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paragon
01-03-2005, 10:18 AM
Horns and different rear chambers.

Look what happens when you inrease (from 20 to 50 L) the rear chamber of a 4530 ! Sim is with a 2205A Driver. You get 10 Hz more low with a little loss in highoutput and a bit more cone movement above 60 hz.

Eckhard

lfh
01-03-2005, 03:52 PM
Those simulations of yours are most interesting. I just browsed the AJ Horn online manual, and here's an excerpt:

"Ob man nun ein Bassreflexgehäuse als Helmholtzresonator bezeichnet oder als rearloaded konisches Horn mit relativ großer Vorkammer, dessen Halsfläche gleich der Mundfläche ist, ist reine Definitionssache. In der Praxis sind beide Typen identisch."

That's a fascinating point of view! These guys think "out of the box" ;)

BTW, I dropped them a mail, asking about the feasibility of simulating compression driver/midrange horn combos. It'll be interesting to see what they say.

Guido
01-03-2005, 06:45 PM
"Ob man nun ein Bassreflexgehäuse als Helmholtzresonator bezeichnet oder als rearloaded konisches Horn mit relativ großer Vorkammer, dessen Halsfläche gleich der Mundfläche ist, ist reine Definitionssache. In der Praxis sind beide Typen identisch."

That's a fascinating point of view! These guys think "out of the box" ;)
Whether you call a ported box a helmholz resonator or a rearloaded conical horn with a relatively big prechamber which neck area is equal to the mouth area, is pure definition. Practically both are identical.

lfh
01-04-2005, 02:37 PM
I've already received their answer: According to Armin Jost (must be the "AJ" in AJHorn), the model isn't limited to low frequencies. As long as the driver parameters are known, mid- and high-frequency horns can be simulated, too. Clearly, one shall keep in mind that most compression drivers have a built in first section of a horn, and that their front chamber volumes are very close to 0. Perhaps you've already tried such stuff?

What about making a few comparisions between measurements and simulations? I dug out good ol' MLSSA from the company storage during the holidays and verified that it still works. Within the not too distant future (read: likely before end of January) I should be able to derive the basic parameters for one of my 244x drivers, as well as measure transfer and impedance functions for a couple of loads (e.g. driver alone and combined with 2311 or 2395).

(Guido, thanks for jumping in!)