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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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In Reply to: Horn Response uses math that is innaccurate. posted by Bill Fitzmaurice on July 28, 2003 at 11:45:23:
Hi BillGiGo is very true, anytime there are assumptions there are places for “exceptions†to leak in..
I am not too familiar with the program Horn resp but much more so with ML’s alignments.
If horn resp makes the same assumptions that ML does, then the answer is that what is plotted is NOT on axis SPL but acoustic power with out directivity being accounted for.ML’s math does calculate based on the band limits of acoustic power, not on axis response (possibly horn resp does also).
In one parsing of ML’s math, one can enter the driver stuff and get the horn stuff.
If one enters parameters corresponding to the motor, mass and area of a compression driver, one gets a horn that has about a 10:1 compression ratio and mass roll off around 2-3KHz (just like the real thing).
Measure a compression driver on the real horn (which is a curved wall flare) and one can see more or less flat response (on axis) for octaves past 2-3KHz.
In this case the difference is that the horn’s narrowing pattern with increasing frequency acts to confine the radiation to a smaller and smaller angle, compensating the actual power roll off on axis.
In this case, if one measured the sound radiated from the speaker in all directions and averaged it, one see’s that the acoustic power does indeed fall due to the mass corner (and inductive corner) its just that the changing directivity can add back 8-10-12 dB of frequency dependant level on axis compared to the total acoustic power.I don’t know if that explanation makes sense.
Another way would be:
Acoustic power response is not the same shape curve as on axis SPL unless the directivity is constant.
Cheers,Tom
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Follow Ups
- On axis SPL -VS- acoustic power response - tomservo 07/28/0313:38:14 07/28/03 (22)
- Re: On axis SPL -VS- acoustic power response - Bill Fitzmaurice 15:06:03 07/28/03 (21)
- Re: On axis SPL -VS- acoustic power response - tomservo 18:44:03 07/28/03 (12)
- We're getting a bit off the question, Tom. - Bill Fitzmaurice 05:55:21 07/29/03 (1)
- Re: We're getting a bit off the question, Tom. - tomservo 06:46:21 07/29/03 (0)
- Thank you Tom, could have not said it better! - JLH 20:10:00 07/28/03 (9)
- Re: Thank you Tom, could have not said it better! - Bill Fitzmaurice 06:19:52 07/29/03 (8)
- Disagree - JLH 16:42:27 07/29/03 (7)
- You've got it backwards. The opposite is true. - Bill Fitzmaurice 05:03:47 07/30/03 (0)
- Bends - John Sheerin 21:06:12 07/29/03 (5)
- Re: Bends - hancock 07:21:27 07/30/03 (4)
- Re: Bends - John Sheerin 12:57:53 07/30/03 (3)
- Very interesting - Bill Fitzmaurice 06:06:57 07/31/03 (2)
- Re: Very interesting - John Sheerin 08:00:08 07/31/03 (1)
- Re: Very interesting - Bill Fitzmaurice 08:39:34 07/31/03 (0)
- Re: On axis SPL -VS- acoustic power response - John Sheerin 16:03:37 07/28/03 (7)
- I use three rates of flair over the course of the horn. - Bill Fitzmaurice 16:54:31 07/28/03 (6)
- Re: I use three rates of flair over the course of the horn. - John Sheerin 17:13:54 07/28/03 (5)
- Olsen - Bill Fitzmaurice 05:29:40 07/29/03 (4)
- Re: Olsen - JLH 19:32:07 07/29/03 (3)
- Olsen did what he did - Bill Fitzmaurice 13:34:26 07/30/03 (2)
- Re: Olson, Newton, Einstein and physics (long ramble). - Paul Eizik 21:55:43 07/30/03 (1)
- Hey Paul - Bill Fitzmaurice 05:41:04 07/31/03 (0)
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