Isobaric tapped horns

[Josh Ricci]

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.

[NEO Dan]

I think I'll leave this here


So much for the collective Josh

[Djim]

Or try this Patrick, if you insist in searching a way that might beat a TH. It will only take two drivers;

[Djim]

Oops, that was the wrong picture;

[Xoc1]

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

[tinitus]

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

[weltersys]

Originally Posted by tinitus

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?

[tinitus]

better ?

[weltersys]

Originally Posted by tinitus

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.

[tinitus]

ah, ok