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In the Forum: Horn-Loaded Speakers
In the Thread: Eventually - a reasonable midbass horn from GOTO
Post Subject: The multiple drivers: when sound in horn changes.Posted by Romy the Cat on: 2/18/2008
Ygoh,
Most of compression drivers have phase plug. A phase plug is very genomic center line oriented devise. A phase plug must be parallel to diaphragms and perpendicular to the axis of the driver. Practically all compression drivers have begging of the horn inside of the driver so the initial throat that the front chamber sees is not the throat of the horn but the throat of the driver. The little internal beginning of the horn has own genomic axis and this axis must be well-aligned with axis of horn. If you take a distortion analyzer or even a good RTA and will move a compression driver a few mm in relation to the throat of the horn then you will see that it will highly affect measurements. In a horn with multiple drivers the phase-plugs are a wasted devise to begin with. Moreover, even if we presume that the drivers are absolutely identical then they, just because of the geometry, form an ugly resonating chamber in front of the adaptor output – a resonating chamber in a horn? Not a good idea. Do not forget that sound in horn changes what the surface changes and the rule #1 is that surface shell change gradually. Any sudden change = reflection and resonance chamber. Pressure curves excellently. Sound does not. The multiple drivers with the stupid labyrinths before the horn’s throat? Come on, it is not serious. People try to bend mouth of the horn and very seldom get any more or less acceptable result. To bend a waveguide right before throat is too devastating and the most important - not necessary. The double, triple or quadruple compression drivers is a tribute to a stupid persons who have seen it implements at some kind of old crappy cinema system or at some air-defense alert system. Why “stupid person”? Because anyone why imitate without understanding what he mimics is not too smart. I would not even go into the subject of multiple drivers as a sales opportunity… BTW, there are other problems with multiple drives besides what I have mentioned...
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