Audio quality checklist before a gig.

Audio quality checklist before a gig

This is one checklist, designed to be completed in a single sitting and in the same order whenever you add tracks or prepare for a gig. It brings together material currently spread across three guides: format and spectrogram auditing, loudness and peak measurement, and device preparation. It does not replace them; it invokes each exactly where more detail is useful. The goal is for failures to appear at home, with time to correct them, rather than in the booth.

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1. Format and container

Check that every file uses a format your equipment actually supports: WAV, AIFF, FLAC, and MP3 are the usual foundations, but details depend on the model. Before loading the library, compare your player or software’s format list with the Pioneer compatibility guide and the limits described in USB errors, files not loading, and unsupported formats.

Reject any DRM-protected file or unusual subscription-download container: these files will not play, and failure appears exactly when loading them. As for encoding mode, variable-bitrate MP3 (VBR) works well on modern equipment, but a coherent convention across the library avoids surprises when changing setups.

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2. Size versus bitrate: quick arithmetic

One check needs no tools: declared bitrate multiplied by duration and divided by eight gives expected file size. Thus, 128 kbps over 3600 seconds divided by 8 equals approximately 57.6 MB per hour, while 320 kbps is around 144 MB per hour.

A file labelled “320” whose size matches a 128 file of the same duration is an obvious indication it is not a genuine 320. With variable encoding, the calculation is approximate because the actual average bitrate varies: use it to estimate major discrepancies, not deliver a verdict. If the number does not fit, proceed to the next step before deciding anything.

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3. Spectrogram: a sample, not a dogma

A genuine 320 kbps CBR MP3 shows audio content up to around 20.5 kHz. A clear, hard cutoff well below that, for example around 16 kHz, indicates that the file came from a lower-bitrate or older source later saved as 320.

The word is indication, never proof: a spectrogram guides you, and you make the final decision. There is no need to inspect every track: a sample of those intended for critical moments usually suffices. The complete method, including typical bitrate cutoffs and their interpretation, is in the audio formats and spectrograms guide; auditing metadata and DC offset complements it in formats, bitrate, and DC offset.

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4. Loudness, peaks, and clipping

Use an analyser to measure every track’s integrated loudness (LUFS) and true peak. Look for exceptions: a track clearly louder or quieter than the rest disrupts the set’s flow even with the same channel level in the booth.

Two defects are caught in the same pass: clipping, meaning samples reaching 0 dBFS and flattening the signal, and direct-current offset, which consumes headroom without adding anything. dBFS, LUFS, and true peak are not explained here: they are in the meters and gain staging guide, and the loudness measurement references supporting this practice are EBU R 128 and the ITU recommendation on loudness and true-peak measurement. Here, only the result matters: separate anomalous tracks from the rest of the list.

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5. Collection consistency

The final file check concerns the collection, not individual tracks. Check that the library does not mix formats without reason, contains no unsupported containers, and maintains a consistent bitrate convention in sections played consecutively. Consistency does not improve quality by itself, but prevents neighbouring tracks from behaving differently on the same equipment.

If the previous pass separated any track because of loudness or clipping, now is the moment to note it and decide whether it enters the set unchanged, with manually corrected level, or stays out.

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6. Final USB routine (by reference)

Enough free space on the drive, a recently exported library, and a pre-load routine: this guide invents nothing here; it refers you onward. Connect the USB, check that it appears on the computer and player, load one track per format, and play five seconds; the full protocol and booth errors it covers are in USB errors, files not loading, and crashes. Including that routine in your performance checklist makes these few minutes a habit.

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7. What is unnecessary

• You do not need to inspect every track second by second: sampling and quick numbers cover the real risk.
• You do not need to become a mastering engineer: measuring, identifying exceptions, and deciding are enough.
• You do not need to rebuild spectrogram theory: the formats guide handles that, not this checklist.
• You do not need to repeat the USB loading routine: consult it rather than copy it.

The complete list fits into one sitting. If every track going onto the USB passes the six preceding sections, any failure reaching the booth will no longer come from the file.