Building A Subwoofer Enclosure Using WinIsd

[MattRyans420]

Hey Tuners I Would Like To Know Just How Accurate WinIsd Is In Terms Of Real World Performance Vs. Virtual Performance.

[kurpal_v2]

viewtopic.php?f=3&t=404635



That thread could give you a thought on how it works. Right now Ive not done any real testing but keep looking at it, Ill update within the next month with real results.


From past experience however its a good gauge for what you are about to build so you arnt building in the blind.


http://online.physics.uiuc.edu/courses/ ... kor_TS.pdf

This is a good read of how subwoofers react free air vs in cabinet so you get an idea of how parameters change and therefore render virtual compositions "wrong". This is not a standard across the board change so it should be looked at with a grain of salt.

[Brian Steele]

From past experience however its a good gauge for what you are about to build so you arnt building in the blind.

I believe that design programs that like WinISD are more accurate when the type of build being considered involves ports that are small in relation to the box size. If you design around large vents, a possible end result of building exactly what you're modelled is you may end up with a box that's tuned a bit lower than expected (not always a bad thing, but if there's a significant dependency on hitting Fb properly (like if you're building bandpass boxes), it's something to watch out for. See this link for an example of where Fb worked to be much lower than predicted, quite likely due to the use of very large vents - http://www.diysubwoofers.org/projects/home/inf10bp/

This is one of the reasons why I'm slowly shifting to using HornResp instead of other programs for my modelling. Not only does it seem to be more accurate for situations where vent size is comparable to the box volume (like almost every car subwoofer box being built these days, LOL), but you can also model horns, TLs, MLTLs and almost any configuration you can think of. E.g. try modelling the box below in WinISD:

HornResp tells me that the response will be something like the following:

This is a good read of how subwoofers react free air vs in cabinet so you get an idea of how parameters change and therefore render virtual compositions "wrong".

Nope - that change in resonance frequency can be predicted by a box modeller like WinISD. Basically the chap who did that report put the driver in the box that ended up in a Qb so low that Fb ended up being less than Fs.

Finally, it must be remembered that these programs, including HornResp, use t/s parameters, which are SMALL SIGNAL parameters. From the moment the subwoofer's cone starts moving appreciably, those parameters will change, sometimes appreciably.