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calling all Guru;s, Ideas on audiophyle high effeiciency speakers solicited

Wanting to enter the "Tube system" realm. After extensive research I've come to realize that my current low efficiency speakers B&W 803D2 require a lot of power and may not cut the mustard using tube gear. Although I truly love the speakers I may end up swapping them out in the future to accommodate my new found rabbit hole. Tube amps in general provide only minimal power certainly not enough for my listening habits. 
Anyway what , by any standard, constitutes a high efficiency speaker? is it a rating of 80....... 90, 92,......97? just what is it. Do speaker manufacturers fudge the number on occasions? How do we know? Is a 2 way design inherently more efficient than a 3 way? Does  the amount of speakers in a cabinet affect efficiency?
Last of all what are some audiophile grade speakers? 
gillatgh

Showing 2 responses by helomech

helomech
1,782 posts
 
You're speakers allegedly have 90db sensitivity with a nominal impedance of 8 ohms. In theory, that's fairly efficient by today's standards, and should work with a tube amp of about 50 watts. After all, B&W recommends a minimum of 50 watts. However, it seems most B&W owners end up settling with powerful SS amps. 

If you want to try tubes with your B&Ws, I have no doubt that a Rogue Audio Cronus Magnum will drive them to sane volumes. That's about the most glass power one can get for the money. If your heart is set on low power SET amps, you'll need different speakers, ideally some of 94db sensitivity or greater.

 Some will tell you that tubes necessitate 3-digit sensitivity. That's complete rubbish. I can drive my 87db spec speakers to loud volumes with 45 tube watts. Also, room gain, listening distance, music genres, particular amp design, and desired headroom play a significant role.
helomech
1,782 posts
 
Is your SPL meter measuring with "C" weighting?

Most quality 4 ohm amps can handle 2 ohm impedance dips. The Rogue will be fine in that regard. From personal experience with that amp, I can tell you that it doesn’t sound anything like a full tube design, even with vintage 12AU7s. It seems many buy these (and the Sphinx) amps thinking they’ll get the best of both worlds: high damping factor and power combined with a lush and 3-dimensional midrange for which tubes are known. I’m sorry to say that is not the case. These hybrids merely sound like other Hypex class D amps. But not only do they not emulate a true tube amp, they don’t possess the impressive bass depth and heft of a good SS design. Compare one, level-matched, at about 70db to any decent class AB amp and you’ll notice a huge disparity in bass extension. However, if driving your speakers to high SPLs without clipping is your goal, they’ll do just fine.

I’ve also had the Rogue Audio Cronus Magnum II. I was surprised by how much it outperforms the hybrids in every respect, partly because a Rogue employee suggested I buy the Pharaoh.

In fact, my performance ranking for their integrateds: Pharaoh < Sphinx V2 < CMII.
Yup, I actually preferred the Sphinx to the Pharaoh. Its soundstage wasn’t as wide but it was better balanced and actually seemed more powerful.

Use the Pharaoh in your system for a while so you can truly appreciate a real tube amp when you finally take the plunge.
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