help! audio getting quieter!

[MaloventEvil]

hi all,

i just bought an e30 a couple weeks ago (89 325is) and today the sound output started to get quieter while at the same volume level (HU is a JVC kd-lx50). Does this mean my head unit is bad? (i suck at audio stuff -- i just want my sound back!)

thanks!
-aurash

[MaloventEvil]

I have some more data points that might help narrow the problem..

- when the car has been sitting for a while and i turn the radio on, it works for a longer period of time before the outputted volume gets quieter.

- if the volume cuts out, i can turn off the head unit for 30 seconds or so and turn it back on. the volume goes to the normal level for a short period of time (another 30 seconds or so before it gets quiet again).

[MaloventEvil]

Also, when I turn off the pre-amp output, it turns the sound off. I assume this means that I am using an external (or the stock) amp? If it is the stock amp, what are my replacement options?

The car has the factory tweeters installed, so I assume it had premium sound? (there is no "dash" fader though)

Thanks!
-Aurash

[StereoInstaller1]

OK, so now you got my curiosity aroused.

EXACTLY what deck do you have? How can you shut off the pre-outs? Does the fader on the deck work? Does the fader in the dash work?

[MaloventEvil]

OK, so now you got my curiosity aroused.

EXACTLY what deck do you have? How can you shut off the pre-outs? Does the fader on the deck work? Does the fader in the dash work?

I have a JVC KD-LX50. It has an option in the settings called pre-amp and allows it to be toggled on / off. There is no fader in the dash, and I haven't tried the one in the deck yet but will post tonight.

[StereoInstaller1]

Nope. Your "pre-amps" are not able to shut off, but the built in amp can be.

Just to make things goofier, it is called "P-AMP"

So yeah, your deck can be connected to the stock amp, or drive the speakers directly.

It could be done in such a fashion that it pisses off the deck, and would do exactly what you are describing. In fact, if it were done like that it could potentially work fine for a few years and then screw up.

Get that deck out of the dash, make damn sure I can see ALL of the wiring connections, maybe even list what they have connected to what.

I bet this is nothing but a shitty install.

Luke

[MaloventEvil]

Nope. Your "pre-amps" are not able to shut off, but the built in amp can be.

Just to make things goofier, it is called "P-AMP"

So yeah, your deck can be connected to the stock amp, or drive the speakers directly.

It could be done in such a fashion that it pisses off the deck, and would do exactly what you are describing. In fact, if it were done like that it could potentially work fine for a few years and then screw up.

Get that deck out of the dash, make damn sure I can see ALL of the wiring connections, maybe even list what they have connected to what.

I bet this is nothing but a shitty install.

Luke

Will do!

Thanks Luke!!!

-Aurash

[MaloventEvil]

This morning I was pulling the head unit after driving the car for a bit, and the back of the HU was literally BURNING hot. It was so hot that I burned my hand.

I will have pictures of the wiring up later, thank you very much for the help!

-Aurash

[MaloventEvil]

HU WIRE COLOR -> CAR WIRE COLOR

SOLID GREEN -> YELLOW / ORANGE
GREEN / BLACK -> YELLOW / BLACK
GREY / BLACK -> WHITE
WHITE / BLACK -> WHITE
WHITE -> WHITE
PURP RED -> BLUE RED
PURP BLACK -> BLUE BLACK
YELLOW -> RED GREEN
BLUE WHITE -> WHITE
RED -> PURP WHITE
BLACK -> BROWN BLACK


HU DISCONNECTED:
ORANGE WHITE ->

CAR DISCONNECTED:
-> RED WHITE
-> YELLOW BROWN x2
-> BLUE BROWN

pics to come

[StereoInstaller1]

Oh my fuck, that is horrid.

Pic, please.

[MaloventEvil]

I was hesitant to show pics because it is very hard to see what is going on....
Here is what I got:

[StereoInstaller1]

Dammit, those pics really don't help, do they?

Now we need to know what is in the trunk. That looks like it might be a partial rewire.

[MaloventEvil]

Pics of the stock amp location? (is that the drivers side?)

[MaloventEvil]

If the trunk has the stock amp, that means that the speaker level inputs are running to the amp? What would that mean in terms of fixing it? What are you currently thinking my problem is? (or is it too early to tell)

Will take pics of the trunk when i get home

[StereoInstaller1]

OK, here are the basics: you cannot connect the decks output negatives to ground, or to each other.

The easy way to do that is simply don't use the decks negative output.

However, the guy who did that install didn't know that the BMW wiring uses black stripe for positive, so he basically had his ass kicked by a 20 year old factory amp integrate.

However, it also looks like he added some other wiring, like he was trying to bypass the stock amp. He obviously had no clue.

IF you see solid blue or yellow, that is the input to the fader. Red or black strips on blue or yellow are inputs to the amp, assuming your "i" had one, or has one still.

So, how you do this is to use the stock amp to run the speakers, use:

Yellow/red as front left +
Yellow/black as rear left +
Blue/red as front right +
Blue/black as rear right +

ALL grounds go to ground EXCEPT (and this is absofuckinglutely crucial) DO NOT CONNECT THE DECKS SPEAKER NEGATIVE WIRES TO ANYTHING!!!

NOTE HOW i CALL THEM "SPEAKER NEGATIVES" INSTEAD OF "GROUND"...do NOT use them as ground...your deck will overheat.

So yeah, that whole thing took me longer to type than it does for me to do.

Luke