Truncated horns [message #16920] |
Tue, 31 August 2004 07:44 |
Kevin Jordan
Messages: 20 Registered: May 2009
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Chancellor |
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Can I make horns small for PA use if I always use them in groups? I ask this because it would be easier to carry several small horns. Rgs, Kevin
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Re: Bass in groups [message #16923 is a reply to message #16922] |
Thu, 02 September 2004 02:21 |
GraemeG
Messages: 54 Registered: May 2009
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Baron |
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As Bill pointed out, just one of the factors is mouth area. A small bass horn can have a mouth area 1/10 of optimum size and therefore will have very low efficiency at the low end. The more of these horns you put together, the closer to ideal the mouth area becomes, and the more efficient the box becomes at the low end. However, just as there is an ideal mouth size, there is a minimum horn length for a given frequency. A short horn will not behave as a horn where the length is less than 1/4 wavelength. If you have a horn with say 1m path length, then even with a large mouth area the response will drop off below 80Hz. Increasing the length to 2m can get you to near 40Hz. Therefore, if you want to make small horns to be used in groups, make them small by reducing mouth area without sacrificing horn length. This is most easily achieved using small drivers (hence small throat to start with) such as 10". Cheers Graeme
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Re: Scoops [message #16932 is a reply to message #16930] |
Sat, 04 September 2004 13:23 |
Bill Fitzmaurice
Messages: 335 Registered: May 2009
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Grand Master |
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The same as any horn: acoustic impedance matching between the driver and the air, and lowering of system resonance. Rear-loading is usually employed with high Fs high SPL low Qts drivers (which most MI drivers are, as are Fostex/Lowther style full-rangers) to get more bass from the driver rearwave. Most high SPL drivers in sealed or reflex boxes have F3s around 80-100 Hz; hornloading the rear wave can take that down to 40-60 Hz. That's good, but system SPL remains at the the raw direct radiating SPL of the driver, around 95-100dB/watt. Horn loading the front wave instead allows both lowering of F3 and raising of broadband SPL by 10 to 15dB on average. The downside to front-loaded horns is that to make them long enough to impact the bass they usually are folded, which can limit their high-frequency bandwidth, although that's not the case in my DR horns.
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