What's the greatest bargain in SET these days?


Hi, Gang,
I response to my recent review of the Reference 3A De Capo BE speaker, someone wrote that if you really want to hear them sing, you should try them with a SET amp, or words to that effect.
That got me thinking. The De Capo's are 92 db efficient, which (correct me if I'm wrong) seems kind of borderline for low-power SET amps.
In any event, right now I'm running mine with a pair of Manley Mahi mono-blocks. They are switchable from triode (20 watts) to "ultra linear" (40 watts). I run them in triode all the time, and in my room, the volume knob almost never goes past 9 o'clock; more would just be too loud.
All that said, what do you guys think of running the De Capo's with a SET amp? And if I did, what's the best bargain in SET's these days?
Thanks!
rebbi
Rebbi, my sense is exactly what you got from Steve Deckert. If I were going to use an SET with the deCapos for Mahler, it would have to be something like the Franks. Otherwise, I think I'm going to be very happy with the dynamo driving the deCapos.
I tend to agree with Deckert and Brownsfan. But I will say this: on large orchestral pieces, in my 16x14 foot office where the Dynamo's currently reside, hooked up to 95db 8ohm speakers I would not want to push the volume control much beyond 10 o'clock, even though they can go much, much louder without strain, but I'd like to save my hearing. Today I was playing large scale movie music, Gladiator, Ben Hur, El Cid and others, pretty wow experience.
Like Tubegroover I don't want to rain on anyone's parade, but I thought I would point out what appear to be highly credible measurements of the Reference 3A MM de Capo BE, performed by the National Research Council of Canada. They indicate a measured sensitivity of 86.7 db/2.83 volts/1 meter. As can be seen in the first graph, the sensitivity is in the vicinity of 92 db at a few specific frequencies, but is considerably lower at a great majority of frequencies.

Also, the impedance curve shown near the bottom of that page indicates that their impedance is about 6 ohms throughout much of the mid-bass region, where lots of energy is often required. 2.83 volts into 6 ohms is 1.33 watts, which is 1.2 db greater than 1 watt. So on a per watt basis, the 86.7 db figure is arguably optimistic by 1.2 db, meaning that 85.5 db/1 watt/1 meter is probably all that can be counted on with a lot of music.

Something to consider, despite the comments by the esteemed designers mentioned above. Regards,

-- Al
Hi Al,
Your insight and technical perspective is always welcome. This is a fine example of very logical use of measurements (Al) vs actually listening to the pairing of amplifier and same speaker (Bill).It seems this combo can do quite a lot with the exception of orchestra music at really high volume. If this isn't a requirement for Rebbi there's the potential to be very happy with this match. Reviewer Tim Smith says the Dynamo was a good match with lower sensitivity Harbeths.
Charles,
Its gotta be. It goes against physics for a small box to be more efficient and have flat extended bass. Just cannot be. But might sound quite good still at low to moderate volume and soft clip increasingly as the volume goes up, limiting dynamics. Large scale dynamic works would suffer most. End results at higher volume might still be quite good, but can't be optimal in terms of dynamic headroom.

Smaller high efficiency speakers with low ends that roll off at higher frequencies, 50-60 hz or above say, like my "90db" Triangle Titus XL speakers for example would be less affected and probably a better match overall. Or larger more full range high efficiency designs.