I'm dragging part of this over from a post I made earlier today on another thread. It is more food for thought on the subject you are discussing.
The original question to which I was responding was (paraphrasing) "Why not use this pro surround speaker as an LCR?"
There's a couple of things that would get one's attention. LCR speakers have to meet much more demanding specs than surround speakers with regards to on/off axis response and directivity. The most obvious thing about this speaker is that it utilizes the cinema X curve. Reference the performance graphs here http://www.jblpro.com/catalog/suppor...pe=3&docid=638
Take a look at the FR above 10KHz.
Modern EQ such as Audyssey could handle that I think. Given the difference in size of the transducers, it's kind of surprizing that off-axis horizontal response is not wanky in the crossover region like we see it is vertically.
The other thing to notice from the generous performance graphs is that you might have to be careful with vertical aiming if being used as an LCR.
Here is another possible reason that this speaker is disappointing at lower volumes. The very high sensitivity may not make it a good match with your amp. Below is quoted from this article: http://www.enjoythemusic.com/Magazin...e/whyhorns.htm
"The first problem is electronics. Weiner talked about listening to some Klipschorns with high power solid state amps. The amps were one source of the bad sound. Horn systems typically have sensitivities of 100 to 108 dB SPL with one watt input. Even at the loudest sound that you would realistically audition any speaker system (95-100dB), the amplifier is only delivering a watt or so to the horn system at peaks. Most of the time the amp is idling at 100's of milliwatts; yes, I said milliwatts. At this level many high power solid state amps have real problems with crossover distortion. For this reason, I tell people who buy my horn systems to try different amps with them along with their existing amp. The low power requirement of horns means that single ended tube (SET) amps can easily fill a room with sound. However, not all single ended tube amps are created equal. Some SET designs have relatively high levels of distortion that can be easily heard on the horn system. And of course, the horn gets the blame for the distorted sound."
The different size of the transducers (10" and 1") alone make a smooth crossover region a significant challenge. Add to it other issues that compound this, and you could get a rather disappointing LCR. As surrounds, they don't have to worry about this so much. The bottom line is that I don't think this speaker is designed to be an LCR, and will only disappoint in that role.
Spoken by a long-time Klipsch THX U2 owner.