Redmi K20 Pro Stereo Dual Speaker & Harman Tuning

Overview

Redmi K20 Pro Stereo Dual Speaker & Harman Tuning (authored by Eriol Sakura) is an exhaustive hardware-specific audio modification tailored specifically for the Redmi K20 Pro and Xiaomi Mi 9T Pro (code-named raphael / raphaelin).

While the Redmi K20 Pro was acclaimed for its flagship Snapdragon 855 processor and pop-up selfie camera, one of its primary cost-cutting compromises was the inclusion of a single bottom-firing loudspeaker. This module bridges that hardware deficit by pairing the bottom loudspeaker with the top earpiece receiver, creating a rich stereo soundfield.

Furthermore, it integrates Xiaomi’s proprietary Harman Kardon acoustic tuning library and upgrades the stock sound control application (MiSound.apk) to provide spatial audio controls under MIUI and Xiaomi HyperOS.

Technical Architecture & How It Works

The module delivers targeted hardware enhancements through three coordinated vectors:

1. Qualcomm Tavil Codec Pathing

The Snapdragon 855 incorporates Qualcomm’s premium WCD9340/WCD9341 “Tavil” audio codec. The module replaces:

• /system/vendor/etc/mixer_paths_tavil.xml
• /system/vendor/etc/mixer_paths_overlay_static.xml

It routes media channels to SLIM RX0 and SLIM RX1, simultaneously activating the earpiece power amplifier (EAR PA) and bottom speaker smart amplifier (SPK PA), calibrating impedance to prevent clipping at high output levels.

2. Framework Property Injection

Injected via system.prop:

# Expand volume steps from 15 to 25 for fine-grained acoustic control
ro.config.media_vol_steps=25

# Unlock OEM Harman Kardon DSP equalization algorithms
ro.vendor.audio.sfx.harmankardon=1
ro.vendor.audio.sfx.scenario=true

# Enable Xiaomi 3D virtual spatial soundfield processing
ro.vendor.audio.feature.spatial=7

# Disable aggressive hearing-protection attenuation
ro.vendor.audio.sfx.earadj=false

3. Integrated MiSound.apk

The package bundles an updated system/app/MiSound.apk compatible with HyperOS, providing access to the equalizer, scenario sound effects (Music, Video, Voice), and Harman Kardon toggles directly within Settings > Sound & Vibration.

Installation & Verification

1. Verify that your device codename is raphael or raphaelin.
2. Flash the module in Magisk, KernelSU, or APatch.
3. Reboot the device.
4. Verify by pressing the volume rocker: the volume slider should smoothly increment across 25 steps.
5. Navigate to Settings > Sound & Vibration > Sound Effects to configure the Harman Kardon profile.