Eminence theater speaker....questions before moving forward.... - AVS Forum
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post #1 of 11 Old 01-11-2013, 07:30 AM - Thread Starter
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Very much considering building new high sensitivity speakers for theater.
Have used Eminence alphas before in an OB setup and loved them versus their cost, so looking at using their step-up Beta series.
Here goes my parts list (which includes the drivers and premade XO, as I would rather buy than build one) :

Beta 12LTA - http://www.parts-express.com/pe/showdetl.cfm?partnumber=290-409

a full range 12" driver

APT-50 Tweeter - http://www.parts-express.com/pe/showdetl.cfm?partnumber=290-530

screw-on horn tweeter

H12RW Waveguide - http://www.parts-express.com/pe/showdetl.cfm?partnumber=270-312

Shallow 12" horn

Eminence 3,500HZ XO - http://www.parts-express.com/pe/showdetl.cfm?partnumber=290-636

Premade crossover for Eminence pro-cabinets

A thought behind combo is the aesthetic nature of 2 12" round shapes, looks very good to me and am kind of set on it. Beyond that, the pre-packaging of all the bits leaves me with only having to build the simple enclosure.
The questions come as 1) Is the x-over point appropriate? (It was recommended by Eminence for the APT50 tweeter with another full-range 8" driver)
2) As I'm no engineer, what will the enclosure dimensions be for the 12" driver? (I'm assuming that the lower section of the enclosure will need to be sealed from the tweeter/horn, as the horn is plastic and won't be ideal for sealing the cabinet up) I would prefer a sealed enclosure (due to size limitations), but not sure if that is appropriate for the driver, you guys tend to know a lot more based on specs than I do.

Appreciate your help fellas....kinda excited about this project, as I've done nothing to upgrade my theater in a long while, as I've been so focused on my 2-channel rigs. And the increased sensitivity will allow me to keep using my Pioneer Elite VSX-92Txh receiver's internal amp.

TV's ain't theaters buddy.

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post #2 of 11 Old 01-11-2013, 09:35 AM
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I would suggest this as a similar yet significantly better design. Yes, it will cost you 50% more.

http://www.diysoundgroup.com/waveguide-speaker-kits/karma-series-kits/karma12-kit.html

The 3500Hz crossover is higher than optimal for the beta 12 and the crossover was not optimized for the tweeter/waveguide combo.
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post #3 of 11 Old 01-11-2013, 09:42 AM - Thread Starter
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thanks for the link smile.gif

Would anyone happen to know the sensitivity of this kit?

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post #4 of 11 Old 01-11-2013, 09:59 AM
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I've used a beta 12a in a bass guitar cab build. It's a good driver, but I'm not sure I would use that dual cone version, in fact, there is little point in doing so w/ a 3500 hz x-over. If you use the dual cone beta and that tweeter a 5k x-over would be better. The standard beta 12 should be crossed at 2.5-3k at most.

3.5k is the minimum rated x-over freq for that tweeter and as such I would want a 3rd or 4th order at that frequency. Like I said, 5k would be about right with a simpler 2nd order. It really should be designed for the impedance of the woofer and tweeter at that frequency though. Off the shelf x-overs are not the best choice.

I would port it. I think my bass cab is 2.3 cu ft and tuned to the mid 30's somewhere. I just used a simple 4" port from PE. If you use a 12" waveguide you will have plenty of box size.

That kit is a real good option. A little more money though.
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post #5 of 11 Old 01-11-2013, 10:00 AM
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Quote:
Originally Posted by Theonetruegreg View Post

thanks for the link smile.gif

Would anyone happen to know the sensitivity of this kit?

The sensitivity of the Delta 12a in the kit is 98.3 dB 1W/1m.
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post #6 of 11 Old 01-12-2013, 07:49 PM
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sounds like a "kit" with an optimized crossover might be more of what you are looking for.

the crossover in the original post is not optimized for the significant difference in sensitivities between the woofer and the compression driver. as a result the final system is likely to be way out of balance (highs might be 10db or more louder than the midrange).

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post #7 of 11 Old 01-13-2013, 03:31 PM - Thread Starter
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Was only going by the combination recommended as a bundle by Eminence (the manufacturer of the drivers and crossovers)

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post #8 of 11 Old 01-13-2013, 03:37 PM
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Quote:
Originally Posted by Theonetruegreg View Post

Was only going by the combination recommended as a bundle by Eminence (the manufacturer of the drivers and crossovers)

My guess would be the intended use is PA.

What's your goal, and budget for this project?
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post #9 of 11 Old 01-14-2013, 07:39 AM - Thread Starter
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Quote:
Originally Posted by Jay1 View Post

My guess would be the intended use is PA.

What's your goal, and budget for this project?

Gotcha. Not a genius on this end.

Goal is use as a well rounded, fairly accurate trio for the front stage in my theater with decently high sensitivity. My theater room setup is linked in signature...currently using just the receiver with no external amp, compression at excessively high volumes from the current setup, but, my experience with my 2-channel rig makes me lean more towards the-simpler-the-better, so prefer higher output from speakers rather than add more watts. (and I just want new stuff!)

Budget hasn't really been considered. I suppose throwing $1k at it wouldn't hurt at all. I have just been so impressed with the Eminence stuff used by me and by people I have met in our OB setups on SET amps. (None of which I designed, I'm the laborer, not the engineer)

TV's ain't theaters buddy.

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post #10 of 11 Old 01-14-2013, 05:22 PM
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Any of the speakers featured here would serve your needs, and greatly exceed your expectations. Many feature Eminence woofers.

http://www.diysoundgroup.com/waveguide-speaker-kits.html
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post #11 of 11 Old 01-16-2013, 08:28 AM - Thread Starter
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Thanks for the direction, never saw those kits before...will likely be heading that way then

TV's ain't theaters buddy.

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