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Discussion Starter #1
OK, I'm flip flopping again, trying to decide what I want to install. My car really only lends itself to a set of IB subwoofers in the rear deck. It is a W210 Mercedes (E-class).

The trunk is VERY isolated (has a gas tank in between trunk and rear seat), so boxes in back don't do very well. I also need most of my trunk space on a regular basis (family man ya know), so I probably wouldn't put a box there anyway.

Another complicating factor is the depth of the rear deck. At first glance, the deck is very deep, BUT, Mercedes put fold down headrests that take up almost half the space, and there is a rear sunshade that comes out of the rear and steals 4-6 inches. That leaves a pretty narrow range to fit the subs in. It has four 6.5" factory cutouts. I could put four 8"s in no problem. There is one person in the UK who did two 12" in the deck, but his car did not have the rear sunshade like mine. I think I am really limited to either four 8"s or two 10"s.

Now, I've hoarded a foursome of old-school Kicker Freeair 8" subs. That has been my plan for the last few weeks. They model very nicely in a 20cu ft sealed (emulating my trunk) with a Qtc of .678 which should sound very nice.

However, I wasn't really paying attention to the limits of this arrangement due to their Xmax of only ~5mm. Feeding the four drivers only 50w puts them near Xmax limits. At that 50w, WinISD shows them hitting 110dB @100Hz, 106dB @ 50Hz, and around 99dB @ 25Hz. Within a mid size sedan, the transfer function should bring that low end up considerably, so I'm not worried about them not being loud enough. I am not a basshead. I'm just looking for good SQ and a solid low end to my music, not ear shattering, hair moving, or chest thumping.

I guess I am really just worried about over driving them since they hit Xmax with such little amount of power. I had planned on powering them with my Hifonics Falcon which pumps up to 280w when bridged mono, but I know now that is overkill.

The other option I'm looking at is putting a pair of DLS OA10D. They are not as efficient, but they have much greater Xmax and model out in the same size trunk to a Qtc of just under .5 which may not be as ideal, but it is still pretty good. They don't hit Xmax until you hit the pair with ~180w (@25Hz) which is much more friendly to my Falcon amp (2x90w). They do also get a louder in that arrangement (almost 3dB higher at 25Hz).

With either setup, I would probably apply a subsonic filter around 25Hz.

Any thoughts? Should I shoot for the higher Qtc for SQ that comes with the Kickers, or the higher output and better power handling of the DLS? Obviously price is a factor as well. I gathered all four of the Kickers for under $150. The DLS are currently ~$130 each.
 

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Look into the new Alpine Type-R subs. I own their dual-2ohm 8 and it sounds phenomenal. SWR-823D.
 

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I would not hesitate to run the kicker rig with that amp.... Just be mature with it and I doubt you will run into issues..
 

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Discussion Starter #4
I would not hesitate to run the kicker rig with that amp.... Just be mature with it and I doubt you will run into issues..
My concern is that I'm running an 8v Eclipse HU and the amps are old, min gain setting is 2.2v.
 

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build a pad or don't be goofy with the big-knob. that head-unit is only gonna hit 8V when it's WFO and at 0dBFS. You would be shocked at how little of that 8 volts you are actually using... Try it, if you need a pad build one, it's a quarter in parts, even with 1% tolerance. Peel 6dB off that 8V and you have...... ding, ding, ding... 2V!

Uneeda Audio - Build your own attenuator pads
 

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Discussion Starter #6
Thanks for the advice Chad. I'll probably just go ahead with the Kickers then. Worst case, I have to cut a new baffle for a pair of tens down the road. I can certainly build a pad if need be.
 

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Discussion Starter #7
Chad,
What do you think about wiring the four (4 ohm) subs in series to get a 16 ohm mono load (or 8 ohm stereo pair)? Am I right in thinking that would cut the power output of that Falcon down to about 90w mono (or 2x45w) Since I only need 50w to get to xmax, I don't see much sense in wiring the amp to get more power when I need less. This is a classic A/B amp, so there shouldn't be any issue in running 8 ohm stereo.
 

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if you want to do that I'd almost run it in 2 channel mode with 8 ohms per channel. that way you aren't putting 4 inductors (voice coils) in series. Granted it should not make a difference, but in simplicity it makes a whole lot more sense.

Methinks you are kind of over thinking this. Just because an amplifier is CAPABLE of a certain wattage does not mean it has to make it there ;)
 

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I wouldn't worry about the QTC too much. Most people say to aim for .7 but quite honestly I like the sound of the lower QTC. I've recently removed the trunk vents (to the outside world) and put a screen over them. IMO, the lower QTC sounds more natural and blends with the front better.
 
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