What is your opinion regarding electrostatics?

Sean, don't you think that most good planars today have a fairly decent bass response well under 100hz? Just think of the new Quads or the bigger Sound Labs. Also the more expensive Maggies are no slouch in this regard at all. So I find your remark perhaps a bit misleading, at least for a newbee. But just because we seem to be in disaggreement here, I find your thoughts about bass response and planar speaker placement all the more important: When I originally experimented with this, I adhered to the one third/two third rule and got muddy bass amd fuzzy images. Finally I ended up not quite halfway into the room, more or less in the middle between the 1/3 and 1/2 position to get things right.
Also here there are no really hard and fast rules. Every rig and room is different, not to speak of the furnishing in it.
As for Altecs and Klipschhorns, I have of course never heard all and every make of them, but the ones I had the chance to listen to, I found very statorlike, as you said in your first post, but also coloured. So I never really considered horns as an alternative until I came across the a-capellas, which I would suggest everyone look into, who is seriously considering hornspeakers. I don't know however, if they already are being imported to the States.

Hi Sean,

Great to hear from you again! Hey by the time you and I are done, we'll have all these dynamic guys lining up for either horns or 'stats...

You are a true gentleman, and it is a pleasure exchanging ideas with you. Your ideas are worth way more than the customary $.02. I'm a dealer (see the fin on my back??), so my ideas have to be taken with so many grains of salt I oughtta buy stock in Morton...

Okay, here we go...

I gotta differ with your statement that "LOW frequencies are omnidirectional" (which, if true, would refute my assertion that dipole bass is less colored by the room). Low frequencies are only omnidirectional with a monopole direct radiator source. For example, a true low frequency horn would be just as directional over its passband as a midrange or high frequency horn.

A dipole is directional in the bass because, in the plane of the driver, the out-of-phase front and rear waves cancel. In a true anechoic chamber, you would not hear any bass if you stood exactly to the side of a dipole. But you would hear plenty of bass if you stood in front of it. In a room, what you hear to the side of a dipole is the reverberant field.

If you did an overhead graph of a dipole's radiation pattern at low frequencies, it would look like a figure-8 [see - more bass out front & to the back; less bass to the sides]. A monopole has a figure-O [omni-directional] radiation pattern in the bass.

The Stereophile 1998 "Speaker of the Year" was a dynamic dipole called the Audio Artistry Beethoven, designed by Siegfried Linkwitz. Go to this address and you will find an in-depth description of dipole bass: http://www.linkwitzlab.com/rooms.htm

You can also find an excellent but less technical discussion of dipole bass at Gradient's site (the Revolution uses dipole bass loading). Be sure to click on the link to the picture of the bass radiation pattern on the second page: http://www.gradient.fi/En/Products/Revo/Revo1.htm

Hopefully these sites will establish that a dipole is indeed directional in the bass.

Now, I'm sure you'll agree that one of the advantages of a horn is that its directional nature minimizes room-induced colorations. Well, dipoles have the same thing going on with their directional bass - they have significantly less room-induced colorations.

Mind if I try to bolster up my assertion that dipoles have similar direct and reverberant fields?

I said that with a good dipole the direct and reverberant fields sound pretty much the same. Okay, this is easy to test. Go to your Maggie or Sound Lab dealer and turn the volume up louder than normal. Walk into the next room, leaving the door open. Does it sound convincingly like live music is going on back in there? From outside the room, all you can possibly hear is the reverberant field. If it sounds realistic, then the speaker's reverberant field response is very good. By the way, Klipschorns are also very good at this, because their full-range horn loading maintains essentially the same radiation pattern at all frequencies.

As an example of the reverberant field, consider this situation: You're walking past a night club and you hear saxaphone music coming through the open door. You don't even have to look inside - you know instantly if it's live or if it's Memorex. All you can possibly hear through the open doorway is the reverberant field. With live music, the reverberant field sounds right. Over most loudspeakers, it sounds wrong. One of the most significant but most often overlooked factors in the difference between live and reproduced sound is the reverberant field. Papers published in the Journal of the Audio Engineering Society decades ago established the correlation between listener preference and good reverberant field response, but this has been all but forgotten.

I can't think of any arguments in support of my 3rd assertion in my post above, so I'll pass on that one for now.

Just for the record, many planars are indeed capable of substantial output below 100 Hz. Sound Labs and Maggie 20's go down into the mid-20's, and can shake the room, as can the dipole Beethovens mentioned above (which go down to 18 Hz). The dipole active Gradient Revolution system demo'd at the 2001 CES easily went down into the lower 20's, and had by far the most natural sounding bass I heard in any of the smaller rooms (and better than many behemoth direct radiator systems).

Frankly, I don't think placing planars in the middle of the room is necessary (or practical). Perhaps we have had different experiences?

Also, I have heard many planars that have superb imaging and do not sound the least bit "thin". Just like there are horn speakers out there that do not "honk"! I will admit that it takes more effort to get excellent imaging out of a planar, but you also get a greater sense of acoustic space and ambience. A diffuse, well-energized reverberant field is desirable in the concert hall, and in the listening room as well. Again, this from published research.

I gotta ask one clarification. I'm not clear on just what the "ONE advantage" of planars is that you concede. Hey, I gotta trumpet and celebrate any little point in our favor here!!

Hey Sean, I'm having a blast. Thanks so much for writing back. Like you, I invite reply from anyone who wishes to offer correction or a differing point of view, and I will try to offer them the same respect you have.

Kindest regards,

Duke

Duke, nice post. Nothing to add, except to remind you that even though a large panel does manage to "shake the walls" at 28cps, they still do not have the piston action of a great 12 or 15" woofer system, to give the "slam in your gut" bass delivery.
A woofer assembly like the one used in the Infinity IRS V or the many great subs that have been made with proper attention to ideal dampening Q ratios, is the only thing that can give something like "The Sheffield Drum Record" its proper dues. I wish it were'nt this way, because the only way that I have found to integrate the ESLs and the subs sucessfully is to run the panels full range and then overlap the subs. Just a thought to those that want it all in a system. When Levinson brought the HQD to the shows in 78, I think he really did have the right basic idea that stands to this day, at least in concept........Frank

Thanks for jumping in there Frank. You made the same point that i would about large panel's having "reasonable" (albeit very good quality in terms of being quick and tight) bass but nothing in the same league as an array of large dynamic pistons that are well tuned.

It takes both surface area and displacement to move a lot of air. Panels simply lack the excursion capabilities to do this unless you have a LOT of them. Having said that, i've never heard ANY panel type speaker ( planar, ribbon, e-stat, etc...) that could give you chest compression let alone sound clean attempting to do so.

As to the comments about low frequencies NOT being omni in some designs, that goes against all of my audio education. This is NOT to say that you are wrong ,it is impossible or that i know everything. I am surely just as "pea brained" as anybody else ( and maybe even moreso ) on a more than a few subjects. I'll have to do some digging and see what i can come up with using various resources.

While i will look into the examples that Duke was so kind enough to present, i dislike having to rely on someone trying to push their own product as the sole source of info on the subject. I hope that you can understand where i'm coming from on that one Duke. If anyone can come up with some "unbiased" sources of info, PLEASE post them so that we can all learn from them.

As to what the advantage of dipolar bass response was, i was trying to make clear that a standard "front loaded box" will ALWAYS have to deal with unequal pressure in the room. The dipole, when situated near mid room, will have relatively equal loading and pressure drops both fore and aft. In effect, this cancels a LOT of the loading effect of the room and can offer truly outstanding "clean" and "linear" bass reproduction. Kind of like having even weight on both sides of a well balanced "teeter-totter" (sp ???). Everything remains balanced so long as there is no outside interference. Sean
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Point conceded, Frap - a first-class brace of 12's or 15's will indeed outslam a big panel.

I agree with you that very good results seem to come from running the panels full range and then using a low-Q sealed sub to add the ultradeep bass. This preserves all the superb pitch definition the panels have to offer. The REL's come to mind.

Sean, I have yet to hear an electrostatic or planar magnetic that can displace enough air to give you that solid chest-whump that a big dynamic can. However, a dynamic dipole (using say a dozen or so 12" woofers) can do it.

I don't blame you one bit, Sean, for wanting information on dipoles from source besides some guy selling them. And if I have come across as pushing my product, then I owe you all an apology. I believe in dipoles, and I've tried to articulate their advantages because they aren't common knowledge.

Just for the record, my background is that of an amateur speaker builder, not a salesman. I'm not blowing ad copy at you - I'm telling you things I learned over the course of 20 years of seriously studying and building loudspeakers. My intention was to one day become a manufacturer (which I almost did), but when I encountered a particular speaker I hung up my table saw and became a part-time, in-home dealer.

Sean, if you would like, I can find for you papers published in the Journal of the Audio Engineering Society that are the basis for many of the things I talk about. I didn't want to come across as some kind of name-dropper by tossing out references left and right. And frankly, unless people are really going to look them up, I'd rather not go to all the trouble to dig them out. But I understand your skepticism of claims made by a dealer, so if the references would help please let me know.

Again, I enjoy very much engaging in such dialogue. Thank you, Frap and Sean. Until next time!

Kindest regards,

Duke