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Old 22nd July 2015, 07:02 PM   #1
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Talking (4) REx 10's

So I was modelling some boxes for (4) RE Audio REx 10's for my '14 Kia Soul. I only have about 4 cubes to work it, both boxes tuned to 37hz.

I will have 1000rms being fed among all four.

These are the boxes that I modelled:
Click the image to open in full size.

Assuming no losses:
In the green is simply a ported box, 6.7 db peak 50hz, f3 31hz, f10 24hz
In the orange is IsoBarik, I get 11 db peak 39 hz, f3 28 hz, f10, f10 23hz

I'm not familiar with IsoBarik--Would loading them in a push/pull configuration really give me a theoretical 6db gain at a lower frequency? I'm not a fan of 50hz bass (30s are my favorite.) I'm assuming I'd have less cone area in a push/pull configuration, though, resulting in about an equal gains...can someone provide insight on this?

I'm really limited by space and alternator power with this build otherwise I'd go way bigger.

You guys are the best!
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Old 22nd July 2015, 09:24 PM   #2
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I'd tune the boxes lower, or even go sealed - much better match for the cabin gain typically seen in car install apps.
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Old 22nd July 2015, 11:06 PM   #3
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I'm not aiming for a flat response, I want it to be louder. I have my home system for accuracy, I want my car for fun.

My previous system was 4 15s on 4000 rms.
My onw friend, for example, has 12 15s on 30,000 rms. I like big bass. He does a 157+ at 33 hz
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Old 23rd July 2015, 11:02 AM   #4
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Okay, fair enough.

The isobaric is using twice the number of drivers (and presumably twice the power - the old WinISD isn't too good for that) to get 6dB gain at one frequency. If you double the size of the normal ported box and add a 2nd driver, you'll get 6dB gain right across the band. Way more output.
Only use isobaric if you want things to be as small as possible, accepting that you'll need to throw power and extra drivers around.

Chris
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Old 23rd July 2015, 12:39 PM   #5
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I'm using WinISD Pro (I'm under the impression when you say the old one, you mean non-pro?)
I've accounted for "2-pairs" when setting it to IsoBarik. I mean if it's literally mounting the subs in a push pull, wiring internal sides opposite polarity, I think I can wing it with cutting two holes and mounting them before I put the last panel on. If I don't like it, I'll simply cut two more holes so I can access the internal subs again.

Image for the lulz:
Click the image to open in full size.

Like I said, I can't double box or power, I'm limited to a 110-amp alternator (12volt) and 4 cubes. I know most people on here aren't car-audio guys but i'd consider this forum way more knowledgeable in acoustics than diyma/diymobileaudio.
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Old 23rd July 2015, 02:23 PM   #6
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After reading a few articles that didn't give a concise answer regarding efficiency, this one seems to explain it well:

Audio Innovation - by Dan Marx www.danmarx.org
An excerpt:
...When you compare isobarics to a system which houses two drivers each in their own enclosure, this system was actually 6 dB less efficient.

So I suppose that's my answer. Maybe one day I'll play with it for ***** and giggles.
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Old 23rd July 2015, 03:29 PM   #7
Zwiller is offline Zwiller  United States
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I think it's clicking with you now. You actually posted the page I have bookmarked for myself to recall the theory differences. Personally, I still dig the look of the iso cabs. A plexiglass top or side so you could view the clamshells would be killer. While you might not achieve your intended goal the sound quality is still there too.
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Old 23rd July 2015, 07:14 PM   #8
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by Kelocyde View Post
I'm not aiming for a flat response, I want it to be louder.
I have my home system for accuracy, I want my car for fun.
Hi,

Well I wouldn't call loud one note 50Hz bass with no depth much fun at all.
The fast vented roll-off below 50Hz does not utilise the cabin gain well.

Here 1 cuft per driver sealed and stuffed is ideal to utilise the cabin
gain for very deep bass, which will be far more even and tuneful. *

Volume wise with 4 x 10" 12mm excursion drivers and 1000W
on tap, in the volume of a car should be more than plenty.

rgds, sreten.

* As a further point sealed will mean you can hammer the drivers
as hard as you like with a common overload point in the low bass,
you can't do that with vented, it needs high pass protection.
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Last edited by sreten; 23rd July 2015 at 07:28 PM.
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Old 23rd July 2015, 07:30 PM   #9
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Quote:
Originally Posted by sreten View Post
Hi,

Well I wouldn't call loud one note 50Hz bass with no depth much fun at all.
The fast vented roll-off below 50Hz does not utilise the cabin gain well.

Here 1 cuft per driver sealed is ideal to utilise the cabin gain for very deep bass.

rgds, sreten.
Opinion.
I've built many sealed setups (why not, it's less work?) and have never been satisfied.

Most music with real instruments barely goes below 40 hz, yet alone 20 hz so I don't know why -you- would need "low extension" anyways. Maybe for home theater applications.

Have you ever heard 25 hz @ 145-150+db?
In a vehicle with thin sheet metal, even with layers upon layers of deadening and foam, it's hard to contain, causing resonances and basically fighting the woofers. Fast bass comes from good midbass-speakers, which I would disable subs if I truly wanted "accuracy." Not that I'd call the interior of any vehicle accurate.

Oh, also, I think you're forgetting about this thing EQ... You should read about it!
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Old 23rd July 2015, 07:40 PM   #10
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There is no such thing as fast bass and you can't effectively EQ a ported box below tuning.

This little writeup might be helpful for ideas on how to tune with cabin gain in mind.
http://www.diysubwoofers.org/projects/car/sub3/

Last edited by zettairyouiki; 23rd July 2015 at 07:50 PM.
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