WinISD comparison question

[wannabang 13]

I compared a Gcon 15 and an SA15 and found something that sparked a couple questions for me:

1. Is there any simple reason why the Gcon requires a 1.5 ft^3 bigger than the SA15 to achieve the same curve

and...

2. Why is it that the Gcon's curve is not a smooth curve in the same box?

I know they're different drivers and will perform differently in different conditions, but more in depth, or rather, the science behind it.

Could I just not know how to use the program? lol

[Impious 1,476]

Simple answer is because the Gcon has a more compliant suspension (meaning it's not as stiff) as indicated primarily by it's larger Vas and secondarily by it's lower Fs. The Vas of the Gcon is almost twice that of that SA, since they are both 15's (which means Sd will be approximately equivalent) that means the compliance of the Gcon's suspension must be about twice that of the SA. And although the suspension of the Gcon is almost twice as compliant, the SA's moving mass is nearly 60% heavier, which is why their Fs' are only ~10% different.

Vas plays a significant factor in determining how a driver will respond to a given enclosure volume, Qts and Fs play dominate rolls in determining the shape of that response. Generally speaking, a driver with a larger Vas is going to need a larger enclosure for a given response/alignment. If we place both drivers in the same enclosure, the Gcon is going to "see" that enclosure volume as being relatively "smaller" compared to the SA, which is why the response for the Gcon rolls off a little sooner (and it's group delay will be a little lower)

[wannabang 13]

Thank you for the enlightening response, good sir.

[duanebrow 6]

If you go to the spl tab on WinISD I would guess that you will see the gcon has more spl at the same power as the sa. Better power handling and a higher xmax of the gcon will lend it to getting louder, with lower distortion, than the sa - if you have room for the larger box. Every sub has trade offs, SSA and Sundown chose different ones.

[///M5 2,833]

Both good points. One other quick comment. The frequency response (default view) curve in WinISD is by far the least useful of them all. Not that the information isn't useful, but without regards to your input signal you don't learn all that much.

[wannabang 13]

Gracias, amigos. This is one thing I love about this site: y'all are helpful and extremely knowledgeable without raggin' on a guy. It's nice to learn, and yes, I did notice the SPL difference. M5, I will definitely take that tip in future plots.