MrPerfectionest

This is incorrect, in essence adding polyfill makes the sub thinks it is in a larger box. The polyfill dissipates energy (in the form of heat from vibrating) which the sub 'feels' as more damping. More damping happens from a larger box (up to the point the box gets too large and begins to act like an infinite baffle arrangement). In general if you want the flattest most transparent sound for a given sub, you build a box such that the Q of the box is .707 based on that subs theile-small parameters. In my experience some sub manufacturers that give pre-calculated box dimensions will generate Q values lower than .707. This will mean the speaker (sub+box) will have an output gain (ie more bass) near the lower F3 point of a .707 Q box. Of course a manufacturer will want to do this so their sub sounds louder and boomier than the other manufacturer so that people will buy their subs.

In general you are attacking the problem from the wrong angle. Most of the punch in rock music is easier to generate with good midbass speakers. Take note that many hardcore sound quality car audio competetiors will stuff 8" midbass drivers in their kick-panels where no normal car audio buff would do this. You are also working against the problem that car audio equipment (especially subs) is made to be tougher than what you find in your home (ie rubber surrounds, thicker cones) which also makes them more sluggish than ideal and a 10" or even some good 8" subs would be much more ideal than a 12" for rock tracks.


But this is all well and good in hindsight, since you are stuck with the equipment you have. You really need to get above 90hz a bit to get a lot of the punch that happens in rock tracks. Only problem is this can start to color (muddy) the lower end bass a bit and limit overall output if you aren't careful. Also, if you don't have some really good components up front then using two crossovers at your sub is probably leaving out some sound information in your setup. In general you want the crossover between the two set at the same frequency and having both of them rolling off at the same rate. So no need for both crossovers (they could also introduce some unnecessary phase shifting). Just try out one of them and I would try to go a bit higher than 90hz.

But like someone else said, its impossible to tune it without hearing it.

TaylorMade

Ah yes, that must be what I meant to say.
heh heh... it's been about 8 years since I've done car audio seriously. We must have put the polyfill in SMALL boxes to make the sub think it's bigger. I did that with my two 12" Polks because I build a small box for them (didn't want to lose that much cargo space). Sorry for any mis-information Shakes (and anyone else who ran to the store).

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