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Old 24th September 2006, 09:43 AM   #1
jzagaja is offline jzagaja  Poland
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Default Bandor 50 time transmittance

Can you supply me with impulse, waterfall or step reponse of the Bandor 50 or Jordan JX6?

I'm planing mount two drivers on the disc (infinite baffle simulation).

Jack,
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Old 25th September 2006, 07:28 AM   #2
Colin is offline Colin  United Kingdom
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If you go here there is a waterfall response for the JX53, the previous driver to the JXR6. Although not identical, it should be similar above 200Hz. The Jordan site doesn't have a waterfall for the JXR6 yet. Having listened to the 53 and the 6, the JXR6 is slightly more delicate in the HF and has a much better LF output (mine have a measured Fo of 65Hz).
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Old 25th September 2006, 12:55 PM   #3
jzagaja is offline jzagaja  Poland
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It seems that older driver was smoother:

http://www.hifisound.de/oxid/out/oxb...JJ-1110856.pdf

As I see they offer electrostatics quality. What interesting me the most is how to cancel small pressure changes in the step response at transmission times ca. 100 and 400 microseconds or 8000 and 16kHz.

Does anyone tried non-electrical corrections? For example if you build rotationally symmetrical baffle like a disc you can build in the shape bulges or cavities that will change a pressure fall but don't know if they can smooth frequencies >1kHz.

Do you know maximum continuous SPL of this small single drivers?
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Old 26th September 2006, 01:53 PM   #4
Colin is offline Colin  United Kingdom
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[QUOTE]Originally posted by jzagaja
[B]It seems that older driver was smoother

Or they measured it slightly differently. It's not what my ears tell me, anyway. To be honest, I wouldn't worry about trying to iron out trivial differences in the response. The JXR6 sounds like a good electrostatic or ribbon and any room they sit in will introduce more variables than the driver. Make sure the mounting s free from obstructions, give it a good, non-symetrical enclosure and see what you think to the sound.

SPL figures are on the Jordan site. It will go loud and handles sustained high inputs ok but it's ultimate power handling depends on how you use it (an array of four, or with crossover to a bass unit and at which freq).
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Old 26th September 2006, 02:22 PM   #5
Dumbass is offline Dumbass  British Antarctic Territory
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Having a circular, hard-edged baffle would create more problems than it would "solve," in my estimation at least.

Do you have any links to projects using such a method to correct for frequency abnormalities? I can >>maybe<< imagine it being successful for cheap drivers, but I think you are splitting hairs with high-quality drivers like the Jordan and Bandor.
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Old 26th September 2006, 02:27 PM   #6
Dumbass is offline Dumbass  British Antarctic Territory
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Quote:
Originally posted by Colin
SPL figures are on the Jordan site. It will go loud and handles sustained high inputs ok but it's ultimate power handling depends on how you use it (an array of four, or with crossover to a bass unit and at which freq).
Linkwitz has a nice spreadsheet showing the relationship between driver area, frequency, excursion, and SPL:
http://linkwitzlab.com/spl_max1.xls
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Old 26th September 2006, 03:50 PM   #7
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by jzagaja
It seems that older driver was smoother:

http://www.hifisound.de/oxid/out/oxb...JJ-1110856.pdf

As I see they offer electrostatics quality. What interesting me the most is how to cancel small pressure changes in the step response at transmission times ca. 100 and 400 microseconds or 8000 and 16kHz.

Does anyone tried non-electrical corrections? For example if you build rotationally symmetrical baffle like a disc you can build in the shape bulges or cavities that will change a pressure fall but don't know if they can smooth frequencies >1kHz.

Do you know maximum continuous SPL of this small single drivers?
I suspect the surround formula changed. Metal cones are sensitive to surround formula and weight. The JX53 used to have a spider that could help in the damping process, but add to the effective mass. I think you will find that they will actually sound much better than what the graphs tell you. But one you get to listening to them, it might be still possible to slightly tune it by using tooth paste, the kind that drys hard instead of the gel type. Normally you want to keep the dry weight within 0.2 grams. Two areas that might help is some on the cap and some on the outer edge of the cone. It can be applied using a cotton swab.
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Old 26th September 2006, 03:53 PM   #8
MarkMcK is offline MarkMcK  United States
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Consider that the acoustic wave front is propagating away from the transducer/baffle at the same time it is propagating across the baffle. Thus, when dealing with a flat baffle, if the original phenomena are generated by the cone and dust cap (as I predict those evident in the Hobby HiFi test are) that there will be a leading edge containing the error ahead of the outward propagation from the "corrective" baffle features.

The sum is to increase the complexity of the step or impulse response while not actually compensating for the original error.

Also, while I judge the Hobby HIFI tests to be more representative of performance than the Jordan tests, there are still a couple of things that give me pause. If you want to continue with your experiments, I suggest that you acquire the necessary instrumentation to allow you to do your own before and after tests.

For the type of work you propose, I believe that impulse responses will be easier to work with than a step response. In graphing, the DC component of the step response tends to swamp out the high frequency information. An impulse response should more graphically show the high frequency components of a transducer's transient response.
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Old 27th September 2006, 06:58 PM   #9
jzagaja is offline jzagaja  Poland
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Colin - you are right about the room effect. We can also discuss opposite points of view e.g Moulton vs. Geddes but in fact the first pressure changes that aren't room dependant are IMHO important.

Colin and Dumbass - please read US patent 4268719:

http://ucz.tme.szczecin.pl/~jacek/temp/4268719.pdf

MarkMcK- in the paper above Mr. Manger is using correction via bulge. He wants step response between reversal points to be monotonic and linear. Why? As I know a perfect speaker should reproduce an impulse as a doublet with some ringing or overshot. Correlated step response is then e-function with some undershot.

In the opposite to the design described above is 2" compression tweeter in a waveguide and 18" woofer. Impulse and step is very clean but decays quicker and with higher undershot:

http://ucz.tme.szczecin.pl/~jacek/temp/Summa.gif

At the end - can we count for DSP? I think no, see equalized speaker/room (1D measurement):

http://ucz.tme.szczecin.pl/~jacek/te...ncorrected.png
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Old 27th September 2006, 08:15 PM   #10
Dumbass is offline Dumbass  British Antarctic Territory
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Quote:
Originally posted by jzagaja
[B]Colin and Dumbass - please read US patent 4268719:
Aha, what the folks 'round here call "bipole", very cool.

I'll need to spend more time reading that to get the deets.
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