Speaker weirdness...
11-03-14, 08:12 AM
#1
Speaker weirdness...
Ok, this is my second SC400 and the second time I've installed an Alpine stereo in them. Both times I get half the speakers working. I expected each car had one dead amp or something I hadn't discovered yet but this weekend made me really scratch my head. I was replacing the O2 sensors and had to disassemble the console, obviously removing the stereo. I thought I had hooked-up the RCA connectors just as before but when I started the car the stereo is no longer playing out of just the front speakers, now it is playing only out of the rears, just as my 1992 did. Obviously the speakers all work, what the heck am I doing wrong with the wiring? I have 6 pre-outs on the head unit, I'm using the 4 RCA jacks that are found behind the stereo as full-range connections, are 2 of them for the sub? I'm about to rip the entire stereo harness out and install amps and my own wiring...
11-03-14, 02:38 PM
#2
you need to check out the sc wiring thread in the audio section of the forum.
https://www.clublexus.com/forums/lex...b-working.html
This is a summary of the thread above and why its best to bypass the main amp in a sc300/400 when installing aftermarket headunit.
I have done it this way and its the best way to do it, just takes an extra 15 minutes to run some speaker wire to bypass the main amp.
So you would run all new line level outs 4 total, not the rca outs (low level) that are meant for an amp.
you know, 4 of the speaker type wires each one having a + and - wire.
you run your 4 new wires FL, FR, RL, RR, to the stock amp location by following the passenger bottom edge of the door (you can pull up plastics and run wires in there, rest under the carpet and under the back seats and into the trunk.
at the stock amp you disconnect the stock amp plugs, you follow the wiring guide and connect those 4 wire to the 4 wires that go out of the stock amp to the speakers.
then you bypass the whole stock system and get good sound to all the speakers.
If you have an aftermarket amp for the main speakers, then run the RCA's instead of the speaker wire to the amp, and from the aftermarket amp to the stock amp plug I said above. this plug is where the wires for all the speakers start and only place in the car you will find all of them on 1 plug.
For the sub if you do not have an aftermarket amp, you can use the stock sub amp just splice into the RR speaker (its all on the rear deck so wiring is easy), the factory sub amp wont mess with the RR line it will lowpass filter the signal and put out some decent bass.
If you have an aftermarket sub amp, then run a left and right RCA with those 4 wires out to the trunk and connect them up to your amp in the trunk, and then run the wires to the sub in the trunk its easy.
The reason why yours doesn't work the same is likely cause you got a pair of RCA's switched, but it wouldn't work well anyways as you found out.
The reason why you should run the wires all the way to the amp is because there are not 4 wires going to the amp stock, you cant do an easy install on this car.
The stock headunit only outputs 2 signals to the stock amp, and then the stock amp processes it into 4 signals plus a sub for all the speakers.
From the stock amp in the trunk starts the normal speaker wire going to all the speakers in the car (its done backwards I know its a Toyota/BOSE sorta thing they loved to do)
so if you are wiring at the headunit its only expecting 2 signals that are low level to mid level depending on volume, and you have 4 low level lines connected now.
you should be able to get some sound out of all the speakers in some way of using just 2 of the wires out of your headunit, but the volume control may be very limited.
So essentially you need to do what I wrote above in an sc300/400 and bypass the main amp. you can leave the sub amp and splice into a rear speaker but you need to do that wiring on the deck unless you can figure out the wires at the amp plug.
once you do the bypass you can remove the factory amp and CD changer. Its actually the perfect place for a battery after that, which is where my current battery is mounted right now.
https://www.clublexus.com/forums/lex...b-working.html
This is a summary of the thread above and why its best to bypass the main amp in a sc300/400 when installing aftermarket headunit.
I have done it this way and its the best way to do it, just takes an extra 15 minutes to run some speaker wire to bypass the main amp.
So you would run all new line level outs 4 total, not the rca outs (low level) that are meant for an amp.
you know, 4 of the speaker type wires each one having a + and - wire.
you run your 4 new wires FL, FR, RL, RR, to the stock amp location by following the passenger bottom edge of the door (you can pull up plastics and run wires in there, rest under the carpet and under the back seats and into the trunk.
at the stock amp you disconnect the stock amp plugs, you follow the wiring guide and connect those 4 wire to the 4 wires that go out of the stock amp to the speakers.
then you bypass the whole stock system and get good sound to all the speakers.
If you have an aftermarket amp for the main speakers, then run the RCA's instead of the speaker wire to the amp, and from the aftermarket amp to the stock amp plug I said above. this plug is where the wires for all the speakers start and only place in the car you will find all of them on 1 plug.
For the sub if you do not have an aftermarket amp, you can use the stock sub amp just splice into the RR speaker (its all on the rear deck so wiring is easy), the factory sub amp wont mess with the RR line it will lowpass filter the signal and put out some decent bass.
If you have an aftermarket sub amp, then run a left and right RCA with those 4 wires out to the trunk and connect them up to your amp in the trunk, and then run the wires to the sub in the trunk its easy.
The reason why yours doesn't work the same is likely cause you got a pair of RCA's switched, but it wouldn't work well anyways as you found out.
The reason why you should run the wires all the way to the amp is because there are not 4 wires going to the amp stock, you cant do an easy install on this car.
The stock headunit only outputs 2 signals to the stock amp, and then the stock amp processes it into 4 signals plus a sub for all the speakers.
From the stock amp in the trunk starts the normal speaker wire going to all the speakers in the car (its done backwards I know its a Toyota/BOSE sorta thing they loved to do)
so if you are wiring at the headunit its only expecting 2 signals that are low level to mid level depending on volume, and you have 4 low level lines connected now.
you should be able to get some sound out of all the speakers in some way of using just 2 of the wires out of your headunit, but the volume control may be very limited.
So essentially you need to do what I wrote above in an sc300/400 and bypass the main amp. you can leave the sub amp and splice into a rear speaker but you need to do that wiring on the deck unless you can figure out the wires at the amp plug.
once you do the bypass you can remove the factory amp and CD changer. Its actually the perfect place for a battery after that, which is where my current battery is mounted right now.
Last edited by Ali SC3; 11-03-14 at 02:51 PM.
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