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Old 14th March 2013, 11:10 PM   #31
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Quote:
Originally Posted by just a guy View Post
I did show you the sims and measurements I could find online from several years ago, which were first run measurements with no care taken to get an accurate result, only to make sure there were no major problems like air leaks.
I missed them, what post were your sims and measurements you found online from several years ago posted in?
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Old 14th March 2013, 11:19 PM   #32
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Originally Posted by weltersys View Post
I never claimed my simulations were accurate.
An accurate simulation by definition would match measurements .

Art
I'm talking about accurate inputs, which you apparently never tried to do before claiming Hornresp isn't accurate.
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Old 14th March 2013, 11:23 PM   #33
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Originally Posted by weltersys View Post
I missed them, what post were your sims and measurements you found online from several years ago posted in?
Difference between Super Scoop and Folded Horn Subwoofers

In the same thread you requested them.
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Old 14th March 2013, 11:23 PM   #34
OMNIFEX is offline OMNIFEX  Jamaica
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Quote:
Originally Posted by just a guy View Post
Understood, but soho54 has shown over and over that accurate simulations match measurements very well, at least at small signal levels.
To attain accurate measurements one would need to measure the TS Parameters of the driver to confirm if indeed the TS Parameters are close to the manufactures stated TS Parameters. The majority of designers don't measure the TS Parameters of the actual driver. This is why many attain measured results differing from the simulation.
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Old 14th March 2013, 11:49 PM   #35
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Quote:
Originally Posted by just a guy View Post
Difference between Super Scoop and Folded Horn Subwoofers

In the same thread you requested them.
Looking at them it appears the low corner as measured is about 4 Hz higher than simmed, nearly 1/3 octave higher than the sim predicted.

To me, that is a fairly big difference, but close enough for rock and roll .

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Old 14th March 2013, 11:56 PM   #36
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Originally Posted by weltersys View Post
Looking at them it appears the low corner as measured is about 4 Hz higher than simmed, nearly 1/3 octave higher than the sim predicted.

To me, that is a fairly big difference, but close enough for rock and roll .

Art
In both this thread and that one I stated that I imported this design into Akabak to refine and also shorted the horn a bit to raise the tuning at that time for more max spl vs the shown lower tuning, but kept the response curve shape the same (only the lowest impedance peaks shifted up a bit as a result). Unfortunately I don't have the final Akabak sim anymore but the higher tuning was not a mistake, I did that on purpose in Akabak after this Hornresp data was captured but unfortunately this is all I have left to show.

I'd be more than happy to show you the final Akabak sim and the measurements that I took outside at 10m and well away from any boundaries but I don't have them anymore, I never posted them online anywhere and my old computer died.

In the absense of more accurate data on my part, I suggest we can look at Lilmike's data instead (if you are interested), he's got at least a few examples of very well documented sims and measurements done properly outdoors.

Last edited by just a guy; 15th March 2013 at 12:10 AM.
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Old 16th March 2013, 11:54 AM   #37
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Originally Posted by OMNIFEX View Post
To attain accurate measurements one would need to measure the TS Parameters of the driver to confirm if indeed the TS Parameters are close to the manufactures stated TS Parameters. The majority of designers don't measure the TS Parameters of the actual driver. This is why many attain measured results differing from the simulation.
Further to OMNIFEX's comments -

In Hornresp, fs is taken to be the driver free-air resonance frequency. Manufacturers often don't state under what conditions their fs values are measured. If a given fs figure happens to be for a driver mounted in an infinite baffle, then the Hornresp predictions will be inaccurate. This is one reason why I prefer wherever possible to use the fundamental electro-mechanical parameters as primary inputs to specify the driver, rather being required to derive the values from perhaps questionable Thiele-Small equivalents.

Kind regards,

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Old 19th March 2013, 10:52 AM   #38
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This is all very interesting information! i think ive made my decision.... im going for accurate bass moreover power, and just have more cabs

ill start a thread when i start the project !
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Old 16th January 2017, 05:23 PM   #39
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Hey guys.
Hope that opening this old thread isnīt a problem. I only need to "exploit" one. Or, I hope so. After (still to do) reading the 100+page topic about keystone, I might be tempted to pop even there.

After having 18SW115 in compact 135l bassreflex box, which works awesome, Iīm looking further. I considered 21" 170l bassreflex, and also a tapped horn design.
But I did my homework, and I quite donīt buy that TH superiority yet.

Firstly, when I set some strict box volume, I never see compact TH outperform BR where I need it - under 50 or 40Hz. Then there is all that sensitivity and power talk, and efficiency, but NOONE looks at it from the impedance and real loading and power level angle of view. Therefore Efficiency is not what is measured. Just VOLTAGE SENSITIVITY, which is not really good way to look at it to be fair.
High BL speakers have close to 200Ohm peak impedance, and still over 60Ohm in the upper peak when enclosed in BR box. Thatīs not a lot power going into the speaker. How is TH?
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Old 16th January 2017, 06:04 PM   #40
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Originally Posted by Crashpc View Post
Firstly, when I set some strict box volume, I never see compact TH outperform BR where I need it ...
Acoustic gain (and therefore ultimately efficiency) is largely a product of enclosure size (vs low knee frequency). If you keep the box sizes the same your efficiency is going to be roughly the same no matter what kind of box style you use.

If you look around at tapped horn designs they are usually about 4x larger than a normal sized ported box for the same driver and low knee. That's where the efficiency comes from.

There are also advantages that can't be seen so easily like the lack of port compression from any type of horn. Also horns (which are usually larger) hit their excursion limits with less power than ported boxes (which are usually smaller) and this might show some small gains in lack of power compression issues as well.

There's not much to gain from a compact TH, the whole point is that you can make them large and get some benefits over a ported box.
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