Beyma 8CX300ND/N for ATMOS Surround use? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 14 Old 07-26-2014, 01:13 AM - Thread Starter
AVS Special Member
 
Elill's Avatar
 
Join Date: Dec 2007
Location: Sydney, Australia
Posts: 1,458
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Liked: 20
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/beyma%208cx300ndn-1.htm

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

Peter the Greek

Downunder Theatre MkII
Redefining snail pace construction
"what is worth knowing is difficult to learn"

Elill is online now  
Sponsored Links
Advertisement
 
post #2 of 14 Old 07-26-2014, 01:57 AM
AVS Special Member
 
A9X-308's Avatar
 
Join Date: Mar 2008
Location: Australia; now run by adults.
Posts: 5,383
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 138 Post(s)
Liked: 99
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.
A9X-308 is offline  
post #3 of 14 Old 07-26-2014, 02:56 AM - Thread Starter
AVS Special Member
 
Elill's Avatar
 
Join Date: Dec 2007
Location: Sydney, Australia
Posts: 1,458
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Liked: 20
I can land those for AUD230 each with crossover so not too bad

Peter the Greek

Downunder Theatre MkII
Redefining snail pace construction
"what is worth knowing is difficult to learn"

Elill is online now  
post #4 of 14 Old 07-26-2014, 07:25 AM
AVS Special Member
 
pgwalsh's Avatar
 
Join Date: Feb 2008
Location: Colorado Springs
Posts: 1,431
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 66 Post(s)
Liked: 66
Quote:
Originally Posted by Elill View Post
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/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.

Builds: Maelstrom 21 Ottoman Build, Dual Opposed MFW's x 2, Statements, SEOS-12/TD12M x 5. 
pgwalsh is offline  
post #5 of 14 Old 07-26-2014, 11:09 AM
AVS Special Member
 
DS-21's Avatar
 
Join Date: Jun 2005
Posts: 3,487
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 162 Post(s)
Liked: 212
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.

--
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait
Serious Audio Blog 
Multichannel music (and video) urban loft living room system 
DS-21 is offline  
post #6 of 14 Old 07-26-2014, 11:17 AM
Senior Member
 
splotten's Avatar
 
Join Date: May 2009
Posts: 468
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 84 Post(s)
Liked: 52
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.
splotten is offline  
post #7 of 14 Old 07-26-2014, 03:36 PM
Advanced Member
 
mtg90's Avatar
 
Join Date: Aug 2011
Location: Millbrook, IL
Posts: 865
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 218
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).
HopefulFred, Elill and popalock like this.
mtg90 is offline  
post #8 of 14 Old 07-26-2014, 09:29 PM - Thread Starter
AVS Special Member
 
Elill's Avatar
 
Join Date: Dec 2007
Location: Sydney, Australia
Posts: 1,458
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Liked: 20
Quote:
Originally Posted by mtg90 View Post
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

Peter the Greek

Downunder Theatre MkII
Redefining snail pace construction
"what is worth knowing is difficult to learn"

Elill is online now  
post #9 of 14 Old 07-27-2014, 12:51 PM
AVS Special Member
 
DS-21's Avatar
 
Join Date: Jun 2005
Posts: 3,487
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 162 Post(s)
Liked: 212
Quote:
Originally Posted by splotten View Post
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.

--
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait
Serious Audio Blog 
Multichannel music (and video) urban loft living room system 
DS-21 is offline  
post #10 of 14 Old 07-27-2014, 01:53 PM
Senior Member
 
splotten's Avatar
 
Join Date: May 2009
Posts: 468
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 84 Post(s)
Liked: 52
Quote:
Originally Posted by DS-21 View Post
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.
splotten is offline  
post #11 of 14 Old 07-28-2014, 05:02 PM
AVS Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 20,608
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 281 Post(s)
Liked: 166
surprised no one has mentioned this

Design Challenge - Ceiling speakers for Dolby Atmos

Noah

Last edited by noah katz; 07-28-2014 at 05:25 PM.
noah katz is offline  
post #12 of 14 Old 07-28-2014, 09:23 PM
AVS Special Member
 
DS-21's Avatar
 
Join Date: Jun 2005
Posts: 3,487
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 162 Post(s)
Liked: 212
Quote:
Originally Posted by splotten View Post
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.

--
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait
Serious Audio Blog 
Multichannel music (and video) urban loft living room system 
DS-21 is offline  
post #13 of 14 Old 07-29-2014, 01:21 AM
Senior Member
 
splotten's Avatar
 
Join Date: May 2009
Posts: 468
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 84 Post(s)
Liked: 52
Quote:
Originally Posted by DS-21 View Post
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?
splotten is offline  
post #14 of 14 Old 07-30-2014, 06:50 PM
AVS Special Member
 
DS-21's Avatar
 
Join Date: Jun 2005
Posts: 3,487
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 162 Post(s)
Liked: 212
Quote:
Originally Posted by splotten View Post
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.

--
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait
Serious Audio Blog 
Multichannel music (and video) urban loft living room system 
DS-21 is offline  
Reply DIY Speakers and Subs
Gear in this thread

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off