subwoofers and panels don't mix

hi duke:

as a dealer of soundlabs, wouldn't you think the problem of integrating dissimilar drivers is one of coherence.

regardless of where and how many cones you place in a room, a cone does not sound like a ribbon, electrostat or planar magnetic driver.

magnepan has the right idea. at ces 2007, i heard a prototype magnepan woofer. coherence is not a problem with such a driver.

it would seem that the best sybwoofer for a panel is another panel, rather than a cone.

Mrtennis,

As a SoundLab dealer, for many years I believed that cones could not possibly blend well with panels.

But is it panels and cones that sound so different from one another, or is it really dipoles and monopoles?

I've spent time with maybe a dozen different dipole panel systems and a half-dozen different dipole cone systems. I'd say that dipoles tend to have very similar bass (below 80 Hz), whether produced by a panel or a cone. Maybe not identical, but very similar - close enough to blend well if done right.

What I have presented in my preceding post is a rough sketch of a technique for getting dipole-like in-room smoothness from a judicious array of four monopole subwoofers. The line-source vs point-source discrepancy can be addressed at the same time by the four-piece subwoofer system (I can explain how if you'd like).

While a dipole panel or even cone subwoofer might be the theoretically ideal solution, how much would it cost for a dipole subwoofer that will give you significant bass extension and enough headroom to keep up with Maggies driven by a powerful amplifier?

Since you raise the question of cones & panels blending and I'm arguing that it can be done if done right, I hope it's alright for me to post links to online commentary about my prototype subwoofer system, one from a Maggie owner and the other from a Quad owner. This doesn't constitute proof of course, but I think it does constitute evidence:

http://www.audioasylum.com/forums/MUG/messages/108124.html

http://www.audioasylum.com/audio/speakers/messages/247336.html

Let me know if you have any questions.

Duke

Although it's not really a subwoofer/ribbon combi, I feel that Apogee has managed to combine a cone/ribbon succesfully around the '90's. I'm not saying my Apoge Centaur Major is perfect - it just isn't. But the transition between woofer and ribbon is flawless, even considering they're crossed at a remarkably high 350 Hz. Apogee has done several things to achieve this. The woofer is placed in a closed enclosure, which helps transients. The centre of the woofer is on the same height as the centre of the ribbon, so the woofer is not, like for instance Martin Logan, placed under the ribbon, but beside the ribbon. That also means the woofer is placed about one metre above the floor.
So all I'm trying to point out is that it is possible to succesfully combine a cone woofer and a ribbon/planar. It's just a lot of hard work.

I became really frustrated with trying to integrate subs with Maggie 3.5R's. About 6 months of trying with Carver true subs (they were poor, slow and had horrible overhang).
I spun them off for a brutal loss and moved on.
They literally had a delay before playing and 1-2 seconds of overhang afterwards. I guess when they glued a 4 pound hunk of steel to a passive radiator to calm it down that's what you should expect.

So I went on to smaller Velodynes (can't remember the model). Mass loading and spikes helped, but still seemed far too dissimilar to be acceptable. In either case with the Carvers or Velodynes, I tried every possible combination of electronics, internal XO and external Bryston XO, low pass/high cut frequencies, running the panels high passed and full range, different cabling, etc. None were acceptable to me.

I've heard REL subs in a few situations with Maggies and they were better, but still not great. I can say that I prefer 2 subs far more than one, regardless of location and implementation. Also, generally, that smaller the sub driver, the better luck you'll have.

I really can't believe that Harry Pearson in Absound recommended 3.6's and Carvers- shockingly bad IMHO. That would have been the point I stopped listening to reviewers as any reference other than anecdotal.

RFG

Just a thought - having never experimented - but could the issue be related to dynamics? A panel is not known for punchy dynamics (typically they compress audio signals and are preferred for classical listening)

...yet most subs are evaluated on their dynamic impact.

My suggestion would be to use an adjustable audio compressor on the sub signal so the sub can work in a "balanced" way with the rest of the audio frequencies from the panel....limit the dynamic range of the sub to match the panel.

A balanced sound will be correct at a variety of listening levels/dynamic ranges rather than over a very limited range or sweetspot.

This works if we assume that the panels bass roll-off remains consistent at different volume levels (like cone speakers generally do)....if the panel roll-off is also level dependent then I can't see a way to ever achieve a proper match.