bought a 75 3.0
AO Silver Member
155 Lounge Winner 09
Join Date: Dec 2006
Re: Aftermarket Headunit has no SOUND!
what model is the new headunit? that may be useful info.
a couple things:
1. alfa's ISO connection does not follow the standard wiring pattern; i think you'll find that wires #4 and #7 are swapped around compared with normal ISO; this means the 'permanent(constant)' and 'ignition(switched)' wires are swapped; the implication is that a) HU may not receive a robust-enough power supply b) when you turn the key to OFF/remove the key, you'll lose any settings that are usually backed up by the 'constant' wire (eg: radio station presets); do you find this to be the case?
2. the bose should be triggered on/off via the C1-#6 wire; you should connect the blue/white from the new HU to this wire
note that the audio signals that the bose amp relies on are 'low level' (low voltage, up to ~2V from factory blau), like the RCA preouts of an aftermarket HU. it will still work from the speakerwire outputs on your new HU, but these are 'high level' (high voltage, could be up to ~4V depending upon model). the implication is that it will appear much louder, but is because the amp is pushed harder. you will have less volume-sweep to play with on the new headunit before the amp clips (runs out of power).
GT . 3.2 . Q2 . Kyalami Black - Red . Eibach . KONI . ASSO . ATP 19" . TAROX . FERODO . Mille Miglia exhaust
155 . 2.0 8V TS . Grigio Grey - Grey . H&R coilover . Enkei 17" . TAROX . GOODRIDGE . REMUS
75 . 3.0 . Alfa Red - Grey