Response curve for Live Send Pot?
does anyone have information regarding the send pots in Ableton Live?
I’m trying to build an equal-power panning system for an 8-channel application and have found that the send pot is not truly logarithmic. In fact, it looks like it’s modelled on a "real life" log pot.
Does anyone know what function Ableton use to produce this response?
OK. In case this is of use to others, I’m going to answer my own question:
The Live Send pot is neither linear nor truly logarithmic.
This is of particular importance if you are using it for an equal-power application like panning. Multichannel spatialisation devices like [Max Api SendsXnodes] and [Max Api SendsPan] that control Live Sends via the API and do not address this issue produce a marked drop off in level when sounds are panned in-between speakers in multichannel environment.
I talked to Ableton who say the design is procedural and not given to a mathematical solution, so I did some measurements and produced a lookup table (antipot.aif) to make the necessary corrections.
Here is the .aif file and a small example patch.
I have also applied this technique to a couple of audio-rate M4L devices which I will put up online soon.
I ran into this exact same issue earlier this week trying to implement equal power quad panning in Live. It drove me nuts for a while because all the sources and tutorials I found online claiming to do this seemed to get it wrong.
I ended up using the curve~ subpatcher from the Max Api SendsPan device. If I remember correctly a value of about 0.83 gave me – 3db between speakers.
So happy to see someone has looked into this. Thanks fellas.