How to Unlock the Subwoofer Menu on Audi A4 B9 (MIB3)

The Audi Sound System (PR-9VD) in your A4 B9 includes a 10-speaker configuration with a dedicated subwoofer. But the MMI Sound settings only give you two sliders: Treble and Bass.

After activation, a third slider appears — Subwoofer — giving you independent control over the subwoofer output level. This means you can:

• Boost the subwoofer independently without making the mid-range bass muddy
• Reduce subwoofer output if you find the low end overpowering on certain tracks
• Fine-tune the balance between the main speakers and the subwoofer to match your listening preference

The slider sits right next to Treble and Bass in the Sound menu — exactly where you would expect it.

The Subwoofer slider exists in the MIB3 software but is not enabled by default on vehicles with the standard Audi Sound System. Audi reserves certain audio controls for higher-tier sound packages (Bang & Olufsen, Bose).

On the A4 B9, the standard 10-speaker system has a physical subwoofer that responds to this hidden control. The software interface is already there — it just needs to be activated.

This is not a hack or workaround. The control is a genuine part of the MMI software that Audi chose not to enable in the default configuration.

Audi A4 B9 models from 2020 to 2023 with:

• MIB3 Navigation System
• Audi Sound System (PR-9VD) — the standard 10-speaker configuration

Not applicable if your A4 has:

• Bang & Olufsen or Bose sound system (these have their own audio management)
• MIB2 infotainment (pre-2020 models)

Submit your VIN to verify your A4's sound system configuration.

What you need: Windows PC + ENet cable, or iPhone 15/16/17 + USB-C to LAN adapter + ENet cable.

Price: €50 — the most affordable activation in the RetroLab Pro lineup. One-time, permanent, VIN-verified.