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knight rider.
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Discussion Starter · #1 ·
Ok, im in the states first off, and i wired a line level converter into the rear of my headunit (spliced into the rear speaker wires) and it worked gravy until the day it quit working...(it makes the subs make noise still, but the noise is not musical. Its very poppy and distorted and the louder it gets the worse it sounds...)(about 6 months or so) and ive trial and errored the problem back to the unit.

The subs are good, and so is the amp, and so is the amp wiring. So that leaves the signal creater (line level converter, without it, sound just goes to the rear speakers and bypasses the subs as i have 0 RCA outs on the stock headunit.)

So can Line Level Converters go bad? Or should i just check to see if a splice came out? Or should i check the splices again (checked once already,and everything was still holding tight. No breakage.)

Im lost as to what the problem is if it is not the line level converter. It was a 25$ piece though, so i figured you get what you pay for :rolleyes: ...

Shouldi trial and error a new LLC in its place?

Mike any input on this? Or should i just give up and buy a new alpine deck..... :D


Will.
 

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knight rider.
Joined
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40 Posts
Discussion Starter · #3 ·
ive quadruple checked the connections, because it just stopped working one day. out of the blue, not a constant degredation of sound quality. I think something may have melted in the LLC.

I just dont know if those units can go bad, i didnt think that much power was going through them...but maybe the signal strength out of the stock HU, over time, weakened it.

I'm just mainly trying to stay away from splicing anything else into those wires becasue BMW left me SOOO much wire to work with ...ha ha ha.

I guess i will take the LLC apart and examine it. I'll post pics when im done (camera phone quality).

Will.
 

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It is possible for line level converters to go bad!

They have to jobs to do.

1) Speaker load
They need to simulate the speaker load. So the converter should present a load across the speaker leads of the head-unit. This is to prevent the amp from cooking, not a problem on most modern units because of all of the built in protection but older amps could blow if not connected to any load. Because of this power is dissipated in the level converter. If you run the unit loud a lot it may well be that the device simulating the loads have burnt out.

2) Level conversion
The unit needs to lower the volume of the speaker outputs to a line level while matching the input impedance of a line level. This side of the converter should be pretty bomb proof.

Generally there are two types of converter a very compact and light one based on a resistor network or a larger and heavier one based on a matching transformer. The later is fairly rare.

A quick way to test the amp and speakers is to run them up using a Walkman as the signal source.
 

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knight rider.
Joined
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40 Posts
Discussion Starter · #6 ·
GaryM said:
It is possible for line level converters to go bad!

They have to jobs to do.

1) Speaker load
They need to simulate the speaker load. So the converter should present a load across the speaker leads of the head-unit. This is to prevent the amp from cooking, not a problem on most modern units because of all of the built in protection but older amps could blow if not connected to any load. Because of this power is dissipated in the level converter. If you run the unit loud a lot it may well be that the device simulating the loads have burnt out.

2) Level conversion
The unit needs to lower the volume of the speaker outputs to a line level while matching the input impedance of a line level. This side of the converter should be pretty bomb proof.

Generally there are two types of converter a very compact and light one based on a resistor network or a larger and heavier one based on a matching transformer. The later is fairly rare.

A quick way to test the amp and speakers is to run them up using a Walkman as the signal source.
i never would have thought of that...lol. I'll check out the signal when im back home this weekend or next, thanks for the info on LLC's !! It helps a lot.
 
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