Ableton Forum

I have an audio effect rack with different chains to be used for different songs. I mapped a rack macro knob to the chain selector but I can tell that the effects are still being processed by looking at the CPU. turning off the chain speaker button doesn't disable the effects either. The only way to disable them is to map the macro to the specific device or devices Activator button

Is there a more elegant way to save CPU when you only need to hear one effect rack chain at a time? Same question goes for instrument effects.

This is the exact same issue I am researching! I'm not completely convinced that leaving all of my devices activated at all times is good for the CPU. I'm using ClyphX to toggle devices on and off-however, it won't allow me to toggle racks within racks and my set is full of those!

An easy way to debug CPU usage is to set your sample rate to 96K with a reasonably small buffer size to make the CPU meter more sensitive. Then start trying out enabling/disabling things. I am using racks within racks everywhere as well, and I have found that disabling the parent rack is enough.

For my situation, I just stuck with using the first macro knob to indicate the song index, and mapped the first rack in each chain to only enable when that index is selected, and did the same for the chain select ruler. Then I used the midi loopback technique (using IAC bus on mac) with a dummy MIDI track to set the macro knobs before I start any song. Works really well and CPU usage at runtime is totally manageable now.

I'm racking ( ha ha) my brain trying to figure out what you mean by song "index."

Your solution sounds perfect however I can't quite figure out how to do it. Might you be able to provide a step by step?

Clyphx is really cool if you have not checked it out yet.

Another thing I just noticed-disabling parent racks on helps by 2-3%.

I'm not sure the CPU meter is accurate. I do have a single rack that plays back at 60% and no matter what I do it always spikes at random times. Some instruments just need more processing power.


I'm installing a 6g SSD this week. I'm curious if that will help at all.

I will let you know.

Song index refers to the value of the macro knob, which is mapped to the rack chain ruler, as well as the device enable button for the instrument rack for that song. See attached screenshot.

I'm going to put together a comprehensive layout as a separate post, also as a followup to this post viewtopic.php?f=1&t=195685

Oh ok! Awesome! This is exactly what I need. I will check back for the post. I'm trying to figure out the map pings but no luck thus far.

One MAJOR thing to note, is that the white midi track on the far left is a dummy that sends out a CC value through MIDI loopback (IAC on mac), and I mapped that CC to the song index. So all I do when I start a new song is trigger the first scene which sets the tempo and triggers the dummy midi clip to set the song index. It's totally awesome. And you could do the same with any other CC value and any other settings all over your set. I still can't get over how awesome that is, actually.

I'll post another reply here when I get that comprehensive post finished.

Here is the step-by-step:

viewtopic.php?f=1&t=195844