DIY HT Design Coax or Seperate Mid/High? - AVS Forum
View Poll Results: Coaxial Mid/High or Seperate Mid/Hi?
Coaxial 0 0%
Seperate Midrange/Tweeter/CD 0 0%
Voters: 0. You may not vote on this poll

Forum Jump: 
Reply
 
Thread Tools
post #1 of 265 Old 08-05-2009, 05:42 PM - Thread Starter
AVS Special Member
 
mayhem13's Avatar
 
Join Date: Jan 2008
Location: nj
Posts: 3,951
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 13
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.
mayhem13 is offline  
Sponsored Links
Advertisement
 
post #2 of 265 Old 08-05-2009, 08:57 PM - Thread Starter
AVS Special Member
 
mayhem13's Avatar
 
Join Date: Jan 2008
Location: nj
Posts: 3,951
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 13
Thirty one views and knowbody has any comments? Now i'm really shocked!
mayhem13 is offline  
post #3 of 265 Old 08-06-2009, 02:00 AM
AVS Special Member
 
A9X-308's Avatar
 
Join Date: Mar 2008
Location: Australia; now run by adults.
Posts: 5,279
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 89 Post(s)
Liked: 72
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.
A9X-308 is offline  
post #4 of 265 Old 08-06-2009, 04:52 AM
AVS Special Member
 
zero the hero's Avatar
 
Join Date: Aug 2004
Location: NJ
Posts: 1,360
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I think it would be an awesome design with one, but like you noted the biggest hurdle is the budget so I voted for the standard config
zero the hero is offline  
post #5 of 265 Old 08-06-2009, 04:55 AM - Thread Starter
AVS Special Member
 
mayhem13's Avatar
 
Join Date: Jan 2008
Location: nj
Posts: 3,951
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 13
Here's an interesting Coax from PHL. hvaen't been able to find an online retailer but it looks interesting. Here's the link.

http://www.phlaudio.com/datasheets/17_pdf/1520_1530.pdf

At 6.5", might be the right driver at the right time. It doesn't come with a CD, so not unlike the Eminence, some work would be required.
mayhem13 is offline  
post #6 of 265 Old 08-06-2009, 05:17 AM - Thread Starter
AVS Special Member
 
mayhem13's Avatar
 
Join Date: Jan 2008
Location: nj
Posts: 3,951
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 13
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

With the bass extension of this unit, a compact 2way is a real possibility...for those willingly to do the work on the XO. Would make an interesting compact system.
mayhem13 is offline  
post #7 of 265 Old 08-06-2009, 08:02 AM
HOME THEATER CONTRACTOR
 
BIGmouthinDC's Avatar
 
Join Date: Jan 2003
Location: Northern VA
Posts: 20,819
Mentioned: 5 Post(s)
Tagged: 1 Thread(s)
Quoted: 271 Post(s)
Liked: 612
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.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
PROJECTS:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,

BIGmouthinDC is offline  
post #8 of 265 Old 08-06-2009, 10:44 AM
AVS Addicted Member
 
penngray's Avatar
 
Join Date: Feb 2006
Location: Florida
Posts: 26,779
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
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.

It is not "open-minded" to reject knowledge - Bob Lee
penngray is offline  
post #9 of 265 Old 08-06-2009, 11:38 AM
AVS Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 20,507
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 201 Post(s)
Liked: 153
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?

Noah
noah katz is offline  
post #10 of 265 Old 08-06-2009, 12:24 PM
AVS Special Member
 
DS-21's Avatar
 
Join Date: Jun 2005
Posts: 3,427
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 108 Post(s)
Liked: 187
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.

--
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
 

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
 
DS-21 is offline  
post #11 of 265 Old 08-06-2009, 12:27 PM
Advanced Member
 
ZilchLab's Avatar
 
Join Date: May 2009
Location: Berkeley, CA
Posts: 944
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Unless the mains use the same, timbre matching gets flushed.

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

Here's Beta 10CX with a bunch of different drivers:

http://www.diyaudio.com/forums/showt...=&pagenumber=4

The answer is "No."

.
....Crank up the SIGNAL ... cut back the noise....
ZilchLab is offline  
post #12 of 265 Old 08-06-2009, 03:22 PM
AVS Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 20,507
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 201 Post(s)
Liked: 153
"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.

Noah
noah katz is offline  
post #13 of 265 Old 08-06-2009, 04:09 PM
Advanced Member
 
ZilchLab's Avatar
 
Join Date: May 2009
Location: Berkeley, CA
Posts: 944
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
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....

.
....Crank up the SIGNAL ... cut back the noise....
ZilchLab is offline  
post #14 of 265 Old 08-06-2009, 05:05 PM
AVS Special Member
 
Monger's Avatar
 
Join Date: Feb 2005
Posts: 1,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 62
I sent Auger an 8cxt to test so I guess we'll find out.
Monger is offline  
post #15 of 265 Old 08-06-2009, 06:09 PM - Thread Starter
AVS Special Member
 
mayhem13's Avatar
 
Join Date: Jan 2008
Location: nj
Posts: 3,951
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 13
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?
mayhem13 is offline  
post #16 of 265 Old 08-06-2009, 06:26 PM - Thread Starter
AVS Special Member
 
mayhem13's Avatar
 
Join Date: Jan 2008
Location: nj
Posts: 3,951
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 13
Quote:
Originally Posted by noah katz View Post

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.
mayhem13 is offline  
post #17 of 265 Old 08-06-2009, 08:33 PM
HOME THEATER CONTRACTOR
 
BIGmouthinDC's Avatar
 
Join Date: Jan 2003
Location: Northern VA
Posts: 20,819
Mentioned: 5 Post(s)
Tagged: 1 Thread(s)
Quoted: 271 Post(s)
Liked: 612
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.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
PROJECTS:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,

BIGmouthinDC is offline  
post #18 of 265 Old 08-06-2009, 11:38 PM
AVS Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 20,507
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 201 Post(s)
Liked: 153
"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!

Noah
noah katz is offline  
post #19 of 265 Old 08-07-2009, 12:29 AM
AVS Special Member
 
A9X-308's Avatar
 
Join Date: Mar 2008
Location: Australia; now run by adults.
Posts: 5,279
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 89 Post(s)
Liked: 72
Quote:
Originally Posted by noah katz View Post

What's FS?

Resonant frequency (of the LF driver.)
A9X-308 is offline  
post #20 of 265 Old 08-07-2009, 04:32 AM - Thread Starter
AVS Special Member
 
mayhem13's Avatar
 
Join Date: Jan 2008
Location: nj
Posts: 3,951
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 13
Quote:
Originally Posted by BIGmouthinDC View Post

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.
mayhem13 is offline  
post #21 of 265 Old 08-07-2009, 04:37 AM - Thread Starter
AVS Special Member
 
mayhem13's Avatar
 
Join Date: Jan 2008
Location: nj
Posts: 3,951
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 13
[quote=noah katz;169586871)
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.[/QUOTE]

I probobly shouldn't get stuck on manufacturers FR plots, but i keep finding myself weighing the positives you mention against this



Please tell me i'm wrong in my thinking as i wanna believe!

The FR graph of the cone says to me no point in crossing above 1.5khz and the CD looks horrible. Looks more suitable for a two way as the LF driver is capable of the extension but everything else fails in the upper octaves.
mayhem13 is offline  
post #22 of 265 Old 08-07-2009, 04:52 AM
AVS Special Member
 
Kevin Haskins's Avatar
 
Join Date: Feb 2005
Posts: 1,008
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
The best reason is for the physical alignment of the tweeter-midwoofer. You get around all the problems of having the tweet-midwoofer in two different locations on the vertical plane. You get less lobing on the vertical axis, and better power response.

The biggest problem is as Noah mentions. Most of the devices on the market have some design issues. The tweeter/midwoofer directivity doesn't match up at their crossover points. The response of the tweeter, midwoofer or both tends to suffer from the environment it is forced into by the physical constraints. You are forced into some compromises on transducer design based upon the physical limitations.

Overall though.... I think most of the negatives can be overcome. I just need a pile of money to do so. ;-)

Kevin Haskins
Exodus Audio
Kevin Haskins is offline  
post #23 of 265 Old 08-07-2009, 05:42 AM
Member
 
dlneubec's Avatar
 
Join Date: Jan 2006
Posts: 137
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I gotta agree with Mayhem. If anyone were to look at that woofer response and suggest to you that you should spend 100+ for it and expect to cross it over above 2khz, most designers would say no way. The tweeter response is much worse at another $100. I doubt anyone whould buy those two drivers were they sparate, with that kind of response at that price level, crossed where they would have to be crossed. These are horrible looking on axis responses. I believe first arrival sound should be first on the priority list and that means excellent on axis response should be a top priority. Why is anyone willing to sacrifice that first arrival sound quality in favor of a bit higher sensitivity and the ability to play to an unrealistic, ear damaging, peak spl levels? I wonder why you don't see Geddes using coaxes in his Pro driver/constant directivity solution? As Mayhem said, it can't be a good thing to have a constantly moving waveguide or a waveguide whose design is secondary because it has to act as a driver first. To me, there is so much compromize in the design of the coax, as can be seen by observing BOTH drivers responses, that it swamps any possible benefits it may have and compromizes the design of both drivers. So you end up with two very substandard driver responses just so that you can make them into a coax? I don't get the attraction, personally.

There is a reason why MT or TM is predominant, because it works. You can use a pro midrange, which is pretty flat out to 4khz. The SB29 Ring radiator tweeter looks to be have a sensitivity in the 93-94db range and very good low end performance, flat down to 1khz, for a nice diver overlap. Mated with a pro woofer you should be able to get in the 92-93db range, depending on applice BSC, have very low distortion and be clean at all but insane levels, IMO.

If you want to increase the low end output of the dome tweeter, potentially increasting its power handling, increase directivity and create some pattern control above 3khz or so, you can mount the tweeter (less flange) from the rear of the baffle in a shallow waveguide. A DIY waveguide, at 3/4" deep with a 3/4" roundover you can get a boost in the range of 4-5db at the centered around 3-4khz and get some directivity benefits etc. Even Geddes admitted that if he were to use a dome tweeter, he would mount it in a waveguide.

Below is a study of the Peerless HDS in various depths of shallow DIY waveguides, but first is a pic of the final WG mount (in Lexan and wood, with open baffle mid, not suggesting that for this project). The waveguide is created by nothing more than a 1-5/16" forstner bit and a 3/4" roundover bit, so it easily doable by most DIYers. With the tweeter flange removed, you can decrease the CTC distance of the mid to tweeter which improves vertcial polar response. Put the waveguided tweeter on a sloped baffle and you can align or come close to aligning the tweeter and mid AC in the vertical plane as well.


HDS mounted Flush: 0-15-30-45-60º



1/2" deep WG, 1/2" roundover: 0-15-30-45-60º


1/2" deep WG, 3/4" roundover: 0-15-30-45-60º


3/4" deep WG, 3/4" roundover: 0-15-30-45-60º


3/4" deep WG, 3/4" roundover, with 1/2" deep 45º chamfer after, sharp edges sanded round by hand: 0-15-30-45-60º


3/4" deep WG, 3/4" deep 45º chamfer, sharp edges sanded round by hand: 0-15-30-45-60º
dlneubec is offline  
post #24 of 265 Old 08-07-2009, 05:43 AM
AVS Special Member
 
Mark Seaton's Avatar
 
Join Date: Jul 2000
Location: Chicago, IL, USA
Posts: 6,037
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 61 Post(s)
Liked: 253
Quote:
Originally Posted by Kevin Haskins View Post

The best reason is for the physical alignment of the tweeter-midwoofer. You get around all the problems of having the tweet-midwoofer in two different locations on the vertical plane. You get less lobing on the vertical axis, and better power response.

The above is the primary reason for using a coax, along with the flexibilities these qualities afford. If you're used to looking at dome tweeters or a smoother responding horn over a limited angle, the high frequency will look like garbage.

On second thought, Zilch & dl are right, the response is worthless, nothing to see here, please move along... Those things can't possibly sound good.

Mark Seaton
Seaton Sound, Inc.
"Make no little plans; they have no magic to stir men's blood..." Daniel H. Burnham
Mark Seaton is online now  
post #25 of 265 Old 08-07-2009, 08:48 AM
AVS Special Member
 
Monger's Avatar
 
Join Date: Feb 2005
Posts: 1,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 62
Quote:
Originally Posted by mayhem13 View Post

Thanx Big, and yes you're correct. I hope to see this thing through though.

I'm not sure how to interpret this. It comes across like you are taking your ball and going home.
Monger is offline  
post #26 of 265 Old 08-07-2009, 08:50 AM
AVS Special Member
 
DS-21's Avatar
 
Join Date: Jun 2005
Posts: 3,427
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 108 Post(s)
Liked: 187
Quote:
Originally Posted by ZilchLab View Post

Unless the mains use the same, timbre matching gets flushed.

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

Here's Beta 10CX with a bunch of different drivers:

http://www.diyaudio.com/forums/showt...=&pagenumber=4

The answer is "No."

First, anyone who doesn't use not just the exact same drivers, but the exact same drivers in the exact same cabinet at the exact same elevation for all three front speakers just doesn't care about high-fidelity reproduction. So who cares what they use?

A big advantage of coaxes, as I mentioned above, is that because of their inherently symmetrical polar response, one can mount them higher than one can MT's, to clear LCD's or other things, and not suffer sonically for it. (Yes, one can also design an MT to work at any given height, but then you move and need a new placement, and have to go back to the drawing board. With a coax one just modifies the stand height.)

You're basing a dislike of coaxes generally on the basis of a cheap Eminence? Really?

I hate JBL. I once heard this laptop that had JBL speakers, and it sounded really tinny.

Quote:
Originally Posted by mayhem13 View Post

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.

That's nonsense. Tannoy, for instance, has long used fairly low slopes, I believe 1st order/3rd order asymmetric on my the DMT series.

Quote:
Originally Posted by noah katz View Post

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.

2.2kHz is probably still too high. I think one should be thinking of 1.4-1.6 kHz with an 8" driver. That's what Tannoy does, and their Dual Concentrics are still, of what I've heard, the best of breed.

--
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
 

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
 
DS-21 is offline  
post #27 of 265 Old 08-07-2009, 09:48 AM
AVS Special Member
 
Kevin Haskins's Avatar
 
Join Date: Feb 2005
Posts: 1,008
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Mark Seaton View Post

The above is the primary reason for using a coax, along with the flexibilities these qualities afford. If you're used to looking at dome tweeters or a smoother responding horn over a limited angle, the high frequency will look like garbage.

On second thought, Zilch & dl are right, the response is worthless, nothing to see here, please move along... Those things can't possibly sound good.

You just smooth it a little more until it looks good Mark. ;-)

I don't really care about top octave jaggies. Once they start moving down below 10K though I become progressively more concerned.

I'm convinced it could be done without any tradeoffs in terms of smoothness of response. It would require tooling a lot of parts though.

The idea is really attractive to me for home audio sized devices. It certainly makes designing different configuration speakers easier as you can turn them anyway you like.

Kevin Haskins
Exodus Audio
Kevin Haskins is offline  
post #28 of 265 Old 08-07-2009, 10:16 AM
AVS Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 20,507
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 201 Post(s)
Liked: 153
It's true the FR looks awful, but the integrated response w/XO is much better, and Earl Geddes has noted that B&C's data is accurate vs. the sugar coating you get from a lot of other mfgr's.

Also, I'm counting on auto EQ to smooth out the significant bumps, and a 100 Hz XO to the mains should keep cone excursion under control.

Anyway, I bet if anyone measure's the raw FR of their surrounds from any one listening position that most of them are pretty bad because of the reasons Kevin noted, unless they're far enough away to minimize angle differences between drivers.

Noah
noah katz is offline  
post #29 of 265 Old 08-07-2009, 11:14 AM
AVS Special Member
 
Kevin Haskins's Avatar
 
Join Date: Feb 2005
Posts: 1,008
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by noah katz View Post

It's true the FR looks awful, but the integrated response w/XO is much better, and Earl Geddes has noted that B&C's data is accurate vs. the sugar coating you get from a lot of other mfgr's.

Also, I'm counting on auto EQ to smooth out the significant bumps, and a 100 Hz XO to the mains should keep cone excursion under control.

Anyway, I bet if anyone measure's the raw FR of their surrounds from any one listening position that most of them are pretty bad because of the reasons Kevin noted, unless they're far enough away to minimize angle differences between drivers.


That isn't that bad either. Sure... it isn't perfectly smooth like some small domes but it is usable. You can easily get that +/- 2dB without any trouble. The power response is more important than an extra +/- 1dB of linearity in a non-smoothed curve.

Kevin Haskins
Exodus Audio
Kevin Haskins is offline  
post #30 of 265 Old 08-07-2009, 11:24 AM
Advanced Member
 
ZilchLab's Avatar
 
Join Date: May 2009
Location: Berkeley, CA
Posts: 944
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Mark Seaton View Post

The above is the primary reason for using a coax, along with the flexibilities these qualities afford. If you're used to looking at dome tweeters or a smoother responding horn over a limited angle, the high frequency will look like garbage.

On second thought, Zilch & dl are right, the response is worthless, nothing to see here, please move along... Those things can't possibly sound good.

Presumably, you have some measurements to post in the interest of furthering this discussion.

Quote:
Originally Posted by DS-21 View Post

You're basing a dislike of coaxes generally on the basis of a cheap Eminence?

They were mentioned as an option here. We have found them suitable for PA at Burning Man; Eminence themselves have indicated "appropriate" application.

Quote:
Originally Posted by DS-21 View Post

I once heard this laptop that had JBL speakers, and it sounded really tinny.

Best Buy Insignias are coaxes....

.
....Crank up the SIGNAL ... cut back the noise....
ZilchLab is offline  
Reply DIY Speakers and Subs

User Tag List

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