a3 8p sound equalisation and coding

The normal A3 coding has a smiley face EQ, so more bass and more treble with less middle, which is essentially what you need in a car unless you have your own separate EQ.

I have removed BOSE and fitted JL after market speakers / sub + 500/5 amp.

I have left the coding for BOSE and the sound was alot better but did sound like the sound was flat.

I have now cut the BOSE wire and sounds miles better, much richer sound with the Bass and treble control which now work correctly. (BOSE coding is still enabled)

Hope this helps

The Bose wire earths the Bose pin on the back of the HU. This flattens the EQ of the HU's preamp stage so you get less bass and less treble. It also reduce the effect of the treble & bass controls (because obviously Bose know how you like to listen to music better than you do).
There are 2 coding options via VAGCOM, both of which are purely cosmetic in terms of sound quality.
1. just flashes up "Bose" when you turn the HU on
2. turns off the HU's internal front power amp as it's not used with the amped Bose system and saves valuable power on the HU (god only knows what for). I think this option is there purely to annoy anyone buying a secondhand HU for a non Bose system as their front speakers won't work unless they have VAGCOM and can switch it back on.

Regardless the only thing that effects the sound is the Bose wire on the back and I suggest anyone wanting to improve the sound on their Bose system cuts this wire as it gives you back some control of the woolly Bose sound.