NeoNz

Hey guys, im looking to rewire my system to get nice deep clean bass!!! I currently have it wired through the door speakers but im looking to tap directly into the wires running from the head unit, before the amp. The amp tends to filter out the lows and makes the bass sound like crap!! Can anyone point me in the direction of where the factory amp is and which wires coming from the head unit I should tap into?

Thanks

-Brett

LEXveryG8

Hey Brett,

I'm not sure about the wiring but the amp is underneath the seating possibly the passenger side or the rear seats. I'll check on that.

LophatRX

Okay, I just completed a simple hookup of a second amp and small subwoofer. The factory amp is located behind rear seat, and no need to remove the seat, just push all the way forward. Pull up the clips, but do it carefully unless you are going to replace the interior clips. Finally the wires for the speaker are on the large connector. The four wires that I used are, red/yellow for (+) right rear, blue is (-) right rear, red (+) left rear and gray for (-) left rear. I installed a simple LOC(line output converter) to have RCA hookups. I have heard other people do the same thing. One problem you will find is there is no power on wire for the factory amp, it actually senses the power from the speakers. So I ran a wire to the front cigarette socket under the gear shift panel.
The last thing will be careful I am not sure if my amp is just underpowered but the sound output from this connection seems low, even with my amp and LOC levels all the way up. But I really didn't want some deep overpowering bass since I don't drive it all the time. If you want more info got to www.The12volt.com they have wiring listings there.

NeoNz

i looked under all the seats i couldn't find an amp. there is no room in the rear the front seats dont have much clearance either.

NeoNz

i have the same problem of an underpowered amp, did you tap into the wires before the amp filtered them out? can you take a pic of the amp where it is? what are these interior clips?

LophatRX

To get to it you have to pull up the panel behind the seat, it too is held down with clips but the pull up with gentle tug. You will see the other plastic clips and those hold down the carpet and the backing of the seats, small plastic clips, I used a interior clip remover you can probably pickup at an auto parts store unless you already have one. I have only one picture right now of the plugs on the back of the factory amp. (see below) The big plug is the one that I tapped into.

AM1

iTrader: (6)

i would say bypass the factory amp and go aftermarket. factory amp is tiny.

NeoNz

id def install a secondary amp, is it posible? someone said the stock headunit is tri-amped? is this true?

take a look at this

Originally Posted by scubadoo
nightmare.. Tweeter totaly screwed my 400h. the factory stereo causes BIG problems for aftermarket amps.. the factory head unit is tri amped. internaly.. so the only way to tap into it for the aftermarket amp is to take the 3 speaker level outs... tweet mid and bass and use a SUMMING device... sucks...

then on top of that my installer told me that the factory head is turning down the bass and teble at high levels to protect the factory speakers from blowing.. well they are long gone but there is no way to tell the factory head unit to just put out a full signal...

my lexus is so messed up now.. i want to go trade it in.... Tweeter has filed bankrupcy so i am screwed..

dont mess with the factory stereo... i am pretty sure you will regret it I do..

anyone want a 400h cheap?

NeoNz

how did you get to the back of the amp? i can feel the amp and the plugs your referring to, but I can't get my rear seat to move up enough to get access to that clamp. My seat folds down but it doesn't fold all the way to the floor like in my old ML 500. is there a trick to folding the seat down? I only have like 6 inches of clearance between that metal part and the back of the seat. I can barely get my hand between the seat and the metal part that encloses the amp. I can take a picture but the rx400h seats dont move much at all. Am I doing something wrong here? should i approach them from the trunk?

On the other hand, if i do get to the big plug, what wires do i tap into? did you consider running a cleansweep? take a look at my post above from some other forum i copied, tri amped?!?!

thanks for your help,

brett

LophatRX

see my first post for the wiring connections, I think the most the seats move forward is 8 inches. I really didn't put the backs of the seats all the way down cause I have a child seat in the back seat, when I got to the amp. I just used the levers under the front of the seats and pulled them forward. I didn't want to spend to much on this install and the amp and speaker I had was left over from one of my old cars. And I don't plan on keeping this RX much more than a year longer so I will be removing the amp and speaker and installing it in my next RX or GX if the stereo isn't better than this one.

NeoNz

ok thanks, it seems you still have the problem of the sound being extremely low, do you know which wires on the amp tap into the tweeters and the front/rear speakers? you think i can use a different amp altogether? what do you think about the tri-amped theory??

LophatRX

Naw, I have thought of a few things. But the wiring I used I had to research and finally get the right ones from. Here on this site is a good write up about removing the factory radio and it is pretty straight forward and easy to do in less than 30 minutes. I thought about tapping into those wires but I didn't want to run a bunch of wires from the front to the back. Maybe that would give me better sound but not sure. As the days go by it seems the small sub I installed is really blending well with the whole system of the RX. The small sub is used, which really is only a 6 inch old pioneer from a broken pioneer tube. I built a small box that is really big for that woofer, and when I connected my amp, that is an old Hifonics single channel amp, through my other sony 2002gtr amp in my other car, it did sound very good. I am thinking that there is something with the connections that I could do to make it sound like it did then, but I am not in a big hurry to mess with it. I have heard some things about the way the signal is produced even from the head unit is a more digital sound and connecting to the wires using a simple LOC may not solve the whole deep base issue. If I feel the need to increase the bass I may pick up a small sound processor I saw on Crutchfield.

NeoNz

ok well to sum things up... I ripped everything out last night..literally all of my trunk, i shall post pictures later

i did the 9v test with the speakers and located all front/rear/tweeters on the harnesses, found there are 2 tweeters up front on each side, but i need to test them again to make sure they are wired together. it said on the test that you can watch the speaker with the 9v battery and if it pops out that wire is positive and if it goes inward its negative. they are both like 1 ft from each other on my dashboard.

last night and i hooked up 3 wires (coming from the front speakers going into my Line Output Converter) not the 4th though, somehow its louder than with all 4 hooked up into the LOC. Dunno why but it is. maybe its not as clean or clear. with 4 wires hooked up it sounded the same as before, when i had the LOC running from both of the rear speakers, i figured that it might pull more bass up top from those since they aren't 6x9s. maybe its a a little louder than the 5" in the rear but not noticiable. I have a feeling that even if i were to get a clean sweep it might sound the same, its worth a try though i guess.

as far as ripping out the stock head unit and tapping the wires back there, but if its amped internally then it wouldn't matter where i tap the wires right?
I just realized that the speaker wires going from the head unit to the amp are extremely thin, you think that could be a reason there is no bass? even though the output wires for the speakers are thick would it matter at all? if I tapped into the head unit, the wires are still going to be razor thin going from the head unit to the amp, which isn't good. there isn't really anywhere we can tap into then if the wires are tiny leaving the head unit itself, its not like its aftermarket with a pre-out for subs already made.

the best thing might be to run a clean sweep and try and raise the gain on the subwoofer itself

i might try and tap into the wires leading into the amp even though they are really tiny it can't hurt. maybe that amp filters out some bass?! ill find out tonight.

i might just use my own amp for the door speakers and bypass the factory garbage, well see.

LophatRX

So, sounds like you went way beyond what I was planning. I would like to see some pics of your Surpa, if you get a chance to share some. Anyway, good luck, the only thing I agree with the Lexus system is that the bass sucks but figuring that I would say 95% of the owners don't go around booming bass in a RX330. Now if I had the money, I would go all out get me a 2010, airbag it on some 20's and replace all the factory stereo and stuff some big 12's in the trunk and probably get a full panoramic roof installed just for the fun of it.

NeoNz

ah now your talking, ill try and upload the pics tomorrow, my supra too, ive been doing some serious work on that baby as i plan on ripping out the whole interior and dynamatting the whole damn thing!

my soundsystem is working perfect now, i might mess around some more but its good for me for now, its funny how easy it was to rip apart the interior though, im not sure about a clean sweep everything seems fine