Installing New Free-Air Sub
08-05-09, 03:16 PM
#1
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Installing New Free-Air Sub
i just got a pioneer 500w 8in to replace my factory sub in my ls 400. its a 99'. i was just wondering if the factory amp will do or do i need an aftermarket one. oh and where would i find it?
08-05-09, 03:42 PM
#2
The stock sub I think is 40w 2ohm. Theres a tutorial on lexls.com about the sub, and basically there was a Kicker sub that was compatible with stock receiver, but it has since been discontinued, so you wont find anything that is compatible anymore. Nobody seems to make a 40w 2ohm 8" free air sub.
08-05-09, 04:43 PM
#3
Other than being 2ohm like och said, the stock sub is very light (thin paper cone). I doubt the stock amp would have anywhere near the grunt to drive your average PP/rubber cone 8" sub - even if you found a 2ohm one. It would probably sound worse than the stock one.
If you're running the stock head unit, just stick with the stock sub/amp until you're prepared to replace the lot. If you've already replaced the stock HU (and are using it to power the door speakers), rip out the stock amp and sub, install a small 200-300w amp in the trunk and mount a fairly low power 10" sub in the factory location (some cutting required). Because of all the hard work lexus put in sealing the boot/trunk from the cabin, most normal subs will work fine free-air. Just make sure you seal around the sub well (i used sticky foam tape between the sub and shelf). The rear shelf isn't that solid though so don't put a 1000w monster in there, it'll just rattle the shelf and defeat the purpose.
If you're running the stock head unit, just stick with the stock sub/amp until you're prepared to replace the lot. If you've already replaced the stock HU (and are using it to power the door speakers), rip out the stock amp and sub, install a small 200-300w amp in the trunk and mount a fairly low power 10" sub in the factory location (some cutting required). Because of all the hard work lexus put in sealing the boot/trunk from the cabin, most normal subs will work fine free-air. Just make sure you seal around the sub well (i used sticky foam tape between the sub and shelf). The rear shelf isn't that solid though so don't put a 1000w monster in there, it'll just rattle the shelf and defeat the purpose.
08-05-09, 06:09 PM
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if the stock amp puts out say 20w at 2ohms.. expect to see LESS power on a 4ohm load.
i would really reccomend a new larger amp if you wanna make the most out of the new sub. it shoudl WORK with the factory amp it just wont sound much better.
oh and dont listen to the person sayin to cut it up and put a ten in the spot where the eight went. u wont get much of a difference because it is free air which kills the sub in the first place.
i dont know many "normal" subs that are designed to work in that big of an enclosure. u will see reduced power handling and less than "normal" sound. (most subs are designed to work in 1-2 cubic feet.. not 25 cubic feet.
for best sound put a NORMAL sub in a NORMAL box.
good luck.
i would really reccomend a new larger amp if you wanna make the most out of the new sub. it shoudl WORK with the factory amp it just wont sound much better.
oh and dont listen to the person sayin to cut it up and put a ten in the spot where the eight went. u wont get much of a difference because it is free air which kills the sub in the first place.
Because of all the hard work lexus put in sealing the boot/trunk from the cabin, most normal subs will work fine free-air
for best sound put a NORMAL sub in a NORMAL box.
good luck.
08-05-09, 08:00 PM
#6
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lots of 
in this thread.
first off, if you're looking for real output you should use an aftermarket amp. 40w @ 2 ohms just isn't much. but...
1) "free air sub" is just a label. what you need to do is look at the t/s parameters of the sub. what you are looking for is a strong suspension (qts), low fs, and suitable air space requirements (vas). there are a lot of subs that work well free air, and even some that even work well despite having unfavorable t/s specs.
2) power ratings are worthless (even more than usual) as free air application reduces power handling.
3) sensitivy ratings (spl) will judge how loud the speaker will be, not rms.
4) cone area and x-max are the name of the game in ib (free air) apps. using a 10"/12"/15"/18" will produce more output, all other things being the same.
5) free air is regarded for it's low frequency extension and linearity ("best sound") rather than it's output.
6) anything other than a 2 ohm or dual 4 ohm sub will be a waste of time. running a higher ohm load will give you less power and there's just not much to start with.
7) the lexls.com method isn't great (in my experience) because of the hard plastic spacer. i would recommend and mdf ring mounted directly to the rear deck. sound deadening will also help.
in this thread.first off, if you're looking for real output you should use an aftermarket amp. 40w @ 2 ohms just isn't much. but...
1) "free air sub" is just a label. what you need to do is look at the t/s parameters of the sub. what you are looking for is a strong suspension (qts), low fs, and suitable air space requirements (vas). there are a lot of subs that work well free air, and even some that even work well despite having unfavorable t/s specs.
2) power ratings are worthless (even more than usual) as free air application reduces power handling.
3) sensitivy ratings (spl) will judge how loud the speaker will be, not rms.
4) cone area and x-max are the name of the game in ib (free air) apps. using a 10"/12"/15"/18" will produce more output, all other things being the same.
5) free air is regarded for it's low frequency extension and linearity ("best sound") rather than it's output.
6) anything other than a 2 ohm or dual 4 ohm sub will be a waste of time. running a higher ohm load will give you less power and there's just not much to start with.
7) the lexls.com method isn't great (in my experience) because of the hard plastic spacer. i would recommend and mdf ring mounted directly to the rear deck. sound deadening will also help.
08-05-09, 08:15 PM
#7
oh and dont listen to the person sayin to cut it up and put a ten in the spot where the eight went. u wont get much of a difference because it is free air which kills the sub in the first place.
i dont know many "normal" subs that are designed to work in that big of an enclosure. u will see reduced power handling and less than "normal" sound. (most subs are designed to work in 1-2 cubic feet.. not 25 cubic feet.
i dont know many "normal" subs that are designed to work in that big of an enclosure. u will see reduced power handling and less than "normal" sound. (most subs are designed to work in 1-2 cubic feet.. not 25 cubic feet.
Free air, when done right (like lexus did it), works great. As long as there is no or very little pressure transferred between the opposing sides of the speaker cone it doesn't matter (lexus sealed the trunk off pretty well). It could be 10,000 cubic feet, or even infinite. It would still sound good. What makes the sound is the pressure difference, not the fact that the speaker cone is in a box. One reason (among others of course) manufacturers say their subs should be installed in a box is because the box limits the throw of the sub - so your average ricer is less likely to destroy it. True, you will usually get *more* noise from a boxed sub but;
1) There is a fuel tank and a ****load of sound deadening and sealing between the trunk and cabin. You'll need to make a LOT of noise in the trunk for it to sound as good in the cabin. With the stock sub gone you will at least have a port but it wont be very accurate bass.
2) Like many, I didn't want a sub box taking up any space in the trunk - I need to be able to fit snowboards in there - a 10" in the factory location with a little pioneer 300w amp is a BIG improvement over factory (personal experience here - don't bother arguing).
Like BlkonBlk98 said, i chose a sub with quite stiff suspension, thinking it would be better suited to free air. It works great, but the stock sub actually has very weak suspension... take what you want from that.
Last edited by gmacrae; 08-05-09 at 08:33 PM.
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08-05-09, 08:29 PM
#8
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mine was completely rotted out so i never heard it, but i'd bet my last dollar it was nothing to get excited over. 17 years is a long time in terms of technology, not to mention that oem sound sytems are generally sub par.
08-05-09, 09:24 PM
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thanks alot for the replys. i think im just gonna go with the aftermarket amp and replace the sub with the new one. i knew the factory one would be weak but wasnt sure. where exactly is the amp in my car? is it under the seat?
08-05-09, 09:58 PM
#10
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If the cone is okay but the foam ring around it is disintegrated, you can buy a refoam kit. I ended up doing this on mine and its good as new!
08-05-09, 10:08 PM
#11
17 years isnt a long time in terms of speaker systems either, not much ever changes with speakers (except marketing) - most of the theory was understood 50 years ago.
08-06-09, 05:14 AM
#13
Would either of these be suitable?
http://www.sonicelectronix.com/item_...ms+SWS-8-.html
http://www.crutchfield.com/p_2067C8V...82.html?tp=111
http://www.sonicelectronix.com/item_...ms+SWS-8-.html
http://www.crutchfield.com/p_2067C8V...82.html?tp=111
Last edited by Schnitz; 08-06-09 at 05:20 AM.
