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Coaxial Mid/High or Seperate Mid/Hi?

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Discussion Starter · #1 ·
Lot's of thread responses over this series have indicated an interest in a design including a Coaxial Mid/High driver...for different reasons..some to be different and others as a perfrormance bonus. At the risk of 'leading' the group, i'll keep my view point to a minimum. First off, they still need a crossover so they won't make things any easier. They DO for the most part have improved off axis response. They DO have a more ragged freq response than the better Mid/High combo's mentioned throughout the series. Most employ a compression driver for the highs, or at least the ones needed in our case. They are a safe saving option. They ARE NOT cost effective in our budget range.

IMPORTANT>>PLEASE READ BEFORE VOTING!


Truth be told, there's not a lot of choices that this design can accomidate mostly due to the budget. Here's the options


B&C 8CX21-8"

Cost $157.00



Scroll to the bottom and click the B&C spec link. Check the individual driver responses and the XO point. The T/S parameters are available on the prosoundservice homepage as well.


B&C 8CXT

Cost $229.00 each


Blows the budget completely but here's a link and pic for those that like speaker porn



http://www.prosoundservice.com/m9_vi...tem=B%26C-8CXT


And coming fall 2009


B&C 8CXN51

Cost $235 each


Not much info but here's the link
http://www.prosoundservice.com/m9_vi...m=B%26C-8CXN51


Pretty much a budget buster as well. Unless there's a magic woofer other than the Silver Flute's that's cheap.


Eminence Beta 8CX 8"


Price $69.95 without tweeter



http://www.parts-express.com/pe/show...number=290-500


A cost effective option IF we were able to locate an affordable CD driver and interface option for it. FR's got quite a few peaks and dips...pretty severe ones but not impossible to deal with but possibly cost prohibitive. I've heard this combo with the suggested APT Eminence tweeter and this IS NOT an option.....sounds pretty bad. There may be a real benefit to the DIY community to work out a design using this driver and an acceptable CD, i'm just not sure this is the right design for that kind of effort. We'd need alot of support from members here to sample/test/ different combos. I'll let the poling decide.


Ok. So there's some viable options. You guys decide if the improvement over a dedicated Midrange and tweeter/CD is there.


If there's any others out there that meet the design criteria, please feel free to post them and as much info as you can find. Added info to my submissions would be apprecitated as well. I didn't post any comparable seperates.....for a good reason.....and to remain out of the line of fire( i'm a bit shell shocked lately) i'll keep it to myself.
 

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In general principle I like coaxes and have owned others in the past, mainly a lot of Tannoys. So I would vote yes to a coax based design, but it would depend upon the alternative's performance and the listening distance.
 

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As I've stated in other threads I'm hoping someone would develop a poor mans catalyst without amplification and a passive crossover. If you go with a coax you are one step closer to something I could get interested in. I'm also closely monitoring the CD/W designs under development. If I wanted a speaker made with the same old mix of T/M/W I would build the Statements, Khans, or any one of the other engineered and tested designs that have been throughly documented.


I can't explain why I am only interested in something that is different, perhaps it is the misguided belief it might be somehow better mixed with a spirit of DIY adventure.
 

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Quote:
If I wanted a speaker made with the same old mix of T/M/W I would build the Statements, Khans, or any one of the other engineered and tested designs that have been throughly documented.


You are not alone, I have also posted this opinion during this process.
 

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I'd like a high efficiency coax-based design to use for surrounds to go with WG fronts.


I'm partial towards the B&C's, as I've read nothing but good things about them.


The wrinkle is the XO. B&C sells one for $60 I think, but I don't know if any of the good things I've read are with it.


"Another noteworthy Coax, that MIGHT fit the budget. $175.00 is workable, i we can find some independant performance data.

http://usspeaker.com/homepage.htm "


That's just the home page; which driver do you mean?
 

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One advantage of coaxes that hasn't been mentioned is symettrical polar response. In practice, that means one can stick her/his speakers above an LCD without problem, or without changing the design compared to one designed for use at ear level.
 

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"I've never met a co-ax I liked."


Mark Seaton's acclaimed Catalysts uses the B&C (active XO though), and it's also used in a highly regarded pro speaker with hifi tendencies that I can't name.
 

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There are "issues," even with the new one:

http://www.bcspeakers.com/PDF/PRD/8CXN51.pdf


Why'd they grab 16 kHz for the polar plot?



The BMS ones intrique me because they've got a "proper" horn.


Early pics of GPA's 12" Altec Duplex reissue/upgrade also looked promising, but I don't know if he stuck with that design....
 

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Discussion Starter · #15 ·
I like doing things for the sake of being differnet as well, BUT simply wanting to use a Coax because it's different when it comes to a speaker design overlooks a lot of facts, and makes quite a few tradeoffs in performance as far as i can tell. Those craving ths Coax really need to explain the benefits to the group....Show Us The Money! References to an Active system using Coax's is useless in these discussions, as the steep slopes may be the only way to get these to perform properly for our purposes and an ctive XO is clearly not withinh the scope of this particular project.

Don't misunderstand me, i'm not a cynic...but a realist. If someone can clearly show the benefits of a Coax at our price point over dedicatd M/T's i'm all over it and i'll be the first to buy the pair. I wasn't really planning on this project as a Pioneer into new territory but if that's the direction it takes, so be it. Just as long as everyone understands we're not reinventing the wheel. I'd be perfecly happy with a 'Statements on Steriods' design because fundamentally, the statements is a sound design based on tried and tested audible principals. There's been some talk of off axis response and i clearly understand the role it plays. But if i apply the thinking to my own 14X20 space, given the placement of the mains and the seating, no one will be more than 15 degrees off axis. If i were designing this for my space, which i take for granted is fairly typical of most HT's, off axis response would be farther down the priorities chain, below L and NonL HD and Freq response.

Brandon would probobly have an insight to the directivity of Coax's and i'd like to hear his thoughts on it. Someone make me a believer please?
 

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Discussion Starter · #16 ·

Quote:
Originally Posted by noah katz /forum/post/16955115


I'd like a high efficiency coax-based design to use for surrounds to go with WG fronts.



"That's just the home page; which driver do you mean?

Sorry Noah, it's the 18Sound 8CX400f. Here's the link.

http://usspeaker.com/homepage.htm




I'd like to hear your thoughts on it. My take on the coax's working as intended would be bypassing as much Midbass as possible to avoid too much movement of the cone. A moving waveguide can't be a good thing no matter how you spin it. With my limited knowledge of the principles involved, a 6.5" high FS cone with a CD crossed 3-3.5khz makes the most sense. The only offerings i could find were from PHL who doesn't include a CD, a good thing IMO. They're also quite pricey, too much for this design i fear.
 

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Mayhem, I sense an edge in your comments that leads me to believe you are reaching your tolerance level for this noble but frustrating path you have chosen to build an AVS unique speaker design. From the beginning it was all about a survey based consensus building model of product design.


Unfortunately the reality is that some members of your voting audience are hacks like myself who rely on the heavy lifting of others to do the really technical engineering.


Pay attention to the true experts, keep soliciting input but build what serves your needs. If you try to please us all it will drive you bonkers. If it turns out great you will have some followers.
 

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"Those craving ths Coax really need to explain the benefits to the group"


For the pro-based drivers:


1) High efficiency


2) Low power compression


3) Clean at high SPL


4) For the B&C's at least, largely CD (constant directivity) behavior which gives even power response and may bring the same benefit of wide sweet spots to surrounds as given by cross-firing CD L/R's.


"I sent Auger an 8cxt to test so I guess we'll find out."


"a 6.5" high FS cone with a CD crossed 3-3.5khz makes the most sense."


What's FS?


Also, I think 3-3.5 kHz is too high to properly match directivity at XO; I think the B&C XO is at 2.2 kHz.


Great!
 

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Quote:
Originally Posted by noah katz /forum/post/16958687


What's FS?

Resonant frequency (of the LF driver.)
 

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Discussion Starter · #20 ·

Quote:
Originally Posted by BIGmouthinDC /forum/post/16958119


Mayhem, I sense an edge in your comments that leads me to believe you are reaching your tolerance level for this noble but frustrating path you have chosen to build an AVS unique speaker design. From the beginning it was all about a survey based consensus building model of product design.


Unfortunately the reality is that some members of your voting audience are hacks like myself who rely on the heavy lifting of others to do the really technical engineering.


Pay attention to the true experts, keep soliciting input but build what serves your needs. If you try to please us all it will drive you bonkers. If it turns out great you will have some followers.

Thanx Big, and yes you're correct. I hope to see this thing through though. We may have to wait for Brandon's Coax testing to see if they're viable. I'll try and remain optimistic.
 
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