12" or 15" with PRs.. Can't decide


2013-04-18 11:05 pm
So I have a bit of a dilemma... I can't decide whether I should go with 12 inch or 15 inch. Here's my setup so far to get better insight of what my goals are:

This is in a 2004 Toyota Corolla
Alpine INA-w910
Alpine PXA-H800
Rainbow Germanium 6.5 front stage.. (ripped out the 6x9's in the back)
running it on an old Rockford Fosgate 500X4
I have an Audioque 2200.1, and I'm dead set on buying the Fi Q subwoofer to pair with it.

It will be in a passive radiator box because honestly I like ported better but I don't wanna give up too much space. So I decided to go with this setup because it will be the best of both worlds.

My question is should I go with a 12" or 15"? I listen to mostly Hip-hop, R&B, Trance, and sometimes Dubstep. Will the 15 be a better choice because of the cone space? or will the 12" be better overall? I'm really aiming to get the best SQ but in the same time, I gotta have my bass. Maybe the Fi Q 12 is good enough to push enough air to get that full effect without compromising the quality of the bass.

If I go with 12", I will put two 15" TC sounds passive radiators.
If I go with 15", I will put two 18" TC sounds passive radiators.

it's going to be in a perfectly cubed box.. passives facing sideways. sub facing trunk.

Sound deadened my whole car with Second Skin Damplifier Pro mostly.

Currently I have two 12" Diamond audio D6's in a sealed box.. running 4 gauge.. with yellow top battery in the front. Will be upgrading to 0 gauge.. and doing the big 3 and upgrading my alternator.

The setup I have right now is cool and all but very lacking in the low end and isn't enough power for me.

Any input will be appreciated.. Thank you
Hi icecreamxd,
Look at this two possible alignments for your car.
2004 Toyota Corolla
(3m³ = 105.94ft³)
Car gain: 11.00 dB/octave < 60Hz

1a. Fi Q12 DUAL 2: VB = 12.0 L, FB = 30.0 Hz ~87 dB
2a. Fi Q15 DUAL 2: VB = 36.0 L, FB = 26.0 Hz ~90 dB
(blue line = w. car-gain, red = far field)

You will need lots of (KWs) power to move this drivers.
Note: This is just a simulation of two possible alignments doesn't mean they are the best. I don't know the crossover you are using, following all those infos you might need different set-up (alignments/enclosures). As you see this gives a flat (alignment) output curve when you consider the gain from the car cabin what possible is or isn't interesting when you consider max. SPL levels, I don't know (haven't the experience with auto-audio).

An ideal (home) alignment for comparison, for the two same drivers:
1b: VB = 19.5 L, FB = 29.5 Hz
2b: VB = 72.8 L, FB = 24.5 Hz

F3 for the 15" is ~6/8 Hz lower in frequency comparing with the 12".
If you use this alignments in your car (peaks @30Hz/12" and @22Hz/15") you can crossover the subwoofers @~50/60 Hz for the 12" and @~40/50 Hz for the 15". It all depends if you are using the subs above the 60 Hz frequency or not (peaks and deeps or providing EQ). Have fun. :)

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  • Fi Q12 DUAL 2, VB = 11.0 L, FB = 30.0 Hz, 86.8 dB2.83Vm..jpg
    Fi Q12 DUAL 2, VB = 11.0 L, FB = 30.0 Hz, 86.8 dB2.83Vm..jpg
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  • Fi Q15 DUAL 2, VB = 36.0 L, FB = 26.0 Hz, 89.6 dB2.83Vm..jpg
    Fi Q15 DUAL 2, VB = 36.0 L, FB = 26.0 Hz, 89.6 dB2.83Vm..jpg
    55 KB · Views: 57
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