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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: DATA posted by John Sheerin on July 24, 2009 at 14:07:00:
Hello John,
Thanks for your informative post.
Simulations are heuristic devices. In other words, simulations are a way to try and predict what might happen in a given situation, and to learn how the real world works in relation to our expectations. Simulations in speaker design are just the same- they are no substitute for the real thing, which is building actual speakers and testing them. This is what we’ve been asking from you, and which you evidently have not done yet. A simulation is no substitute for the real work involved in designing good sounding horns, something I doubt you would disagree with.
When you do simulations, which we do a lot of, by the way, its best to choose ones which will tell you useful information, something you really want to know. The same goes for comparisons.
In your first simulation, shown below, for example, you have a LeCleach horn modeled against a conical horn. You choose a 20kHz frequency to do this. 20,000hz is at the very end of the audible frequency spectrum, which is a rather ridiculous place to locate any such comparison. We don’t make a 20,000 hz horn, and I doubt this simulation has any value, except to show that you were really looking hard for places to make strong visual contrasts between the LeCleach and a conical horn.
For that matter, its best to also be clear in comparisons, and to compare apples with apples, and oranges with oranges. Meaning, compare a LeCleach 500hz or 800hz or whatever cutoff horn with a similar conical, such as the ones we make (if you are going to attack our products, at least use them for comparison, and don’t erect “straw men†), and specify actual horn length, mouth area, etc. This you did not do, or if you did, its not very clear (to me, at least.) Furthermore, do this with a given driver, one which makes sense for the context of the comparison. In fact, we don’t do any modeling of horns without the driver being part of the equation, as it ALWAYS IS part of the equation. At least in the real world, which is where we make our products. Not in SimVille.
I don’t want to belabor this with a discussion of how your sims were done (they don’t look like ours, I can tell you that) but I can suggest that your conclusions, for example with off axis directivity are very, very strange. The conical profile has superb off axis response, and the LeCleach does not, at higher frequencies, where the wavefront does not even “see†the rapidly expanding walls of the horn and simply beams like a headlight. Any session with a LeCleach horn and actual listening will prove this- no computers are necessary.
So we are back where we started- we asked you to provide actual, hard measurements of a LeCleach horn with and without the mouth rollback, which you credited with reducing HOMS, etc, and improving the sound of the horn. Such measurements should be done at 10 degrees, 20 degrees, 30 degrees off axis. Outside, preferably, unless you can get back into that anechoic chamber of yours. We contend such actual measurements of the LeCleach horn with mouth rollback and without will show negligible real world benefits, either measured or audible. But you have not done any such measurements, or if you have, you have not posted them here. In fact, the LeCleach is really just a hyperbolic horn with a very squeezed throat, which colors the sound greatly, even if it simulates well, and that is the actual cause of the “honky†colorations which you, Geddes, and LeCleach have mistakenly taken to be a result of a non rolled back horn mouth termination.
As for your comments on Geddes, I think his credibility here has already suffered greatly, as when Tom Brennan linked to the thread that you mention over at DIY Audio in which people were complaining about the truly absurd, cheap, and poor quality of the horn kits he was selling. But this is a respected scientist, who has published major papers, you may contend. Such papers as to how there is no difference between the sound of different compression drivers (!!!!!?????) If that is so, there must be a lot of deluded people on this Forum, as a good deal of the traffic here is about the difference in sound between the various compression drivers, but which Geddes cannot hear or differentiate between. When he posted references to that work on this Forum originally, I read the abstract, and his methodology involved hiring college kids to hear 10 seconds of a Talking Heads song from the album Stop Making Sense, I believe at high volume. From that setup, Geddes derived his conclusions.
I find that about as satisfying and useful as your simulations and discussion of horn design.
Jonathan
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