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Old 9th February 2013, 02:49 PM   #21
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You both said that I am wrong yet then both proceed to agree with what I said.

Patrick seemingly said that isobaric loading a pair of drivers cuts excursion in half for the same given output level as a single identical traditionally loaded driver. It does not. You do not gain any maximum displacement limited output over a single driver by using two identical drivers in isobaric. You are not utilizing the SD of both drivers for output, only one and driver mechanical stroke is not changed therefore total displacement potential does not increase.

In a standard configuration you gain 6dB by doubling the drivers (total displacement) but in isobaric you are not doubling the total displacement since half of the driver radiation is not coupled to the outside. Effectively you are combining both motors to the SD of a single driver with an isobaric config essentially creating the same driver as before with a much more powerful motor. I just don't want anyone who may be reading to get confused and believe that they will get significant increases in headroom by using isobaric driver configurations because they won't. Using the second driver conventionally will allow for 6dB of potential headroom over a single. Isobaric does not. That would be getting your cake and eating it too and it just doesn't work like that.

EDIT: I see that the comparison is of 4 drivers isobaric versus a single conventional in order to gain the 6 dB Patrick was mentioning. I missed that part. That is correct. You need 4 drivers to 1. You sacrifice 6dB potential by isobaric loading. How often is it that a real world build will be able to cram 4 drivers into a smaller space than 1 would work especially in a horn which is usually crammed to begin with? Not to mention 4x the driver cost and weight for any actual increase in performance over a single driver. Typically it makes more sense to just take the increased budget for the 4 drivers and upgrade to a much more powerful, larger or higher displacement unit to begin with and keep the build complexity down.

Last edited by Josh Ricci; 9th February 2013 at 03:00 PM.
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Old 9th February 2013, 04:53 PM   #22
NEO Dan is offline NEO Dan  United States
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I think I'll leave this here
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So much for the collective Josh
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Dan
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Old 9th February 2013, 11:45 PM   #23
Djim is offline Djim  Netherlands
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Or try this Patrick, if you insist in searching a way that might beat a TH. It will only take two drivers;


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Old 10th February 2013, 01:19 AM   #24
Djim is offline Djim  Netherlands
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Oops, that was the wrong picture;

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Old 10th February 2013, 06:16 PM   #25
Xoc1 is offline Xoc1  United Kingdom
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I spent a short time today playing around with isobaric TH design.
It would be possible to fit 8 10" drivers into a Cubo sub
Unfortunately the Hornresp sim is very ugly in 8 X isobaric mode!
Looks OK with 4 conventional drivers though.
Cab is Cubo sub as on freespeakerplans Home
Driver was B&C 10NW64
This is at 2.83V with all of the drivers in parallel
Regards Xoc1
Attached Images
File Type: jpg Cubo Sub ISO 8.jpg (33.1 KB, 257 views)
File Type: jpg Cubo Sub ISO 8 HR.jpg (38.1 KB, 255 views)
File Type: jpg Cubo Sub 4 x 10.jpg (29.7 KB, 81 views)
File Type: jpg Cubo Sub 4 x 10 HR.jpg (40.3 KB, 93 views)
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Old 10th February 2013, 09:32 PM   #26
tinitus is offline tinitus  Europe
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how about the 'symmetric' version with two drivers in the middle, playing against each other, and two port openings, one each side ?

very quick drawing
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File Type: png tapped.png (9.5 KB, 74 views)
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Old 10th February 2013, 09:42 PM   #27
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Quote:
Originally Posted by tinitus View Post
how about the 'symmetric' version with two drivers in the middle, playing against each other, and two port openings, one each side ?

very quick drawing
Your very quick drawing does not look like a tapped horn, and is not an isobaric loading.

What is your "question" asking?
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Old 10th February 2013, 10:03 PM   #28
tinitus is offline tinitus  Europe
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better ?
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Old 10th February 2013, 10:20 PM   #29
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Quote:
Originally Posted by tinitus View Post
better ?
The arrangement you show in post #28 uses a lot more wood to achieve a given path length than the fold patterns similar to the DSL TH-115 or 118.
I fail to see anything "better" about that feature, unless you prefer cabinets to be heavier, more expensive and larger for a given Fb.

Last edited by weltersys; 10th February 2013 at 10:36 PM.
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Old 10th February 2013, 10:29 PM   #30
tinitus is offline tinitus  Europe
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ah, ok
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