I'm basically wanting to compare frequency response curves of subs, and I'm wondering if people feel Winisd Alpha is a legit way to do that? I believe the program calls it "transfer function magnitude". The program also has a "spl" field that I also wonder about. Thanks.

I am not sure if I use the alpha version, it just says WinIsd 0.44 at the top. I've always been under the impression it works fine. I've used it for every box I've ever made which has been 12 years now. 

 

Edit - It's just the basic free version I use. It doesn't give box dimensions or anything like that, I do all that myself. I just use it to configure port size and view the gain curves based on the box size/sub I input. 

Edited March 7, 201312 yr by Polish

Mine is version 0.50a7. I wonder about it's credibility to guesstimate spl (and maybe more). I'm comparing my lil Tidal Audio 12's at 600w to the upcoming Sundown Z.4 15 on 2500w, and it shows both setups about dead even from 45hz and up. The Sundown pulls away down low, but I would guess it would dominate at mid and higher frequencies too. Maybe I entered some info wrong, but wondered if this free software was very trustworthy in the first place.

Oh yea, as far as the SPL graph goes I wouldn't put a ton of stock in that, especially once you increase the wattage but it doesn't hurt to check it out. There are just so many more variables once an enclosure is placed in a vehicle it can't possibly predict all that. I mostly just look at the gain curve myself. The thing is, the only real test is building the box and trying it out. This is why you see many of the serious builders making boxes with interchangeable ports. 

Mine is version 0.50a7. I wonder about it's credibility to guesstimate spl (and maybe more). I'm comparing my lil Tidal Audio 12's at 600w to the upcoming Sundown Z.4 15 on 2500w, and it shows both setups about dead even from 45hz and up. The Sundown pulls away down low, but I would guess it would dominate at mid and higher frequencies too. Maybe I entered some info wrong, but wondered if this free software was very trustworthy in the first place.

 

Its not SPL as in what you will hear once placed in the car, it doesn't take into effect cabin gain, etc. It is a tool you can use though to compare theoretical performance of two different drivers or different enclosure designs. But with all audio there are about a million factors to account for, WinISD gives you a starting platform.  

Mine is version 0.50a7. I wonder about it's credibility to guesstimate spl (and maybe more). I'm comparing my lil Tidal Audio 12's at 600w to the upcoming Sundown Z.4 15 on 2500w, and it shows both setups about dead even from 45hz and up. The Sundown pulls away down low, but I would guess it would dominate at mid and higher frequencies too. Maybe I entered some info wrong, but wondered if this free software was very trustworthy in the first place.

 

Its not SPL as in what you will hear once placed in the car, it doesn't take into effect cabin gain, etc. It is a tool you can use though to compare theoretical performance of two different drivers or different enclosure designs. But with all audio there are about a million factors to account for, WinISD gives you a starting platform.  

I guess the main thing I am interested in is frequency response. I know what I'm dealing with now with my current setup in my SUV, so I have an idea of what I'd like to improve.

 

The program just seemed off when it had similar SPL #'s on what I'd call "mid" subwoofer notes (say 40-60 hz). I don't have good midbass, so I cross the subs at 80hz. IF I get better midbass performance, I may be fine with 50 or 63hz for the subs, so the "high" subwoofer notes would matter much less. 

 

My cabin seems to cancel out notes pretty harshly from about 55hz+, so in the end, I may have to upgrade to some good midbass speakers in the doors to take over that range I'm trying to get out of the subs now. Ok I'm rambling, just trying to figure out the future direction of my system...again.

I'm comparing my lil Tidal Audio 12's at 600w to the upcoming Sundown Z.4 15 on 2500w, and it shows both setups about dead even from 45hz and up. The Sundown pulls away down low

It's a sub. That is what it is supposed to do. I LP my sub in my truck at 45Hz. Preferably anything higher is from your midbass.

As for is it correct, only if you input all the correct information and then yes it is pretty damn accurate. This of course requires that you measure your cabin gain and adjust appropriately.

I guess I'm used to my old school ways where subs were generally playing to 80 hz, and usually sealed which seems to help that upper end extension. I'm sure dedicated midbass in the doors is a better solution...but I think I may have to do fiberglass enclosure or something like that. Then more amps, processing, money...

Porting doesn't affect high frequency extension, at those frequencies the behavior is essentially the same as a sealed enclosure....the difference is a ported enclosure generally has significiantly more output on the bottom end so the high frequency subjectively appears comparatively lower due to the greater difference in output levels.

Some of us would prefer if no sub were necessary

Porting doesn't affect high frequency extension, at those frequencies the behavior is essentially the same as a sealed enclosure....the difference is a ported enclosure generally has significiantly more output on the bottom end so the high frequency subjectively appears comparatively lower due to the greater difference in output levels.

 

Yeah I get that, just didn't convey it in that post. 

 

I guess I'm also coming to terms with cabin gain that I'm not used to. First system in this new truck and it's quite different than what I'm used to. 50-80hz seems really weak from the sub. May have to do it the best way and get serious midbass upfront.