Chris Bell

I have a 2000 GS 400 with the factory NAV system. Does Lexus or an aftermarket co. make an add on amplifier that will allow me to use the existing setup or do I need to replace everything? I really like the way the stock set up works with the touch screen...I just would like a little more volume out of the system...

RON430

Chris - Hopefully the experts will answer you. We have all been through this multiple times. Because of the way the GS sound system is set up, you either do some major surgery and replace everything or grab the speaker signals and send them to the aftermarket amp. Either get an amp that will accept speaker level signals or use LLCs and any amp you want. Not that easy, but not that difficult either.

Audio PHD

Chris.........I highly recommend the xtant x603 it will power the entire system with ease! It will takw the speaker level in put and every will work perfectly fine...........I suggest you go to the nearest dealer and check it out! I have 1 in each of my cars and love them..........

stevie

Just curious here, but why can't you take the line level signals going to the stock amp and divert them to another amp?

Stevie

RON430

I looked at this initially on the wiring diagrams but have forgotten the whole story. Basically, the CD player does not go through the head unit but goes directly to the amp. Making the head unit with cassette and CD player work makes it impossible to just take the low level inputs before the amp. I would have to look at the wiring diagrams again. In addition, I believe there is yet another problem but I am not sure what it is, might be something with the sub channel. In any event, the way the GS is set up is not like an aftermarket headunit/amp setup. If you want a head unit with low levels to feed to an amp, you are going to be starting all over. THE BOOK has an explanation of this but I don't have it with me right now.

Percy

Ron,

You basically hit it right on the head. Also, there's a problem of the head unit having dual lines for each source. One is just for the CD (just a pair of L/R wires) and the other is a pair for the tape/radio. Very difficult to adapt since the unit internally switches between the pairs of outputs. No standard chips inside the HU either so it makes any adaptation fairly challenging to say the least.

Chris,

What are you system goals? SPL? SQ? I know Brian Morris who drives a Ford Probe uses xtant amps (and world champ), but they've been modified from some of my suggestions. He admits that they're not McIntosh or Brax (the top dogs) but they do the job nicely. If you do go with Xtant, watch out for the metal...they'll cut up your hands easily.

Percy

j2tha0e

isn't the factory amp 7 channels?

biggie27

what Ive seen done before is that a guy just disconnected the stereo from the main nav screen totaly ( as in if he turns the volume up on the nav nothing happens ) and then under the nav where the tape deck was he added a new deck and ran his stereo off of that, this way he has the function of the nav minus the sounds from it , and he has a better stereo , there is a picture of the car in the lobby somewhere it was under the topic of " hot import nights seattle "

stevie

> isn't the factory amp 7 channels?

I can only speak for the Mk I GS300, which I guess is only three channels. There is a disgusting little electrolytic is the enclosure for the front speaker that crosses over to the tweeter. I haven't followed the wiring through but it would be logical for the rear door speakers to be wired in parallel with the front two.

The front speakers are 2 ohms, the rear door 4, which would give a 3 ohm load total with more power to the fronts.

Before I started digging, I thought that the HF must be crossed over electronically, because the HF control seems to shelve the tweeter. It does not seem to act like a normal tone control.

I measured the stock drivers yesterday. Response goes up to 10K. -3dB point is 120 Hz in the stock enclosure out of the car. At 1k5 there is a 5 dB peak with a lot of distortion and delayed resonances.

Stevie

Percy

stevie,

The only real component that does the job (xover) is that little capacitor. Using an electrolytic means the capacitor is polarized, or has polarity. The capacitor should be bipolar, or no polarity as commonly found in crossovers.

Easiest way to make a level / treble control is to have dual outputs that are the same with different xover values. This way they don't have to be active. Active would mean taking their output to op amps as a buffer and then controlling them through some other sort of semiconductor which would allow variable adjustment of the frequency being crossed.

Percy

stevie

Let me correct myself. A 4 ohm speaker connected in parallel with a 2 ohm speaker gives a 1.5 ohm load. Doh!

Stevie