Question

I have both Studio One 2 Producer and Studio One 3 Artist with the VST pack. When I open a song made in SO2 that I used a compressor with, the volume in SO3 was low. After I looked into it, the compressor Auto Gain behaves differently between the two. 

Here is what it looks like in SO2:

and SO3:

You can see the difference in the curves...why does it do this?

Answer 1

Some of the plugins were improved and/or updated in the early 3.x cycle which may at times give different sonic results.  See the release notes for version 3.1...

• Improved Auto Gain in Compressor and Channel Strip with further improved gain response in Limiter and Tricomp [NOTE: this may affect levels in pre-3.1 songs]