How good is this Excel QW folded pipe calculator

[kvk]

http://melhuish.org/audio/software.html
I was playing with John Rutter's TQWT calculator on this site.

How good a job do you think it does getting the design right?

What's the opinion on what to put for the Frequency? Should it always be the Fs of the driver or lower?

I'd pay the $25 for those MathCAD sheets to play with but I haven't figured out how to get MathCAD installed yet.

[MJK]

Originally posted by kvk
http://melhuish.org/audio/software.html
I was playing with John Rutter's TQWT calculator on this site.

How good a job do you think it does getting the design right?

What's the opinion on what to put for the Frequency? Should it always be the Fs of the driver or lower?

I'd pay the $25 for those MathCAD sheets to play with but I haven't figured out how to get MathCAD installed yet.

The Rutter calculator you reference does not work very well. It is hit or miss. If you have just the right driver it might produce a good design.

You can download the free MathCad Explorer 8 program from my website. It will self extract and install, use the default settings during the installation. Then you can try it with the sample file to make sure it works right and to try your hand at the worksheet. The driver is fixed in the sample problem but you can change the geometry to see the effect and get an idea of calculation times. The free version of MathCad is probably what 95% of the people use to run the worksheets.

[kvk]

Originally posted by MJK


You can download the free MathCad Explorer 8 program from my website. It will self extract and install, use the default settings during the installation.

That's the first thing I wanted to try. Believe me, if I could get MC to work and the sample to work, I'd spend the $25 just for the fun of playing with the spreadsheets.

I downloaded the zip file and exploded it to a dir. See file list below. Double-clicking autorun.exe or setup.exe does nothing. Any clues as to what to do to get it to launch.

I pretty computer literate so I'm not done trying to figure out what is wrong. I have to hack some more.

I also trying downloading the MathCAD 30day demo version. It's release 14. Will a release that new work?



Directory of C:\Documents and Settings\Ken\My Document

03/21/2008 11:26 AM <DIR> .
03/21/2008 11:26 AM <DIR> ..
01/08/1999 11:11 AM 24,064 autorun.exe
01/08/1999 11:11 AM 29 autorun.inf
03/02/1999 02:22 PM 119 DATA.TAG
03/02/1999 02:22 PM 11,090,984 data1.cab
05/30/1997 11:31 AM 4,557 lang.dat
03/02/1999 02:22 PM 632 layout.bin
04/03/2001 12:50 PM 12,715,922 mcexp802.exe
01/08/1999 11:11 AM 31,207 networksetup.rtf
05/06/1997 02:15 PM 417 os.dat
01/08/1999 11:11 AM 73,473 RELNOTES.RTF
01/08/1999 11:11 AM 80,248 setup.bmp
12/17/1997 06:30 PM 59,904 SETUP.EXE
03/02/1999 02:22 PM 59 SETUP.INI
03/02/1999 02:21 PM 107,113 setup.ins
03/02/1999 02:22 PM 49 setup.lid
07/30/1998 01:59 PM 291,062 _INST32I.EX_
12/17/1997 06:30 PM 8,192 _ISDEL.EXE
12/17/1997 06:29 PM 11,264 _SETUP.DLL
03/02/1999 02:22 PM 209,446 _sys1.cab
03/02/1999 02:22 PM 1,019,067 _user1.cab

[MJK]

I have this program installed on one of my old PCs. If I remember correctly, I downloaded and saved the file to my desktop. Then I opened the zipped file folder it only had one file inside "mcexp802" and this is an application. When I launched the application is installed itself and created a folder in the Programs directory. Take all of the default directory settings. That is how I remember and it has worked fine. The trial version of MathCad 14 should also work, I have only used MathCad 13 but I bet version 14 would also work fine.

[kvk]

Well I have no idea why MathCAD8 Explorer wouldn't run on my desktop but I installed it on my laptop and it runs okay. I played just a little with sample.

Looking at the box in that sample, is that just a simple rectangular box with a driver in the front and a rectangular port on the top of the back panel?

Is there a model for a folded pipe by like the the Excel spreadsheet or would you just use ML TQWT spreadsheet and then work out the dimensions folded after doing the modelling?

I guess the next thing I have to do is print out the tutorial to read on the train on the way home from work.

[MJK]

Not sure why MathCad Explorer works on one PC and not the other, I have heard of this problem before but not very often. That is why I provide a sample problem to actually run, just to make sure the worksheets will function on each user's PC.

The Tutorial and the three worksheets TL_Open_End, TL_Offset_Driver, and TL Sections all model the same problem with different levels of refinement. The design being modeled is my original Focal TL and the geometry is shown in Figure 1 on page 13 of the Tutorial.

The simple worksheet TL_Open_End, which is the sample problem, uses the minimum amount of input and was the starting point in that paticular TL design. The worksheets TL_Offset_Driver and TL_Sections add more detail by requiring additional input, become more complicated, but payback is they are more accurate. A pdf file of TL_Sections can be viewed on the Models page so you can see the additional refinements in the calculations and the plotted SPL response. TL_Offset_Driver is closer to TL_Open_End in regards to the amount and type of input needed.

At low frequenices folds in a TL are not very important. So each worksheet analyzes a straight TL with changes in cross-section along the length to simulate bends or folds, you can see this in the TL_Sections pdf file. When you get to Part 2 in the worksheet, the exterior of the enclosure is modeled so at that point you need to have the geometry laid out and a plan for building the design in your mind. Part 2 analyzes the sound as it leaves the driver and terminus and encounters the box shape and a few nearby room boundaries.

Hope that helps,