Stems vs. Multitracks?

[ar surround]

From time to time I read about multi-channel mixes created from stems. I googled 'stems vs. multitracks' and found some rather technical explanations...more along the line of making stems so as to create alternate stereo mixes. But I am curious as to how people use stems to create multi-channel mixes.

My layman's mind says that if one has a stereo stem with all the guitars, one might be able to route the left front guitars of this stereo stem to the left rear channel and keep the right front guitars in the right front channel. Also, while the optimum method is to sift through 32 tracks of multis, it seems that it might be possible to create a rather convincing 5.1 mix from stems. It also seems more likely that the 5.1 mixed from stems will sound closer to the original stereo recording than one created from scratch using the 32 track multis.

Am I off base here?

 

[jimfisheye]

The definition of "stems" is just a little ambiguous.

Originally is was meant to mean a recording of the final mix group buses off the mixing board. Which would vary mix to mix but follow a pattern. You might have final stereo or surround group channels for drums, bass, vocals, instruments, for example. There might be 5 vocal tracks routed to that vocal bus. That kind of thing.

So the final group buses would be recorded to another multitrack tape. This gave you the opportunity to make coarse mix alterations like "turn all the vocals up a little". This was a big deal back in the analog days where it was kind of impossible to re-dial up a mix exactly the same as what you had (for today's starting point) to then make an alteration. All those analog knobs... All the little differences add up. "It sounds different... Damnit!" These "stems" were a safety net. Putting the stems up all at unity gain equals the mix. The ability to recall the mix session exactly on a computer is more of a big deal in this work than many people might realize!

Now we record on computers. This opened the door to a new scenario: A track element starting half way into the song. You can plunk down the "recording head" cursor and start anywhere you like now.

"Stems" is used now more to refer to all tracks starting at the same zero point. If you recorded something punching into the middle, kindly pad the beginning of that track with silence to make the start point of all the tracks line up, please and thank you.

So now "stems" could very well mean the whole multitrack with every raw isolated track.
"Stems" could still mean the stereo or surround group buses that equal the mix at unity gain.
We often say "raw stems" vs "mix stems" now. Well, sometimes... Often we just still say "stems" because why not have a long conversation about "what I really meant was..."

 

[par4ken]

There is a quad mix of The Beatles, "Abbey Road" circulating out there that was created from stems, ant it sounds quite good.

 

[fthesoundguy]

There's a local band here that put out their "stems" for the latest EP. I got excited because I was hoping I was getting the raw multitracks and was going to mess around and try and create a 5.1 from those. When I imported them, they ended up being stereo groups that are fully mixed, but isolated. I'm guessing it was more for the electronic remix community than an actual audio engineer.

So I got Drum, Bass, Guitar, Keys and Vocal mix groups. They all have their levels, processing, reverb and effects baked in so if I put them at unity, I would get the original stereo mix. The lead and backing vocals are together, stuff like that. It's going to end up more like an upmix than a fully discrete multichannel mix. Drums, bass up front and i'll try and cut up the guitars, keys and vocals so I can get some separation. I'll probably try to copy tracks and filter some other things to try and stretch the sound field to be as surround sound as I can get.

So in layman's terms you are correct. It's going to take a lot more effort to create a convincing 5.1 mix than if I got the raw multitracks. In my case, I hope the guitars are 100% panned so they are not "crosstalking" with each other and just sounding cluttered. I can't just make a drum kit sound big by putting the cymbal tracks in the surrounds because its just a stereo blend of the whole kit.