Trying to decide on subs for my Kia Soul. I'm planning to do a sealed enclosure for the 2 subs with an 800 to 1000 watt RMS amp. I'm looking for a sound as close as possible to my old Kappa Perfect aluminum cone subs. They were extremely clear and hit very deep lows in a small sealed box. I'm looking for clear bass that can hit low enough to feel the bass even when it's too low to hear. Suggestions for other subs in this price range that would give me this would be appreciated as well.
The chances of someone having heard both subwoofers are pretty low. Type-S is relatively new. Who knows, perhaps there is an installer who heard both.
For what it's worth, the Infinity Kappa 120.9w, running at 4ohms in a 1cu sealed box with a bit polyfill, hits the lows pretty well in my car. WinISD predicts that this is a perfect box for this subwoofer. This subwoofer produces seemingly effortless, powerful, and transparent sound in deep bass notes. I can feel it with my body. My steering wheel is shaking, though that could be a testament to how crappy my car is. The lows are very smooth and powerful, but it can also produce punchy midbass kick if you let it play higher frequencies. I suppose two of these Kappas would do more of the same, only better. This subwoofer does need more power to get moving than its 350watt power handling rating suggests. I run about 400-450watts to it (confirmed with DMM) on daily basis and I feel like it could take and use a bit more. Though, for my music tastes, 400-450watts is about perfect as far as this subwoofer is concerned. The only time it uses those 400watts is probably when I play the albums of a Russian rapcore band Kirpichi. One interesting experiment to try, if you're obsessed about powerful lows, is to build a custom vented box for this subwoofer. Once I tried to model a vented box in WinISD, and it was of a very reasonable size.
To compare the Infinity to Alpine Type-S, I could pull the PDF manual from Alpine web site and speculate that Kappa should hit the lows better because Type-S has a higher resonance frequency and 2mm less of xmax. However, going by small signal parameters does not always render accurate predictions of real world performance. The Alpine does come with a higher power rating, which feels more reassuring if you want to run that kind of power to it. I tried to model the SWS-12D parameters in WinISD, and WinISD recommended a +6cu ft sealed box for 0.707 qtc, which is bizarre. If you model it in 1cu ft sealed box, qtc jumps into 0.9-1 range, as also pointed out in the Alpine PDF manual, and WinISD seems to be right. I heard that the rule of thumb to interpret the qtc is that "well above" 0.7 means more power handling, less transient response, and significantly below 0.7 it's the reverse, but those are predictions for a big room, not a small space like in a car. Perhaps Jim Walter, who works at Alpine and posts here sometimes, would chime in on the optimal box requirements.
PS: I did notice over the time that often the box sizes that Alpine recommends often result in qtc of around 0.9-1.0. The nice thing about Alpine is that they usually write the qtc number next to sealed box size recommendation. The question is, why does Alpine often recommend box size where qtc often falls near 0.9-1.0. Do engineers at Alpine think that this qtc works better in car environment? I'd like to hear about this.
Extremely useful post Zakoh, thanks! I'm definitely leaning towards the Infinity subs. I'm impressed by the xmax of the Infinity, it's almost 3mm more than the old Kappa Perfects.
Alpine Type S vs Infinity Kappa 120.9
Linear Mode
