Can some briefly explain sound stems? (1 Viewer)

[Dave F]

Whenever the topic of original audio tracks comes up, there are often references to the sound stems. Can someone either point me to a description of sound stems, or give a "sound stems for dummies" description?
Thanks,
Dave

 

[Chad R]

Certainly. Sound stems are the individual sound effects, dialogue and music tracks which are used prior to the film's final sound mix.

Basically, they used (now it's done on a computer) multi track tape machines to record sound for a scene.The tapes would have 12 or 18 seperate individual tracks for which to record sound. Track one would have the sound of a door recorded in time with the picture, track two would have the footsteps, etc.

Then at the final mix they play these tracks (sometimes 3 different machines with up to 24 or more tracks) back in time with the picture and mix them together to make the final sound mix.

Here is where they 'pan' the sounds on a stereo track left or right, front or back and so forth. Or for a mono movie just mix them toghether on one track. Unlike the original sound stems the sounds now exist together on the same track.

So when they say that they can only re-mix the sound to stereo if they have the original sound stems, this is the reason. After the final mix (on mono films) all the sounds are locked toghether and there's no easy way of seperating them now.

I hope that wasn't confusing.

 

[Dave F]

Thanks Chad! That was very clear.
-Dave

 

[Derek Miner]

I would add, however, that when most references to "stems" are made, they are talking about a set of three final elements.

All those individual sounds are mixed at a session that results in master stems. This set is often called a DME, short for Dialog/Music/Effects. In a mono movie, it's one track of all the dialog, one of all the music, and one of all the sound effects. When you get into Dolby films, a stem has more channels. In a full 5.1 mix, each stem is going to have 5.1 channels.