> ## Documentation Index
> Fetch the complete documentation index at: https://rockboxzig.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Equalizer

> 10-band parametric EQ — independent gain, frequency and Q per band.

Rockbox uses a **parametric** EQ rather than the more common graphic EQ.
Each band has independent control of gain, centre frequency and bandwidth
(Q), which buys you the same shaping power with fewer bands than a graphic
EQ would need.

<Tip>
  Using more bands than necessary wastes CPU and adds rounding noise. Disable
  or zero out bands you aren't using.
</Tip>

## Bands

| Band | Filter type    | Default centre / cutoff                     | Q recommendation                                  |
| ---- | -------------- | ------------------------------------------- | ------------------------------------------------- |
| 0    | Low-shelf      | 32 Hz                                       | 0.7 (higher Q adds an unwanted boost near cutoff) |
| 1–8  | Peaking (bell) | 64 / 125 / 250 / 500 / 1k / 2k / 4k / 8k Hz | Higher Q = narrower band                          |
| 9    | High-shelf     | 16 000 Hz                                   | 0.7                                               |

Per band:

* **Cutoff / centre frequency** — Hz
* **Gain** — dB; positive boosts, negative cuts
* **Q** — bandwidth (peak filters); 0.7 for shelves

## Top-level settings

| Setting   | Storage      | Type / range | Description                                                       |
| --------- | ------------ | ------------ | ----------------------------------------------------------------- |
| Enable EQ | `eq_enabled` | bool         | Master on/off                                                     |
| Precut    | `eq_precut`  | 0..24 dB     | Negative gain applied before EQ to prevent clipping when boosting |

Applied via `dsp_set_eq_precut()` and `dsp_set_eq_coefs()` in
`lib/rbcodec/dsp/eq.h`.

## TOML

```toml theme={"theme":{"light":"catppuccin-latte","dark":"min-dark"}}
eq_enabled = true
eq_precut  = 3      # 3 dB headroom before EQ

[[eq_band_settings]]   # band 0 (low shelf)
cutoff = 32
q      = 7         # Q × 10 — Rockbox stores fixed-point
gain   = 30        # dB × 10

[[eq_band_settings]]   # band 1
cutoff = 64
q      = 7
gain   = 0

# ... bands 2-9
```

<Note>
  `q` and `gain` are stored as fixed-point (×10) in `global_settings`. The
  GraphQL API accepts plain decimals — see
  [Settings TOML reference](/reference/settings-toml).
</Note>

## Configuring via the API

<CodeGroup>
  ```graphql GraphQL theme={"theme":{"light":"catppuccin-latte","dark":"min-dark"}}
  mutation EnableEqAndShapeBass {
    saveSettings(input: {
      eqEnabled: true
      eqPrecut: -3
      eqBandSettings: [
        { cutoff: 60,    q: 7, gain:  3 }
        { cutoff: 200,   q: 7, gain:  0 }
        { cutoff: 800,   q: 7, gain:  0 }
        { cutoff: 4000,  q: 7, gain: -2 }
        { cutoff: 12000, q: 7, gain:  1 }
      ]
    }) { eqEnabled }
  }
  ```

  ```ts TypeScript theme={"theme":{"light":"catppuccin-latte","dark":"min-dark"}}
  await client.settings.save({
    eqEnabled: true,
    eqPrecut: -3,
    eqBandSettings: [
      { cutoff: 60,    q: 7, gain:  3 },
      { cutoff: 200,   q: 7, gain:  0 },
      { cutoff: 800,   q: 7, gain:  0 },
      { cutoff: 4000,  q: 7, gain: -2 },
      { cutoff: 12000, q: 7, gain:  1 },
    ],
  });
  ```

  ```python Python theme={"theme":{"light":"catppuccin-latte","dark":"min-dark"}}
  await client.settings.save(
      eq_enabled=True,
      eq_precut=-3,
      eq_band_settings=[
          {"cutoff": 60,    "q": 7, "gain":  3},
          {"cutoff": 200,   "q": 7, "gain":  0},
          {"cutoff": 800,   "q": 7, "gain":  0},
          {"cutoff": 4000,  "q": 7, "gain": -2},
          {"cutoff": 12000, "q": 7, "gain":  1},
      ],
  )
  ```
</CodeGroup>