Win ISD help please.

[Earl K]

Good to see you are starting to take a more measured approach to this ( rather than just building boxes & hoping for the best ) .

Ultimately ( after playing with all the permutations & combinations / ie; alignments or tunings ), you're going to find that all 604 variants, generate the most extended bass response when used in a large enclosure ( ie; in a Bass Reflex box that means up to about 9.5 cu ft and typically no smaller than 7 cu ft ).


- Yes, you are looking for a "good" curve that extends well down into the LF areas .
- Your curve can be considered "bad" , if you are expecting reasonable bass response .
- OTOH, your curve can be considered "good" / if there's a "helper" woofer handling the bass duties .

I consider the following curve "good" / especially considering the size of box / as well as after factoring in a bit of LF room gain ;




cheers

[westend9]

Earl pretty much nailed it. Did you know that you can drag the curve (a point on the curve, actually) to have a better alignment? So.....if you want the rolloff of the bass to be steeper, you can choose the -3db point and drag that to the left side of the screen.

Two tips: Make sure you have the exact T/S parameters of your driver entered into the program, don't rely on the Winisd params. Try increasing or decreasing box sizes and alignment numbers to get a port that will will be friendly with your drivers and allow for the best rolloff characteristics. The 172" port length is not going to work.

Good luck with your enclosures.

[cradeldorf]

So what Earl is saying is if I want good Bass response I want the curve to cross the -6db line at as low a frequency as it can? Right?... That is if I want the house to jump off of it's foundation...which I do. : )

[cradeldorf]

Earl pretty much nailed it. Did you know that you can drag the curve (a point on the curve, actually) to have a better alignment? So.....if you want the rolloff of the bass to be steeper, you can choose the -3db point and drag that to the left side of the screen.

Two tips: Make sure you have the exact T/S parameters of your driver entered into the program, don't rely on the Winisd params. Try increasing or decreasing box sizes and alignment numbers to get a port that will will be friendly with your drivers and allow for the best rolloff characteristics. The 172" port length is not going to work.

Good luck with your enclosures.

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.

[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

[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

[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

[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