound better. The real reason they sound better is they have less of the distortions to which the ear is very sensitive (specifically higher ordered harmonics) although some designs may have more of the types to which the ear is not.

Many recordings are in fact made to present a true stereo image, which means a 3D soundstage with depth and Left-right extension, with everything in between.

20% of full power (I'm assuming that means average power) is a significant % but not outrageous if the speakers aren't crazy-sensitive. Am I to understand that SET owners go into it knowing they NEED to keep this contract if they want to enjoy their sound? If the "SET sounds a lot more dynamic" as it encroaches on this forbidden region, isn't it reasonable to think that SET owners (or dealers or wannabes) might poke through that limit just a wee bit to enjoy the subtle excitement of the extra dynamics? I need to hear this myself to know, but my guess is that doing such a thing might lead to one of those "wow, I never heard THAT before!" kind of moments.

I do see more people using speakers that are less efficient then the SET should really be used with, and they still enjoy the result. But its a simple fact that they are not getting nearly the performance out of their amplifier, simply because they are pushing it too hard. Most SETs don't employ feedback (this has a lot to do with the fact that you can't use feedback to extend bandwidth in a power amplifier, and if you are not really really careful with your timing constants in the feedback loop, the poor high end response of most SET OPTs will really get you in trouble- peaks before the roll-off, unstable operation, that sort of thing.

So since feedback is unwieldy and sounds wrong because it rarely can be applied properly in an SET, most designers don't do it. As a result, if you run it over 20% full power (on peaks, not average) the higher ordered harmonics will come into play, causing exaggerated dynamics and harsher sound. BTW once you know that distortion is responsible for a lot of the 'dynamic' quality of SETs, its easier to hear that it is in fact distortion doing it, so by reading this I may have ruined if for a lot of people. Sorry about that.

To take this a bit further, distortion is really a problem in all systems, not just SETs or tubes in general. As a result, I suspect that in about 90% of all audiophile conversations, the word 'dynamics' can be substituted with the word 'distortion' without altering the meaning of the conversation at all. For this reason I am careful to use a different word, like 'impact' when I want to talk about dynamic contrast. Too much unconscious stigma with the word 'dynamics'.

I've said it before, but it bears repeating even if I'm the only one who believes it: Tube amps make you a better person, they display signs of life in their glowing hot little selves, and SS amps that just sit there like a metal lump of "meh" are far less interesting regardless of how they sound, unless they have some sort of fluctuating meter on them in which case I give 'em a pass (no pun intended). A home run amp I heard recently was a Rogers (there are others) that had tubes AND a meter...a goal for all tube amps to strive for.

Atmasphere. Thanks for clarifying Peak vs Av.

Orpheus10- I almost skimmed past your post. Most helpful - thank you.

"That's definitely true that in the studio it's processing the signal - but at home, tube amps are often doing the same thing. It is a form of distortion. Not all tube based systems distort this way, but I do see lots of listeners using underpowered amps for the speakers they have."

Just to clarify, I was talking in general theory as to what is expected of a home stereo. Reproduce the original event as accurately as possible, etc... You've heard it all before. I wasn't suggesting that everybody approaches their system that way. There's the 2 extremes, and most people are somewhere in the middle.

"Tubes are a great way to emotionally get close to the music - I think of tubes as a way to create an illusion that performers are in the room with you - but I never think of this as accurate or neutral - but it can be very involving..."

Why not? When you go see live music, do you expect it to be accurate, neutral and not emotionally involving? lol. I know I do. I want it to sound just like my stereo system at home.

Zd- say again? Just that last paragraph - not sure what you mean.

,
Live music is all about inducing emotions,
involvement and simply being fully engaged. That's the joy of music's
ability to communicate. Tubes don't totally equal that live experience but
they bring me much closer than any SS amplifiers I've heard so far (25
years of High End awareness).How can something be considered
"accurate" and fail to be involving? The more effectively a
component can mimic live sound the more involving it will sound. This is
what I call "natural" sound or realism. In my personal discovery,
SET amplifiers have pushed me the furthest in this beautiful direction and
there's no going back. Everyone must find what works best for their needs
and ultimate satisfaction.
Charles,

Thanks to everyone who posted here - there most certainly is more to this than meets the eye, and ear!