What is a reference mix?

[Stanlavisbad]

Can someone explain what a reference mix is? I read on quora that it's a song/mix that you know sounds good so you can compare against the song you're currently mixing, but I don't understand how that definition fits with the LZ deluxe companion audio tracks. 

[Archetype]

Based on what I hear in those companion tracks:  A mix-down of existing tracks to use as a framework to work out additional parts, solos, and melodies for vocals - and to consider what you might want to do with the final mix and to re-consider and determine whether & how to change or fix existing tracks.   Basically a working copy of the song as it currently stands (that you can take home, for example, to use as backing for noodling experiments). 

[SteveZ98]

In general, they are what quora described, a standard against which other tracks can be compared to make sure they sound similar. There are programs that let you load the reference track into your mixing or mastering session and compare it on the fly to what you're working on. It lets you hear the differences between the two at the press of a button.  There are also programs that let you copy the EQ of the reference track and apply it to the one you're working on, and others that let you copy the dynamics of the reference track to the new one. This kind of thing is helpful if you have an early mix of a song you like and want to make sure later versions of it sound similar. However, the reference track can also be a different song from the one you're working on and you use it to make sure the other songs on the album sound similar to it. 

In regard to the companion audio tracks specifically, the songs I listened to recently that are labelled reference mixes sound more like final mixes with slight, if any, variations from the versions that were originally released on LP back in the day. I suppose they could have been used as references, basically to say "hey, we're almost there. Make sure when we add the last few touch ups that the final version sounds like this."