The Concert radio can be coded for two different Bass/Treble Vehicle-specific tone control slopes. One is for Bose/Concert and the other for Concert only. You can change this setting by recoding the radio module with either a VAG1151/1552 or VWTOOL. The standard coding for a TT w/bose and secondary display is 00517. If you don't have a cd changer, secondary display, etc. this value may vary in the first decimal place (see page 5 of audi tech document on adding a CD-Changer for complete details. URL at end). We are only concerned with the value at the second decimal place (in the example above it is 1 for Bose tone slope). If you have the radio recoded and change the 1 to a 0 (zero), you will enable the other Vehicle-specific tone control.

Once the radio is recoded you will notice the "Bose" missing from the display on powerup. The Bass/Treble range is now +-6 but the adjustment is more dramatic.

I must say, the effect on the Bass is incredible! It may not be a "true" sound in the Bose universe but many will find it an improvement.

Paul adds: "I changed the code in my old TT 4 years ago and the extra boost I got from the bass was superb. I have bought a new TT and need the code again (I have unfortunately forgotten it). Are you saying that the code (in the case of Bose/Concert with CD changer) should be changed from 00517 to 00507? - 4/2/2004