Speaker Effeciency and Bass Production


How much speaker efficiency is gained if the bottom two octaves or so don't need to be produced? I'm considering trying an SET or OTL amp but am wondering about the ability of these amp types to drive my speakers (Opera Quinta; 89db efficiency and 6 ohm nominal impedance; 6-8 ohms from 100Hz up). I am using a pair of corner placed subwoofers which can easily produce the lower 2-3 octaves. So the question is if the amps driving the main speakers don't have to produce anything below 100Hz or so, then is the ability to use them on my main speakers more doable? The room is fairly large, but I sit only around 10 feet from them.
smeyers
Onhwy, I don't know specifically yet which amps I'm considering, but thinking about some type of SET or OTL amp. Both can be attained with fairly high amounts of power, but I don't want the complexity or power consumption of anything above say 50 watts or so. A couple of amps I noticed were ASL Explorer 805 and Atma-sphere S-30 (I am concerned about the Atma-sphere's ability to drive my speakers due to impedance).

"So the system could sound cleaner, less distortion, but it won't go any louder."

Yes, the question is how much more *clean* non clipping volume can be had by not pushing the main power amps to provide low frequencies?

Cyclonicman, what are the amps that are powering the main speakers, and is it enough power?
Good point!! It is a Vintage Conrad Johnson Premier 1, about 20 years old, but very good sound and power, 200 Watts per channel, which you aren't going to get with the SET/OTL. However, I was also using the same setup with a Rogue stereo 90 in Triode mode, which was about 40 watts per channel. The powered subwoofwer has a 175 Watt continuous amplifier and 475 Watts dynamic range.
You will probably need about 20 watts with those 89db speakers. The rule of thumb is that your speakers should be able to produce 101db at 1meter with the amp that you will use, and 89db speakers will require 16 watts to do that. But it is only a rule of thumb and other factors can come into play such as- size of istening room, and how complex the crossovers are in your speakers (complex crossovers can eat up power) and what type of music you listen to (orchastra music will require more power than simple music with few instruments playing) and lastly, how loud you like your music to be. For single ended try a 845 output tube (Antique Sound Labs makes a descent one) if your thinking about OTL call Ralph at Atmosphere and ask him what he thinks and don't forget Transedent Sound OTL amps.