headunit problem

[dave1709]

hi guys, i've just put a new headunit into my car and am having a couple of problems with it.

firstly, i have amplified rear speakers and they are not very loud with the new headunit installed

secondly, the headunit doesn't seem to remember any of the settings i change once i take the key out the ignition.

Can anyone help me out?????

[HDi fun]

Yes - you need to provide a permanent 12v supply to the head unit in order to maintain the settings, tuned radio stations etc. If necessary take straight from the battery +ve terminal via a 5amp fusible link.

For the active (amplified) rear speakers we need to know the input impedance (not of the drive units themselves but of the amp inputs on the speakers - could be anything from 300 ohms to 100k ohms) and the required peak-to-peak mean input voltage for full output.

Some systems (and I'm thinking of commercial audio here, stage systems etc.) require a +6dB 2v ptp input, others work on -10dB which is about 0.5v ptp. I'm not overly familiar with specific car audio items but the principles are exactly the same.

Are the rear speakers getting a decent 12v supply? - being active they will need a good current source.

If there is a mismatch here then that's the first thing to resolve.

The units (speakers and head unit) should have this in the supplied documentation.

Are they just quiet or is the sound muddled and distorted as well?

[dave1709]

thanks for the advice HDI fun. solved the not remembering problem by switching the red and yellow wires on the harness adapter around. was doing a bit of googling and its a fairly common problem with audi's and the simplest solution i have found is to re-wire the speakers straight to the new headunit as the built in amp is only 2 x 20 watts and the head unit is over double that so is more than powerful enough to run them. thanks again for the advice though.

[HDi fun]

No worries. So you're going to run 'em (speakers) in passive mode then?

Sounds like a good workaround. Enjoy!