How to Make a Rack gain respond inversely to Song Output Gain... e.g. -3db Song = +3db rack?

I tried a binding at Song level and it does respond inversely but not exactly proportional… -3 song = +1.2 rack. Ideally, this would be a binding within the rack itself. I tried various values but it’s not exact. I played a bit with the curve but it’s still off; I suspect this needs a script. Which I know virtually nothing about :grimacing:

The problem is that, as my songs and mix have evolved, I’ve used the shortcut of using the Song Output gain. (All my song states are mixed well relative to each other, but sometimes when I get to rehearsal the whole song needs a bit of adjustment.) So the Song output changes from song to song… some are -2.2db, some +3, etc. But I need this rack’s output to be consistent across all songs.

I could manually set it for each song I suppose, but it would be nice to have a binding inside the IEM rack to do that.

My application is that I’m adding a global IEM rack to every song, which simply takes a STEREO feed from the board into my interface (8in/8out so plenty of un-used inputs), and routes it into my IEM rack. Then inside the rack I can EQ or compress as needed. And it feeds it to my stereo “Monitor” outs on my interface. (I’m doing this because I had a recent gig where the sound guy had waaay too much low end on my IEM mix, I had him turn it down, then there was no low end, and so on. Not the first time. So the more control I have the better. )
Here’s the song view:

And here’s inside the rack:

BTW adjsuting the rack’s input level, or the song input level, would work too, but if the binding is in the rack then I think the rack gain is preferable.

Just FYI, I also have my footpedal controlling my Cantabile Stereo Output gain just for my monitor output. So when I’m done, the rest of the band from the board will be a consistent level, but I can bring my playing up or down as needed, which occurs on occasion. Especially on new songs I haven’t gigged yet.
Any advice is greatly appreciated!
Tom

BTW, I just started to manually set the rack’s gain on a few songs, and discovered that it’s not always proportional even if the inverse is exact. Using a 1K tone and meter, for a song that’s - 2db it’s fine… +2db is good. But one song’s output is -4 but the rack gain had to be +5.3. Strange. Anyway, that may be an outlier. I’ll try a few more…
Tom

I don’t know if it will make sense to work with the new expression feature, there were some discussions about dB at some point, e.g. Introducing Binding Expressions - #9 by brad

1 Like

Thanks Torsten I’ll take a look at that!

Expression binding with:

fromDb(-toDb(input))

Demo video.

How about something as simple as this?


No expression needed at all…

Key is defining source and target range - you could also map -6…+6 to +6…-6 if you just want to react to a specific range of dB values.

Cheers,

Torsten

That’s just the way the math works for decibels. If you reduce (let’s say) a 1 volt signal by 50% you get 0.5 volts … but then increasing it by 50% doesn’t get you back to 1 volt, but just 0.75 volts.

– Jimbo

All good ideas, many thanks! I’ll try the expression binding, but Torsten’s mapping idea is simple and easy too. Thanks again,
Tom