Do you think you need a subwoofer?

Raul:

I agree with your basic thesis about using stereo pairs of subwoofer for improved performance in virtually all sonic categories. I note that you are proposing using a high pass filter to prevent the bass drivers from handling the lower frequencies. In fact, you are suggesting this approach even for such stellar bass producers like the Wilson Alexandria. I prefer a slightly different approach: I would characterize it as “low bass augmentation”. In my system, I am running the Magnepan 3.5 full range. In my room the Maggies are down about 3dB at about 30Hz. I am running a stereo pair Sunfire Signature subwoofers with x-over point about 30 Hz. The slope and phase are adjusted to ear. I have been able to obtain seamless blending among the Maggies and the subwoofers.

I did not want to use the high-pass filter in the subwoofer because I felt that any gain in freeing up the Maggies from handling the bass frequencies would be offset by the added distortion or corruption of the signal due to the additional filtering. In fact, I experimented with both scenarios and preferred running the main speakers full range. The sound was less mechanical sounding.

Dear Gmorris: As you point out a different sub's integration with different trade-offs ( advantages/dis-advantages ).

I prefer to lower the IMD on the main speakers in favor of an improve in the quality performance on the main speakers and to handle the low bass with a dedicated speaker ( sub s) that was designed in specific to that frequency range along its self-powered amplifier.
IMHO no full range passive speaker ( like the great Alxandria's. ) can show/even the quality performance in the bass range like a dedicated self powered sub, the right sub and at the same time I don't know any amplifier ( SS/tube/hybrid. ) that can even the matching between the driver ( woofer ) and the amplifier in the sub's that was designed to the specific needs of that woofer for that specific frequency bass range, synergy is the name of the game.

The key is the quality of the crossover that in Velodyne, Revel, and the like are very " decent ".
The ideal " key " is to make directly the crossover high-pass filter at the main ( internally ) speaker amplifier(s) and if you can't do it then through the sub's own crossover.

The choice of the sub's model is a critical subject, not all the sub's are the same and not all the sub's have the same quality performance and the same quality " self " electronics specially its crossover.

I prefer too the use of the same amplifier in the main speakers, the right amplifier.

When we use two different amplifiers ( like in your system ) IMHO we have two different performances due to the diferences between these two amplifiers: different output impedance, different frequency response, different THD, different gain, different slew rate, different colorations,...different noise level,....different.....diferent..., etc, etc, the only and almost the one similarity between both units is its name: amplifier.
I know that you like it and this is the important factor because is you who are living each day with that system.

I respect your approach, however the targets and its quality level that you achieve are totally different from the targets and quality levels that we achieve trough the alternative that I support.

Regards and enjoy the music.
Raul.

"...Maggies are down about 3dB at about 30Hz..."

So why xover @30 hz. That gives you suck out in that region.
if you plot a curve most speakers neither drop of a cliff nor jump on the cliff.
At some point they began to roll off. Especially if you are talking about a xover. So they will start to roll off at say 60hz. There would be a decreasing slope all the way to 30 hz. The subs xover in my opinion should kick in @ 60hz and slowly rise to where it takes over completely. A brick wall approach either means the sub kicks in to early or too late. From the response curves I've seen, this is a better approach.
When I used The CLS they were 3db down at about 40hz. Sometime it is difficult to tell because manufacturers don't tell the truth. With exception of Stereophile, reviewers don't measure. Too make matters worse measurements are done in anechoic chamber which can't measure the response in your room. Thus the nonadjustable xover point of the Janis was 100 hz. Most of the xocer slopes are in the 6db/octave,12db/octave or 18db/octave. 6 being considered very gentle with 18 being very steep. It depends on the design philosophy of you speaker.

if you check the Stereophile review of your speaker there is probably an example of the xover and how it rolls off. I admire those who can adjust speakers by ear. I bet that using a spectrum analyzer in yuor room reveal they are not exactly right.
Gregadd

Dear Gregadd: From the planar speakers the Maggies are one that I like it, I had the opportunity to heard he 3.6 in my system ( years ago ) due that the dealer here was a close friend of mine and in a friend's system the 20.1, very good ones.

Yes, certainly I have " anomalies " in the frequency response spectrum on my speakers/room, however I can tell you that our ears ( yours, mine and everyone. ) along our know-how/experience are very good, sensitive and discriminate tools on sound reproduction perception.

Almost all different sub's approaches are valid , this depend of what targets do you want to achieve and what quality level do you prefer.

Regards and enjoy the music.
Raul.

The aerial sw-12 takes a correct approach. While not cheap (approximately $10k)offers a variety of slopes up to 24 db/octave. It is flat to at least 2Hz and allows a maximum cut in of 100Hz. Thus it will mate well with mini-monitors.It also offers a variety of beautiful finishes for those who are turned off by black cubes. If you like black, you can get that too.
gregadd