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Master Asylum 
Silver - Posts: 400
Silver spacespace
Joined: November 05, 2004
Location: United States
Posted: February 25, 2005 at 9:54 PM / IP Logged  
Hmmm... Stephen, are you human? You seem, well, too, I can't put it... Oh yeah, unbudgeable. Now either you are a REALLY good business person(IN America, that is hard as hell to find) or well, you are simply not human... I don't think I've ever seen anything RESEMBLING heated flaming. More so, you work for a big company(I'd say fairly well up there too) and still take the time to put your input in. Must say kudos. And no, I'm not butt kissing, unless you'd be willing to sponsor me for IIT training :). *end shameless attempt*
1998 Monte Carlo w/
Eclipse CD8454
2xRockford 5.25" Power 2-way T152C
2xRockford 6"x9" Punch 3-way FRC4369
1xMemphis 16-MCH1300 5-channel
2xKicker 12" L5 Solobaric-2 Ohm
Member - Posts: 6
Member spacespace
Joined: May 25, 2004
Location: United States
Posted: February 26, 2005 at 11:32 AM / IP Logged  

Hi all,

My experience with WinISD (and it's Pro variant) have been less than impressive.  Many T/S parameters are not correct (I don't think any of our drivers are properly defined).  It requires much data that can be auto-calculated (for instance, given Fs, Vas, and Sd - all typically given on a data sheet - you can calculate Mms and Cms, which typically are not given on datasheets).

WInISD also seems to incorrectly calculate port air speed; for example, a Tempest in a ~193L box tuned to ~20 Hz and powered with 100W will have an airspeed around 18.5 m/sec (based on measurements with a thermal airflow sensor).  LspCAD estimates 19.3 m/sec - pretty close.  WinISD claims 28 m/sec, well out of range of reality.

WInISD does not allow calculations of series/parallel wiring options for DVC drivers.

WinISD does not even attempt nonlinearities.  Oilcanning of spiders - which happens when they are pushed near their limits - can cause a strong jump in actual excursion below the Fs of the driver.  When designing a box for "running near the limits", any software that does not include nonlinearities is woefully lacking.

Note that many of these criticisms also apply to UniBOX, particularly the nonlinear and inductive effects.  However, my experience has been the that the typical UnIBOX user is a bit more familiar with T/S theory and its limitations, and thus typically do not over-do the design nearly as much.

IMHO, WinISD is a very basic tool, and it should be treated as such - do not rely on it for anything more than a few W power input.  The errors in vent sizing alone are reason to avoid it, IMHO.

Dan Wiggins

Adire Audio

Platinum - Posts: 5,816
Platinum spaceThis member has made a donation to Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spaceThis member consistently provides reliable informationspace
Joined: January 24, 2004
Location: Pennsylvania, United States
Posted: February 26, 2005 at 1:17 PM / IP Logged  


Dan wrote:
It requires much data that can be auto-calculated

There is an 'auto-calculate' box at the bottom of the parameters window that is used when entering driver parameters.  Click it to calculate unknown values.  The Help section details the steps in entering the numbers.

  • Parameters may be and should be auto-calculated.


Dan wrote:
WInISD also seems to incorrectly calculate port air speed

WinISD displays vent air speed by using a graph, and by default the output is shown as 'peak'.  Place the cursor on the "peak" and click to change to RMS.  Changes like this are made by using File > Options > Graph.  Changes made will be set as default the next time the program is opened.

In the Tempest example, which I duplicated after entering parameters from the Adire site (and using a port diameter of 4"), WinISD displayed air speed at 27 m/sec.  But, after changing the graph to display RMS, the display showed 19 meters/second.

  • Same as LspCAD.


Dan wrote:
WInISD does not allow calculations of series/parallel wiring options for DVC drivers.

The choice of parallel or series for DVC subs is made in the database editor under the parameters tab.  DVC drivers have a different designation (name) than do their SVC counterparts, so when you enter data for that driver and save the file, the program will remember how you have the coils wired.  If you want to change series to parallel (or vice versa), open the database editor and change it there.  You can save the change and give it a different name, so now you'll have both ways of wiring in your saved database.  And you are not limited to DVC;  any number of voice coils can be entered.

  • Multiple voice coil drivers are calculated according to wiring.


Dan wrote:
WinISD does not even attempt nonlinearities.

Nonlinearities at max excursion is beyond the scope of my understanding.  And I will bet that is also true with the vast majority of enclosure builders who are looking for a good design help program.


Dan wrote:
The errors in vent sizing alone are reason to avoid it, IMHO.

Some people expect the program to give an opinion on vent diameter when a new project is opened.  It does not.  Instead, a default value of 102 mm (shown as 4.02 in) appears with the calculated port length for that diameter.  The program just simply calculates port length according to the port diameter, box volume and tuning frequency.  The user must be aware that he can highlight and change the port area to the size  he wants to use,( then input wattage and check the graph display to see if the vent air speed is less than 10% of mach).  If it's too high, enlarge the port opening.  Vent air speed can be verified by using other calculators, such as these two combined.

  • I have heard this criticism (errors in vent sizing) more than once, but no one has yet to demonstrate an example where it errs, or has ventured a reason as to why they believe it errs in calculating vent any manner that can be substantiated.

There are a number of ways to verify port volume, or diameter vs length calculations, several of which are found in this list.


Dan wrote:
Many T/S parameters are not correct

Any part of the overall build can and should be double-checked with other calculators or information, especially the very basic aspect of making sure the driver parameters are correctly entered

  • One should enter parameters himself and not rely on those entered by someone else at some other time.  I think that would be wise when using any of the design programs.

The more I use this program the more I find how useful it is.  It may be substandard in the eyes of a world-class speaker designer, but for the majority of posters on this forum who want to build their own box it is a good design tool, and becomes very user-friendly with use.  Anyone wanting to get some good help in designing enclosures should give it a fair trial, but put forth the effort to learn how and why it forms its calculations and how to interpret the results.

Here is the link to download:

It is free to use.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Gold - Posts: 2,121
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Joined: April 30, 2003
Posted: March 30, 2005 at 11:49 PM / IP Logged  
I just ran across this thread in searching for one of Stevdart's excellent explanatory posts on a feature of WinISD.
I must have been MIA when this thread was completed. Great post Stevdart. I also share your conclusion. Thanks for doing the heavy lifting. :-)
New Project: 2003 Pathfinder
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