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Old 29th December 2003, 01:14 PM   #1
tda is offline tda  Romania
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Default 2 Question regarding Math Cad Sheets

I have 2 question regarding MK MathCAD Sheets.

1. When I build a ML-TQWT based on MathCAD sheets, where should I put the port? What I mean, it matters if I put it at 90% from total length of TL instead 75% for example? Should I put it as low as I can?
2. I used the same parameters in ML-TQWT and Ported Box spreadsheets, but the SPL graphics are not the same? Iím a little bit confused? Shouldnít be the same results?
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Old 29th December 2003, 05:25 PM   #2
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This thread may answer some of your questions.
Tl Basic Design Question.
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Old 29th December 2003, 07:24 PM   #3
MJK is offline MJK  United States
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Hi tda,

1. When I build a ML-TQWT based on MathCAD sheets, where should I put the port? What I mean, it matters if I put it at 90% from total length of TL instead 75% for example? Should I put it as low as I can?

(MJK) If you are using the ML TQWT worksheet, you should put the port at the very end of the cabinet that you build. The worksheet assumes that the port is an extension of the bottom of the enclosure. If you put a 3 " diameter port 3" form the bottom of the cabinet that would be fine.

2. I used the same parameters in ML-TQWT and Ported Box spreadsheets, but the SPL graphics are not the same? Iím a little bit confused? Shouldnít be the same results?

(MJK) The Ported Box worksheet was written after the ML TQWT worksheet by at least a year. The Ported Box worksheet accounts for the position of the driver and the port. If you model an ML TQWT using the Ported Box worksheet, and place the port at 95% of the length, the two worksheets should match closely. If you put the port at 75% of the length, then the two worksheets will give very different results. The Ported Box worksheet is more accurate then the ML TQWT worksheet because it includes the location of the port.

Hope that helps,
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Old 29th December 2003, 08:06 PM   #4
tda is offline tda  Romania
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WHAT SHEET DO YOU USE? WICH ONE IS THE BEST?
Why should I use ML-TQWT if Ported Box is more advanced???
Also I discovered that the results are the same (with 95% distance for the port) only when the stuffing density is almost 0. When I increase the density, I see small differences between the models. Maybe because the ML-TQWT is stuffed only 2/3 and Ported model is 100% stuffed?
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Old 30th December 2003, 12:32 AM   #5
MJK is offline MJK  United States
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Hi tda,

"WHAT SHEET DO YOU USE? WICH ONE IS THE BEST?"

(MJK) I use a customized version of the Ported Box worksheet. The developing worksheets have more power then the ones on my site and represent my latest attempts to upgrade the math. Each worksheet on my site was set-up to simulate a specific enclosure geometry and stuffing arrangement. All the data can be entered using a few entries on the first page of each worksheet. If you want ot analyze a configuration that does not fir one of the predefined cases you need to hand edit the detailed entries on the second page. Most people do not want to go down that path.

"Why should I use ML-TQWT if Ported Box is more advanced???"

(MJK) ML TQWT is set up to analyze that particular geometry, it is easy to input the minimum amount of data required. Ported box will do the same thing but requires adjustments to the data on the second page as you have discovered. It is up to you if you feel comfortable editing the detailed input.

"Also I discovered that the results are the same (with 95% distance for the port) only when the stuffing density is almost 0. When I increase the density, I see small differences between the models. Maybe because the ML-TQWT is stuffed only 2/3 and Ported model is 100% stuffed?"

(MJK) Yes, I had forgotten about that difference. If you edit the density data for the Ported Box worksheet the results will be even closer to the ML TQWT worksheet.

There is no magic or tricks being played in the different worksheets. With the exception of the Ported Box worksheet, the other worksheets contain almost the exact same math but just different input interfaces. I was trying to provide tools that were easy to use and required the minimum amount of input data and the minimum amount of messing around with MathCad.

Hope that helps,
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Old 30th December 2003, 07:32 AM   #6
tda is offline tda  Romania
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Dear MJK,
Do you think you can provide me the latest MathCAD sheets ?
Thank you,
tda
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Old 30th December 2003, 02:37 PM   #7
MJK is offline MJK  United States
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Hi tda,

The latest release of the MathCad worksheets was posted this past week. These are the last versions that I am willing to make available for free at this time. The newer worksheest are still being worked on and are not ready to be made available. I am unsure about how, and even if, I am going to release any more worksheets for free because of the problems I am having with a few people using them for commercial products. They are making money with the software and I am seeing nothing in return.
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Old 5th January 2004, 01:26 PM   #8
tda is offline tda  Romania
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I'm very sorry to hear that. Unfortunately, copyright it's a very sensible subject...I'm not seeing an easy solution, especially that the modeling software itís in MathCAD, not in a stand-alone product. Did you ever think to build commercial software?
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Old 6th January 2004, 12:13 AM   #9
MJK is offline MJK  United States
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Hi tda,

I agree there is no easy solution but I have a few ideas on how to make things a little more difficult for people who are not DIYers looking to have fun and build a speaker or two for themselves.

I am not sure I want to get into a commercial software situation, I want to design and build speakers and not design and write computer code. Nothing is ready for release yet so I still have time to think my plans throught a little bit more. Eventually the right situation will appear.
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