Eight Alpine SWR-1223d modeling help! - AVS Forum
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post #1 of 7 Old 04-01-2012, 06:51 AM - Thread Starter
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I'm in the planning stages of a new sub build. I want to build 2 flanking subs each with 4 1223's. I want to keep a small footprint, so I'm thinking of a cabinet around 14wx16dx52h. That will give about 5ft^3 after bracing. My gut tells me thats on the small side. Each would be wired for 4 ohms and each powered by a bridged Qsc1850hd, Qsc says that's 1800watts. I don't have any problems with the carpentry part but I just don't trust my winsd skills. I think one of the issues I was having was accounting for dual voice coils. Could someone help me model this?

Ts parameters
http://support.alpine-usa.com/produc..._S06212011.pdf

Any help would be greatly appreciated. I will do a build thread when I get the drivers, but I need to sell my ib3-18's first.

Thanks,
Brad
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post #2 of 7 Old 04-01-2012, 03:05 PM
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14wx16dx52h is about 4.4cu ft after bracing and drivers.

Wiring 4 dual 2 ohm drivers get you either 1ohm or 4ohms. Best to go with 4ohms.
http://www.the12volt.com/caraudio/wo...4&I=22#results

4.414cu ft
1800 watts
Attachment 242391
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post #3 of 7 Old 04-01-2012, 04:04 PM
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mr k's post is accurate, if a little confusing.

the 1223 has dual 2 ohm coils. when you wire them in series, you get 4 ohms.

when you wire 4 drivers in series/parallel, you again get 4 ohms, but 6db more spl.

for a 4 ohm load, you do not need the high current 1850hd, better i think would be the higher voltage 2450. current draw is the inverse of the impedance. and unless you are pushing 10hz sine waves at full power, you will not actually ever use the full current, so the higher voltage amp is the better choice, kindof.

this is roughly how the power drawn from your system will appear with an 80hz low pass.
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post #4 of 7 Old 04-01-2012, 04:52 PM - Thread Starter
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Thanks for the help so far guys.

I already have the amps, or I have one and another is on the way. I have heard that the 1850 was different in that it handles a lower ohm load better. It still isn't recommended to do 2 ohms bridged according to qsc, but I wonder if it would in a home environment? The current vs. voltage is new to me, I just thought it was built to be "tougher" than the rest of the rmx series.

Looking at Mrkazadors winsd file, I'm thinking that more volume would be better. Correct? It looks like it reallly falls off quick.

Maybe I should have phrased my original question different.

What would the ideal sealed box volume be for 4 1223's powered by a bridged 1850?
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post #5 of 7 Old 04-01-2012, 05:40 PM
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there is not a simple answer to that question. lots of tradeoffs involved.

in most home rooms, there will be pressure vessel gain that will give you significant boost below the critical frequency, which tends to be about ~25hz in an average sized home room.

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post #6 of 7 Old 04-01-2012, 05:47 PM
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Quote:
Originally Posted by gracey View Post

What would the ideal sealed box volume be for 4 1223's powered by a bridged 1850?

Double in size, same power.
Attachment 242397

You gain 2db at 20hz and 3db at 10hz but reach xmax at 10hz.
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post #7 of 7 Old 04-01-2012, 05:53 PM
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"Double in size, same power."

if all you are concerned about is low end sensitivity, go as large as possible.

there are other considerations.

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