Stereo & Electronics - Understanding WinISD graph

I came across this thread (http://ls1tech.com/forums/stereo-electronics/660922-small-10-couple-12-sub-comparison.html#post6477750) and started playing with WinISD. What I tried doing differently is changing the parameters of the boxes to .6 to match the Subthump box. What is it I am supposed to be looking for?

You generally want it as flat as possible, and to extend as low (=to the left) as far as possible.

Note that while I advocate WinISD, it does not model distortion/sound quality, and some manufacturers (*coughedcough*) often give T/S parameters that are way off. Also, there are variances between every individual drivers. Still, it helps.

So what does it mean when the Rockford goes above 0 around 80 hz with .5db? Does that mean that sub is going to be punchier? Does the Fi Q10 and it's long gradual slope mean it is going to play bass more accurately?

The Fi Q10 f6 is 35hz. The RF is 31.5hz. Is this going to be an audible difference? What I want is a sub that will work well in a subthump box while getting the deepest note possible.

The humps in the JL and Rockford means they are supposed to be in bigger boxes, though it's not too bad.

Rockford subs are not good sounding and have crap excursion, though.

Wouldn't the SPL graph be more important since that is what you would actually hear? By looking at the the SPL chart the JL would be louder in the upper range while the Fi would be louder in the lower note range.

The Fi Q10 @ 20 hz is 94db @ 100 hz is 106.95 db
The JL 10w3 at 20 hz is 92.7db @ 100 hz is 109.97 db

Thoughts? What else should I be looking for on the Phase and Group Delay graphs?

Does anyone know if the SPL graph is more important that the gain graph?

The SPL graph is only good for comparing sensitivity. You need the relative graph to compare frequency response.

The Group Delay graph is very useful with ported enclosures, with sealed enclosures the group delay is usually very low with little variation between subs.

Also I would focus more in the 30hz to 70hz freq. range .

I recommend picking up the loudspeaker design cookbook. It's a good basic project-related "idiots guide" to building boxes. I learned all of this stuff a long time ago with that book, a copy of winISD, a truckload of MDF and a trusty Dayton Titanic MKIII.

The humps in the JL and Rockford means they are supposed to be in bigger boxes, though it's not too bad.

Rockford subs are not good sounding and have crap excursion, though.That's because they, like most companies now, put out a cheap $50 subwoofer with a $300 price tag at retail stores. If you want a good product, you look to small internet companies with a lot of passion making the best products. CSS, TC Sounds, Mach5, Incriminator, Sound Splinter, Stereo Integrity, Fi etc. RE Audio and Adire used to be good too.

heh, I've recommended pretty much all of those brands myself