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Multi-Way Conventional loudspeakers with crossovers

The Preference for Direct Radiators
The Preference for Direct Radiators
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Old 5th December 2018, 07:26 PM   #31
youngho is offline youngho  United States
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It seems to that many of the Harman speakers generally aim for a relatively constant or else smoothly changing directivity index between 500-700 Hz and 7-8 kHz. The JBL speakers seem to have a higher directivity index than the Revel ones, as shown in the various figures posted in this thread, but it was interesting to me that Toole's book included the sentences "When they are put against each other in double-blind tests, the audible differences are small, somewhat program dependent, and listener ratings tend to vary slightly and randomly around a high number. In the end there may be no absolute winner that is revealed with any statistical confidence; the differences in opinion are of the same size as those that could occur by chance." This must have been in one of the Harman listening rooms, possibly the reference one that I recall having a very even/consistent RT across the frequency spectrum.

A newer Revel speaker is the F228Be, which has an extremely smoothly changing directivity index: Revel Owners Thread - Page 407 - AVS Forum | Home Theater Discussions And Reviews. Interestingly, I believe that Kevin Voecks posted in AVS Forum that Revel's listening tests still have the Salon 2 as the top performer, which I believe that he related in part to the very low diffraction enclosure for the smaller drivers, due to the round-overs.

It does seem to fit that the higher DI speakers may be preferred in certain contexts (audio professionals or studio engineers, good recordings with recorded natural ambiance, etc) and the lower DI speakers in others (listening for enjoyment, the majority of commercial recordings with close-miking, more reverberant listening spaces).

Young-Ho
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Old 7th December 2018, 02:04 PM   #32
anji12305 is offline anji12305  United States
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May I ask a question by PM?
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Old 7th December 2018, 07:19 PM   #33
Patrick Bateman is offline Patrick Bateman  United States
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Old 7th December 2018, 08:27 PM   #34
Patrick Bateman is offline Patrick Bateman  United States
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A couple of things have been vexxing me lately:

1) If you put a *significant* roundover on a cabinet, the polars get measurably better. Here's an 18Sound XT1086 with and without a roundover. In particular, notice the improvement in the midrange.

Click the image to open in full size.

Click the image to open in full size.

2) According to Charles Sprinkle, his speakers imaged better with a tall narrow waveguide, versus the wide short waveguides we're accustomed to.

Click the image to open in full size.

So I wonder how something like this would image, with a significant roundover

I've probably built more car audio waveguides than anyone in history, and something that I've noticed with them is that it's possible to get surprisingly good performance out of a wildly narrow horn. I've built horns with mouths that were less than an inch tall, and they perform surprisingly. No, not as good as an OS waveguide, but not terrible either.

Click the image to open in full size.
Picture one of these, but mounted vertically
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Old 7th December 2018, 09:03 PM   #35
LineSource is offline LineSource  United States
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I believe that "The Preference for Direct Radiators" listening experience also extends to dipoles with their "figure-8" radiation pattern which produces a direct front soundstage, combined with diffuse delayed rear wall reflections which trick the imagination to believe the soundstage extends further. Also, the figure-8 pattern reduces soundstage confustion with less short delay side wall reflected energy.

Reviews of dipole speakers designed by Siegfried Linkwitz praise the realistic listening experience.
My Full Range Apogee dipole linesource speakers create an accurate front image, plus produce a large realistic 3D soundstage.

WIKI
"The on axis, free space directivity factor for sound sources with several common free space radiation patterns are as follows: Monopole: DF = 1.0, Dipole: DF = 3, Cardioid: DF = 3, 90x90 Horn: DF=8.27. What this means is that if these three different sources are to radiate the same total acoustic power then if the monopole has an on axis intensity of 1.0 the dipole and cardioid will have an on axis intensity of 3.0 or 4.77 dB greater, and the horn will have an on axis intensity of 8.27 or 9.2 dB greater. Conversely, if the difference sources are to have the same on axis intensity then the dipole and cardioid will radiate 1/3 the acoustic power of the monopole, and the horn 1/9 the acoustic power of the monopole. When studying room acoustics and reverberation this means that the "critical distance" from the speaker will be greater for a dipole or cardioid or horn than for a monopole. The "critical distance" is the distance at which direct and reflected sound are equal. The level of the reflected sound, above the modal region of the room, is usually considered constant and proportional to the total radiated power. Thus when sitting the same distance from a conventional speaker and a dipole/horn, the dipole/horn can potentially sound more detailed since at the position that ratio of direct to reflected sound is greater. "
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Old 7th December 2018, 09:25 PM   #36
mark100 is offline mark100  United States
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Quote:
Originally Posted by Patrick Bateman View Post
A couple of things have been vexxing me lately:

1) If you put a *significant* roundover on a cabinet, the polars get measurably better. Here's an 18Sound XT1086 with and without a roundover. In particular, notice the improvement in the midrange.

Click the image to open in full size.

Click the image to open in full size.
Not to nitpick, but I'd really like to see the two graphs with the same smoothing before I could get convinced enough to give it a try.

The roundover looks to have 1/6th smooting....or maybe even 1/3???.. can't make it out
Having scaling the same would help comparisons alot too...
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Old 7th December 2018, 09:51 PM   #37
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by mark100 View Post
Not to nitpick, but I'd really like to see the two graphs with the same smoothing before I could get convinced enough to give it a try.

The roundover looks to have 1/6th smooting....or maybe even 1/3???.. can't make it out
Having scaling the same would help comparisons alot too...
Yeah I need to get the same compression driver and measure it on the same waveguide, one with a roundover and one unbaffled. And no smoothing.
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Old 7th December 2018, 10:10 PM   #38
oivavoi is offline oivavoi  Norway
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This is an extremely interesting thread. Thanks to P Bateman for putting in the effort of writing, and to you others for chiming in.

I’ve come round to the same conclusion lately. I find that I prefer direct radiators. I also seem to prefer direct radiators on a narrow baffle. This probably has to do with their wider directivity. But is that all there is to it? I’m not completely sure.
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Old 8th December 2018, 03:50 PM   #39
Robh3606 is offline Robh3606  United States
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Quote:
So I wonder how something like this would image, with a significant roundover
Hello Patrick

Well I own a pair of 1400 Arrays and a pair of Revel Performa F206'S and the Arrays are every bit as good as the Revels are in this respect. Horns seem to get a bad rep for imaging and these are definitely an exception. I know a couple of people who own both the Arrays and Everest 2 and K2 and that orientation does make a difference as the Arrays beat out both of the larger systems imaging wise.

Having that slot in a vertical orientation does make a difference. All of the 100x100 are set-up that way and all 3 of them 2344, PTH1010 and M2 image very well.

Rob
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Last edited by Robh3606; 8th December 2018 at 03:54 PM.
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Old 8th December 2018, 04:30 PM   #40
Pallas is offline Pallas  Pakistan
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Quote:
Originally Posted by Patrick Bateman View Post
2) According to Charles Sprinkle, his speakers imaged better with a tall narrow waveguide, versus the wide short waveguides we're accustomed to.

Click the image to open in full size.

So I wonder how something like this would image, with a significant roundover


Sprinkle or Timbers? I think Iíve read similar from Timbers before, but Sprinkleís horns have always been conventionally oriented.
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