The five rules

1. Bounce all stems from the same start point

The single most important rule. Every stem starts at the project's bar 1 / beat 1, NOT from the first note of each stem.

If your drums come in at bar 4 and your vocals come in at bar 16, both stems still start at bar 1 in the bounce — they just have silence at the beginning until their respective parts start. This guarantees the stems align when they're loaded into mastering's session.

The wrong way: bouncing each stem from its first note. The drums stem starts at second 6.3 (where the drums enter), the vocals stem starts at second 24.1 (where the vocals enter), and now mastering has to manually align them.

2. Same sample rate and bit depth as the project

If you mixed at 48 kHz / 24-bit, bounce stems at 48 kHz / 24-bit. Don't sample-rate-convert during the bounce. Don't downsample to 44.1 for delivery.

The reason: the stereo mix you also bounce as a reference should match the stems exactly. If the stems are 48/24 and the reference mix is 44.1/24, mastering has to reconcile the sample-rate gap before doing anything else.

If your distributor needs a 44.1 kHz delivery, mastering handles the final SRC at the end of its chain.

3. Stems should sum back to your stereo mix at unity

The sum-check test. Load all the stems into a fresh DAW project at unity gain, route them all to a single stereo bus, and play. The result should be identical (or extremely close) to your stereo mix reference.

If the sum doesn't match — too quiet, too loud, missing elements, EQ-shaped differently — something went wrong in the stem export. Fix it before sending.

This catches the most common stem-prep errors: forgetting to include a return bus (the reverb stem might be missing), applying mix-bus processing to individual stems (the drums got the bus comp applied), or accidentally including the master bus limiter in the stem bounce (the stems are pre-limited).

4. Group sensibly — fewer stems are usually better

8 stems is more flexible than 4, but the flexibility usually isn't worth the complexity. For most R&B / pop / hip-hop / indie productions, this grouping works:

• Drums — all drum elements (kick, snare, hats, percussion, drum bus FX)
• Bass — bass guitar / synth bass / 808 / sub
• Vocals — lead vocal + backing vocals (lead and BVs can split into separate stems if you want independent control, but most songs don't need that)
• Instruments — guitars, keys, pads, leads (everything that's not drums, bass, or vocals)
• FX — reverb returns, delay returns, atmospheric elements

5 stems covers most needs. 4 stems is fine if the FX live inside the instrument stem. Going above 6-8 stems starts creating complexity that mastering can't fully benefit from.

If your song has unusual production demands (e.g., a very prominent string section that needs its own treatment), one extra dedicated stem for that element is fine. Don't go overboard.

5. Bypass mix-bus processing on individual stems

This is where most stem-prep goes wrong. The mix-bus glue compression, bus EQ, bus saturation, and stereo widening should be OFF the individual stems but applied to the STEREO REFERENCE MIX that you bounce alongside the stems.

The reasoning: mastering will apply its own mix-bus equivalent processing on the SUM of the stems (which is the same thing your mix bus was doing). If the bus processing is baked into individual stems, it gets applied twice — once on the stems and once at the sum — which over-processes the master.

The check: load your stems into a fresh project, sum them at unity, and the sum should be identical to your stereo reference mix INCLUDING all mix-bus processing. The bus processing is in the sum, not the individual stems.

(Some engineers explicitly include the mix-bus processing on stems and label them as "post-mix-bus stems." That's a valid workflow but communicate it clearly to mastering. By default, stems are "pre-mix-bus.")

The full delivery package

When you send stems for mastering, the package should include:

• All stem WAVs (4-8 files, named consistently — 01-drums.wav 02-bass.wav etc.)
• The stereo reference mix (your final mix bounce — the target the summed stems should match)
• Any alternate mix versions (instrumental, TV mix, a cappella) if applicable
• The session BPM and key (useful metadata for the mastering engineer's notes)
• The intended LUFS / loudness target if you have one in mind
• Any specific notes about the song (e.g., "the chorus should feel bigger than the verse," "the vocal should sit right at the top of the mix")

A clean handoff saves a round of clarifying questions and tightens the turnaround.

Naming convention

A consistent naming convention helps mastering load the session faster and prevents stem mix-ups. The simple shape:

<song-title>/
├── 01-drums.wav
├── 02-bass.wav
├── 03-vocals.wav
├── 04-instruments.wav
├── 05-fx.wav
└── 00-reference-stereo-mix.wav

Numbered prefix forces consistent ordering. Lowercase, hyphen-separated names avoid OS-level case issues. Reference mix gets 00- to sort first.

The 60-second pre-send check

Before you send the stems:

1. Load all stems into a fresh DAW project, route to a single bus, play at unity
2. Confirm the sum sounds identical to your stereo reference mix
3. Drop the stereo reference mix into the free Mix Readiness Checklist and run the 11 automatic checks (file format, sample rate, bit depth, peak / TP / clipping, DC offset, head/tail silence, channels, balance, bus-limiter signature)
4. Spot-check 1-2 of the individual stems through the same tool
5. Send

That 60-second routine catches almost every stem-prep mistake before it makes it to mastering.

Common stem-prep mistakes (and the fix)

Stems don't sum back to the stereo mix. Usually a missing return bus or bypass-mismatch on bus processing. Re-bounce with the missing element included.

Stems are loaded but the timing's off. You bounced from the first note of each stem instead of bar 1. Re-bounce from project bar 1.

One stem is much louder than the rest. Usually an accidentally-soloed track or an unbypassed solo button during the bounce. Re-bounce.

Mastering reports that the master bus limiter was on during the stem bounce. The stems are pre-limited and mastering can't unwind that. Re-bounce with the limiter bypassed.

Stems are at different sample rates. Some DAWs let you bounce stems at different rates if the project has mixed-rate elements. Standardize on the project's primary sample rate.

The bottom line

Stem mastering is a powerful tool when it's prepped correctly. The prep takes maybe 20 extra minutes vs a stereo bounce. The 60-second sum-check is the single most important step — it catches almost every stem-export error before mastering ever opens the files.

If you're booking stem mastering for the first time, the free Mix Readiness Checklist on your stereo reference mix is the easiest sanity check. And the stem mastering page has the full pricing and turnaround.