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Old 12th June 2006, 06:55 PM   #1
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Question Isobaric mids?

I am thinking about doing an intresting component set, .....

I know if you isobarically load two speakers into the same enclosure. From what I understand, when you do this, you effectively double the volume of an enclosure. The midbass response should also be much stronger. I have a 2004 Ford F-150. I just ordered an extra set of door panels really cheap from Ebay.

My idea is to get two 8 ohm speakers for each door panel between 4 and 5 inches. Wire them so they presents as 4 ohms to my clif designs cross overs which are crossed at 3500. Maybe some Dayton DA135-8 5-1/4" ALUMINUM CONE WOOFER.

What do you guys think??
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Old 13th June 2006, 01:05 AM   #2
lndm is offline lndm  Australia
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Hi fujio001
That's a creative idea, but watch for the catch. At higher frequencies where wavelengths are similar to the distance between the drivers, you may have cancellation problems.
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Old 13th June 2006, 03:54 AM   #3
adason is offline adason  United States
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i bet there must be reason why this is done only for woofers not midrange
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Old 13th June 2006, 07:32 AM   #4
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What you could do to get past the cancellation is to place them very close to each other. Then the tweeters can take over after a 3500.

Any other thoughs on what speakers would work well in such an enclosure?
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Old 14th June 2006, 09:08 PM   #5
dangus is offline dangus  Canada
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I don't think it's worth the effort. The volume inside the door cavity should be plenty for such small drivers, unless you were going to build a sealed enclosure into the door. It'll take a bunch more work to fabricate an isobarik tunnel to join the drivers, and the extra depth could be a problem. So, maybe use two drivers but side by side, normally.

Even with woofers the benefits are questionable: the isobaric tunnel takes up space, so the volume saving is never as much as 50%. You need twice as many woofers and twice as much power compared to using a single driver. Might as well just mass-load the driver until it works in the smaller box, or buy a more appropriate subwoofer to start with.
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Old 15th June 2006, 08:09 AM   #6
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you would be better off with a 6.5 or 7 inch driver with more linear xmax considering you have an amplifier,the dayton rs 180 4 ohm drivers are excellent for 35.00 ea or so,wont be ideal with the 3500 hz lp but should sound better than the 2 5 in mids in each door- spend the xtra cash on dampening for the doors , its a must if you expect much of a performance up-grade with any speaker, the peerless autosound 6.5 inch drivers are about 38.00 ea at madisound they will mesh better with the 3500 hz lp
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Old 16th June 2006, 02:01 AM   #7
Eva is offline Eva  Spain
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The air volume inside the door of a car is already too big an enclosure for most 4", 6.5" and even 8" drivers, which usually results in poorly controlled cone displacement at low frequencies and a too low Qb.

Mount two drivers on each door in a conventional arrangement and you will get far better performance.
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Old 16th June 2006, 02:33 PM   #8
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4 sure...

6.5 or 8...the door is fine and most car audio drivers are designed for free air applications..
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Old 16th June 2006, 02:34 PM   #9
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you never want to invert any mid of any sorts...any and all motor and suspension noise would be heard...plus unless they do midbass only "150HZ and lower" you will get a diffused sound from lower vocals etc from the interaction of the basket...
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Old 16th June 2006, 03:50 PM   #10
sreten is offline sreten  United Kingdom
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Hi,

there is no difference between two 8ohm isobaric drivers with say Vas = 10L each and
cone mass = 10g each and a single 4 ohm driver with Vas = 5L and a cone mass of 20g.

Get the right midrange driver, isobaric has no midrange advantage.
(And it will not give "a much stronger midbass response")

Isobaric only makes sense when you want a bass enclosure
half the size most drive units are designed to work with.

/sreten.
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