rkw77080

As others already pointed out on this post, the likely scenario is that the previous owner installed an after-market head unit and made some modifications to your speaker wires.

Based on what you have described thus far, the after-market head unit probably had a built-in amplifier and the ML amplifier was bypassed altogether. The previous owner cut-and-spliced into the existing speaker wire pairs for the new lower-impedance door speakers and tweeters. At the cut, the section of wires going to the speaker is re-used to connect to the new head unit; the section going back to the ML amplifier is abandoned in place.

As you already suspected, go ahead and pull out the radio head unit and look for these 4 abandoned wire pairs in the space behind it. Of course, you are looking for new "jumper" wires that the previous owner used to get from the after-market head unit to the splices, so there's no telling what type or color of wires are used. If luck would have it and they are found back there, you can physical trace each one of them back to the point where the cut-and-splice occurred and revert the modification. Alternatively, you may decide to run a new 8-conductor speaker cable (or bundle 4 pairs together) from the ML amplifier in the trunk to where the radio head unit is and re-use the signal paths the previous owner created.

As for now, we know that the 4 door speaker wire pairs connected to the ML amplifier are cut. For all we know, one or more of them can be exposed and is/are touching bare metal (grounded). This can potentially cause damage to your amplifier if it is driving a signal directly into ground.

Good luck!

Jabberwock

On the 04-06 LS430s the non nav audio system and amp are Pioneer and not Mark Levinson. Not sure if this was also true on 01-03 versions of the LS430. The pioneer amps may have different ohm specs for its speakers.

As others have posted you likely have a missing, dead, or turned off non OEM AMP located (or previously located) somewhere in the car that may have been either removed or disabled. Find that AMP or where it was located and you will likely find missing and/or disconnected wiring. Mostly likely places to hide non OEM amp are under the seats, anywhere under the front dash, or in the trunk.

swilli89

ITS FIXED!!

Thanks to everyone that helped and big shout to rkw77080.

I'm still not 100% what the previous owner had going on, but I found that they had wired the door speakers in series with cut off dead end cable pairs ending around the back seats.

I simply bypassed and rewired the original wires and I'm all good now for the door speakers! To think I was about to send my amp in and pay $400... Everything seems to be working beautifully!

swilli89

Question, are there crossovers on the lines for the front door speakers?

All 4 door speakers are fine, but when installed the fronts sound SUPER mid-rangey and I hate it. The back sound so much better and for some reason the fronts are like I said, very bright sounding, almost like AM radio with the middle range of the EQ jacked up.

Aron9000

Perhaps just the tweeters on the front doors are the only ones working, the woofers in the front doors are still dead.

swilli89

I have actually disconnected the tweeters so it should be going straight to the door woofers.. They sound totally different from the back and I read a reference in the main ML audio thread that there are crossovers somewhere filtering out the higher end frequencies.,. need to find that and eliminate! I just have no idea where it is.

rkw77080

If there is a crossover, it is not from the factory. Have you tried moving a known good speaker from the back to the front to see if the problem lies in the wiring or the speaker? The problem may not be related to the wiring. BTW, when you originally tapped into the green and blue wires at the amplifier for the front passenger-side speaker, did it sound normal?

One other thing to try is to switch the 2 signal wires of one of the front speaker (not both speakers) and see if the sound improve. I suspect that maybe one of the speakers is wired backward. When wired properly, the audio signal thrusts the voice cone forward, but if wired backward, the voice cone is pull back instead. The opposite movement tents to cancel out some of the sound. Normally, this effect is not very drastic, but is detectable.

Jabberwock

What was highlighted in the pictures at the start of this thread as "breakout boxes" are usually the crossovers. Third party crossovers supplied with component speakers are typically fixed frequency but sometimes they can be adjusted/changed to customize cross over frequency. The OEM amp is sending a signal to the door speakers that has already been equalized to send high freq to the dash tweeters. I'd pull the cross over boxes out of the doors and wire the door speakers direct to OEM amp wires.

swilli89

In the ML thread they say that there are actually crossovers for the front doors. It must be the box hidden up behind the fuse box.
https://www.clublexus.com/forums/ls-...ml#post5620260
I bypassed and removed the after market breakout boxes that were in the front doors and yet they still sound muddy, blurry and mid-rangey. Even so, I left them in the rear doors and the 6.5" speakers still sound much more clear and full.

swilli89

Well to add to my confusion I traced the speaker wires all the way through the junction box (they were actually already bypassed so I left alone). The speakers are getting wire from what I believe is directly from the amp.

I pulled the front speakers and they sound great wired with the back speaker wires or inside in my home system.. Talk about frustrating!

rkw77080

OK, now that you’ve confirmed that both your amplifier and speaker are functioning properly, the sound quality problem is likely related to the speaker wires. That is, the pair is either shorted to each other, or one or more conductor is touching metal (grounded).

It’s time to pull out the multimeter again. First, disconnect the speaker wires from the speaker, and unplug the S30 connector from the amplifier. Set your multimeter to its resistance (ohm) test mode and test the front speaker pairs.

For the driver-side speaker, measure resistance between S30-2 (pink) and S30-9 (violet) at the S30 connector. We are checking to make sure these 2 conductors are NOT touching each other, and neither one should be touching the ground. You should get a very very large resistance measurement. If you get a small reading, say 1000 ohm or less, the signal pair is shorted to each other somewhere along the run and need to be repaired. Repeat the same procedure for each conductor against the car’s metal part. Again, a small reading means that the wire jacket is damaged and the copper wire is making contact with the ground somewhere along the run.

If all is well up to this point, twist the 2 conductors together at the speaker's end, and measure resistance between S30-2 (pink) and S30-9 (violet) at the S30 connector. Here we are checking to make sure the signal current flow can go out on one conductor, through the twisted connection, then back on the other conductor without obstruction. You should get a very very small reading, say 10 ohm or less. If the reading is large, that means something (e.g. resistor) has been added to the speaker wires somewhere along the run - it should be removed.

For the passenger-side speaker, perform the above for S30-1 (green) and S30-8 (blue).

swilli89

Your guidance is invaluable, thank you. I have an update which I am not too happy about..

So I connected the speaker right out of the amp and it STILL SOUNDS THE SAME. Super muddy and with zero frequency in the high range. The amp is processing the front two speakers like this on purpose. I'm thinking about stealing the dash tweeters outputs and just using that for the front speakers.. I highly doubt my amp is defective as the rear doors and front dashboard tweeters all work fine and at great volume.

I can't help but think the post I quoted from the ML audio thread has some bearing. Maybe in the EQ that I can't access it has adjusted the FR and FL channels to only do mid-range?

Edit: Yep.. I hooked up the door speaker to the tweeters wires directly from the amp and you guessed it.. sounded super high-rangey and too thin. The amp is purposefuly putting out different audio signals to different channels..only midrange frequencies to the front door speakers and only high frequency to the tweeters. Really frustrating that they couldn't have just sent full signals to each. The rear doors get full signals and they sound great! There's no way this sounds good even with the factory door speakers and it seems like now my ONLY way to not get awful sounding sound from the front of the car is to do a total aftermarket install. Sigh......

rkw77080

I just confirmed on my LS430 that both front door speakers delivered mid-range audio. On my 04 model, I can "balance" the sound towards the front, can you do that on yours? There's a good possibility that maybe the front channels of your amplifier are damaged.

As you have confirmed, the rear channels are working properly. If so, there's still one more option to get good sound to the front speakers. You can switch some wires around at the S30 connector to "series" the front and rear speakers together. The increased resistance due to the series configuration will not harm the amplifier, but will require you to turn the volume up a bit higher. The total wattage will remain the same as before. The other downside is that you can no longer "balance" between front and rear.

Please let me know if you want to give this a try, and I will sketch something up for you. BTW, did you test the front speaker wires while you have the speaker out of the vehicle? Grounded speaker wires can cause overheat and damage the output circuit.

swilli89

I actually thought about attempting that a while back when I saw that the aftermarkets that I have are 4-ohm. I decided against it because I wasn't sure how the amp's power circuitry would handle only driving 2 channels instead of 4. I know the resistance would double so would the amp strain to over drive two channels while 2 remain unused? Or would it balance?

PS I'm fine losing the balance from front to back, i keep at 50/50.

rkw77080

As I said, increased resistance will not harm the amplifier. In fact, the ML door speakers should be rated at 8-ohms.

Power output varies proportionally with current flow, and inversely with resistance. A good analogy to this relationship would be something like using a garden hose to clean your driveway. At the start when the nozzle is closed, you have a very large resistance (high resistance) to water flow. Then you squeeze the trigger half way to reduce the resistance (medium resistance) to allow some water to flow, and when you encounter some stubborn debris that need extra blast of water to remove, you pull the trigger all the way in (least resistance) to allow the maximum amount of water to pass.

The only difference between water flow and electrical current flow is that the latter generates heat. This is the whole theory behind electrical fuses. Each fuse is designed to pass a certain amount of current, and should its maximum rated current is exceeded, the heat generated will melt the fuse element and the fuse is said to be “blown”.

Here's a sketch of how you can use the rear speaker channel to drive both front and rear in series. Wire colors shown are based on factory equipment since I have no way of knowing what modifications had been made. Also, please check to make sure that the front speakers wires are not grounded and are not shorted to each other (see previous post). As with any advice you obtained from the internet, please proceed with caution, and at your own risk. I cannot be responsible for any damage or injury this may cause.