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Old 15th August 2007, 02:50 AM   #61
soongsc is online now soongsc  Taiwan
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One thing also to consider is that mic characteristics and mic calibration files to have an effect on generation of the frequency response charts since these are applied when generating such and not in the impulse generation.

Look forward to seeing more information on the W4-657SB.
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Old 20th August 2007, 02:21 PM   #62
MarkMcK is offline MarkMcK  United States
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I support science and logic and thinking. All require a degree of skepticism. There is nothing wrong with being skeptical about what others claim. What could possibly be wrong with asking for evidence?

Language, that characteristic of humans, is rich in its possibilities of meaning. That richness can used for purposes both good and bad when authors begin to do what we call "coding."

A few posts ago I referenced a phrase from a Hollywood movie. A variation of that phrase turned up in the August 17 to 19, 2007 edition of USA Weekend.

An article about the hip-hop artist Kayne West was titled "Genius is As Genius Does." This title was likely inserted by an editor and not the article's author. What could this editor be trying to say? The saying is just as empty whether you use the word "stupid" or the word "genius."

Be skeptical. Don't just take what is said or written for granted. It might have other possible meanings or purposes.

Now, I have written a little report on the performance of the stock Tang Band W4-657SB. I have posted this report as a pdf file at the following location. This is just my attempt to produce some characterization of a starting point. It is nice to know where you begin before seeing what changes are possible.

The reports location is:

http://madspeaker.com/extras/W4657SBanatomy.pdf
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Old 20th August 2007, 03:25 PM   #63
soongsc is online now soongsc  Taiwan
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Mark,

I salute to you for posting this report. Looking at the responses at your web site, they are certainly impressing. I have been studying the impulse response for a short time, thank you for organizing these thoughts.

The onset response I assume would be like the slew rate in electronics, which is the fundamental limiting factor of bandwidth.

I would say that the motor design is responsible for the time frame prior to excitation of the cone and other structural modes, and component material is responsible for how fast the rest of the decay takes place. Both the surround and spider are very important.
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Old 21st August 2007, 02:41 AM   #64
DDF is offline DDF  Canada
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Quote:
Originally posted by MarkMcK
I support science and logic and thinking. All require a degree of skepticism. There is nothing wrong with being skeptical about what others claim. What could possibly be wrong with asking for evidence?

There's a difference between scepticism and libel, and that's why the dictionary carries both words. Be careful.

Iím flattered that you think I might be faking the data but frankly, I don't have the time, inclination, nor probably the talent, to bother.

I just retrofitted a D26 to the same box as the Tang band, my way of treating the TBs top end break up. It is in the same box as used for the prior measures. I'll be remeasuring the driver, along with the Vifa tweeter.

How do you want me to measure the TB for you? Provide details on the window you want, and any other details and Iíll measure it and post the results here.

Cheers,
Dave
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Old 27th August 2007, 07:09 PM   #65
MarkMcK is offline MarkMcK  United States
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Again, I offer no solution for the problems in the transducer. I only want to indicate that it can be done and to examine what is and what is not caused by vibration modes.

This will also lead to a two-prong approach of combining mechanical modification and electrical equalization for transducers that may require both. For some transducers, doing a mechanical correction is enough. For a slightly larger number of transducers, even correcting vibration modes will not quite make what I believe should be minimum standards

I have inserted a link to a second pdf document attempting to determine what is possible with a better performing diaphragm.

http://madspeaker.com/extras/W4657SBImprov.pdf




Also, thanks for the previous message. I confess to sloppiness in staying on topic. I mentioned several times that I was barely on topic.

I apologize if I have caused you distress. I take solace in your profession of flattery. I did not mean to imply that you were the target of my criticism. That my off topic and general comments were made in a thread you started does not indicate that you were the private person targeted.

I do not desire to limit your free speech. If you wish to post additional test results on your W4-657SB, please do so.

I would prefer not to try any remote trouble shooting. I do not have any reason to believe that any problem is related only to the windowing. In an earlier post you reported not being able to see the energy spiking in the impulse response. The spikes are present in your own data, yet you cannot see them when you graph this data. This is not a window problem.

Mark
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Old 28th August 2007, 09:03 AM   #66
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In order to increase the frequency response of the W4-657SB, it seem the cone shape needs to change.

If I recall correctly, the VC former ridge extrudes beyond the cone. I wonder of cutting that out so that the former blends with the cone better will give a better step response.

About the resonance in the 14KHz ~ 16KHz region, I wonder whether it has to do with the leads from VC to terminals. Second thing to look is the VC former if these are aluminum. Third would be , to see if grounding the motor provides improvement or not. the last would be the spider.
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Old 29th October 2007, 06:02 PM   #67
MarkMcK is offline MarkMcK  United States
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I have added a third article on equalizing the cone and surround modified W4-657SB. I also report on a stability problem with the previous modification.

http://madspeaker.com/extras/W4657SBequalized.pdf

Mark
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Old 30th October 2007, 10:22 AM   #68
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It looks like significant improvement there. I do wonder what the off-axis response is. Components used in the equalization circuit becomes quite critical. Solid core inductors generally do not have good resolution in the higher frequencies. Most air core inductors are designed for minimum material rather than maximum performance, while the stray electromagnetic field will also effect components that are placed very close.
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Old 15th May 2010, 05:23 PM   #69
vladli is offline vladli  Germany
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Hi,
I’m looking for some measuring files for w4-657 (Boxsim). Can somebody help me?
Vladli
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