Art-Central Audio Technical Standards V1.0

Document No.: AC-PDS-2026-001
Effective Date: April 2026
Scope: All audio recordings and masters intended for distribution via Art-Central

TL;DR

Format: 24-bit / 44.1 kHz (or higher) encapsulated in FLAC (lossless).
Dither: Dither must be applied when converting from 32-bit Float to 24-bit.
Integrated Loudness: $\le -14$ LUFS (Strictly enforced; preserve micro-dynamics).
True Peak: $\le -1.0$ dBTP (Reserved headroom for lossy encoding and physical cutting).
Low-Frequency Phase: High correlation required below 100 Hz. Forced mono-summing in post is strictly prohibited; phase conflicts must be resolved at the source to prevent vinyl skipping and mono-summing energy collapse.
Zero Artifacts: All edit points must use Cross-fades; digital clicks are unacceptable.
Stems: Provide grouped stems (Drums, Bass, Inst, Vocal).
Dry Tracks: Effect-free (dry) versions of vocals and key instruments must be archived.

I. Loudness & Levels

This section outlines standardized quantitative metrics to ensure consistent perceived loudness across distribution platforms. These standards maintain signal integrity across various hardware terminals and streaming codecs while preventing reconstruction distortion.

1. Integrated Loudness Control

Integrated Loudness (LUFS-I) represents the average perceived volume of a work from start to finish. It is the primary metric for cross-platform compatibility.

The recommended target is -14 LUFS ( $\pm 0.5$ LU).
The absolute ceiling is -14 LUFS. If a track is too loud, streaming normalization algorithms will force the volume down, often resulting in a loss of “punch” and sonic density.
Art-Central advocates for natural micro-dynamics. The use of brickwall limiters to achieve a “sausage” waveform is strictly discouraged. Prioritize fine-tuned automation over heavy compression ratios to balance loudness.

2. True Peak & Headroom

To prevent physical anomalies during Digital-to-Analog conversion or secondary encoding, peak levels must be strictly managed.

True Peak must be kept within -1.0 dBTP.
Traditional sample peak meters cannot detect “inter-sample peaks” created during analog reconstruction. A -1.0 dBTP threshold provides the necessary redundancy for Sample Rate Conversion (SRC).
For lossy formats (Ogg Vorbis, AAC, MP3), reconstruction algorithms often cause peak levels to rise slightly. Sufficient headroom prevents the metallic distortion caused by clipping.

3. Dynamic Range Audit

Dynamic range is not just a technical spec; it is a fundamental element of musical expression.

Professional loudness monitoring tools (e.g., Youlean Loudness Meter, MAAT DR Meter, or iZotope Insight) should be used on the master bus.
Except for specific genres (e.g., certain industrial noise or high-compression EDM), an average Dynamic Range (DR) score of 8 or higher is recommended.
Ensure that drum punch and vocal attacks remain distinct to avoid listener fatigue.

4. Short-term Loudness & Range

To ensure a balanced listening experience, monitor the following auxiliary indicators:

Short-term loudness should not exceed -10 LUFS during the most intense sections of the track.
Loudness Range (LRA) should ideally stay between 4 LU and 9 LU. An LRA that is too low indicates a lack of musical movement, while an excessively high LRA risks losing low-level details in noisy environments.

II. Format & Archiving

As core digital assets, master files must meet high-fidelity archiving requirements to ensure long-term reusability across future distribution media and licensing scenarios.

1. Delivery Format & Quantization

To balance storage efficiency with lossless quality, delivery files must adhere to strict standards.

FLAC (Free Lossless Audio Codec) is the required format for final delivery. FLAC provides bit-perfect reconstruction of original data with superior storage efficiency and metadata support compared to WAV.
Quantization depth is standardized at 24-bit. If the original mix session is 32-bit Float, Dither must be applied when exporting to 24-bit to eliminate non-linear distortion from quantization noise.
The sample rate must be at least 44.1 kHz. We recommend maintaining the native sample rate of the recording/mix session (e.g., 48 kHz, 88.2 kHz, or 96 kHz). Unnecessary resampling before delivery is prohibited to avoid interpolation inaccuracies.

2. Naming Convention

Standardized naming ensures that digital assets remain searchable and traceable over time.

Recommended format: [ISRC/Serial]_[Artist]_[Title]_[Version]_[Date].flac
Avoid special characters or spaces. Use underscores for field separation to ensure compatibility across Linux, Windows, and macOS.

3. Stems & Dry Tracks

To prepare for future Atmos adaptation, remixes, or sync licensing, assets with independent editing capabilities must be preserved.

Preserve grouped stems that have passed through the bus processing (e.g., Drums, Bass, Instruments, Vocals). When phase-aligned and played simultaneously, the sum of these stems must be identical to the Full Mix.
Archiving dry tracks for lead vocals and key solo instruments is mandatory. These must be free of spatial effects (Reverb, Delay) to allow maximum flexibility for future reconstructions.

4. Session Persistence

Audio processing relies on specific DAW and plugin versions. To mitigate the risk of software obsolescence, sessions must be “hardened.”

Artists should “Freeze,” “Commit,” or “Bounce in Place” all processed tracks.
Include a README file containing the BPM, key signature, and a list of core hardware or unique plugins used.
Ensure that the original sonic character can be reconstructed via audio snapshots even if plugins become unauthorized or incompatible with future OS updates.

III. Translation, Imaging & Frequency Response

Works must demonstrate robustness across different monitoring systems, ensuring the aesthetic intent translates from the studio to consumer mobile devices.

1. Frequency Balance

The overall frequency response should be smooth and proportional, avoiding energy buildup that causes listener fatigue.

Final monitoring should be conducted in high-resolution reference environments (e.g., beyerdynamic DT 880 Pro).
Pay close attention to non-artistic harshness/resonances in the 6 kHz - 10 kHz range.

2. Cross-Platform Translation

A great master must survive non-ideal listening environments, particularly mobile devices.

Check the mix via smartphone speakers. Ensure the mid-high frequencies maintain clarity without generating significant Intermodulation Distortion (IMD).
Core musical information should be focused in the midrange frequencies that small drivers can effectively reproduce.

3. Phase & Low-End Integrity

Phase consistency determines the “weight” of the sound and its mono compatibility, especially in the low end.

Rigidly check phase correlation below 100 Hz.
Low frequencies should remain centered (Mono-compatible) to ensure impact on large PA systems.
Direct “forced mono-summing” to hide phase cancellation in the original tracks is strictly prohibited. Phase conflicts must be resolved early in the processing flow to prevent irreversible energy collapse or comb filtering when switching between stereo and mono.

Notes on Low-End Phase:

Vinyl Cutting: In vinyl mastering, the stereo difference (Side channel) is created by the vertical movement of the lathe. If the low end has severe phase cancellation (out-of-phase), the needle will vibrate vertically with such intensity that it creates shallow or irregular grooves, causing the record to skip during playback.
Mono Systems: Many mobile speakers, mall background systems, and club PAs are mono. If low-end phase is inconsistent, summing to mono will cause the kick and bass to vanish completely. Addressing this early guarantees the “punch” remains intact.
Lossy Encoding: Algorithms like Joint Stereo (used in MP3/AAC) compress data based on channel correlation. Severe low-end phase conflicts can confuse the encoder, resulting in a smeared spatial image or a “squeezed” low-end feel.

4. Spatial Imaging

The width and depth of the soundstage must serve the musical intent and remain physically stable.

The Phase Correlation Meter should consistently hover between 0 and +1. Frequent dips into the negative region indicate a high risk of mono-summing issues.
The “center of gravity” (e.g., the low-end foundation and lead melody) must remain stable. Avoid unintended wandering caused by over-processing with stereo wideners.

IV. Signal Integrity & Digital Audit

Signal purity is the baseline for professional work. Rigorous digital auditing eliminates artifacts and editing flaws, enhancing transparency.

1. Aliasing & Oversampling

When using non-linear processing, be wary of high-frequency harmonics bouncing off the Nyquist frequency and creating aliasing noise.

When using saturators, distortion, or heavy limiters/clippers, it is strongly recommended to enable Oversampling.
By increasing the internal processing rate, extra harmonics are mapped to a higher frequency space and filtered out, ensuring high-end clarity and reducing “digital grit.”

2. Edits & Zero-Crossing Audit

Fine editing is essential for continuity. Any digital discontinuity will distract the listener.

Check all clip boundaries; digital clicks or pops at edit points are unacceptable.
Utilize micro Cross-fades at all junction points or punch-ins to ensure seamless transitions.

3. Masking & Clarity

Overlapping frequencies in multi-instrument mixes can lead to energy cancellation and reduced clarity.

Resolve conflicts in the low-end core (Kick and Bass). Use sidechain compression or dynamic EQ to ensure the kick’s transient and the bass’s sustained energy do not mask each other.
Perform spectral checks on midrange instrument groups to identify and prune unnecessary frequency overlaps.

4. Fades & Tails

The ending of a work defines its professional polish.

The conclusion of a track must feature a natural decay. Ensure that reverb tails or delays fade out completely into digital zero.
Hard cuts while a tail is still audible are prohibited. Audit the end of the track using high-gain monitoring to ensure no sudden digital “drop-offs” occur due to automation stopping prematurely. Art-Central Audio Technical Standards V1.0.md 11 KB