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Old 7th May 2012, 08:09 PM   #11
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An excerpt from Ed Kabotie’s song, “7 Cities of Gold” with voice, acoustic guitar and wood flute was used to compare the output of various HF drivers all fitted to the same type horn.
Ed Kabotie Freedom Songs - DreamCatcher.com

The specifics and SPL level of each music recording are in the OP "Tests" section.
The "- 2" output of the "PA" driver was too low to make a decent recording, "-10" has been included instead.

The file type suffix < .zip > must be changed to < .mP3 >, the music files will then open with your mP3 app.


Art
Attached Files
File Type: zip 1Ap1312.zip (581.6 KB, 28 views)
File Type: zip 02p0125.zip (554.5 KB, 13 views)
File Type: zip 50n0125.zip (542.3 KB, 19 views)
File Type: zip 52n0125.zip (541.2 KB, 14 views)
File Type: zip 52n0630.zip (564.2 KB, 12 views)
File Type: zip 82n0630.zip (591.2 KB, 13 views)
File Type: zip 82n20630.zip (569.3 KB, 10 views)
File Type: zip PAn0630.zip (566.8 KB, 10 views)
File Type: zip PAn10630.zip (558.1 KB, 9 views)
File Type: zip 52n20630.zip (543.3 KB, 10 views)
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Old 7th May 2012, 08:25 PM   #12
IG81 is offline IG81  Canada
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Not long ago, I did some response tests on 3 different drivers (including BMS 4550), as well as three vastly different waveguides. This was rather basic and took me an entire evening. I can only imagine how much work and time this took you! Thanks for sharing it!

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Old 7th May 2012, 08:35 PM   #13
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quote from OP:
When pushed hard, even with a 1250 crossover, the "s" sounds in the word “cities” seemed to get the most “spitty” with the BMS drivers, and the harmonics of the flute seemed a bit odd. The BMS drivers have the smallest diaphragms of the drivers tested, whether this type of distortion is simply the result of the higher throat SPL required by the smaller diaphragm and exit diameter, or the driver design itself is an unanswered question.
Quote:
Originally Posted by RockLeeEV View Post
What do you define as "pushing hard"? Are these levels one would approach in their living room or are we moreso talking about PA application?
The “spitty” distortion increases in the higher power levels used in the tests, starting at a few watts of power, around 110 dB at two meters. Typical horns would have about 6 dB less output level, so would require about 8 watts to achieve that SPL, with an additional rise in distortion.
Although that level (and far higher) is common in PA use, most home users don't play music that loud.

For those that desire the levels achieved by live brass, reeds and percussion (which can easily exceed 110 dB at 2 meters) in their living room, it would be accompanied by some degree of distortion using the BMS 1" drivers.

Many of the music recordings of the horns are now available for you to listen to, you may determine at what level the distortion becomes unacceptable to you, or you may find that the levels of distortion at the loudest levels I recorded at are still acceptable.

The OP is updated at the bottom listing the post #s containing the recordings.

Art
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Old 7th May 2012, 09:11 PM   #14
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An excerpt from Ed Kabotie’s song, “7 Cities of Gold” with voice, acoustic guitar and wood flute was used to compare the output of various HF drivers all fitted to the same type horn.
Ed Kabotie Freedom Songs - DreamCatcher.com

The specifics and SPL level of each music recording are in the OP "Tests" section.

The "1Ap1763" and "02p15 125" were "oops" moments, recorded at the full (un- clipped ) output level of the amp, around 367 watts peak. None of the other drivers were tested at these levels.

The file type suffix < .zip > must be changed to < .mP3 >, the music files will then open with your mP3 app.


Art
Attached Files
File Type: zip 1Ap1363.zip (580.5 KB, 15 views)
File Type: zip 1Ap1763.zip (563.7 KB, 11 views)
File Type: zip 02p15 125.zip (575.4 KB, 10 views)
File Type: zip 02p10125.zip (564.2 KB, 9 views)
File Type: zip 50p13125.zip (577.5 KB, 11 views)
File Type: zip 52p13125.zip (539.7 KB, 11 views)
File Type: zip 82p1312.zip (579.0 KB, 11 views)
File Type: zip PAp363.zip (554.5 KB, 9 views)
File Type: zip PAp912.zip (586.1 KB, 9 views)
File Type: zip 82p1363.zip (597.4 KB, 10 views)
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Old 7th May 2012, 10:15 PM   #15
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Art,

can you post a picture looking down the mouth of the horn?
And lit well enough to see what is going on there??

In practice, do you array these horizontally like an old multicell to get the required horizontal coverage??

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Old 7th May 2012, 10:30 PM   #16
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Art, thanks - I've been listening to these and hearing the differences.
Alas I'm having some trouble with the cyrptic file names and would like to rename the MP3s I have here.

I'm thinking that the first three characters are the driver name, the next 2 the dB level and last 2 are the crossover frequency (630Hz or 1250Hz), right?
So 82p1363 is the B&C driver, +13dB, 630Hz high pass. P= "program".
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Old 7th May 2012, 10:31 PM   #17
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Also, while the tests are interesting, I am wondering about the transition between the compression driver's short exit/throat and the throat of the horn. If there is a discontinuity there - the angle changes - then you may have a place where there is diffraction. Might be effecting the distortion and the HF response. Wondering about that.

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Old 7th May 2012, 10:34 PM   #18
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Quote:
Originally Posted by bear View Post
If there is a discontinuity there - the angle changes - then you may have a place where there is diffraction.
Quote:
Originally Posted by weltersys
Care was taken to insure a smooth transition between driver, adapter and horns, requiring a fair amount of drilling, filing and cursing those that made poorly aligned adapters and drivers that have unique bolt patterns.
Might not be an issue. Art?
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Old 8th May 2012, 12:35 AM   #19
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Quote:
Originally Posted by bear View Post
Art,

can you post a picture looking down the mouth of the horn?
And lit well enough to see what is going on there??

In practice, do you array these horizontally like an old multicell to get the required horizontal coverage??

_-_-bear
The horn is too deep to get a clear view down the throat.
The pictures in post #1 show the side view of the Maltese horn, the four horns arranged as a Maltese cross show why it was named. The 2" throat of the horn is a simple transition from square to round.

In practice, the horns were arrayed horizontally, the last time I used them for PA I used three per side, which left HF "holes" spread to 90 degree coverage, seven Maltese horns would be required for a 13 x 90 degree pattern.
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Old 8th May 2012, 12:47 AM   #20
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Quote:
Originally Posted by Pano View Post
Art, thanks - I've been listening to these and hearing the differences.
Alas I'm having some trouble with the cyrptic file names and would like to rename the MP3s I have here.

I'm thinking that the first three characters are the driver name, the next 2 the dB level and last 2 are the crossover frequency (630Hz or 1250Hz), right?
So 82p1363 is the B&C driver, +13dB, 630Hz high pass. P= "program".
The explanations for the tests names are in post # one, each "Test" sequence details the tests undertaken for each of the six drivers.
I'd suggest printing out a copy of the tests for easy reference.

The first capitol characters are the driver name. "ds" stands for Dual Sine.

The music tests used a crossover frequency, and a variety of test levels covering as much as 37 dB range from the -20 (n20) tests to as high as p17 + 17 dB.
"n" stands for "negative" and is carried through to the "0 db" , then changes to "p" for positive (+), which carries through to +10, +13 or in a few cases +15 and + 17.

The crossover frequency was 630 or 1250, sometimes only the first few numbers, 63, or 12, or 125 were used.

Last edited by weltersys; 8th May 2012 at 01:10 AM.
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