Win ISD help please.

[aditya]

Thanks Westend, They didn't have the 604 in the list so I had to put it in manually. I used the T/S parameters from the altec literature and filled in as many as I had. The only one that might be iffy is when I described the speaker magnet size I guesstimated it at 6 inches in dia and 7 inches long. I had read about the dragging of the curve but hadn't tried it, makes good sense though.

WinISD, unless an updated version has been introduced off late, does not take into account all of the T/S parameters except for Fs, Qt & Vas to give the projections. Ofcourse it uses Qes & Pe for the vent-mach calculations. But this way it just gives a rough idea of the enclosure size and vent sizes. But it really misses out on the sim-ed projection of the FR as it does not use Le. Its nowhere near the true one. So only for a rough Vb idea its good. One can play with as many drivers as possible and very quickly will find/learn the relationship between Vas, Qt, Fs and the different resultant cab sizes. WinPRO, its cousin, is far better, but is very unstable to use and also probabely not free (?)

Aditya

[voice of the theater]

Now I'm gonna have to do more listening to see what I really have.....they do sound a lot better now though.

Great! I don't know what the internal volume of those black cabinets is but of course the bottom line is how good do they sound to you/in the acoustical environment of your listening room. If, with the new ports (and proper balance setting) they sound great, you can always go by the old rule "if it ain't broke, don't fix it"! I'd still do my suggested tweaks to those Heathkit cabs and compare them to the black ones--it would be a quick fix and you might be blown away by the sound of those things with the "shelves" removed and the adjusted "correct" port size....

[cradeldorf]

WinISD, unless an updated version has been introduced off late, does not take into account all of the T/S parameters except for Fs, Qt & Vas to give the projections. Ofcourse it uses Qes & Pe for the vent-mach calculations. But this way it just gives a rough idea of the enclosure size and vent sizes. But it really misses out on the sim-ed projection of the FR as it does not use Le. Its nowhere near the true one. So only for a rough Vb idea its good. One can play with as many drivers as possible and very quickly will find/learn the relationship between Vas, Qt, Fs and the different resultant cab sizes. WinPRO, its cousin, is far better, but is very unstable to use and also probabely not free (?)

Aditya

The Program I have is win ISD pro. and it was free.

[aditya]

Win ISD & Win PRO are the two I knew. You can check its limitations by varying/ommiting the Le value, an see. If it is affected then it is the better one.

Aditya

[GM]

Greets!

Ideally you want a response curve that most closely mirrors your room's acoustics that combined yields a flat response throughout the listening area over whatever BW you design to.

Obviously, without extensive room measurements one is left just picking a response that the driver can handle in the max acceptable bulk, so the main thing is to not under-damp it, i.e. have excessive peaking at Fb or require too large, long a vent if vented such as you posted. A good rule-of-thumb (ROT) for a max vent length: 13,560"/(20*Fb)


The vent's end correction refers to how it is terminated, i.e. well away from any boundary or flanged at one or both ends:

Flanged-Flanged: 0.850
Flanged-Free: 0.732
Free-Free: 0.613


Flanged is flush with an enclosure wall and free is not, so for most all vented cabs it should be 0.732.

The reason for it is due to the pipe opening having an elastic component to it that makes it act like an acoustic version of a passive radiator (PR). As such, the mass air plug in the vent extends outside it a small amount based on its diameter and whether or not there's a baffle around it to increase its acoustic efficiency, so the end correction calculation is used to shorten the vent's physical length. Indeed, most simming programs treat it as a PR with a perfectly linear excursion, though a few $$$ ones also models vent non-linearity if it's too small for the power input.

WinISD Pro tutorial: WinISD Pro Tutorial and Download (A detailed guide on how to use WinISD Pro) - Home Theater Forum and Systems - HomeTheaterShack.com

Additional WinISD Pro driver database downloads: Downloadable WinISD Pro Files - Home Theater Forum and Systems - HomeTheaterShack.com

GM

[cradeldorf]

Great! I don't know what the internal volume of those black cabinets is but of course the bottom line is how good do they sound to you/in the acoustical environment of your listening room. If, with the new ports (and proper balance setting) they sound great, you can always go by the old rule "if it ain't broke, don't fix it"! I'd still do my suggested tweaks to those Heathkit cabs and compare them to the black ones--it would be a quick fix and you might be blown away by the sound of those things with the "shelves" removed and the adjusted "correct" port size....

I figured the cabinet volume to be around 5.75 cf. I just put in the Pink Floyd Pulse DVD and I'm actually going to step out of my realm and describe it as serene, divine, titillating and absolutely mesmerizing. they have not sounded this good in a while. it was literally fantastic. I noticed right after putting the ports in that the volume had to be up more than it used to be....well to make a long story short, It doesn't need to anymore. :2thumbsup: The bass was just thundering at -11 volume.

[GM]

Ofcourse it uses Qes & Pe for the vent-mach calculations. But this way it just gives a rough idea of the enclosure size and vent sizes. But it really misses out on the sim-ed projection of the FR as it does not use Le.

The pro version's vent calcs are more accurate than the basic WinISD, matching Hornresp's predictions using wave equations plus it sims Le's effect on response. Both fall a bit short of MJK's MathCad software though since it takes any damping into consideration. AkAbak is free and probably the most accurate of all, but can require lots of inputting till you get a database built up and the learning curve is ballistic steep for many folks.

GM

[cradeldorf]

Greets!

Ideally you want a response curve that most closely mirrors your room's acoustics that combined yields a flat response throughout the listening area over whatever BW you design to.

Obviously, without extensive room measurements one is left just picking a response that the driver can handle in the max acceptable bulk, so the main thing is to not under-damp it, i.e. have excessive peaking at Fb or require too large, long a vent if vented such as you posted. A good rule-of-thumb (ROT) for a max vent length: 13,560"/(20*Fb)


The vent's end correction refers to how it is terminated, i.e. well away from any boundary or flanged at one or both ends:

Flanged-Flanged: 0.850
Flanged-Free: 0.732
Free-Free: 0.613


Flanged is flush with an enclosure wall and free is not, so for most all vented cabs it should be 0.732.

The reason for it is due to the pipe opening having an elastic component to it that makes it act like an acoustic version of a passive radiator (PR). As such, the mass air plug in the vent extends outside it a small amount based on its diameter and whether or not there's a baffle around it to increase its acoustic efficiency, so the end correction calculation is used to shorten the vent's physical length. Indeed, most simming programs treat it as a PR with a perfectly linear excursion, though a few $$$ ones also models vent non-linearity if it's too small for the power input.

WinISD Pro tutorial: WinISD Pro Tutorial and Download (A detailed guide on how to use WinISD Pro) - Home Theater Forum and Systems - HomeTheaterShack.com

Additional WinISD Pro driver database downloads: Downloadable WinISD Pro Files - Home Theater Forum and Systems - HomeTheaterShack.com

GM

Awesome Greg, Thanks for the explanation. I'll go through the links and get a better Idea of how it all plays together. :2thumbsup:

[aditya]

The pro version's vent calcs are more accurate than the basic WinISD, matching Hornresp's predictions using wave equations plus it sims Le's effect on response. Both fall a bit short of MJK's MathCad software though since it takes any damping into consideration. AkAbak is free and probably the most accurate of all, but can require lots of inputting till you get a database built up and the learning curve is ballistic steep for many folks.

GM

Yes, the PRO version takes Le into account. But it was a little unstable with the simulation part & the data entry part. May be its time to check up again for the latest version. I have been using Bass Box PRO6 for quite sometime now. I have also used Hornresp, and yes it is good. I read about AkAbak from one of your earlier posts, and infact today only while browisng the forum's older threads, and was thinking of giving it a try. AkAbak used to cost around 700$ 4/5 yrs back, and now its free ! Will definitely try to learn to use it. It wiil pay back.

Thanks
Aditya

[aditya]

Hi GM,

I visited the WinISD Pro site, but my version seems to be the latest one. There are two types there:- WinISD (Beta)v.44, and WinISD Pro (Alpha) v.7.

About WinISD Pro the Linear site says this (just pasted from the site):
"NOTE This version is early ALPHA version for preview and test purposes only. If you are looking stable tool, please download WinISD 0.4x series instead. Because of almost complete rewrite of software, there is many things which do not work like they should. All comments about this _ALPHA_ version are very wellcome"

They actually recommend the basic version for stable performance. This is what I was pointing at.
And I just confirmed that it does not take Le into consideration. It just shows the projected FR flat upto 20K (or whatever one sets at).

I have downloaded AkAbak, and all its relevant documents (whatever were available). This is a MS-DOS 16bit thing, and I hope it will run on XP, as the testing was upto Win2k. It seems the learning curve is steep mostly due to the dos format of data entry. A bit of relief here for me, as I was seriously into programming for 2/3 yrs while trying to develop a software for my personal use, and as a result keyboard habbit. Let me see......

Regards
Aditya