Basically, the car has the usual 4 speakers connected to the head unit through the standard DIN connection, but also has a small Bose amp powering a sub and 2 tweeters in the boot.
I wanted to get this working, so pulled it apart and got the multimeter out and figured out the connection. It's connected via an EQ unit under the passenger seat, but I figured out that it was quite straight forward to bypass the EQ and wire in the amp - all the live feeds and grounds were there, leaving 2 pins for the input (its mono).
After faffing about with the line out, I figured out that it wanted a speaker level input, so fed some bog standard speaker cable through to the head unit from the boot. However, when I connected it to the speaker outputs on the head unit, all output cut out. Now I'm led to believe the speakers are fairly low impedance (2 ohms I believe) so it makes sense that wiring the amp in parallel reduces the overall impedance, probably too much for the head unit. Oddly though, connecting only the speaker +ve make it work. Odd, but wasnt going to knock it! Sounds brilliant for a standard setup
The only problem is I'm getting a fair bit of interference - a quiet whine in pitch with the engine speed, which isnt too bad because it doesnt increase with volume and it's not that loud. But I noticed today that having the lights on creates a louder high pitched whine.
So, what would be the best approach to eliminate this? Use a resistor or wire the amp in series at the expense of sensitivity? Disconnect both rear door speakers and rely on the fronts and the amplified setup in the boot? Replace the cheap speaker cable with something better? Any other suggestions?
I wanted to get this working, so pulled it apart and got the multimeter out and figured out the connection. It's connected via an EQ unit under the passenger seat, but I figured out that it was quite straight forward to bypass the EQ and wire in the amp - all the live feeds and grounds were there, leaving 2 pins for the input (its mono).
After faffing about with the line out, I figured out that it wanted a speaker level input, so fed some bog standard speaker cable through to the head unit from the boot. However, when I connected it to the speaker outputs on the head unit, all output cut out. Now I'm led to believe the speakers are fairly low impedance (2 ohms I believe) so it makes sense that wiring the amp in parallel reduces the overall impedance, probably too much for the head unit. Oddly though, connecting only the speaker +ve make it work. Odd, but wasnt going to knock it! Sounds brilliant for a standard setup
The only problem is I'm getting a fair bit of interference - a quiet whine in pitch with the engine speed, which isnt too bad because it doesnt increase with volume and it's not that loud. But I noticed today that having the lights on creates a louder high pitched whine.
So, what would be the best approach to eliminate this? Use a resistor or wire the amp in series at the expense of sensitivity? Disconnect both rear door speakers and rely on the fronts and the amplified setup in the boot? Replace the cheap speaker cable with something better? Any other suggestions?
