Every file starts at the same point
Print every part from the very beginning of the song, even if it does not enter until the second chorus. A backing vocal that starts at two minutes should be a file with two minutes of silence in front of it. The engineer can then drop every file into a session at zero and they line up without guessing.
Keep the sample rate and bit depth the same across the set, and ask the engineer what they prefer before you export. Send WAV files rather than MP3s. If the song has a tempo change or a free-time section, say so in your notes.
Leave the decisions they are paid to make
Turn off the limiter and any other processing on the master output before you print, because it squashes every part and cannot be undone. Leave enough headroom that nothing clips. If an effect is part of the sound you want, such as a particular delay throw, ask whether the engineer wants it printed, and send a dry version beside it.
Send separate parts rather than one combined music file wherever you have them, and finish your own choices first: pick the final takes, remove what you are not using and finish tuning and editing. An engineer can do that work too, but it is a different job from mixing.
Name it, explain it, add a rough mix
Names should explain a file without anyone opening it: 01_Kick, 02_Snare, 08_Bass, 14_Lead_Vocal, 15_Lead_Vocal_Double. Put the song title and tempo on the folder. Include a rough mix of the song as you want it to feel, a reference track and a short note on what matters most. “The vocal should feel close and the chorus should lift” helps more than a list of plugins.
Dhun keeps your uploads, separated stems and exports in the project. To print a part, ask the producer to solo that track and render it. Renders start at the beginning of the timeline, so the parts stay lined up. Repeat for each part, then download the files. Tell the engineer which files came from separation, because they will treat those differently from clean multitracks.
Common questions
What is the difference between stems and multitracks?
Multitracks are every individual recording. Stems are groups of those tracks mixed down, such as all the drums or all the backing vocals. Ask which your engineer wants, because many prefer individual tracks for finer control.
Can I send stems separated from a finished song?
Yes, but say so. Separated stems can carry traces of other instruments, so they are not the same as original tracks. An engineer can still work with them if they know what they have.
Does each render use my allowance?
On the free plan each render uses one audio processing run. Producer and Studio plans include unlimited rendering.