About the mixes
You should be happy about the quality of your mixes before the mastering, and it’s not usually useful to try to figure out how mastering might affect the mix. A professional mastering engineer will take good care to not alter the mix balance too much. Remember, the purpose of the mix is to set the final sound of the track, and the mastering should only define it a little further along with fixing minor errors in the overall tone.
If you feel you didn’t get the mixes sounding like you wanted, it is possible to somewhat help it in the mastering. If you’re looking to get radical changes to the mix, please consult me well in advance.
The final mixdowns should be saved as a 24 bit or bigger WAV/AIFF files and the sample rate should be kept at the same rate the project was mixed at. Changing it at this point may affect the quality of the sound. I like to do sample rate conversion myself. It’s also nice to have the files at “stereo interleaved” format, both left and right channels included in the same file.
Please check that the files actually work before you send the to mastering!
Delivering the mixes as separate tracks – or “stems”?
Mostly I only work with full stereo mixdowns. I always take good care that the mix balance you carefully built doesn’t change in the mastering. In some cases, delivering the vocals separate from the rest of the mix might be a good idea, but only if you also deliver a final stereo mixdown as a reference. The so called “voc up/down” mix versions are also a fine, if you provide me the info on which track you personally prefer to use.
If you deliver stems to me, please check that the tracks sync properly from the beginning and that summing the tracks gives me the same exact mix balance you’ve been working on. If you feel like delivering more than 2-3 separate stems, I highly recommend taking a break from mixing the project. If you postpone the mixing decisions later, you will only eat from my focus in the mastering.
Practical tips for mixing
Processing the stereo mixdown while mixing is often more harmful than useful, unless you really know what you’re doing. Especially multiband compression, limiting or clipping the mix can make the mastering session very tricky. Traditional mixbuss compression is of course allowed if it’s done for the sound and not for the sake of pushing up the levels.
Don’t try to help the mastering engineer by processing the mix bigger, brighter or louder. Just concentrate on making the mix work well.
Adequate headroom improves the quality of your mixes and also makes my job easier. There are no rules, but a few dB’s of headroom from peaks to zero is always a good thing. If your mix is clipping at the output, don’t fix it by taking the master fader down – take the levels down at all faders.
It makes no sense in 24 bit (and larger) files to keep the peaks near zero. Even if most modern DAW’s do calculate internally in floating point, some plug-ins might act in unpredictable ways when levels approach the digital zero. Maintaining headroom in the project is a good way of working.