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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Surround: coaxial or not?

   
Author Topic: Surround: coaxial or not?
Hans Van Meenen
Film Handler

Posts: 7
From: Gent / Oost Vlaanderen, Belgium
Registered: Jul 2017


 - posted 10-24-2017 05:01 PM      Profile for Hans Van Meenen   Email Hans Van Meenen   Send New Private Message       Edit/Delete Post 
My QSC 1150 LCR replaced my hifi speakers some time ago in my living room / home theater, and that was a ver good decision.

Now I start to think about replacing some surrounds. I have Kef LS50 that I want to replace by cinema surround speakers, but I'm not sure if I should choose QSC 8200 or go for more expensive coaxial surrounds like QSC's SR-1290.

Output of either is more than enough, only interested in sound quality. Distance to MLP is arounf 10'. My guess is the 8200's are perfect, but just wondering what advantage coaxial speakers could give, I see them more and more, also at other brands, cfr JBL SCS-8.

Will coaxial be better for atmos ceiling mounting, with a shorter listening distance of approx. 8'?

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Jay Wyatt
Film Handler

Posts: 29
From: Los Angeles, CA
Registered: Mar 2015


 - posted 10-24-2017 07:21 PM      Profile for Jay Wyatt     Send New Private Message       Edit/Delete Post 
As far as I understand coaxial speakers have all transducers operating at the same point/axis, so time alignment issues are mitigated. Additionally, you generally get symmetric dispersion patterns which make it a bit easier to 'point and shoot" in ceiling mount scenarios.

If you're a member you can lookup AES 9695 for some more info.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 11891
From: Annapolis, MD
Registered: Dec 1999


 - posted 10-24-2017 10:31 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
The best surrounds I've ever heard/measure were Altec 604s in Altec 620 cabinets. The 604 is a coax. I cannot speak to the QSC sonic quality but the coax speakers in the QSC lineup are supposed to be superior to their normal surround speakers and are geared towards Atmos with 4-Ohm impedances for better amplifier power transfer since it is typically just the one speaker per-channel in Atmos.

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Marcel Birgelen
Film God

Posts: 2322
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012


 - posted 10-25-2017 01:31 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
A coaxial speaker in terms of design, is closer to an ideal point source than a "normal" speaker. The closer the distance to the speaker, the more effective such a design will be.

Creating a good coaxial speaker design isn't easy though, and many of the cheaper designs do have issues, where one driver can severely impact the other and therefore produce a less than ideal representation.

Like Steve mentioned, one of the more legendary coaxial speaker drivers is the Altec 604, but for surround speakers in a home cinema setup, they might be a bit too bulky, even if you put them in a slim cabinet.

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Hans Van Meenen
Film Handler

Posts: 7
From: Gent / Oost Vlaanderen, Belgium
Registered: Jul 2017


 - posted 10-25-2017 03:51 AM      Profile for Hans Van Meenen   Email Hans Van Meenen   Send New Private Message       Edit/Delete Post 
These Altec speakers are really too large. If anybody has experience with the QSC coaxial then I'd appreciate to hear your experience. Same about the JBL SCS8 which might be more popular.
I guess especially for atmos height speakers at home coaxial might be better.

Maybe a silly question: when I look at many pro coaxials, I don's see the tweeter.... am I missing something? It often looks like a regular woofer.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 11891
From: Annapolis, MD
Registered: Dec 1999


 - posted 10-25-2017 09:02 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
One "trick" some coaxials do is to use the cone of the woofer as an extension of the "horn" of the HF so you may not see a traditional horn. EAW on their CR-82i hid the horn behind the dome even. The dome of the cone, if you paid attention, was very "think" and acoustically transparent. Those worked out well.

For home Atmos, I'm thinking some of the better ceiling speakers may do the trick (like JBL Control Contractor series).

For my home theatre, I'm thinking strongly about using 604s for the stage channels and something akin to the JBL Control 1 for the side/rear surrounds. I've always liked them.

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Hans Van Meenen
Film Handler

Posts: 7
From: Gent / Oost Vlaanderen, Belgium
Registered: Jul 2017


 - posted 10-25-2017 09:59 AM      Profile for Hans Van Meenen   Email Hans Van Meenen   Send New Private Message       Edit/Delete Post 

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