Toofast

Hi Guys. I had no idea how to install a subwoofer so I watched some you tube videos and read some post and if you are in the same situation or you need which wired to tap I put this together for you.
My car is a 2007 Lexus Is350. This subwoofer installation can be applied to IS250/350 from 2006-2009. Maybe later models following the wiring diagram for the car year.
You will need some wiring taps, nose pliers, electrical tape, 10mm socket with ratch, 14g-18g wire ends. LC2 $20. (I got one in walmart with volume remote). Add amp kit $20.
Once you select the amplifier with bass volume control or reusing an old amp without remote volume (like my case).
I like the Amp that is stable in one ohm, check the subwoofer ohms setup and the RMS watts max (RMS is the real wattage. Some cheap amps like Boss said 2500 watts max but they dont give you the RMS so the real wattage is much much lower. One trick is to check in youtube if someone check the true wattage of the Amp you plan to buy. For example If the Amp has a 100Amps fuse then watt=amp x volt (100 Amps x 12 V= The Amplifier max wattage=1200 watts).
The Amplifier wiring kit same gauge for ground and power. Remote wire will turn the Amp. I connect this one from the cigarret + wire from the center console to a switch in the glove compartment (so I can turn it off if I like) to the Amp in the back of the trunk.

12 inch alpine type R. (300w at 4 ohms; 600w at 2 ohms) with keenwood 300w at 4 ohms. Or 500w at 2 ohms. This is my old stuff that I recycling back. Unfortunately my old Subwoofer is 2ohms per coil. So with this Amp I can only setting up at 4 ohms because the amp is not stable at 1 ohm.
Installation:
There are some differences between systems with Mark Levison (ML) and not ML factory amplifier. The factory amp located at the passenger site in the truck. System with no ML you can tap the LC2 easyly in four wires from one factory amp connector B. (See pictures below). Also you can see the youtube video "Lexus is250 car stereo budget"

Non ML system. Amp Connector B (the 2nd connector from the front to the rear of the car). Tap the LC2 to this wires. Channel 1= Brown + Green -
Channel 2= pink + Blue -

The ML system you have 3 connectors (rear woofer, R front and L front). I tapped in the R and L front door woofers. (HOWEVER, IT DID NOT SOUND GOOD!!!.THE FACTORY REAR WOOFER WAS CANCELLING MY AFTERMARKET SUB. SOLUTION: disconnect the rear factory woofer and tap only to the rear woofer cables. I did but it sounds better but not perfect. I think I need a full range signal to the aftermarket sub?? Any ideas?

Factory Amp. Connectors A,B,C and D. From the front of the car start Connector A and connector D at the rear of the car. It also the positive wires are in the top row from the connector and the negative at the bottom row.

ML system. Tap the LC2 to this wires. ML amp connector B (L front woofer): LC2 channel 1: White + Red - ML amp connector C (R front woofer): LC2 Channel 2: Brown + Pink -

LC2 with volume remote for the woofer

I use this to connect the switch located in the glove box to the remote wire for the Amp.

I do not cut the wires. I just tap them. I left the factory rear woofer connected plus the extra subwoofer I added.(It does not sound good. Disconnect the rear factory sub for better sound)

ML amp reading from right to left connector A,B in the first slot. C in the second slot. D in the 3rd slot. And the blue socket.

$20. I get it in walmart but you can also get it online.

LC2( 80 watts max input) standard color codes. Solid color wires + solid with black stripe wires - Yellow wire connect to positive 12v (from the positive red thick wire feeding the amp if you plan to use the remote blue wire from the LC2. Otherwise taped it. Blue wire can be use as a remote wire to power the amp( however, every time you turn on your radio the external amp will be on). Black color wire ground (to the sanded metal screw where the factory amp is bolted I put the taps already so I can connect to factory amp wires (already tapped)

Taps in Amp connectors B and C

All the wires are run to the passenger side. I did not have to take off the rear seat. Use a hang rope to feed the wires. I ground the black wire to the metal (sand it first to expose the metal)then fasten it with self tap screw).

Amp kit. Cheap AV wires but OK power and ground wires (wire is not 100% copper)

Toofast

Update: so far I tap in the rear factory sub wires and disconnect the rear factory woofer. It sounds better but not perfect. I think some one put the rear sub signal with the front (Right and Left) woofer signals to the after market sub. Any ideas? I think I need a full signal to go to the aftermarket AMP to the sub? Did you know how to do it?

B00M3R

iTrader: (1)

I am a Sound Engineer as a profession and I used to install car audio years ago so i have some idea what i am talking about but I haven't tested far enough to know for sure.

Your problem is that the ML system is fully crossed over. Every channel has a cross over for that specific speaker thus no speakers in the ML system are full.

I have looked into adding an amp and sub to my car but have chosen not too because of what i expect is happening, But if I were to do it I would look at a Line level converter that accepts more than one input, like the audio control LC2i at the minimum, It has dual inputs so you can get more of a full non crossed over signal.

Problem is figuring out what channels to tap.
I would expect tapping the sub output on the factory amp and the front woofer as the second would get you the best range for a sub but realize the crossover is still in line and that whatever signal processing it is doing will be transferred to your added sub, and there is nothing you can do about it because it is upstream from or built into the factory amp.

I would chose those two because the sub wire is probably cutting off around 100hz maybe as high as 120 and maybe as low as 80hz but the problem is that I expect they are crossing over the bottom at maybe 30hz , so that you cant blow out the factory sub. Your sub will go much lower that this and thus will not put out much of the lowest lows. If you chose both the woofer in the front and the sub you will hopefully get a signal that goes from 300hz to the 30hz cutoff and thus the best signal for your sub. I am hoping the facotry amp doesnt high pass the front woofer and thus you would get everything all the way down.

I have not tested any of this but this is what I expect from what i hear in the system.
This is why I have decided not to modify my system so far.

If I can find a way to get a line level signal directly from the head unit before the crossovers then I will add the sub, till then stock is good enough for me.

Good luck

Toofast

Thank you I will look on it. I keep it post what happens👍

winter

Has anyone located the low level sub inputs going into the factory amp? If so where are they?
I know many are using the speaker level sub and front woofer coming out of the amp but would rather get the low level before the amp.
Thanks

Toofast

I was watching a youtube video and it looks like the low levels which are the thin wires connected to the factory amp the volume is fixed. The radio sends a data signal to the amp to increase the volume. So the only way is to connected to the high output signal (so you can adjust the volume). I also saw another video and said that if you want to get a full signal in the Non-ML amp: to tap the wires feeding the front door sub. Tap the( +)wire from the Twitter or midrange and the (-) from the woofer ( make sure from the same door). I will try it and keep you posted (I tried in a ML amp system and does not work!!)
Also another tread, they use a LC2 with 4 Channels and add all woofer signals to feed the aftermarket amp. He say it sound it better. I will keep you guys posted (this work in a ML amp!!). Any ideas are appreciated.
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bbaugher47

Thanks for the great write up.

winter

Thanks for the info.
Don't just use the rear door low level. There must be a low cut on those. If you listen to the rear doors speakers there is no lows to speak of. I take it they did that as the sub in the rear deck provided the lows.
The rear door is what we used initially. My aftermarket sub sounded very strange with this input. It was getting some lows but realized it was mostly mids coming through. It made the sub speaker almost go out of control. The mids were actually effecting the sub even with the high cut rolled down on the amp. You couldn't turn up the sub very loud. It rumbled and sounded bad.
Evidentially it is common for installers to tap off of rear door speakers for sub inputs.
I just had my aftermarket sub amp wired properly from the sub speaker outs on the factory amp. This seemed to be the preference on here and youtube.
It is working great. We also unhooked the speaker level leads going to the factory sub. I listened without it and it seemed to sound a little better without the factory sub going.
I don't believe adding another speaker mixed with the sub is needed. People here have done that using multichannel hi to low converters.
I don't think the upper frequencies you would gain would even make it though the trunk to hear in the car. Let the other speakers provide these frequencies.
My sub amp has a high level ins so we used just those. The 2 channels that normally go to the factory sub.
I have a Rockford Fosgate R500X1D amp into a JL Audio 12W3 in a Sound Ordinance BB12 150v enclosure.
I like a very balanced sound and only need to turn the amp gain to about 2. We tuned it at a higher gain but it was overpowering.
I am an audio engineer of many years and believe I have a good grasp of what sounds good. I use my car to listen to songs I mix to get another perspective besides the recording studio. Have been doing it for years.
This is my experience. Will probably post a new thread with some pics and other details.

Toofast

Thank you for the input. I just read that the inputs from the rear door are low and you just confirmed it. So Guys do not tap the signal from rear doors!
Moreover, for Non ML amps just tapping to the rear sub outputs (4 wires) the bass sounds great. Read the beginning of this tread.
For ML amp then keep reading. This is a working process.
Previously when I connected signal just to the front doors sub outputs from the ML amp, the bass it did not sound right and I changed it like yours. I tapped to the rear sub outputs from ML factory amp with the factory rear sub disconnected. It sounds better but still not perfect. I have to lower the bass to prevent the bass overpowering the rest of the speakers. Moreover the bass sound like it has no all the frequency bass range (in my opinion). So there is 2 ways I can try.
1)Sum of bass sources: someone did this and said that the bass was fuller and better. He used a 4 channel LC (line converter). Connect in each channel L front door sub, R front door sub and rear sub (he only used 3 channels from the LC. At the LC outputs he had 2 RCA (which he use a Y RCA to convert those RCAs in One RCA (Never use a Y RCA connector to the Amps outputs directly without a device that will sum the signals like mini mixer to prevent Amp burnout!!)Then he adjust the gains to 35 volts (must be at the after market amp outputs?) and at the LC outputs just before the aftermarket amp( the range of voltage is upto 5v). And the aftermarket Amp has an input voltage adjustment.
Now the million dollar question (technical boring questions): what volume number on the radio I can turned up so the sounds do not get distorted. So what will be the voltage from the LC outputs, and then the voltage from the aftermarket amp so my sub wont be clipping? I know there is a tool SMD but $300 which I do not want to expend. So I just bought I portable oscilloscope $30.( I just need to learn how to use it&#128521.

This is the tread for summing the bass frequencies








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Toofast

If the sum of bass sources wont work for me then I will try to get
2) full signal source: (I watched a youtube video) the guy claimed that he got a full signal by tapping the + from the tweeter or midrange and negative from the woofer from the front doors output from the Non- ML amp. I put the speaker diagram and I sheet cheat below. Any input is appreciated.

Speaker cheat sheet

em01463[1][1](1).pdf​​​​​

Toofast

Update: I have a ML amp and trying to find the full range signal is not easy. I tried as described above but it won't work with ML amp system. It said it will work with non ML system. So my next step is to do the sum of all bass in a 4 channel LC. I read that this work great. I will keep you post it with the final results.

Toofast

This is another you video about the sum of all bass signals

Toofast

In the youtube video he used LC2. So one RCA from the Left front door sub signal and one RCA from rear deck sub. He said it works great. I will try it and I will post the results. My old aftermarket AMP does not have Bass **** volume. I was looking for a 4 channel LC with bass **** and there are in $100 price range. So I going to try it with my $20 LC2 with the bass **** first.

Toofast

Toofast

Preliminary final results:
Background: 2007 lexus is350 with ML system. Just using the rear deck subwoofer source, the Bass missing some tones. So it does not sounds right.
I add the L door sub signal and it is much much better! It sound great. However, with the aftermarket tesla style radio, the max volume I can have without distortion it is volume= 31 of 40. When I used the cheap LOC 2 channels the voltage from rear deck was 28 v but the L door sub was 1 volt at the inlet of the LOC. At the LOC RCA output the L door sub was 0.18 Volts. To balance I drop the gain from the rear deck from 28 v to 0.2v to match the L front door. I used that voltage as my preamp RCA. But my 300 w RMS aftermarket amp only was able to give 169 watts because the preamps input (0.2 v) are so low.
So my next move is to put a better LOC. The one I placed it gets very hot (it says that can handle 80 watts). I order a LC6i ($120) to sum the R front door and I hope my preamp gains will be better like 5 volts with better signal quality and bass (plus it won't be a fire risk) If my old amp does not give me the 300 watts then I will buy a new one with more power.
I bought a mini oscilloscope($45) and 1x10 probe ($10) and I was checking for distortion (signal clipping can damage you woofer). I check at the signal source (factory amp with a 40 hz test tone. I got extra toyota wiring connectors in a yonk yard. But you can also order online. The 40 hz tone at 3/4 volume will make your speakers shaking a lot. So with the extra connectors I can test the sine wave without blowing my speakers!). I checked after the LOC and at the aftermarket amplifier output when I was adjusting the amp gain. I will put the link for the video how to test the signal with the oscilloscope.