Speaker Effeciency and Bass Production

Thanks much for the responses! It is interesting to note that so far I have used 3 different sets of tube amps so far on this setup with no as yet noticeable problems (although I've yet to push it VERY hard):

AES Sixpac: 50W push-pull triode
ASL Wave 20: 20W push-pull
Wright Sound: 10W push-pull triode

I do wonder if there is a formula than can calculate increase in efficiency based on low frequency cutoff. In other words if an amp can drive speakers full range to 94db in a room just before a certain clipping distortion, then if the amps are high-pass fed the same signal at a certain frequency (lets say 80Hz), then what SPL can the same speakers in the same room be driven to the same clipping distortion?

Onhwy, thanks for the link to the chart. According to that chart, I would need approximately 30W or so at peak levels; although isn't calculating efficiency a little more complicated as Bob_reynolds suggests above?

The answer to your original question is NO. Adding a subwoofer won't change the speakers sensitivity. Removing low bass frequencies will lessen amplifier clipping (on most types of music), but it won't effect the maximum volume level attainable by the amp/speaker combo. So the system could sound cleaner, less distortion, but it won't go any louder.

Calculating max SPLs is fairly simple. Matching a speaker's impedance to an appropriate amp is more complicated. You need to be more specific about the amps you're considering to get more detailed and better replies.

Usually when a subwoofer is integrated into a system, the lower octaves are not going to the speakers anyway. In my setup, both my pre amp and power amp are connected to a powered subwoofer and the speakers are connected to the power amp, not the subwoofer. In a sense I am biamping the subwoofer, but the lower frequencies are not produced by the speakers. My speakers are very efficient 92db and are rated to about 35-40hz in the lower region, but the lower frequencies are produced by the subwoofer. The speakers are producing anything above 100hz.

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?