The Mixback

A very common technique in the old days was the Mixback. Basically, engineers would print whatever was going through the master bus (the stereo bus) to two open tracks on the 24-track master. Can you believe there was a time when 24-tracks was too many? Actually you can find track sheets from 8-track and 16-track recordings with lots of open tracks.

The mixback tracks were a running record of whatever was in the master bus during the session. They gave the engineer a good-sounding mix just by pushing up two faders.

If you needed to do overdubs, you’d just bring up the two mixback tracks and there was a headphone mix ready to go. Need more of something like the lead vocal? Bring up the lead vocal track a little bit and now the mix has more lead vocal. Need less bass? Piece of cake: reverse the phase on the individual bass track, slide up the fader and the phase cancellation lowers the volume of the bass in the mix! How cool is that? And yes, it really does work!

A better mixback trick: you could “punch in” the mix. If you didn’t have automation, with a mixback you could work on each individual section, punching in and out to do all sorts of difficult mix moves. And if the record company wanted changes to the mix, that was easy to do — add tracks in or lower them using the phase trick.

Automation ended the Mixback, or did it? With a DAW, bouncing rough mixes and then bringing them back into the session is very useful. It makes fixing latency issues a breeze: bring up the mixback mix, mute all the individual tracks and turn off any plugins on the mix bus. You can tweak the mixback by bringing up individual tracks, reversing the phase if you need to lower the volume of something, and then bounce that and bring it back into the session.

With a bit of ingenuity and enough ins and outs on your interface, you can even do a real mixback: route the master bus output to two tracks of the DAW (make sure you mute those tracks to avoid feedback), and then you can punch in and out of your mix just like the good old days. I mix this way all the time, punching the mix in section by section. And because it’s digital, there’s no generational loss or hiss build-up.