Is there a compressor with gain addition?

[mixsit]

This will do what you want: Flux:: sound and picture development. It's $169 list, but $149 from Sweetwater.

God I hope they write their code better than they do web pages.

 

[mixsit]

I mean a way to make softer volumes below a certain treshold louder, while NOT making the louder volumes softer above that treshold. No gain reduction but gain addition.
...I googled 'upward compression' and found this picture:

Now that's out of the way
There's another possible consideration though.

And that is what happens when you can only define your gain as 'increase as the level falls.

Quite likely at some point- on low level passages, pauses!- this means more and more added gain way down low where you (probably) don't want it.
A second parameter is needed- Either in the form of a limit control on the amount of gain allowed, or as a second turning point (back to 1:1 or better) somewhere at the lower end of the range you really want to target.

I was looking for that here a bit back.
https://homerecording.com/bbs/general-discussions/mixing-techniques/dynamics-plug-w-zones-323273/

 

[mixsit]

I'm ready to be shot-down in flames but...... Does it make any difference? Surely a compressor compresses the sound i.e. reduces it's dynamic range. Whether it effectively makes the loud bits quieter or the quiet bits louder depends on where the gain is set. It's just relative isn't it?

It might seem that way at first, but I'm glad he posted the photobucket thingy cause I always forget which is called what.
I tend to think in terms of where (in or 'on) the envelope, which direction (compact or expand), and how fast.

A real big difference is you're picking where to begin your gain change.
Compression (downward assuming with gain) is bringing everything up and knocking the upper part of the range down.
The upper range gets more compact. Below threshold it stays the same.
The compressor also 'sees the top of envelope shapes- rather different than the more steady state body of the signal. It could react a little different just on that.

Flip all that mostly for upward compression.

 

[bouldersoundguy]

I'm ready to be shot-down in flames but...... Does it make any difference? Surely a compressor compresses the sound i.e. reduces it's dynamic range. Whether it effectively makes the loud bits quieter or the quiet bits louder depends on where the gain is set. It's just relative isn't it?

It absolutely makes a difference. Dynamics above a certain level are not affected, only those below that level and above some lower level.