What speaker do you passionately want to demo?

Tannoy Turnberry
Tannoy Kensington

wharfedale Elysian
spendor classic 1/2
stirling broadcast 3/6

@mijostyn: I couldn’t agree more about the wisdom of feeding a loudspeaker a high pass-filtered signal when used with a sub, for a few reasons. Can you imagine not putting a high pass filter on the midrange driver in a 3-way loudspeaker?! Taking the bass out of the midrange amp and driver greatly reduces the distortion they produce, and allows them to play louder and cleaner.

As for dipole subs, I’m going to guess you’ve never heard the GR Research/Rythmik OB Sub. Sure, OB subs have their own unique "problems" (I prefer the term limitations)---all loudspeakers and subs do. One criticism of planar loudspeakers is their inability to produce bass low enough in frequency and at sufficient SPL, a result of their very limited excursion and the dipole cancellation phenomenon (which is addressed in the Rythmik OB sub plate amp via a dipole cancellation compensation network). To address that limitation, planar bass drivers must be made very large, as in your SoundLabs ESL’s.

Hearing the original Magneplanar Tympani ruined me forever; their two bass panels reproduce lower frequencies like nothing I had ever heard, or have heard since. This is until I built my pair of GR Research/Rythmik OB/Dipole Servo-Feedback Subs. The closest a dynamic woofer has ever come to approximating Tympani bass quality (I have a pair of Tympani T-IVa.). I also built a pair of GR Research F15HP subs from the DIY kit, designing my own 4cu.ft enclosures and having a local woodworker cut the MDF for me. Wood glue, clamps, and paint, and voila---done! Pretty easy.

Siegfried Linkwitz didn’t design and build all his OB/Dipole loudspeakers with OB/Dipole subs for no reason (he could easily have used sealed or ported woofers). He knew more about loudspeaker design than perhaps anyone who has ever lived, a genius. Reading his technical papers is time very well spent, though hard work. He used 10" woofers in his OB subs; the GRR/Rythmik has dual or triple 12", and in a much more robust H-frame (made by a Canadian woodworker specifically for GR Research/Rythmik customers, shipped as a flat pack. The walls are 1.5" thick MDF!). And you know all about the controls provided on the Rythmik plate amp, the best in the biz.

The OB Sub may be used up to 300Hz, so can even be mated with planar midrange drivers that play that low. Take the bass out of planars, and they sound much better! If you don’t have room for planars big enough to reproduce, say, 40Hz and below, the OB sub is a viable alternative. Two of the Tympani bass panels measure 6’ tall and 36" wide, per channel. For stereo, that’s 6’ in width, just for bass reproduction! The OB Sub is only 16" wide.

I forgot to mention: For their "30.7 For Condo's" concept speaker, Magnepan chose to use OB/Dipole subs for bass frequencies, in place of the huge separate planar bass panels of the 30.7. Each of their OB subs contains six (I believe) small woofers. I've heard the woofers are 6.5", but can't confirm it. Electronic equalization is employed to compensate for the dipole cancellation discussed in my previous post, though the details of that equalization has not been disclosed by Magnepan. If the concept speaker is never put into production it's a mute point anyway.