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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
rebbi OP
1,326 posts
 
Brownsfan,
I suppose it makes some sense, at least intuitively, that the De Capo's would be particularly sensitive to amplifier topology, since the main driver is coupled directly to the amplifier signal. I'm sure there's more to it than that, but, based upon your experiences, my experiences and the fact that Reference 3A recommends one of the Antique Sound Lab 300 B SET amps, there really is some "magic" with that speaker and this kind of amplifier.
So it makes me think that when looking for a speaker for this kind of amp, it makes some sense to look at brands that are not only high-efficiency and flat impedance, but also otherwise designed with single ended operation in mind. Again, I don't know the physics and engineering of this, but there must be other factors involved in designing a speaker specifically to be "SET friendly."
Almarg, feel free to chime in here. :-)
charles1dad's avatar
charles1dad
10,250 posts
 
Brownsfan (Bill),
It's very interesting to note that you, Rebbi, Rob and the speaker's builder cite the terrific results of 300b or SEP with the De Capo. This in spite of the warnings that the speakers demand more power. Well your Cary and Rebbi's Manley met that criteria yet were found to be inferior sounding. Again proving nothing takes the place of actually listening. Bill you mentioned psychology and for some it is a significant barrier to acceptance.
Charles,
rebbi OP
1,326 posts
 
Yes, Charles, I now find myself firmly in the "measurements are useful, but how does it actually SOUND" camp. :-)
almarg's avatar
almarg
9,670 posts
 
04-30-15: Rebbi
So it makes me think that when looking for a speaker for this kind of amp, it makes some sense to look at brands that are not only high-efficiency and flat impedance, but also otherwise designed with single ended operation in mind. Again, I don't know the physics and engineering of this, but there must be other factors involved in designing a speaker specifically to be "SET friendly."
Almarg, feel free to chime in here. :-)
I don't know either, Rebbi. And in the absence of empirical inputs from users and/or the manufacturer, I doubt that it could have been predicted based on its published and measured characteristics that the De Capo would have any particular synergy with SETs (within the maximum volume capability of the combo). Although as you realize the De Capo's relatively benign impedance characteristics at least do not exclude the possibility.

Some very speculative guesses, though, as to things that might be contributing factors:

1)Although I haven't seen any frequency response specs or measurements on the Kit1, I would suspect that it has a more limited bandwidth at both ends of the spectrum than most push-pull amps. Perhaps that helps to keep frequencies out of the De Capo that don't have much if any audible significance but that it might not be able to handle comfortably (i.e., without intermodulation or other effects that could result in those frequencies affecting audbily significant frequencies).

2)Perhaps the design of the De Capo is such that it particularly benefits from the enhancement of dynamics that SETs will tend to provide, as Ralph/Atmasphere has explained is a consequence of how their distortion characteristics vary as a function of signal level.

3)As shown in the NRC measurements, the De Capo's impedance has a sharp rise to about 30 ohms in the vicinity of 70 Hz, where a lot of energy is often required. Relative to its rated power capability, a SET will be able to deliver more power into that high impedance than most push-pull amps, especially solid state amps.

As I say, though, those are all just speculative guesses as to what might be contributing factors, and I don't think that this particular synergy (within the maximum volume capability of the combo) could be either ruled out or ruled in "a priori." So I agree with the comment by Charles just above.

Best regards,
-- Al
mikirob
955 posts
 
Charles,
Believe it or not one was for sale here for less than $600.00. I just missed it! At any rate I am on the hunt. If I must pay full price, that is ok. Beats paying $7,000 plus for the latest Lampizator. I am happy with the MiniMax DAC, likely even more happy if I change Op Amps per Doug Schroeder of Dagogo.
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