subwoofers and panels don't mix

Lightminer,

I would suggest that Shefield Drum track will highlight most of the reasons panels and subwoofers don't mix. Drums are some of the hardest sounds to reproduce convincingly, although other percussion instruments (like the piano) will work well too...Dave Grusin is a good choice.

My guess is you need a critically damped subwoofer which generally means a very large motor magnet structure within a sealed box and not the usual boomy kind (known for total movie noise capability). This means the woofer goes directly to the rest position when the signal drops to zero without any overshoot or additional resonant oscillations. Remember the panel will have good transient capabilities in the sense that it has very little stored energy...

Maybe its because my panels go so low by themselves, but I can't hear a thing that you guys are talking about!! I have the 3.6s. One thing I've learned since then is that my sub is *theoretically* not optimized for use with panels, the Hsu HO w/turbo has more venting length which slows down the sound. The current Hsu, which you can buy a couple of, should match even closer. But I honestly can't hear a thing you guys are talking about. Everything sounds awesome.

Oh - on the Rel only w/Maggies - some also use Martin Logan Depth as that is designed to be fast. But consider the new Hsu, which is not ported (and therefore not slow) at all. The ULS Quad Drive - crazy fast compared to my extra-ported VTF3HOw/Turbo. i have to think that would match really well.

Is there a physics term we can compare that tells us the 'slowness' of the sound?

Another track - with crazy dynamics and bass - The Serpents Egg, Track 9 (Dead Can Dance). You can't imagine it until you hear it.

I welcome anyone in the bay area to send a note through Audiogon and come over and try and show me what we are talking about and perhaps I can hear your system.

Ah, the term is "Group Delay". I am trying to find Group Delay numbers for some of the subs. It would be great if we could get:

Electrostatic panel itself Group Delay at say 300 Hz as refernce.

Group Delay from Sanders Systems integrated sub
Group Delay from Summit X Martin Logan integrated sub
Group Delay from Martin Logan Depth Sub
Group Delay from Hsu Quad Drive ULS-15
Group Delay from Stentor III REL
Group Delay from Stentor Studio III REL

Oh - and these things should be flat to 20, if I find out they roll off at 24, 22 or even 21 then I'm crossing them off, what is the point of all of spending that much money? Mine is pretty flat to 16.

Oh - and we have to put some sort of price limit on it, wasn't there a Krell Sub that used 30 amps circuits or something?

There is a guy 'CraigSub' on other forums and he is sub-crazy (in a good way!). Maybe I can get him to figure this out :).

I may sound like a broken record here: Room analysis, PEq, felexible x-over. I've used a Velodyne SMS-1 sub controller to seamlessly integrate a pair of Velodyne SPLR 800 subs with Maggie SMGs. It took a lot of time and a lot of tweaking, but I can't hear the crossover at all. Let me emphasize, I've always loved the IDEA of hybrid speakers, but, to my ear, even the best (IMHO - Eminent Tech) have had issues with the planar/dynamic x-over.

Using the SMS room analyzer, you can easily see how dipoles differ from forward firing speakers throughout the bass. The nature of the response irregularities in panels makes integration a real challenge - but it can be done.

IMHO, the key to good sub/speaker is smooth on-axis FR around the x-over point, so I follow the following procedure:

1) Use the room analyzer to find a smoothish chunk of bass and start with a frequency in the center of this area as your x-over point. Be sure that this "smooth area" is reasonably balanced w/the rest of the spectrum. A smooth plateau at + 15db doesn't work very well. You may have to move the sub(s) around the room a bit, 'til you find a good result.

2) Flip polarity (this will usually kill the primary suckout quite effectively) to see whether + or - works better.

3) EQ around the x-over point for further smoothing.

4) EQ below the x-over for best balance of smooth vs extended deep bass response.

IME, this procedure will get excellent results from subwoofers with a dipole, unidirectional, or omni speakers (I've tried all three).

Good Luck

Marty

BTW - I really doubt that your choice of subwoofer model is critical - looking "fast vs. slow" isn't likely to help. IME, integration trumps sub performance. I chose the Velos because of size. There are several other models at/near their price that return far better specs (group delay for speed and distortion for clean output) and will very likely outperform them. Yet, I still get great results despite the mediocre subs I use.

Lightminer,

Are you using your system for HT as well as music? Are you a pipe organ guy? If not, why worry about ultimate LF below 25hz. In my collection of >5,000 records and cds, I can only think of a few that go below 30hz. I only mention this because there are tradeoffs in choosing subs and the first one I'll give away is extension.

BTW, I can't imagine that you'll miss the difference in bass performance between EQ'd subs w/ your 3.6s and full range 3.6s. Both will "go there", but they'll sound quite different in terms of "impact". I personally have little issue with timbre (my subs are actively crossed at 74hz). I assume that this is because timbre becomes less meaningful as you descend in frequency. At 25hz, you feel it more than you hear it. I may be less sensitive to timbre issues higher in hz near the x-over than some other folks, but I don't hear the timbre change im my set up; even in the lower registers of electric bass or piano where fundamentals may fall in this critical area. However, this is a classic YMMV.

AVTalk.com and Hometheatershack.com are the two subwoofer distortion & group delay databases I know of (Thanks Shadorne and Bob Reynolds). None of the data you seek is on either site, but there are several REL model test results vailable. General rule for REL = great group delay #s, ugly distortion #s. SVS subs seem to offer a nearly unmatched balance of distortion & group delay performance (if you value both equally), and they do so at a comparatively low price.

Marty