2005 LS430 -- non nav, non ML. When I bought this car around four months ago the first thing I did was remove the stock sub and install my own 12 inch subwoofer with an aftermarket amp. I also replaced all the door speakers with the correct impedence (2 ohm up front, 4 ohms in back).

This system is still lacking, and it definitely has to do with the lame stock Pioneer amp that these cars came with. I already know that I can install an aftermarket head unit, -- this would make completing the installation with an aftermarket four channel amp very easy. Problem is, there isn't a single good looking aftermarket head unit that I've found, and I'd like to keep the system completely hidden. My questions are:

1. The stock amp (I think) splits the signal going to the front with a hi-pass filter. High frequencies go to the tweeters, mids/lows go to the door woofers. These are separate wires. Is there any way to combine these two to get the full range signal? That way I can just use the existing wiring to power a component system (since component systems use a dedicated crossover with a single input).
2. If the answer to the first question is no, then what about using the input signal coming from the stock head unit? Surely there must be a full range input signal. That is, unless the crossover filter is in the stock head unit anyway.

Thanks in advance

 

Sorry I didn't see this until all this time later. I thought I'd make a reply to your question for the sake of answering it for anyone who might see this thread. Ill answer your questions below:

Answer 1: You're correct. The factory amplifier uses a crossover network to limit the frequencies that the speakers play in the vehicle. The door woofers are actually using a bandpass crossover to limit high and low signals to the doors. If you're installing an aftermarket subwoofer for example and decided to use the door woofers or rear speakers for your input signal to your aftermarket amplifier, you'd lose a lot of low frequencies since the amp is already pulling a lot of sub bass out of the doors. The front doors probably have a crossover set to something like 250hz to 4khz band-pass which means it has almost no sub bass to use and it would probably sound really weak. The tweeters on the ML systems actually have 2 speakers stacked on top of each other. A mid-range speaker sits below the tweeter and plays something like 5khz to 10k and the tweeter on top has a capacitor that limits ranges 10khz and below. This tweeter plays something like 10k to the final 20khz of the human hearing spectrum.
In order to get a "full range" signal (which is still missing 20hz - 250hz) youd need to install a summing device after ML amplifier. A summing device like an Audiocontrol LC7i could be used to sum the signals together (this still requires you have an aftermarket amplifier to connect after the LC7i has summed the signal) and create a single output to install a full range speaker in the front door for example.

Answer 2: In the LS430 specifically (and most other OEM amplified audio systems) the crossovers are contained in the amplifier, not the source unit. There is a "Full Range" signal going from the head unit to the amplifier, but its not really usable. The LS430 uses a conglomeration of separate computer modules to play different audio sources through the ML amp. The FM tuner for example, is in the trunk and is only controlled from the source unit at the front of the vehicle. The same goes for the navigation computer, optional Lexus phone, and Bluetooth calling on models that are equipped. The problem with getting the audio from the source unit before the amplifier gets the signal, is that it is set a single volume, that is not adjusted by the radio *****. The way the LS430 turns the volume up and down via the **** on the source unit, or the controls on the steering wheel is by using a MPX or MUX circuit (multiplex). This circuit tells the amplifier what volume to set the speakers to, the input volume to the amplifier never changes. This means that any aftermarket amplifiers you might want to install will not have any volume control by the OEM source unit. Thus requiring you to get your signal after the amplifier.

Hope this helps.

-Mitch

 

Hey Mitch.

I’m thinking about installing an aftermarket single-DIN head unit and connecting that to an aftermarket 4 or 5 channel amp in the trunk. If I tap into or use a harness to connect to the existing speaker wiring that normally comes out of the ML amp, am I right in thinking that all existing speakers will get a full frequency signal? There are no external crossovers? Ideally, I’d like to replace the door speakers and potentially run a tweeter from the front door speakers up to by the rear view mirrors, but if there are crossovers somewhere along the way that would prevent hi frequency signals from ever making it to the door speakers, that would be moot.

 

Sorry for the really late reply. You need to cut the wiring coming out of the ML amp (and front left speaker from NAV computer) and use that to send signal to the doors and dash. There are no passive crossovers inline with the speaker wiring in the LS430.