Audio Mastering FAQ

What is the difference between mixing and mastering?

Mixing is the process of balancing and processing individual tracks within a recording session — adjusting levels, panning, EQ, compression, and effects for each instrument or vocal separately. Mastering is the final stage of audio production, applied to the finished stereo mix as a single file.

A mastering engineer optimises the overall loudness, tonal balance, and dynamic range of the mix, ensures consistency across a full album or EP, and prepares the audio for distribution across streaming platforms, CD, and vinyl.

Important: Mastering does not allow for changes to individual instruments or vocals. Those changes must be made during the mixing stage and the file re-exported before mastering begins.

What file formats do you accept for mastering?

We accept WAV and AIFF files only. These are lossless formats that preserve the full dynamic range and frequency detail required for professional mastering tools to work accurately.

• Format: WAV or AIFF

• Sample rate: Minimum 44.1 kHz (48 kHz, 88.2 kHz, or 96 kHz also accepted)

• Bit depth: Minimum 24-bit

What about MP3s?

MP3s and other compressed formats remove audio data permanently and limit what we can achieve in mastering. We do not accept MP3s as a mastering source. The only exception is if an MP3 is the only version of the recording that exists - in that case, we will do our best with the material available.

How much headroom should my mix have for mastering?

A mastering-ready mix should have a peak level of approximately −6 dBFS, meaning the loudest point in the file should not exceed −6 dB. This headroom gives the mastering engineer the space needed to apply EQ, compression, and limiting without introducing distortion or clipping.

If your mix is already peaking at 0 dB, there is no headroom available, and meaningful improvements cannot be made. This situation is most often caused by a limiter or compressor left active on the master bus - which leads to the next question.

Should I remove the limiter and compressor from my master bus before sending?

Yes. Limiters and compressors must be removed from the master bus before exporting your mix for mastering. A heavily limited file has no dynamic headroom left, which prevents us from making meaningful improvements.

If you have already attempted to master the track yourself, that is fine - send your version as a reference file alongside a clean, unprocessed export. We will master from the clean version and use yours as a reference for loudness and tone.

Should I apply dithering before sending my mix?

No. Send your files without dithering applied. Dithering is applied by the mastering engineer at the final export stage, based on the intended delivery format and bit depth. Applying dithering before mastering can introduce noise artefacts that limit what we can achieve.

Can I send reference tracks?

Yes, and we encourage it. Reference tracks help the mastering engineer understand your target loudness, tonal balance, and overall sonic character. Submit high-quality files — MP3 at 320 kbps or better, or lossless — as the clearer the reference, the more accurately we can interpret your goals.

Why are mastering rates not listed on this site?

Mastering isn’t a commodity — it’s a collaboration. Our collective includes engineers with different strengths, styles, and specialisms. A quick conversation helps us:

• Understand your project

• Recommend the right engineer

• Confirm the exact deliverables

• Give you a precise quote

This approach ensures you get the best possible result, not just the fastest price.

Email us at contact@masteringalliance.com to receive a quote tailored to your project. Pricing varies based on the type of work, the deliverables you need, and the engineer assigned to your project.

Who takes payments for the work carried out?

Mastering Alliance™ is a marketing hub for its member engineers, not a business entity. Clients do not pay Mastering Alliance™; all payments are made directly to the engineers through their own independent studios. For more information visit the About page.

How should I prepare my mix before sending it for mastering?

The following checklist covers everything we need from you before mastering can begin. Addressing these points before submission avoids delays and ensures the best possible result.

1. Clean Edits & Fades

Ensure your mix contains no clicks, pops, or unwanted noise at the start or end of the file. Fade-ins and fade-outs should be smooth and intentional. Mastering is not the correct stage to repair editing issues — attempting to fix them at the mastering stage risks affecting other parts of the mix.

2. Leave Extra Space at the Start & End

Include a little extra space before the music begins and after it ends. If the file cuts off abruptly at either end, the mastered result will sound chopped. Silence can always be trimmed later, but it cannot be added back.

3. Do Not Send Session Files

Send lossless stereo files (WAV or AIFF) only — not DAW session files such as Logic projects, Pro Tools sessions, or Ableton sets. Mastering is applied to a finished stereo mix, not to individual tracks. If we identify a mix issue that will cause problems in mastering, we will advise you before proceeding.

Example: if the lead vocal becomes buried during the chorus, we cannot raise just the vocal in the master without affecting the overall stereo file. That adjustment needs to be made in the mix and the file re-exported.

***Essential release information to help you plan efficiently and prevent avoidable delays.***

What are ISRC codes and do I need them for mastering?

An ISRC code (International Standard Recording Code) is a 12-character alphanumeric identifier assigned to a specific audio recording. ISRCs are used by streaming platforms, radio broadcasters, and performing rights organizations to track streams, radio plays, and royalty payments.

ISRC codes are not the same as UPC/EAN codes. An ISRC identifies an individual recording; a UPC/EAN identifies a release (album, single, or EP) as a product.

Do I need ISRCs before mastering?

For most independent artists releasing on streaming platforms, no. Your digital distributor (DistroKid, TuneCore, CD Baby, and similar) will automatically generate ISRC codes when you set up your release. Mastering engineers do not need your ISRC codes upfront.

Exception: If you need MP3 files for radio promotion ahead of your official release date, provide your ISRC codes to your mastering engineer so the correct metadata can be embedded. This ensures your tracks are properly identified and you do not miss out on airtime royalties.

How do I get ISRC codes?

• Independent artists: Use your digital distributor (DistroKid, TuneCore, CD Baby). ISRCs are generated automatically.

• Record labels or large catalogues: Apply through your country's national ISRC agency for a Registrant Code.

• One-off codes: Use a specialist provider such as ISRC.com.

A full directory of national ISRC agencies is available at isrc.ifpi.org.

What are Apple Digital Masters and do I need them?

Apple Digital Masters (formerly Mastered for iTunes or MFiT) is Apple’s optional certification program for high-quality audio files distributed via Apple Music and iTunes. Tracks prepared to Apple’s specification are encoded using a high-quality AAC conversion process designed to preserve audio fidelity at lower bit rates.

Apple Digital Masters are not mandatory. Standard masters are accepted for distribution on Apple Music. If you want to release in this format, check first that your distributor supports Apple Digital Masters submissions before requesting it from your mastering engineer.

What is a UPC or EAN code?

A UPC (Universal Product Code) or EAN (European Article Number) is a unique barcode that identifies a music release as a distinct commercial product in retail and digital distribution systems. It allows stores, distributors, and streaming platforms to track sales, inventory, and reporting for your album, single, or EP.

Unlike an ISRC, which identifies an individual recording, a UPC/EAN identifies the release as a whole. Digital distributors typically assign a UPC/EAN automatically when you submit a release. Some will provide this free of charge; others may charge a small one-time fee.

What is a DDP file and do I need one?

A DDP (Disc Description Protocol) file is the industry-standard delivery format for CD manufacturing. It is a self-contained package that includes everything a pressing plant needs to produce a CD:

• The audio masters in the correct sequence

• CD-Text (artist name, album title, track titles)

• ISRC codes for each track

• UPC/EAN barcode data

If you plan to manufacture CDs, confirm with your pressing plant whether they accept DDP submissions or prefer individual WAV/AIFF files with a separate metadata sheet. Many modern CD manufacturers accept both. Either way, you will still need to provide CD-Text, ISRC codes, and a UPC/EAN before production can begin. Some will provide a barcode included in the service, others will make you pay a small fee.

Do I need ISRC codes for vinyl manufacturing?

Yes. ISRC codes are required for each individual track on a vinyl record. These codes are embedded in the vinyl’s metadata during the cutting and production process, allowing performing rights organisations and digital reporting systems to correctly track plays, broadcasts, and royalties.

Although vinyl is an analogue format, ISRCs are still required for proper rights management and commercial distribution. Have your ISRC codes ready before submitting your masters to the pressing plant.

What if I have more questions?

Your assigned mastering engineer is the best person to advise you on any questions specific to your project — including ISRC codes, DDP files, vinyl prep, and distribution requirements. Feel free to reach out to them directly, or contact us via the details below.

Below you will find answers to the most common questions we receive about the audio mastering process, file preparation, metadata, and music distribution. If you cannot find the answer you need, contact your assigned mastering engineer directly.