New version of Martin King's MathCad Worksheets is coming soon! - Page 24 - diyAudio
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Old 30th March 2006, 04:18 PM   #231
MJK is offline MJK  United States
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Quote:
Nobody answered
or comment something
about my post at page 20...
I guess I missed your question. At present none of the MathCad worksheets will analyze the arrangements you have shown in your pictures. I am working on bringing all of the older worksheets and a couple of newer ones, OB and Bipole, up to the latest version. I am also making a few minor changes in what is already available based on some feedback I have received. I doubt that the geometries you are interested in analyzing will be addressed in future MathCad models since thay are so unique.
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Old 30th March 2006, 04:31 PM   #232
MJK is offline MJK  United States
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These worksheets are an astonishing deal for only $25 US for DIYers. Clearly this is a work of passion and the price has no reflection on the intellectual effort and ability behind the worksheets.
Damn, I was hoping to quit my day job! Oh well I guess it is a DIYers gain and my loss.

Quote:
A huge addition to the worksheets is the Part 2 Detailed SPL Response Calculations. In this section, among many things, you can model the baffle step response and it generates a BSC filter recommendation. Most importantly will model the performance of your design in a room (a humbling experience!).
They also account for the directional behavior of the sources as a function of shape using circular or rectangular patterns of simple sources. When people use other freeware programs and struggle to achieve a perfectly flat response using a infinite baffle assumption, which the other programs do, they are really misleading themselves. There will be sharp nulls and wiggles that need to be managed during the design to get the best compromised response. The only new MathCad model that seems to easily produce a "nice" SPL plotted output is the OB designs, these should be up in the next week or two.

Quote:
While this section is incredible it strains the Compaq PIII 933 MHz in my study to the limit. The first room simulation I ran took more than 16 min. (and then I realized I made an error!). If you'e serious about using this part a lot I'd buy a dual core Athlon or Pentium PC. (In retrospect this isn't surprising given the volume of calculations that need to be made).
The BLH worksheets are the most calculation intensive and run the longest. If you try the Ported Box model I think that you will find it calculates in about a minute. One of the things I want to work on is improving the efficiency of the calculations which for now are essentially brute force programmed. When I am running the BLH version I tend to multi-task and answer e-mails, read the forums, or go get something to eat or drink. If you use fewer sources then the run time will drop rapidly and then you can iterate a design and only run the complete fine meshed solution for the final geometry.

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These worksheets are highly recommended!
Thanks!
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Old 31st March 2006, 05:48 AM   #233
holdent is offline holdent  Canada
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I'm also using these worksheets. Though I've only got into the BLH and TQWT sheets and haven't tried the other ones yet I am extremely impressed. These worksheets are an astonishing deal for only $25 US for DIYers. Clearly this is a work of passion and the price has no reflection on the intellectual effort and ability behind the worksheets.

The BLH section has expanded capabilities for handling hyperbolic-exponential horn types, provides and easy way to add in series resistance (if required), and includes a graphical horn profile so you can double check and see that you're modeling what you think the horn looks like.

A huge addition to the worksheets is the Part 2 Detailed SPL Response Calculations. In this section, among many things, you can model the baffle step response and it generates a BSC filter recommendation. Most importantly will model the performance of your design in a room (a humbling experience!).

While this section is incredible it strains the Compaq PIII 933 MHz in my study to the limit. The first room simulation I ran took more than 16 min. (and then I realized I made an error!). If you'e serious about using this part a lot I'd buy a dual core Athlon or Pentium PC. (In retrospect this isn't surprising given the volume of calculations that need to be made).

These worksheets are highly recommended!
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Old 31st March 2006, 05:52 AM   #234
jdybnis is offline jdybnis  United States
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On the new sheets, what listening height is assumed? Is there a way to change it?
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Old 31st March 2006, 10:58 AM   #235
MJK is offline MJK  United States
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Right now the listening height is defaulted to the height of the driver. Since I work with full range drivers this made sense at the time. But a few days ago I realized that people are designing bass systems with the drivers near the floor so this assumption does not make much sense. I will add a height variable that can be editted to the listening position input section. I'll try and make the upgrade to all worksheets this weekend.

Good question,
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Old 31st March 2006, 02:42 PM   #236
Elam is offline Elam  Germany
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For stand mounted speakers it would also make sense to have the ability to raise the speaker without increasing the baffle height.

Elam
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Old 31st March 2006, 03:27 PM   #237
MJK is offline MJK  United States
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I agree. I was planning on adding closed and ported box stand mounted speaker worksheets. I doubt if there will be many TL or TQWT stand mounted designs. This changes the baffle step calculation, by adding an additional side at the bottom, and the floor reflection calculation. It is on my list of things to do.
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Old 31st March 2006, 04:48 PM   #238
jdybnis is offline jdybnis  United States
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Awesome! Thanks.
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Old 31st March 2006, 07:21 PM   #239
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Quote:
Originally posted by MJK
I doubt if there will be many TL or TQWT stand mounted designs.
A couple RAWfests ago, someone brought a rather nice stand-mounted ML-Voigt. And all of the diyAudio FR refs are stand-mount ML-TLs.

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Old 31st March 2006, 07:28 PM   #240
MJK is offline MJK  United States
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The ported box worksheet should do both the ML TL and the ML TQWT enclosures. Actually ML TL = ML TQWT = Ported Box worksheet at the moment, but don't tell anybody. So only the big classic TL worksheets will not have a obvious stand mounted version, if you fiddle with some of the inputs to ML TL you should also be able to model a classic TL (set some of the lengths to 0.001 inches ~ 0 inches).
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