Mating Quad 2905's with crossover and subs?

One of the problems with sub's and Quads is the speed issue. Quads are very fast and clean. Dynamic subs, no so much, unless you have small cone drivers properly implemented and even then the frequencies handled by the cross over slopes will lose some clarity. So if you are at all fussy about sound quality, and I assume you are for chosing Quads in the first place, I would not go there. I tried it and never go it close to right.

But all is not lost! First lots of folks put the Quads on stands. This can put a hole in the upper bass and make them sound thin in the upper bass/midrange. The were originally designed to be on the floor! And, with very careful positioning, on the floor you can get relatively flat FR to 35hz. And, once you have heard good electrostatic (or planer) bass you will have a hard time listening to dynamic woofers. :-)

I went back to dynamic speakers some years ago, but not because of any issues I had with the bass part of the FR.

If you must have loud sub 60hz bass, be sure to get a high quality cross over which has a steep slope roll off of the sub's FR above 60 hz and run the Quads full range.

Good luck.

Wilson Benesch Torus sub is the best match I've heard. Unfortunately, rather expensive and hard to find. The Torus has the speed without the big box woofer bloat.

That said, I've always liked Quads without a sub in a medium sized room. I've owned at least five different subs used in conjunction with my box/cone speakers, and in the end, never kept any of them. Perfect integration is almost impossible to my ear. Another idea might be to try some Martin Logans that have the sub already built in.

I goofed - I was referring to smaller Quads. Sorry 'bout that.

Thanks for the responses. I have tried the ML's (Summit X's). They played LOUD, clean and deep, but I didn't hear the magic that I hear with the Quads.
I used to own Maggie 3.6's, with a REL Storm III (no xover, I ran the Maggies full range) I didn't have a problem integrating the sub with the panels, so I think I can integrate a REL with the Quads.
What I'm trying to accomplish, is being able to play music (with that Quad magic) at Spl's higher than 90db. I'm not a headbanger, but I do like my music at realistic levels. I was hoping that if I could relieve the Quads from the bass frequencies, that I could get more volume.

I'm in the same boat as you, owning 2905's and loving their clarity, delicacy, speed and timbrel purity - yet missing the visceral physical impact put out by dynamic speakers during orchestral and operatic peaks. Like you, I'm considering a sub, knowing that believable integration with Quads may be impossible.

The REL Gibraltor series is a candidate, as their published specs look great in terms of speed. Problem is, they are designed to let the main speakers run full-range, while integration apparently is achieved only through tweaking the sub's volume and low-pass level. The connection is via Speak-on units.

This arrangement seems to me a big trade-off: one the one hand, by omitting a Xover, the sub's presence in the system will not degrade the signal received by the Quads; on the other, because there is no Xover to attenuate the high-pass signal to the Quads, their panels will not be relieved of any mid-to-low bass duties that, in theory, might be restricting their overall dynamics.

However, I'm not convinced such "relief" will allow the Quad panels to play louder, because what restricts their ability to do so is simply the limitation of their membranes' excursions before smacking into the stators - the source of distortion, arcing, and shutdown. Which, by the way, I've not witnessed.

There are two expensive solutions to our dilemma: (1) set up a separate listening room with big Rockport, TAD, Evolution or Magico speakers for rock and opera, or (2) add another set of Quads to move more air, thus fulfilling their namesake's suggestion. OK, back to reality:

Larry Greenhill reviewed a JL Audio Fathom f212, mating it to Quad ESl 989's through a Bryston 10B SUB Xover, using a complex setup to calibrate the sub:

http://www.stereophile.com/subwoofers/jl_audio_fathom_f212_powered_subwoofer/index.html

Keep us posted on your experiments.