| That's logical. [message #16357 is a reply to message #16355] |
Sun, 11 April 2004 15:23   |
Bill Fitzmaurice
Messages: 335
Registered: May 2009
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Grand Master |
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However, I've found in practice that the opposite is true, and that HF transmission through a rounded bend is enhanced as the radii of the bend, particularly the inner radius, is made larger. Thus,while the longest wavelengths require neither reflectors nor radiused bends, as the wavelength is decreased the inner bend radius required for its passage intact though the bend must be increased. As an example, my DR250a loaded with a PAudio SN10 has a HF limit of 4kHz, with an inner bend radius at 2-1/4". The same driver in a larger cabinet of the same basic design with an inner bend radius of 3-1/4" runs to 5kHz. Conventional wisdom says it should be the other way around. So far as I know Sheerin is the only one who's done extensive theoretical work on what happens in round bends. In truth I've done very little, my route being to build the box first and then try to figure out why it works as well as it does. Either way we both end up in Rome.
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| Re: The DR250a [message #16372 is a reply to message #16371] |
Tue, 13 April 2004 06:25 |
Bill Fitzmaurice
Messages: 335
Registered: May 2009
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Grand Master |
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The design is a front loaded 'W' folded horn, loaded with a ten inch woofer. Overall size is about 7 cu.ft., weight 35 lbs, intended usage electric bass/keyboards/PA. The visible drivers are tweeters arranged as two vertical arrays in a cross-firing configuration. This gives 45 degree off-axis horizontal dispersion within 3dB of on-axis SPL and 120 degree total horizontal dispersion within 6dB. The trade off to get this is a falling response above 8kHz, but in pro-sound applications this is not problematic. Link attached to SPL chart.
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| Re: That's logical. [message #16416 is a reply to message #16357] |
Tue, 27 April 2004 06:05 |
John Sheerin
Messages: 8
Registered: May 2009
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Esquire |
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Hi,
This may be a bit late, but my original images are here:
http://ldsg.snippets.org/HORNS/images/roundbend/I would not really say this is theoretical work - there is a lot of theoretical work on horn bends out there, but it seems to be mostly in the JASA which is harder to search or other even harder to get journals. Anyway, looking at my FEA's again, I'd say that for a given frequency, with relatively small horn cross sections, large round bends work well. For larger horn cross sections, reflectors work better. If you're looking at the FEA's, the dimensions on the grid are inches, and as noted, the frequency is 5khz. John
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