New version of Martin King's MathCad Worksheets is coming soon!

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Hi Bostjan,

Jensen Transflex is a transmision line enclosure but the driver is enclosed in a enclosure. I will start a new thread in a subwoofer forum if there is any posibility to simulate this enclosure with worsheets.

The worksheets available, original and upgraded, will not accurately simulate this type of enclosure design.

I thought about the problem yesterday and concluded that a worksheet to model this type of enclosure is possible. It would require some rearranging and extension of the math but I believe it could be done. Unfortunately, it is not on my list of priorities and can only be classified as something interesting to look at if I ever run out of things to work on (there are a few other enclosures on that list also).

So let me ask a couple of questions :

1. What is special about the performance of this design compared to a classic TL?

2. What performance advantages does it offer?

3. Where is this design used and over what frequency range?

If there is some performance advancement possible with this geometry that would be interesting, if this is just an old design cobbled together by a very creative thinking individual that sounded good compared to state of the art at that point in time then I am not sure this is worth pursuing. Is the Jensen Transflex just another Karlson or Hageman style of exotic, outside the norm, or curiousity enclosure that appeals to a small group of enthusiasts or is it truely a high performance design that has fallen through the cracks?
 
bzdang said:
Tom Danley posted some information about the tapped horn concept in these places -

http://srforums.prosoundweb.com/index.php/m/0/8829/32/0

http://srforums.prosoundweb.com/index.php/m/113362/0

Near as I can understand he's using 1/4 wave phenomena to compensate for the compromises introduced when deliberately making a horn 'too small'. And probably has all the math worked out to simulate and design the things. Innovation.

It seems like a design that could reach very low frequencies, but will have some peaks and dips along the way down due to phase differences. It would be interesting to see if those can be flattened.
 
Hi,

I'm already using the new worksheets and I'm very pleased. The simulation correlate *very* well with my in-room measurements.

One thing I'd like to see in future versions of the worksheets is the in-room respond above 1kHz. Maybe up to 3kHz. Then I wouldn't have to use 'The Edge' anymore for my narrow baffle speakers.

Bye, Elam
 
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.
 
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.

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.

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.

These worksheets are highly recommended!

Thanks!
 
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!
 
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,
 
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.
 
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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