Why Mix Problems Survive Mastering (and How to Brief the Mixer)
Published · by Loopin
Mastering makes a mix louder and more even, and that includes its flaws. Use the master as a stress test, then send the mixer notes with a number and a timestamp.
Treat the master as a stress test
Run the mix through free online mastering and play the loudest chorus in the loudness-matched A/B. Anything that gets worse at matched volume is a mix issue. Previews and A/B are unlimited, so you can do this on every revision. Do it at the end of every session, not only when something feels wrong.
Listen for three faults: low end gets muddier, vocal gets harsher, chorus gets crunchy. If you hear one, do not re-master with a different feel; go back to the mix. Try it on your three most recent mixes; the same fault usually repeats, and that tells you where your mixing habit slips.
Know the faults that always survive
A buried vocal stays buried; a master cannot lift one voice out of a stereo file without moving everything. Clashing kick and 808 stay clashing, and a limiter makes the clash louder. Harsh sibilance, a vocal that is too dry or too wet, and a stereo image full of phase tricks also survive.
Small tonal tilts are the exception. A mix that is a little dark or a little bright often improves with a different feel, such as Warm, Crisp or Wide. Large balance faults do not. A thin low end is a half-exception: if the bass is simply quiet, a warmer feel can help, but a bass that is missing from the mix cannot be invented.
Give the mixer a number and a time
“Make it punchier” sends a mixer guessing. “Kick disappears behind the 808 at 0:42, try 2 dB less 808 around 50–60 Hz” is a fix they can do in two minutes. Always give a time, a level and a reference.
If you are not sure of the frequency, say what you hear: boomy, boxy, harsh, thin. Let them choose the move. Our muddy master post lists the usual suspects. Keep notes to three items per round. A mixer can act on three; ten notes become a new mix.
Copy this five-line brief
1. Reference: [track] — I like the [low end / vocal / width]. 2. Problem: [what] at [time]. 3. Mastered test: I ran it through a quick automatic master and it got [muddier / harsher / crunchier]. 4. Don’t change: [what is right]. 5. Deliver: stereo WAV, no limiter on the master bus, peaks around −3 to −6 dB.
Paste it into the email. It tells the mixer what the target is, what you already tested and what format to send back, so you get one revision, not four. Swap the brackets for real values before you send, and cut any line you cannot fill. Attach one short A/B clip, 15 seconds long, so the mixer hears the problem rather than reads it.
Re-test after each revision
When the new mix comes back, master the track free again and compare it to the last test at matched volume. If the fault is gone, you are done. If not, send another note with the same format.
Hand-offs matter. Automatic mastering takes no creative direction and cannot fix mix faults, so if a release is important, book a human engineer after the mix is approved. For the basics, see mixing vs mastering. If you are the mixer as well, do the same exercise: write the five lines to yourself before touching a fader.
Frequently asked questions
Can mastering fix a bad mix?
No. Mastering raises level and evens tone; it cannot rebalance a buried vocal or separate a kick from an 808. Fix big problems in the mix.
What problems can mastering fix?
Small overall tilts: a little dark, bright, narrow or quiet. Large balance faults between elements stay.
How do I give feedback to a mixer?
Give a time, a level and a reference: for example, kick lost behind the 808 at 0:42, try 2 dB less 808 around 50 to 60 Hz.
What should I send for mastering?
A stereo WAV with no limiter on the master bus and peaks around -3 to -6 dB. Loopin takes a stereo mixdown.
How do I test if my mix is ready for mastering?
Master a quick version and A/B it at matched volume. If the low end, vocal or chorus gets worse, revise the mix first.
How many revisions should I ask a mixer for?
Agree one or two rounds up front, with notes of three items or fewer each. Anything more is a new mix and is usually priced separately.