The Volvo HU-601, HU-603, HU-613, HU-801, HU-803, HU-813, HU-850 radios that are found on Volvo S60 (2000 to 2010), S80 (1998 to 2006), V70 (2000 to 2007) and XC70 (2000 to 2007) Audio System have an hidden menu where you can manually adjust the equalizer settings for both front and rear speakers. Proceed as follows:

1. With the radio switched off, press and hold down “SOURCE” button.
2. Press “Volume” button to power up the radio
3. Continue to hold down “SOURCE” button until “Front Low1” appears on the screen (aprox. 5 seconds).
4. You have now entered the hidden equalizer menu, where you can fine tune the sound quality of your audio system.
To adjust the value, turn “SOURCE” button, this will make the current value change between 0 and 6.
5. To change between equalizer frequencies, press “SOURCE” button.

Available frequencies:

FRONT Low1: Adjusts the deep low frequencies in the front.
FRONT Low2: Adjusts the low frequencies in the front.
FRONT Mid: Adjusts the mid frequencies in the front.
FRONT High: Adjusts the high frequencies in the front.
REAR Low: Adjusts the low frequencies in the back.
REAR Mid: Adjusts the mid frequencies in the back.
REAR High: Adjusts the high frequencies in the back.

Share with us your optimal configuration, or default values in your car / model, writing a comment below!

Default S60 HU-803 Hidden Equalizer values:
FRONT Low1: 4
FRONT Low2: 4
FRONT Mid: 6
FRONT High: 4
REAR Low: 4
REAR Mid: 0
REAR High: 6