WinISD box designing help please

[spaz83]

Hello all. I am currently trying to design a box for my sundown sa 15 d4. The thing im not understanding is the Sundown website recommends a ported enclosure at 3.0ft^3, But when I enter the calculations in winisd it recommends a sealed enclosure and the output on the graph looks like it wants to play higher than tuning frequency more in the beginning midrange area. when i compare output seems my 10s would have more output then the 15.  Any help would be greatly appreciated.

[ckeeler11]

A sealed enclosure wont play as low as ported enclosure which is why it looks like that. Cabin gain will influence the response which WinISD does not calculate. I would double check that you entered parameters in correctly as Sundown is relatively close on their specs most of the time.

[Triticum Agricolam]

WinISD "recommended" box spec are for achieving the flattest frequency response in an open area.  Using the sub in a vehicle is a completely different situation, so WinISD's recommendation isn't applicable.  Start with Sundown's recommendation and tweak things from there.  

[spaz83]

3 hours ago, ckeeler11 said:

A sealed enclosure wont play as low as ported enclosure which is why it looks like that. Cabin gain will influence the response which WinISD does not calculate. I would double check that you entered parameters in correctly as Sundown is relatively close on their specs most of the time.

I had designed the 15 model in a ported enclosure, it still didn't seem right. I have it at 3.2ft^3, tuned to 34 hz... I was planning on using the 3.ft3 as per sundown specs. But I was playing around with winISD and wondered why it seemed like an odd frequency range. 

[spaz83]

3 hours ago, Triticum Agricolam said:

WinISD "recommended" box spec are for achieving the flattest frequency response in an open area.  Using the sub in a vehicle is a completely different situation, so WinISD's recommendation isn't applicable.  Start with Sundown's recommendation and tweak things from there.  

Yes I was planning on the factory recs. I didn't know that's how winISD operated as far as the flattest response. Just trying to calculate port length diameter an all when I seen the frequency is a little crazier then th 12, 10 and 8 frequency responses. (Which I own them too). Do you know of any programs that can better help me design boxes and port calculations? I thank you for your help. 

[Quiet]

WinISD is a great tool, but most people starting off don't know how to use it. There's a lot it doesn't account for, and a lot that is completely immaterial and useless.

Do not use WinISD to see which sub will be louder. You WILL be disappointed.

Do not use WinISD to see what your response curve will look like in a car. It will sound nothing like that. Cabin gain and peaks will put your curve in a blender.

The best thing you can do is use it to help calculate your tuning, and to compare different enclosures with the SAME sub. 

 

 

After you look and listen to 10-20 enclosures you've built spec'd in WinISD, you'll get the idea of how to use it.  

[Triticum Agricolam]

1 hour ago, spaz83 said:

Yes I was planning on the factory recs. I didn't know that's how winISD operated as far as the flattest response. Just trying to calculate port length diameter an all when I seen the frequency is a little crazier then th 12, 10 and 8 frequency responses. (Which I own them too). Do you know of any programs that can better help me design boxes and port calculations? I thank you for your help. 

Is your frequency response in WinISD looking something like this:

This is what I'm getting with a SA-15 in 3 cu ft tuned to 34 hz.  With cabin gain that should actually flatten out quite a bit.  

WinISD is very good for determining port velocity, but be careful if you intend to use it for finding port length.  If you use and aero port WinISD can work well, but it doesn't do well with slot ports, you will come out tuned lower than you intend. 

[spaz83]

4 hours ago, Triticum Agricolam said:

Is your frequency response in WinISD looking something like this:

This is what I'm getting with a SA-15 in 3 cu ft tuned to 34 hz.  With cabin gain that should actually flatten out quite a bit.  

WinISD is very good for determining port velocity, but be careful if you intend to use it for finding port length.  If you use and aero port WinISD can work well, but it doesn't do well with slot ports, you will come out tuned lower than you intend. 

This is what I'm coming up with for 34hz with a 3ft^3 box. 

[spaz83]

Won't let me post my pic. If I follow the response curve it starts coming up from 0 at 300 and peaks at 52hz, at 0 again at 32.7hz, the -3 @ 28 hz. If winISD  doesn't work well for response curve then,.....shit.   Lol. I like my response to peak at around 34-35.  

[Triticum Agricolam]

22 minutes ago, spaz83 said:

Won't let me post my pic. If I follow the response curve it starts coming up from 0 at 300 and peaks at 52hz, at 0 again at 32.7hz, the -3 @ 28 hz. If winISD  doesn't work well for response curve then,.....shit.   Lol. I like my response to peak at around 34-35.  

With cabin gain your response probably will peak around 35 Hz.  

WinISD works very well, you just have to understand it limitations.  The frequency response is shows you IS most likely what you would get if you had that sub out in an open area where it isn't going to be affected by cabin/room gain.  

You can ROUGHLY approximate cabin gain for an average size vehicle in WinISD by adding a filter like this:

Note that when that filter in enable it will totally screw up your cone excursion and port velocity graphs, its really only valid for "Transfer Function Magnitude" and "SPL" graphs.