knowledge-base/KB/Linux/Desktop/Audio/EQ.md

---
creation date: 2022-01-08
tags: [note,audio,pipewire,pulse,pulseaudio,linux,archlinux]
---

* See [[KB/Linux/Desktop/Audio/pipewire.txt]] for packages
* See [[KB/Linux/Desktop/Audio/pulseaudio.txt]] for packages

This document outlines how to get a decent audio setup utilizing a headphone EQ called _dsp_. It's targeted for Linux machines, but use [EqualizerAPO](https://equalizerapo.com/) to similarly use headphones EQ presets.

See `HiFi 24bit and 192kHz Music Downloads are Very Silly Indeed` why not more than 44.1 kHz is needed. The following will not enforce 44.1kHz though.

## Why?
A target curve T has been tested and be found most comfortable listening to. Try to get each Headphones with EQ settings near that curve T. [EQ presets for a lot of headphones](https://www.reddit.com/r/oratory1990/wiki/index/list_of_presets).

## How-to for Linux

Baseline for this is the [following website](https://forum.level1techs.com/t/improving-linux-audio-updated/134511).

### With PipeWire

Use `PulseEffects` presets for EQ settings and _enable auto-start_ of PulseEffects.

There are some very convenient settings you probably want to set.

* Handle suspend
  * In `/etc/pipewire/media-session.d/media-session.{conf|confpause}` comment out `suspend-node` to enable suspending feature
  * In `/etc/pipewire/media-session.d/alsa-monitor.conf` set a timeout so that your DAC/output device is able to always receive a signal if you like.

    ```shell
    node.pause-on-idle      = false
    session.suspend-timeout-seconds = 0 # or any number as seconds
    ```

* If you like, set a default _sample rate_ in `/etc/pipewire/pipewire.conf`, e.g. for 44.1kHz

    ```shell
    default.clock.rate        = 44100
    ```

* Use `systemctl --user restart pipewire-media-session.service pipewire.service pipewire-pulse.service` to restart PipeWire

### With PulseAudio

* Allow direct communication to device for PulseAudio. Edit ALSA configuration `/etc/asound.conf`.

    ```shell
    # Use PulseAudio plugin hw
    pcm.!default {
        type plug
        slave.pcm hw
    }
    ```

* (**OPTIONAL, DO IF YOU WANT A REMAPPED VERSION OF MAIN AUDIO DEVICE IN sink_name=**) Add some _default_ sink names (remap them) in PulseAudio `/etc/pulse/default.pa`. Use `pacmd list-sinks` and `pacmd list-sources` to list your devices and insert as _master_ below. Any user could use `sink_main` and `src_microphone` instead of the specific device as `sink_name=`. This is **OPTIONAL** if you use direct sink name in any user specific file later instead of "sink_main" and "src_microphone"

    ```shell
    # create remapped sink/sources with proper names and description
    # pacmd list-sinks
    load-module module-remap-sink     sink_name="sink_main"      master="alsa_output.pci-0000_31_00.4.iec958-stereo"              sink_properties=device.description="Toslink"    remix=no
    # pacmd list-sources
    load-module module-remap-source source_name="src_microphone" master="alsa_input.usb-Samson_Technologies_Samson_Meteor_Mic-00.analog-stereo" source_properties=device.description="Microphone" remix=no
    ```

* Adapt `.config/pulse/daemon.conf`

```shell
flat-volumes = no

default-sample-channels = 2
default-channel-map = front-left,front-right
default-sample-format = s32ne
;default-sample-rate = 44100
;alternate-sample-rate = 44100
;resample-method = speex-float-10

enable-lfe-remixing = no

high-priority = yes
nice-level = -11
realtime-scheduling = yes
realtime-priority = 9
rlimit-rtprio = 9
```

#### EQ

Install [dsp](https://github.com/bmc0/dsp).

Create and adapt configuration for dsp. See example below. Use EQ presets for your headphones.

* Basic file structure

    ```shell
    .config/ladspa_dsp
    ├── config_beyerdynamic_dt1990
    └── eq
        └── beyerdynamic_dt1990.conf
    ```

* The main configuration for an additional Pulse sink `.config/ladspa_dsp/config_beyerdynamic_dt1990`
    ```shell
    LC_NUMERIC=C
    effects_chain=@eq/beyerdynamic_dt1990.conf
    ```

* The EQ settings derived from the target curve found for your headphones, e.g. `.config/ladspa_dsp/eq/beyerdynamic_dt1990.conf`

    ```shell
    # Beyerdynamic DT 1990
    # preamp gain
    gain -4.0

    lowshelf    90      0.7q    +4.0
    eq          220     0.7q    -3.4
    ...
    ```

* Add a new sink _based on above remapped sink_main_ for the EQ present in `.config/pulse/default.pa` (also some other reasonable default settings)

    ```shell
    # load system defaults
    .include /etc/pulse/default.pa

    # unload the cork stuff
    .nofail
    unload-module module-role-cork
    .fail

    # unload the idle suspend stuff
    .nofail
    unload-module module-suspend-on-idle
    .fail

    # dsp EQ stuff for various headphones
    .ifexists module-ladspa-sink.so
    .nofail
    load-module module-ladspa-sink sink_name=dsp_beyerdynamic_dt1990            sink_master="<MAIN SINK NAME> OR <sink_main from OPTIONAL STEP>" plugin=ladspa_dsp label=ladspa_dsp:beyerdynamic_dt1990            sink_properties=device.description="Beyerdynamic\ DT\ 1990\ Pro"
    .fail
    .endif
    ```

* Restart PulseAudio, so that the new sink appears. In your settings, select the newly added DSP sink as default one. Maybe restart device.

#### Linux troubleshooting

* Something weird going on? Delete anything **except for configuration files** in `.config/pulse/`.
* Restarting when changing anything in PulseAudio configuration is highly recommended as some applications might not be able to handle restarting audio system.