Corrective EQ

User Manual

Version 0.9.6

1. Overview

Corrective EQ is a final correction stage for imported frequency-response curves. It can be used for headphone correction, room correction, or other target-curve workflows where you already have a correction file and want the application to render it into the audio path.

This manual is written for the current desktop standalone Corrective EQ product first, then calls out the small ARIA ONE-specific differences where they matter.

The core Corrective EQ processing is the same in both contexts. The main practical differences are:

  • Standalone Corrective EQ opens directly to the dedicated Corrective EQ workspace.
  • Standalone Corrective EQ is enabled by default because it is the main processor in the product.
  • ARIA ONE embeds Corrective EQ inside the larger advanced workspace and may also refer to the same module as PostDSPEQ or Post-DSP EQ in presets, tooltips, and internal status text.
  • ARIA ONE Simple View can label the page HEADPHONE EQ, while the page itself uses CORRECTIVE EQ. Both names refer to the same correction page in the current build.

At a high level, Corrective EQ works like this:

  1. Import a correction file.
  2. Confirm that the correction curve appears in the preview.
  3. Choose how the curve is rendered: FIR or SOS.
  4. Adjust phase, size, rate, or spacing options as needed.
  5. Use GAIN and MIX to set output level and correction amount.
  6. Save a Corrective EQ preset if you want to recall the imported correction later.

Corrective EQ does not take a hearing test and does not replace the hearing-profile system. Hearing profiles belong to the Hearing EQ / Hearing Correction workflow. Corrective EQ is for imported correction curves.

2. Accessing Corrective EQ

Standalone Corrective EQ

In the standalone desktop Corrective EQ product, Corrective EQ is the main workspace. Open the application and you are already working directly with the dedicated correction processor.

Corrective EQ inside ARIA ONE

In ARIA ONE desktop advanced view:

  • Use the Corrective EQ navigation card to open the Corrective EQ workspace.
  • Use the card's power toggle to enable or disable Corrective EQ DSP.
  • The navigation card may show the short label POST EQ in compact areas.

In ARIA ONE Simple View:

  • Open the Sound page for Corrective EQ / Headphone EQ.
  • Use the available Simple View controls for enable state, MIX, GAIN, import, clear, and curve preview.

Naming inside ARIA ONE

ARIA ONE currently uses several names for the same module depending on context:

Name Where It Appears
Corrective EQ Main product name and advanced workspace title
POST EQ Compact navigation label
PostDSPEQ Preset category, import dialogs, and some internal status messages
Post-DSP EQ Home/status text and technical descriptions
Headphone EQ Some Simple View navigation labels

These names refer to the same imported-correction stage.

3. Signal Chain Placement

Standalone Corrective EQ

In the standalone product, Corrective EQ is the processor you are using. The imported correction is applied as the product's main correction stage before output.

Corrective EQ inside ARIA ONE

Inside ARIA ONE, Corrective EQ is a final post-DSP correction stage for imported frequency-response curves. It runs after the main sound-shaping modules and before output metering.

Use Corrective EQ when you want to apply an external correction or target curve after the rest of the ARIA ONE sound state has been created.

Corrective EQ is separate from:

  • Hearing EQ / Hearing Correction - hearing-test-based personalization
  • FullScale - the hearing test used to create hearing profiles
  • Crossfeed - headphone imaging and stereo blend processing
  • Limiter - dynamics, safety, and loudness processing

4. Workspace Layout

The Corrective EQ workspace is organized around file import, correction rendering, output blend, and visual confirmation.

Header and power

The top of the panel identifies the module as CORRECTIVE EQ.

The ENABLED control turns the correction stage on or off.

  • On - the loaded correction is active.
  • Off - Corrective EQ is bypassed.

If no correction curve is loaded, enabling the processor does not add a correction curve by itself.

Correction state

The CORRECTION STATE area reports the loaded correction and processing status.

Common status text includes:

  • No correction curve loaded
  • Correction curve
  • IR status
  • Preparing
  • Ready

Ready means the correction has been loaded and the rendered processing data is available.

File controls

The file controls are:

  • IMPORT FILE
  • CLEAR

Use IMPORT FILE to select a correction file. Use CLEAR to remove the imported correction and return the correction stage to passthrough.

Filter controls

The filter controls determine how the imported curve is rendered:

  • FILTER TYPE
  • PHASE TYPE
  • FIR SIZE
  • SOS RATE
  • FILTER SPACING

Some controls are only relevant for one filter type. For example, PHASE TYPE and FIR SIZE apply to FIR rendering, while SOS RATE and FILTER SPACING apply to SOS rendering.

Output controls

The output controls are:

  • GAIN
  • MIX

GAIN trims the Corrective EQ output level after correction.

MIX blends between the uncorrected signal and the corrected signal.

Correction curve preview

The CORRECTION CURVE PREVIEW graph shows the loaded correction curve. If no file is loaded, the graph prompts you to import a CSV response or EQ file before previewing the curve.

The embedded graph area can also show target and filter views where available.

5. Importing Correction Files

Supported file types

The file picker accepts correction files using these extensions:

  • .csv
  • .txt
  • .eq
  • .apo

The extension alone does not guarantee that the file can be loaded. The file content must match one of the supported correction formats below.

CSV frequency response

CSV files should contain frequency and dB values.

Supported row formats:

frequency_hz,magnitude_db
frequency_hz,left_db,right_db

Examples:

20,-1.5
100,-2.0
1000,0.0
10000,1.2

or stereo correction:

20,-1.5,-1.2
100,-2.0,-2.1
1000,0.0,0.0
10000,1.2,1.0

Notes:

  • Frequency values must be greater than 0 Hz.
  • The current parser accepts correction points up to 24000 Hz.
  • CSV validation requires at least two valid frequency/dB points.
  • CSV files can contain header rows.
  • Duplicate frequencies are replaced by the later valid row.
  • If the curve does not cover the full 20 Hz to 20 kHz range, endpoint values are extended.
  • CSV files with more than 65,536 valid points are rejected.

AutoEQ / Equalizer APO parametric text

Corrective EQ can load supported AutoEQ / Equalizer APO parametric text exports.

The expected format is the common Equalizer APO style:

Preamp: -6.0 dB
Filter 1: ON PK Fc 105 Hz Gain -2.4 dB Q 0.70
Filter 2: ON LS Fc 120 Hz Gain 1.5 dB Q 0.70
Filter 3: ON HS Fc 8000 Hz Gain -1.0 dB Q 0.70

The current parser uses Preamp: when present and renders supported Filter lines into a correction curve.

Supported filter families include:

  • PK / PEQ
  • LS / low shelf variants
  • HS / high shelf variants

Disabled filters are ignored.

Equalizer APO GraphicEQ

Corrective EQ can also load GraphicEQ: lines.

Example:

GraphicEQ: 20 -1.5; 100 -2.0; 1000 0.0; 10000 1.2

Each pair is interpreted as frequency and gain in dB.

Text frequency/dB rows

For non-CSV text files, Corrective EQ also tries to read simple numeric frequency/dB rows if no supported AutoEQ or GraphicEQ: data is found.

This means a .txt, .eq, or .apo file may still load if it contains valid rows such as:

20 -1.5
100 -2.0
1000 0.0
10000 1.2

or:

20 -1.5 -1.2
100 -2.0 -2.1
1000 0.0 0.0
10000 1.2 1.0

Import feedback

After import, Corrective EQ reports whether the correction loaded successfully.

Possible import messages include:

  • Correction file imported successfully.
  • The selected correction file could not be found.
  • Please select a .csv, .txt, .eq, or .apo correction file.
  • No valid CSV correction points were found.
  • At least two valid frequency/dB points are required.
  • The correction file has too many points.
  • Could not load a correction curve from this file.

If a CSV file loads with warnings, the warning dialog can report skipped headers, ignored rows, duplicate frequencies, or range extension.

6. Control Reference

ENABLED

Turns Corrective EQ processing on or off.

In standalone Corrective EQ, this is on by default for a fresh state.

In ARIA ONE, Corrective EQ is optional and may be off until enabled from the navigation card or panel.

FILTER TYPE

Chooses the rendering topology for the imported correction curve.

  • FIR - renders the correction as FIR convolution.
  • SOS - renders the correction as cascaded SOS biquad processing.

Switching filter type can change latency, CPU use, and how closely the correction curve is matched.

PHASE TYPE

Chooses the FIR phase mode.

  • MP - minimum phase
  • LIN - linear phase

MP is the default FIR behavior. LIN preserves phase more directly but adds latency.

This control applies to FIR rendering.

FIR SIZE

Sets the FIR length used to render the imported correction curve.

Available values:

  • 4096
  • 8192
  • 16384
  • 32768
  • 65536

Larger FIR sizes can improve low-frequency resolution. They also increase latency and CPU cost.

This control applies to FIR rendering.

SOS RATE

Sets the SOS oversampling family used by SOS / IIR filter processing.

Available values:

  • OFF - no SOS oversampling
  • 176.4/192 kHz 4X OS - 4X oversampling family
  • 352/384 kHz 8X OS - 8X oversampling family

Higher SOS rates can improve IIR filter performance, especially in higher-frequency correction behavior. They also increase CPU cost.

This control applies to SOS rendering.

FILTER SPACING

Chooses the SOS band layout.

  • LIN - standard linear spacing
  • ADAPT - adaptive spacing

This control applies to SOS rendering.

GAIN

Trims the Corrective EQ output level after correction.

  • Range: -12.0 dB to +12.0 dB
  • Default: 0.0 dB

Use GAIN to restore level after a correction curve changes loudness, or to reduce level if the imported correction adds too much gain.

MIX

Blends between uncorrected and corrected signal.

  • Range: 0% to 100%
  • Default: 100%

At 0%, the correction is not heard. At 100%, the imported correction is fully applied.

IMPORT FILE

Opens the file picker for correction files.

The picker accepts .csv, .txt, .eq, and .apo files. The file must still contain supported correction data.

CLEAR

Removes the loaded correction curve and returns the correction stage to passthrough.

7. Filter Rendering Notes

FIR

FIR rendering is useful when you want the imported curve to be rendered as a convolution filter.

Use FIR when:

  • matching the correction curve closely is more important than lowest latency
  • you want access to MP / LIN phase behavior
  • you want control over FIR length with FIR SIZE

SOS

SOS rendering uses cascaded biquad / IIR filters.

Use SOS when:

  • you want lower-latency correction
  • CPU cost is a concern
  • the correction can be represented well by the supported filter rendering

SOS RATE selects the oversampling family for SOS processing:

  • OFF keeps SOS processing at the current session rate.
  • 176.4/192 kHz 4X OS uses the 4X oversampling family.
  • 352/384 kHz 8X OS uses the 8X oversampling family.

Higher oversampling families can improve IIR behavior, especially near the top of the audible range, at higher CPU cost.

Changing topology

When you change FILTER TYPE, PHASE TYPE, FIR SIZE, SOS RATE, or FILTER SPACING, Corrective EQ may need to prepare the correction again.

During this time, IR status can show Preparing. When preparation is complete, it changes to Ready.

8. Presets

Corrective EQ has its own preset category for the imported correction state.

In ARIA ONE, this category is labeled PostDSPEQ Preset.

A Corrective EQ / PostDSPEQ preset is intended to store the correction state separately from hearing-profile presets, limiter presets, and Crossfeed presets.

Use a Corrective EQ preset when you want to recall:

  • the imported correction curve
  • filter rendering choices
  • GAIN
  • MIX
  • enabled state

In ARIA ONE, a Meta preset can include the larger sound state along with Corrective EQ state. Use a dedicated Corrective EQ / PostDSPEQ preset when you only want to save or recall the correction stage.

9. Suggested Workflow

Quick Start

  1. Open Corrective EQ.
  2. Press IMPORT FILE.
  3. Select a supported correction file.
  4. Confirm that the correction curve appears in CORRECTION CURVE PREVIEW.
  5. Confirm that IR status reaches Ready.
  6. Start with FILTER TYPE set to FIR.
  7. Leave PHASE TYPE at MP unless you specifically need linear phase.
  8. Leave MIX at 100% for full correction, or lower it if you want a partial correction.
  9. Adjust GAIN if the correction changes output level.
  10. Save a Corrective EQ / PostDSPEQ preset if you want to recall the correction later.

Importing an AutoEQ file

  1. Download or export the AutoEQ / Equalizer APO file for your headphone model.
  2. Press IMPORT FILE.
  3. Select the parametric EQ text file.
  4. Confirm that the curve loads.
  5. Adjust GAIN if the file includes strong boosts or cuts.
  6. Save a preset if this will be a regular correction setup.

Importing a CSV response

  1. Prepare a file with frequency and dB columns.
  2. Use either mono rows (frequency_hz,magnitude_db) or stereo rows (frequency_hz,left_db,right_db).
  3. Press IMPORT FILE.
  4. Select the CSV file.
  5. Review any import warnings.
  6. Confirm that the correction curve preview matches the expected shape.

Troubleshooting

If the file does not load:

  • Confirm that the file uses .csv, .txt, .eq, or .apo.
  • Confirm that the file contains supported correction data, not only comments or unsupported filter types.
  • For CSV files, confirm that at least two valid frequency/dB points are present.
  • For AutoEQ / Equalizer APO files, confirm that filters are enabled with ON.
  • Check whether the file contains more than 65,536 valid CSV points.

If the curve loads but does not sound as expected:

  • Confirm that ENABLED is on.
  • Confirm that MIX is above 0%.
  • Check GAIN for large level changes.
  • Try switching between FIR and SOS.
  • If using FIR, try a different FIR SIZE.
  • If using SOS, try a different SOS RATE or FILTER SPACING.