CBT24 line array speakers

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Hello guys,
i've heard recently a duo of Epique CBT24 Line Array speakers with dual Dayton audio Ultimax Sub woofers 18", a very impressive combination but the configuration was a very very high end build with KRELL & MBL amplifiers, Rosita DAC, Tube Pre-Amps, etc ...
I would like to do something more affordable but also oriented as well to Home Cinema needs.
Here are the points where i'm not really clear and would like to get your inputs:
- anyone has had good experience with line array speakers in home theater configuration? if yes:
- my system will be driven by an EMOTIVA XMC-1 pre-amp
- main speakers would be the CBT24
- Sealed Subs would be one size smaller: Dayton Audio Ultimax on 15"
I'm now looking for help on these points:
- Do i need a DSP per channel or the XMC-1 with its dirac LIVE would be enough?
- which Class D power amps with (or without) DSP would be good to drive both sub & line array speaker in each side? ideally one Amp to drive both Full range & sub?
- which would be the best central & rear speakers DIY speakers to accompany these main speakers? smaller vers of line array speakers?
- which power amplifier would be good for these 3 other speakers?

Thanks!
 
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So, how expensive? You could get some very nice line-array results with a much smaller array and higher quality drivers.

For instance, what about 4x 5-6" mid-woofers, and anywhere from 1x to 8x tweeters.

In terms of the crossover, you could do this all with a traditional passive crossover, and use the XMC-1's subwoofer output. This would really simplify your electronics.

OTOH, of course, you could go all DSP crossover, which has some advantages if you have enough amps. :)

Best,


E
 
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I wouldn't compare a small array to a larger one. There are rather large differences between how those two concepts behave.
However I have no hands on experience with the backwards bend CBT.

We do have some members with hands on experience, if you wade trough this thread (mostly at the end of it):
An Improved Array
You'll find some experienced opinions on CBT24 within the discussion. Both Omholt and Rick Craig have experience with the CBT arrays.

Hope this helps...
 
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About Don Keele

Don Keele has worked for a number of companies in the area of loudspeaker R&D and measurement technology including Electro-Voice, Klipsch, JBL, Crown, and Harman International. He is an AES fellow and holds eight patents with topics including “constant-directivity” loudspeaker horns, loudspeaker arrays, and signal processing. Currently, he heads his own consulting company, DBK Associates and Labs. His passion for the last 16 years has been to promote the use of CBT loudspeaker technology in the loudspeaker industry. Mr. Keele holds two BS degrees (EE and Physics) and an MSEE with minor in acoustics. Since 1972 he has presented and published 50 technical papers, among them the paper for which he won the AES Publication Award, “Low-Frequency Loudspeaker Assessment by Nearfield Sound-Pressure Measurement.” In 2002 he received a Scientific and Engineering Academy Award from the Academy of Motion Picture Arts and Sciences for work he did on cinema constant-directivity loudspeakers.
 
About Don Keele

Don Keele has worked for a number of companies in the area of loudspeaker R&D and measurement technology including Electro-Voice, Klipsch, JBL, Crown, and Harman International. He is an AES fellow and holds eight patents with topics including “constant-directivity” loudspeaker horns, loudspeaker arrays, and signal processing. Currently, he heads his own consulting company, DBK Associates and Labs. His passion for the last 16 years has been to promote the use of CBT loudspeaker technology in the loudspeaker industry. Mr. Keele holds two BS degrees (EE and Physics) and an MSEE with minor in acoustics. Since 1972 he has presented and published 50 technical papers, among them the paper for which he won the AES Publication Award, “Low-Frequency Loudspeaker Assessment by Nearfield Sound-Pressure Measurement.” In 2002 he received a Scientific and Engineering Academy Award from the Academy of Motion Picture Arts and Sciences for work he did on cinema constant-directivity loudspeakers.
yes, i saw that too, and for this reason and the fact that i've had the chance to hear these speakers once, i'm quite confident with his work and build ;-) but would like to see if i afford such results with my config & my needs (Hifi + HC) :D
 
Searching for old posts by Speaker Dave on the array topic would be more telling than anything I could write up on the subject. He's written a lot about the differences in several posts scattered around this forum. His research paper(s) are uploaded in one of those posts too.

If one does consider using a short array, a form of (power) shading would certainly be something to consider. I'd always go for tall (floor to ceiling) arrays myself.

The way the CBT is build has shading applied too, both in power as well as over time (the backwards bend).
It's strength comes from the number of drivers used, that tends to average out a lot of (in room) reflections due to location and path differences from each separate driver in that array to the listening spot.
There's more at work than load sharing between drivers alone in these arrays.

I can't comment on driver quality of the CBT's. I never looked them up or know what they are. If they are of good quality, their numbers will make them even better. In line arrays you do tend to get back what you used on steroids, warts and all. So it's best to start with good quality. I assume Don has that part under control. ;)
I know there's even a full range based CBT added to the CBT line up. Maybe the growing number of (full range) line arrays on these forums had something to do with that. :shutup:

I've been asking around for a set of measurements of the (original) CBT arrays without any luck so far. Aside from what Don published there isn't much out there. I'd like to see a little more than what he published so far.

To the OP: I love my straight, full range line arrays for Home Theatre duty. I don't use a center channel, so can't comment on that. I do have ambient channels which do double duty for Home Theatre. Those are single full range drivers of good quality that use diffusion to create the ambience(*). It works surprisingly well for home theatre too.
I do use a healthy dose of processing for my setup, more about that here...

I don't dare give any advise on amplifiers... It would make more sense to me to use one amp for sub duty, another for the arrays. As you'd be able to get what you need for each channel.

(*) a virtual Haas Kicker is a better description.
 
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yes, i saw that too, and for this reason and the fact that i've had the chance to hear these speakers once, i'm quite confident with his work and build ;-) but would like to see if i afford such results with my config & my needs (Hifi + HC) :D

It will work fine.

Fancy cables and expensive amplifiers are pointless, the loudspeaker is the weakest link. (now let me put on my fire suit...)

P.S. I've heard the CBT24 and I posted the thread that wesayso referenced. So I'm not being a COMPLETE troll, just a small time troll ;)
 
Hello guys,
i've heard recently a duo of Prestige CBT24 Line Array speakers with dual Dayton audio Ultimax Sub woofers 18", a very impressive combination but the configuration was a very very high end build with KRELL & MBL amplifiers, Rosita DAC, Tube Pre-Amps, etc ...
I would like to do something more affordable but also oriented as well to Home Cinema needs.
Here are the points where i'm not really clear and would like to get your inputs:
- anyone has had good experience with line array speakers in home theater configuration? if yes:
- my system will be driven by an EMOTIVA XMC-1 pre-amp
- main speakers would be the CBT24
- Sealed Subs would be one size smaller: Dayton Audio Ultimax on 15"
I'm now looking for help on these points:
- Do i need a DSP per channel or the XMC-1 with its dirac LIVE would be enough?
- which Class D power amps with (or without) DSP would be good to drive both sub & line array speaker in each side? ideally one Amp to drive both Full range & sub?
- which would be the best central & rear speakers DIY speakers to accompany these main speakers? smaller vers of line array speakers?
- which power amplifier would be good for these 3 other speakers?

Thanks!

Prestige?
 
Be aware that the measurements in that review are flawed. They didn't measure correctly.

There were also several wrong facts in the review and they guy who listened didn't even use measurements with integrating a subwoofer. It confirmed all my negative bias towards hifi reviewers. :D

Anyway, here are proper measurements of the CBT24. Both raw without EQ and one with EQ. Take notice that the resolution of the Y axis is high with 3 dB increments. Measurements were conducted over a reflective floor in a normal room, meaning room modes are included.

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Pink is with EQ:
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@Kraig, my bad it's Epique and not Prestige :p

Ok - that's what I thought. Dirac should be capable of providing the equalization that you'll need for the CBT-24. If you bi-amp there are many amps that will work fine depending on your budget. The MiniDSP plate amps are a good option.

As far as a center and surrounds that depends on the coverage you need and how much output is desired. Smaller arrays are possible but with a 2.5" driver they become very limited. If you room allows a horizontal CBT array works great as a center channel. I prefer 2-way CBT designs but your budget might not allow that. A conventional center channel with output capability comparable to your arrays is probably more practical. The same is true for the surrounds.
 
Be aware that the measurements in that review are flawed. They didn't measure correctly.

There were also several wrong facts in the review and they guy who listened didn't even use measurements with integrating a subwoofer. It confirmed all my negative bias towards hifi reviewers. :D

Anyway, here are proper measurements of the CBT24. Both raw without EQ and one with EQ. Take notice that the resolution of the Y axis is high with 3 dB increments. Measurements were conducted over a reflective floor in a normal room, meaning room modes are included.

628575d1501678914-cbt24-line-array-speakers-cbt24-eq-jpg



Pink is with EQ:
628576d1501678914-cbt24-line-array-speakers-cbt24-eq-jpg

Bjorn,

Don Keele sent me a copy of the review. Before you jump on the reviewer (which overall was favorable towards the design) you may want to reconsider a few things.

It's possible the MiniDSP settings were not correct as supplied to the reviewer (different measured transfer function). These are probably the easiest speaker of any to measure. If the transfer function is wrong then that may be the major factor. There could also be QC problems, such as wrong wiring / shading, out of spec drivers, etc. (hopefully not).

Whether it's a hard surface or carpeted the response curves won't vary that much. If they did, then they would be supplying different presets for the type of room being used.

A horizontal off-axis curve would've been nice and more informative.
 
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