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Power output of tube amps compared to solid states

I'm having a hard time trying to figure out how tube amp power output relates to solid state power output. I've been looking at the classifieds for tube amps and I see lots of tube amps with 50w or 60w output, but nothing close to the 250w output typical of solid state amps.

So I have no idea what type of tube amp is required for my set up, right now I'm using totem forests with a required power rating of 150w-200w at 8ohms. The bass is so powerful on these that I have the sub crossover set to 40hz.

My question is, are tube amps so efficient that 50w from a tube sounds like 150w from a solid state? Or will 50w output from a tube severely limit how loud I can play my speakers? If so, are tubes usually meant to be driving super-high efficiency speakers?

I had previously tried a tube pre-amp with a solid state power amp (both musical fidelity) and didn't like the results because the imaging suffered greatly, even though the music sounded nicer from a distance. Now I want to try a solid state pre-amp (bryston) with a tube power amp (no idea which brand to look at), but I don't know how much power output I need or if it will even be possible with my speakers. Does anyone know what I would require?
acrossley
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shadorne
7,477 posts
 
04-10-10: Unsound
Shadorne, well done.
The link Atamasphere provided is really worth a look.

Thanks - yes it was very interesting and useful. Please bear in mind that all the experimental results were for "infinite baffles" (no box).

The acoustic suspension is usually the most powerful damping force in a box speaker (until you get below the port resonance in a ported design when it begins to behave like an infinite baffle). This controls whether the speaker will sound "boomy" (underdamped) or "tight" (critically damped) over the designs resonant frequency. In practice it is rare to find a design that is overdamped.

In infinite baffles the amplifier damping along with Qes becomes the dominant factor...and in this case the match with the amplifier is indeed critical as the amp can control the overall system Q to a large degree - to the good or the detriment of the sound.
kirkus
502 posts
 
This particular paper is interesting, but very dated . . . and no disrespect to the author or his work in context of the time. But it's important to understand that this was published some fifteen years before that of Thiele and Small, and the T/S equations predict exactly every aspect of the driver/source-impedance interactions that he gives these approximate, experimental methods for optimizing.

It also bears mention that at this time, typical loudspeakers were designed with a very small back-enclosure and a horn (using Webster's equations), or a very large infinite-baffle . . . reflex designs were extremely rudimentary and typically more like an infinite-baffle as far as the system Q is concerned. Let's also not forget that liberal application of tone controls was also not frowned upon like it is today . . . a great way to compensate for all kinds of unanalyzed factors relating to speaker design.
pubul57
3,712 posts
 
THaks Shadorne, that explasins what Bobby was talking about, with which he then says, which is why it works so well with tube amps, Atma-sphere among the best with my speakers.
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shadorne
7,477 posts
 
THaks Shadorne, that explasins what Bobby was talking about, with which he then says, which is why it works so well with tube amps

Indeed, a critically damped acoustic suspension speaker does not need an amplifier with high damping factor as much as your regular underdamped boomy type designs that will get positively sloppy without amplifier control.
unsound
7,333 posts
 
Shadorne, a long time ago I remember reading(though for the life of me, I can't remember where or when), that one shouldn't use a DC coupled amp with ported speakers. I am under the impression that DC coupled amps are noted for their tight bass response. Not that I doubt you, but, if all that is correct (and it very well might not be), it would seem to disagree with your last post. My, how this thread has taken off on another path!
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