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-   -   Beyma 8CX300ND/N for ATMOS Surround use? (http://www.avsforum.com/forum/155-diy-speakers-subs/1617794-beyma-8cx300nd-n-atmos-surround-use.html)

Elill 07-26-2014 01:13 AM

Beyma 8CX300ND/N for ATMOS Surround use?
 
Hi all,

ATMOS has thrown a massive spanner in the works for me, so I am looking at cheaper alternatives for surround duty (I'll need 10 in total so its not a small exercise).

I keep coming back to this driver from Beyma. Thoughts?

http://www.usspeaker.com/images/beym...dn-size325.gif

http://www.usspeaker.com/images/beym...is-size475.gif

http://www.usspeaker.com/beyma%208cx300ndn-1.htm

It seems fairly well behaved off axis and can go in a small box.

A9X-308 07-26-2014 01:57 AM

I'm sure it will be fine. Very expensive though, once you factor in the $95ea for the xovers. Something like the B&C 8CX21 would do just as well and be considerably cheaper and it's an excellent driver.

The Volt 8 would probably be fine and is cheaper still.

Elill 07-26-2014 02:56 AM

I can land those for AUD230 each with crossover so not too bad

pgwalsh 07-26-2014 07:25 AM

Quote:

Originally Posted by Elill (Post 26051266)
Hi all,

ATMOS has thrown a massive spanner in the works for me, so I am looking at cheaper alternatives for surround duty (I'll need 10 in total so its not a small exercise).

I keep coming back to this driver from Beyma. Thoughts?

http://www.usspeaker.com/images/beym...dn-size325.gif

http://www.usspeaker.com/images/beym...is-size475.gif

http://www.usspeaker.com/beyma%208cx300ndn-1.htm

It seems fairly well behaved off axis and can go in a small box.

Looks nice for the in ceiling channels.

Have you seen the final spec for Atmos at home? I've see write-ups, but not the final spec with placement etc.

DS-21 07-26-2014 11:09 AM

I would not use any coax with an unterminated horn mouth jutting out of the woofer cone for any application where sound quality was remotely an issue.

splotten 07-26-2014 11:17 AM

How about something like a KEF Q300. As far as i have seen the measure very well and is said to have a very nice SQ. Are they not loud enough? Seems to me like a speaker well suited for surround applications.

mtg90 07-26-2014 03:36 PM

I have one of these lent to me by beastaudio for which I am going to design a custom crossover for. I expect the crossover parts will cost far less then $95 and tuned more appropriately for home use.


I have done some preliminary measurements and I agree that horn termination does cause some diffraction/off axis problems at the low end of its range however the top end >6khz is smoother both on and off axis then most that use the woofer cone as the waveguide.


My woofer tester broke about a month ago so I could not impedance measurements to start crossover work but I've managed to get some using a friends so the crossover work should start this weekend if all goes well with the other designs I am wrapping up (Karma-15, Fusion-15 v2.0 and Alpha-8 v1.3).

Elill 07-26-2014 09:29 PM

Quote:

Originally Posted by mtg90 (Post 26064570)
I have one of these lent to me by beastaudio for which I am going to design a custom crossover for.

Excellent, I look forward to the results! thanks for the input

DS-21 07-27-2014 12:51 PM

Quote:

Originally Posted by splotten (Post 26060042)
How about something like a KEF Q300. As far as i have seen the measure very well and is said to have a very nice SQ. Are they not loud enough? Seems to me like a speaker well suited for surround applications.

The Q300 has poor polars and cone break up issues. The smaller, cheaper Q100 is a considerably better speaker.

splotten 07-27-2014 01:53 PM

Quote:

Originally Posted by DS-21 (Post 26081810)
The Q300 has poor polars and cone break up issues. The smaller, cheaper Q100 is a considerably better speaker.

OK? Thats a little surprising to me. Can you provide a link or something? I have seen somewhere that the bigger Q900 had some breakup, but not the Q300.

noah katz 07-28-2014 05:02 PM

surprised no one has mentioned this

http://www.avsforum.com/forum/155-di...lby-atmos.html

DS-21 07-28-2014 09:23 PM

Quote:

Originally Posted by splotten (Post 26083066)
OK? Thats a little surprising to me. Can you provide a link or something? I have seen somewhere that the bigger Q900 had some breakup, but not the Q300.

There are off-axis measurements posted on the KEF forum that clearly show the "midrange mushroom cloud" effect of mismatched directivity.

As for breakup, it's less of a concern than the poor polars (compared to Q100 or Q900) but still...largish metal cone, highish crossover, 1st order electric filter with no notch. There's a reason the R100 and LS50 build on the 5" variant of the current Uni-Q and not the 6.5.

splotten 07-29-2014 01:21 AM

Quote:

Originally Posted by DS-21 (Post 26119634)
There are off-axis measurements posted on the KEF forum that clearly show the "midrange mushroom cloud" effect of mismatched directivity.

As for breakup, it's less of a concern than the poor polars (compared to Q100 or Q900) but still...largish metal cone, highish crossover, 1st order electric filter with no notch. There's a reason the R100 and LS50 build on the 5" variant of the current Uni-Q and not the 6.5.

Ok. Im at a loss here. It may be that the Q100 has better matched directivity than the Q300 but on the other hand I really cant find anything suggesting that Q300 should have "poor polars and cone break up issues" as you stated in you other post. I tried finding the measurements you are referencing but came up empty. Can you please provide a link?

DS-21 07-30-2014 06:50 PM

Quote:

Originally Posted by splotten (Post 26121570)
Ok. Im at a loss here. It may be that the Q100 has better matched directivity than the Q300 but on the other hand I really cant find anything suggesting that Q300 should have "poor polars and cone break up issues" as you stated in you other post. I tried finding the measurements you are referencing but came up empty. Can you please provide a link?

Search through my comments on the KEF owner's thread in the speaker's section and you'll find an analysis of someone else's 3d party measurements.


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