High value, high efficiency speakers for SET amps


Hi, Gang,
I know that some of what I want to discuss here has been dealt with in other threads, some of them quite old, but I wanted to see if any of you fine, knowledgable folks are willing to help update and consolidate some of this info in a more current thread.
I am currently running my new Audio Note Kit 1 300B SET amp with a pair of Reference 3A De Capo speakers. I think it's a fine pairing and I am really enjoying what the 300B SET experience brings to the table in terms of musicality and emotional connection.
Still the De Capo, while supposedly an easy load due to its crossover-less design (only 1 cap on the tweeter with the mid-woofer directly coupled to the amp), is "only" rated at 92 db efficient, and based on the most recent Canadian NRC specs, that rating may be optimistic.
So, I am toying with the idea of trying a pair of more efficient, deliberately SET-friendly speakers in my rig, something that might also play lower and with greater dynamic swing than the De Capo's. Note that the De Capo's have served me well and I am very fond of them, but I can't help but wonder if my lovely Kit 1 would shine even better coupled to a VERY easy to drive speaker.
Devore and Audio Note are obvious options - the O/96 looks really tasty. Unfortunately, both of those choices are out of my budget, which I'm thinking maxes out (for real) at around $1500. I am willing to consider used equipment.
Tekton Lore 2.0: This is the speaker that Eric Alexander of Tekton has recommended when we've spoken on the phone, based upon my medium-small listening room and amp. I've read the epic "Lore vs. Zu" thread elsewhere in this forum, and clearly Tekton has its enthusiastic fans here. What I wonder is whether the Lore 2.0 has the refinement of the De Capo in terms of resolution, sweet high end and imaging. Audiogon'er Mikirob has pointed me to the many rave reviews of Tekton's speakers and I'm definitely interested.
I've corresponded with the Sonist folks (who are super nice) but their really high-efficiency, nearly-full-range floor stander is out of my budget.
Then there's the "vintage" route, going after some used JBL's or other high-efficiency "classics" from the 80's (or '70's). I am not inclined to go in this direction, but mention it because it's been suggested to me.
And then there's Omega. I spoke to Louis some time ago and he recommended his 7XRS hemp cone model. But I know all the raps on single driver designs and I'm cautious, although I would like to hear from any of you who own or have owned Omega's.
I'm in no rush to make a switch but I am very interested in your thoughts. Thanks, folks!
rebbi
REb, I would take advantage of going back and spending some time with Sebrof's or any other SET based system you might have access to that can serve as a reference. Hearing and recognizing a reference standard is really the only way to know what is possible or what one might be missing. In teh end, on a budget, with a SET, I think it will mostly boil down to how much low end extension is needed. That's often the case but even more so when watts are few and precious.
The Classic Audio Loudspeakers have efficiencies that are what you want for a 300b SET (which only makes about 7 watts). The best suited in their line is the Hartsfield reproduction.

Sorry to pop some bubbles here:

The problem you are up against is that with almost any SET, if you really want to hear what the amp really does (the magic) you really **don't** want to push it past about 20% of its full output. If you do, the higher ordered harmonics come into play and there is an interesting interaction that occurs with the human physiology when that happens!

(The interaction is that the higher ordered harmonics will be showing up on transients, and the ear/brain system will interpret that as loudness. As you increase the volume, the loudness cues are thus initially only occurring on transients. Thus the amp will *seem* to be much more dynamic than it has any business being for its output power! This is a common comment about SETs- and one that indicates that the amp is not set up properly. The speaker used needs to be more efficient to avoid this problem. BTW, now that you have read this I may have ruined it for you: knowing that the dynamic quality is really caused by distortion makes it easier to hear the distortion itself.)

(A further note: about 90% of the time when audiophiles are talking about 'dynamics' they are really talking about distortion. The word is so heavily charged that if I really do mean dynamics I often use other words such as 'impact'.)

So with only 2 watts or so to really play with your speaker must be over 102 db or so- otherwise you simply are not hearing what the amp can really do. SETs have the property of distortion that becomes unmeasurable as power is decreased; this is the source of their 'inner detail magic'.

The bottom line is if you have a 300b SET, unless your room is very small you will need a horn system of some sort; single driver speakers like the Zu or Lowther simply lack the efficiency in an average room.
Well, I do have single driver Zigmahornets but also run Coincident Conquest & Mini Triumphs. The Eclipse is out of your budget.
Atmasphere,

I think you are assuming that the speaker is full or near full range with your numbers.

Smaller speakers with less low end extension MUST require less power to achieve a certain level, all else the same.

The lower the frequencies attempted, the more power is needed, all else held constant. I think that is basic physics.

So I think my argument is sound that one way to coax more out of a few good watts is to defer on or even filter out the lowest frequencies if needed one way or another at some point. That allows your watts to go further.

The sacrifice is the lowest octave or so to some extent but the fact is that may not matter much for most recordings, especially in a smaller room.

But you are correct that the only way to get flat response full range sound out of a few watts is very high efficiency speakers. I have only heard it achieved well with very expensive and very large horns, along the lines of Avantgarde or similar custom horns.
Rebbi,
I will email you regarding my personal experience with 300b SET, OTL and speakers with sensitivities of 92-95 db. Believe me you have a fine amp with many good options. Trust me.
Charles,