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Old 13th November 2012, 06:06 PM   #51
dewardh is offline dewardh  United States
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Originally Posted by john k... View Post
Back to the 1st order x-o, if it sounds good that is fine. But my experience for sure is that my revised Note system sounds better with a higher order crossover between the mids.
Different drivers, different baffle, all that stuff. Probably more a matter of perspective, though. You're thinking of the upper mid and lower mid as two separate drivers, independently equalized and then crossed over. SL treats them as a single "blended" driver (with different baffles and 1st order crossover) and then works with/equalizes the combined properties as if it's just one. It clearly didn't hurt that perspective that he had some control over the driver specs as well . . . they do seem to integrate seamlessly.
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Old 13th November 2012, 06:41 PM   #52
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Localization was actually improved. And it remained surprisingly "fixed" over a range of listening positions (walking around the room, not just at one "sweet spot").

Yes, "reflections" do seem to enhance imaging, not detract from it. Turns out to be an advantage of dipoles, which turn out (when well done) to produce a better, more defined and more believable "acoustic image" than other (especially "in-wall") designs.
*sigh* This migth happen with a specific recording, in a specific room, with a specific speaker but it doesn't happen with any recording, in any room with any dipole speaker.
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Old 13th November 2012, 06:45 PM   #53
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Originally Posted by dewardh View Post
... You're thinking of the upper mid and lower mid as two separate drivers, independently equalized and then crossed over. SL treats them as a single "blended" driver (with different baffles and 1st order crossover) and then works with/equalizes the combined properties as if it's just one. It clearly didn't hurt that perspective that he had some control over the driver specs as well . . . they do seem to integrate seamlessly.
No, that is not entirely true. In the original Note design the lower ER18, upper ER18, the 10F and the Neo 3 were passively crossover as a unit and then a single active eq was applied to compensate for the dipole roll off and a couple of other issues. Quote form my web site:

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The design of the NaO Note continues to follow a hybrid approach. An active crossover is used between the woofer and main panel and a passive crossover is used to control the panel driver set. The passive crossover is designed in such a manner that its only function is to control the response of the panel drivers through the crossover regions. Irregularities in the response due to the open baffle design and compensating for the gradient roll off of the woofer and midrange drivers is addressed in the active circuit.
Eliminate the tweeter and it is the same approach as the L521. Blend the mids and the apply a single eq.

It really makes no difference though. EQ x (DXo1 + DXo2) = Eq x DXo1 + EQ x DXo2. Look at my comparison between the original and revised:

Click the image to open in full size.

The original is blend first, apply global EQ. The revise system is treating the drivers individually. The acoustic response is almost identical in both cases except for some fine tuning in the revised speaker.
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Old 13th November 2012, 06:48 PM   #54
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Originally Posted by lolo View Post
there is now enough scientific evidence that lateral reflexions are actually good, as long as they are spectrally close to the direct sound, which rules out 99% box speakers.
check this for example:

White Papers - Sausalito Audio

Dipoles do image very well because they have a stronger D/R ratio (3 over 1) and potentially better CD than standard speakers. The nice thing is that with a diffuse rear wall, you extend the scene and get extra ambiance. You still keep a sharp image. Certainly, if you want "razor" sharp stereo, than you can absorb everything behind. Stig Erik does that, his system is just plain scary in imaging department, it has to be heard really. Dipoles are not only good, they are adaptable!

Reading your comments I just feel your experience with dipoles is probably limited, am I wrong?
Ever heard the Beolab 5? That's the kind of discussion that really doesn't lead nowhere. Looking at actual room data would be a good start.
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Old 13th November 2012, 06:53 PM   #55
lolo is offline lolo  France
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Ever heard the Beolab 5? That's the kind of discussion that really doesn't lead nowhere. Looking at actual room data would be a good start.
yes I have. It's not bad, but what do you mean with that?

The funny thing is that recently there has been some room data posted here, modulation transfer data to be precise, that clearly showed an advantage for dipoles in the bass. How do you get directivity below 500hz? I'd like to know.. If you are not happy with the rear wave thing, as said, just absorb it and you are done, you get a nice 60 directivity just at the front. Or is that too much?
The discussion doesn't lead anywhere because you just seem to chime in with negative comments every time dipoles are mentionned, whatever the design.

Last edited by lolo; 13th November 2012 at 07:09 PM.
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Old 13th November 2012, 06:56 PM   #56
lolo is offline lolo  France
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Originally Posted by dewardh View Post
they do seem to integrate seamlessly.
Dewardh, would you say much better than the Orion?
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Old 13th November 2012, 07:08 PM   #57
ScottG is offline ScottG  United States
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Originally Posted by john k... View Post
Vertical angle?

The side panels are from the NaO II RS. On that system the u-frame woofer is tapered so that the enclosure is hidden by the side panels.

Click the image to open in full size.

The dipole woofer in the new Note can not be tapered and retain the other aspects of the design. I could use the U-frame from the NaO II RS with the SLS woofers but I have decided to go full dipole because the u-frame is a little more complex and harder to set up correctly w/o measurements.

I'm not sure what you mean by Monolith vs. the (Monolith?) III. Just what is it you dislike about the Monolith I and II? I own a pair of II's (well I's updated to II's) and much prefer the look of them to the III's.
Vertical angle = "slant-back/tilt/rake" of the front panel.

Monolith version III (..not "vs." - my bad again. ) The III had much cleaner lines than either I or II (which among other problems had a noticeable/ugly "step" in the front profile from bass-box to upper panel).

What I'm thinking of wouldn't really alter your design much (and almost not at all with respect to your design goals). Again.. I'll try and do a sketch tonight.


BTW, that one with the "grill" in-place looks a lot better than the one in the news section of your site without the "grill" (..though of course it's there in that pic as well, but only in the background).
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Old 13th November 2012, 07:43 PM   #58
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yes I have. It's not bad, but what do you mean with that?
What if I would tell you that I have heard the Beolab 5 too and it was one of the worst listening experiences I've ever had. What does that mean? It means that there is much more to good sound reproduction than "dipole good, boxed speaker bad" or vice versa.

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The funny thing is that recently there has been some room data posted here, modulation transfer data to be precise, that clearly showed an advantage for dipoles in the bass.
No the data did not show that. Just follow the discussion.

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How do you get directivity below 500hz? I'd like to know..
You get directivity by using a cardioid, not a dipole but does it really matter below 500Hz anyway? We're talking about acoustically small listening spaces, right?

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Originally Posted by lolo View Post
If you are not happy with the rear wave thing, as said, just absorb it and you are done, you get a nice 60 directivity just at the front. Or is that too much?
How do you effectively absorb the rear wave? That's just not very practical.

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Originally Posted by lolo View Post
The discussion doesn't lead anywhere because you just seem to chime in with negative comments every time dipoles are mentionned, whatever the design.
The problem is that you're simply defending your belief in dipoles instead of trying to keep an open mind. In case you've missed it, I did a little subwoofer comparison lately and the dipole sub came out on top. So much for calling me biased.
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Old 13th November 2012, 08:00 PM   #59
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Vertical angle = "slant-back/tilt/rake" of the front panel.

Monolith version III (..not "vs." - my bad again. ) The III had much cleaner lines than either I or II (which among other problems had a noticeable/ugly "step" in the front profile from bass-box to upper panel).


BTW, that one with the "grill" in-place looks a lot better than the one in the news section of your site without the "grill" (..though of course it's there in that pic as well, but only in the background).
A) Monolith I, II vs. III. Matter of opinion. I like the I,II better.

B) Yes, that why the revised Note will have a grill. It is to hide the ugly baffle. As with the LX521, it's a form follows function thing. I have even thought about some type of perforated metal or something to fill the open areas between the baffle edge and the side pieces.


Going back to Dewardh and the 1st order x-o between the mids I can't help but wonder if it also wasn't more about trial and error. Certainly it would be easier to put a cap on the upper mid and a coil on the lower and dick around with the values until the desired measurement results were obtained. With a higher order passive I would imaging that it would require using sims to get the axial response right and then building it and measuring the polar response. That's where digital come in so nicely. I can make sims of the axial response and then emulate them digitally to check the polar. When I get what I want I can then decide whether to try to emulate the filter and eq transfer functions passively, in hybrid mode, or fully active, analog or digital.

But more than that, I started with making polar plots of the naked mids and tweeter and then using that info to guide me in the crossover design. See the latest update to my News page at the bottom.
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Old 13th November 2012, 08:16 PM   #60
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Originally Posted by markus76 View Post

You get directivity by using a cardioid, not a dipole but does it really matter below 500Hz anyway? We're talking about acoustically small listening spaces, right?


That is an interesting question. I guess I have come around to Geddes way of thinking. Actually, I always was there but never realized it. This directivity thing at low frequency is a free field thing. There is no such thing as dipole or cardioid radiation in an acoustically small room. All there is are multiple monopoles with different position, phase, delay and eq this way or that. I did some recent measurement of a monopole woofer. I moved it 18" and looked at the response. The degree of differences was not insignificant. So, given that any H dipole woofer has a separation of around 14 to 20" more or less, you can hardly expect the front and rear sources to generate the same response at any point in the room. And what about a large baffle dipole? You can not even begin to model that as multiple point source monopoles. How would you model the effect of the baffle blockage for the source on the back side? It's very complicated.

Assuming the sources can be considered as point sources all that matters is the near filed response of each source, the position of the sources, the position of the listener, the source to listener transfer function for each, and how all this sums at the listening position.
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Last edited by john k...; 13th November 2012 at 08:19 PM.
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