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Multi-Way Conventional loudspeakers with crossovers

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Old 29th April 2013, 02:06 PM   #8651
Ronion is offline Ronion  United States
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All three of my speakers across the front are exactly the same--5" TM. The clarity of the dialog is outstanding!
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Old 30th April 2013, 07:16 PM   #8652
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Lynn,
I have built systems in the past with the earleir versions of the 8" Radian coax and I will warn you that you have to watch out for the notorious horn honk we have come to expect from some older horns and compression drivers. It is all in the crossover points you chose and the implementation. Be careful and you can get what you want, sloppy will make you very disappointed.
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Old 30th April 2013, 07:20 PM   #8653
Pano is offline Pano  United States
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Oh yeah, horns and crossovers take some real skills. You're not likely to hit it by chance. But I assume Lynn know that.
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Old 30th April 2013, 08:01 PM   #8654
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Interesting the latest thoughts..
My reference speakers for the time being is a pair of "Onkens" with HempAcoustics co15v drivers. CO15v is basically Radian 5215 with aluminium throat for the compression driver and Hemp for the 15" driver. They perform remarkable well. The Radians are great drivers.

Absolutely no horn honking. Just pure beautiful smooth sound with alot of attack and "space"
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Old 30th April 2013, 08:03 PM   #8655
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Not bad gear driving them either.
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Old 30th April 2013, 08:41 PM   #8656
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Lynn,

I thought that co-ax systems were ruled-out completely very early-on in this thread for various reasons - impossible to refine to the level you desired due to the known compromises of the woofer being the horn IIRC. Some excellent drivers were considered at the time but ruled-out.

What has changed? Is it because the application is not 2-channel music-only?

Thnx,
-- Mark
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Old 30th April 2013, 08:57 PM   #8657
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Whoa! Hemp Acoustics is still around? And they make a coax based on the Radian 5215? Wow! HA makes great cones, and Radian makes excellent compression drivers. However ... I don't see anything on the Internet about Hemp Acoustics, except a million inquiries about the 8" fullrange driver. Are they still around?

Kindhornman, thanks for sharing your experience with the 8" Radian coax. That model uses the small-format horn and compression driver, while the 12" and 15" use the large-format, 2" exit compression driver, and uses the bass driver as part of the horn flare (similar to Tannoy). The Tannoy coaxial patents expired a very long time ago, so there's no reason anyone can't use Tannoy's woofer-cone-as-extension-of-horn approach.

Part of the reason I'm drawn to the 12" and 15" models is that I haven't had good experiences with small-format compression drivers ... they tend to sound strained in the critical 1~2 kHz region, which makes crossover design very tricky, since the bass driver is at the top of its working range, and kind of tempermental. Plastic diaphragms tolerate working low better than metal diaphragms, which is probably why small-format plastic-diaphragm compression drivers are so popular. If I were forced into using a small-format compression driver, I'd probably choose a plastic diaphragm and cross it no lower than 2 to 2.5 kHz.

Kindhornman, you mentioned you knew some of the people at Radian. Can you confirm the origins of the company for me? I have a 1966 AES paper by J. K. Hilliard and J. A. Renkus (enclosed below), which describes a 4" aluminum-diaphragm compression driver with a Mylar surround. At some point in the Seventies, Renkus left Altec and Emilar, and some time later, Emilar got into financial trouble, and was re-formed as Radian, which continues Hilliard's and Renkus' Mylar-surround technology today. Is that timeline correct? Is there anything to add?
Attached Files
File Type: pdf Hilliard&Renkus_1966_4-in_Emilar.pdf (724.6 KB, 24 views)

Last edited by Lynn Olson; 30th April 2013 at 09:08 PM.
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Old 30th April 2013, 09:06 PM   #8658
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Sorry I didn't mentioned that. HempAcoustics is long time gone I am afraid. But their coax drivers were great. Probably the Radians also. As I said - the HA drivers are based on Radians. I really cannot understand why they should sound so extremely different? ..
If you get lucky a nice pair come out on the market from time to time.. There are always people that never finish their projects
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Old 30th April 2013, 09:17 PM   #8659
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Coax drivers can be tricky animals, especially if there's a great big horn right in the middle of the bass driver. I don't even like what phase plugs do to cone drivers, much less a big horn with reflective sides. The cone response gets really goofy with all those reflections, and reflections do not respond well to crossover equalization. (You can't correct a time-domain error with frequency equalization; it makes the time response even worse.)

The Tannoy approach is the right way to go provided you're willing to limit cone excursion. High efficiency and large size can help here, since the bass cone won't need to move as much as a smaller, lower-efficiency cone. The larger cone also helps create a larger horn, which is appreciated since the horn is going to need all the LF extension it can get. Since Tannoy won't sell drivers to OEMs or DIYer's (I've asked the North American distributor), that's off the table.

The potential gotcha with the 12" and 15" Radians is rough response from the cone above 1.5 kHz. A broad, gentle peak at 1.5 kHz, like the Altec/GPA 416 and Tone Tubby 15" hemp-cones, is easy to deal with. What is not easy to deal with is rough, jagged response, which is more common in heavy, high-power prosound cones. The pros don't care because they use digital equalization and 4th-order crossovers; what they're looking for is durability and power-handling, thus the 4" voice coils and aggressive heat-sinking.

The target crossover for the 12" or 15" coax is in the 800 Hz to 1 kHz range, depending on how the horn and cone behave, with a 4th-order LR or Bessel highpass for the horn, and the bass lowpass yet to be decided. The bass might need delay adjustments; Nth-order Bessel lowpass filters should do this adequately.

Last edited by Lynn Olson; 30th April 2013 at 09:26 PM.
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Old 30th April 2013, 09:23 PM   #8660
BudP is offline BudP  United States
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All of the Hemp Acoustic drivers were built here in the US. I can contact Perry and ask if Misco will build prototypes to his spesc's for the cone material, if you are interested.

Bud
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