Destructive interferrence |
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Augusts
Registered User Joined: 07 January 2017 Status: Offline Points: 179 |
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Posted: 16 November 2022 at 7:43pm |
Does putting two 12" drivers one above the other minimize the destructive interferrence if they are in a horn? If they were in a sealed box with no horn, the interferrence would occur say around 500hz. Two seperate horns for each driver would solve this for sure?
August
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Conanski
Old Croc Joined: 26 January 2006 Location: Ottawa, Canada Status: Offline Points: 2515 |
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No. The short answer is it's WAAAY more complicated than that.
Minimizing destructive interference between 2 drivers means getting thier acoustic centers as close together as possible and then restricting thier operating range to frequencies where they only sum constructively. The other option is to horn load them but they have to be loaded into a single horn.... synergy style, separate horns stacked produces even more interference simply because the drivers are further apart.
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Augusts
Registered User Joined: 07 January 2017 Status: Offline Points: 179 |
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But then how come I see everywhere people stacking horn loaded speakers side by side? Is there a scienece behind this or the interferrence is just being ignored?
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toastyghost
The 10,000 Points Club Joined: 09 January 2007 Location: Manchester Status: Offline Points: 10920 |
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There’s plenty of science behind it. The concept of mutual coupling goes back to Rayleigh in the early 1900s. Most front-loaded horn cabinets are made with a smaller mouth than they’d ideally have, for the sake of being able to transport them more easily. It can be assumed for the most part that the entire frontal area of a horn radiates sound, but this will typically not be at the same magnitude, phase or wavefront shape at all positions. When multiple horns are stacked together the larger resulting mouth from the combined array of cabinets decreases the ripple in the acoustic impedance, producing a flatter magnitude response and a smoother roll off at the low corner. This doesn’t happen by accident, and the horn should be designed appropriately to achieve this effect at the beginning. It’s a common area that people seem to struggle with when moving from axisymmetric straight horn models like Hornresp to actually folding & building the cabinet. If you want a one-stop shop to learn about this, you need this mighty tome: https://www.lean-business.co.uk/eshop/high-quality-horn-loudspeaker-systems-by-bj%C3%B8rn-kolbrek-and-thomas-dunker-p-3317.html It's one of the best things I've ever spent money on. |
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Augusts
Registered User Joined: 07 January 2017 Status: Offline Points: 179 |
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Thanks for the input. I am familiar with basshorn behaviour, I should have clarified- I am thinking about shorter wavelengths of midrange… the book looks like a good investment, thank you.
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1081 |
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In some case intereference is just ignored, either by user not being aware or manufacturer design choices, manufacturers on the whole these day's are well aware though and attempt to minimise interference between elements.
Various line array manufacturers explain the concepts, often somewhat sugar coated though. ProductionPartner have reviews of the Funktion One Evo and L'Acoustics Arcs V2 that may be worth a read.
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