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Will this work? (1 Viewer)

Rob Rockley

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Jeremy
Hi, I'm kind of new to home theater. I hope no one minds a few newb questions.

Really, I'm wondering if there are any major differences between home theater and automotive speakers. I know this is a pretty dumb question. But, I've got 4 Focal Polyglass component sets and 2 old JL Audio 12W4 subs sitting in my garage from previous car stereo builds. I've been toying around the idea of putting together an AV room in the basement. Is there any chance that I could build enclosures for all for the speakers and use them in in my home theater?

I was thinking that I would use the two 6.5" components for the fronts and the 2 5.25" sets for the surround and center. Then, put one (or both) of the subs in a ported enclosure.

Would it sound okay? Are there any major acoustic differences between car audio and home theater speakers?
 

Robert_J

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Properly designed car audio speakers are made to be listened to off-axis (not pointed directly at the listener). Sit down in the driver seat and see where your door speakers are pointing. Your left knee most of the time. The tweeter may be mounted a little higher but they are never pointed exactly at you. Put them in a proper enclosure and point them at you and they may sound harsh.

Not only are there acoustical differences (above), there are mechanical differences as well. More than likely, they are 4 ohm nominal speakers. If your A/V receiver can push a 4 ohm load, it will work harder doing so. Some won't work at all. Because they are designed to be mounted in an infinite baffle (the door), the speakers probably have a high Qts. You would need to measure the Thiele/Small parameters to build a proper enclosure.

Since you already have them you can experiment and see how they sound. Make the baffle as narrow as possible and the enclosure as large as possible. If your crossover has a tweeter dampening setting, use it. If they sound acceptable and your receiver doesn't blow up driving them, then you can go from a raw MDF box to something that looks nicer.

That being said, subs are a lot more forgiving. Post the T/S parameters and I can help you design a good home theater sub. What is your budget for a sub amp?

-Robert
 

Rob Rockley

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I really didn't think it would be my best bet to use the car speakers either. I did a little looking around after I posted last night and came to a similar conclusion.

But, I had to ask. It's snowing like crazy where i'm at. So, I think I need to find a hobby to prevent cabin fever. LOL.

Here are the specs, that i have, for the subs.

fs - 23.1
qts - .391
qes - .417
qms - 6.490
vas - 4.77 cu. ft.
xmax - .400
Efficiency - 87.8 db
eff. cone area - 82.5 sq. in.
Re - 6.44 ohms (in series)
znom - dual 4 ohm
RMS- 200 watts

The only enclosure building software that i have is WinISD. When I loaded that driver, it came up with 4.97 cu. ft. at 22.57 hz for the flattest and lowest response from the driver, in a ported enclosure. I know that with a car stereo I wouldn't have any other choice than to build it smaller with a higher tuning frequency, creating a peak in response. I doubt that that is something that I want to do in this case. I'm anxious to see where my first guess stacks up against someone who actually knows what they are doing.

As for my budget, I could probably spend a few hundred on a sub amp. But, I'm also looking for a new receiver. I really don't know what i should be looking for in either though. I was hoping that I could get away with spending $900 to $1000 dollars on both the sub amp and the receiver.

Thank you for the help. I really know very little about home audio.
 

Robert_J

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Since the drivers are 8 ohm nominal when the voice coils are wired in series, I'd power them with a single plate amp like the 500w model from O Audio. If possible, make a pair of enclosures with the amp in one. Then wire the drivers in parallel for a final load of 4 ohms. If you can't use a pair of enclosures, double the size of the one WinISD recommends (double the ports as well) and mount both drivers in the same enclosure. If you must go smaller, try tuning the enclosure to around 26 or 27 hz. The O Audio amp has an adjustable SSF.

-Robert
 

Rob Rockley

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I just wanted to say thank you for the advice and possibly pick your brain a little bit more.

I tried out the focal speakers in some enclosures that I built. You were absolutely right. They sounded okay. But, not really good. I also built a few temp enclosures for the subs. But, I can't seem to find any info on the amp that you recommended. Every time I try to go to the O Audio site I get an error message from my browser. What I really wanted to know is, are there any online sellers of home audio equipment? I know there are a bunch for car audio like sonicelectronix.com and onlinecarstereo.com. Are there any sites like that geared toward home theater?
 

Robert_J

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There are hundreds of sites for home audio. But most already know what they are looking for. For amps like this, the sellers are limited though. Very few people want to go through the process of building a sub.

Try a direct link to the amp - O Audio - 500W BASH Subwoofer Amplifier

-Robert
 

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