Welcome to the second part of this tutorial. In the first one you’ve seen how to make your own single band dynamic EQ with parameter modulation in Reaper. I hope you have tried around for yourself with this feature.

You may have noticed, that there’s a slight “problem” with the kickloop. The 2nd and 4th kick contains a clap, and at that points it’s triggering the EQ “harder”, because it’s simply louder there. So let me show you how to prevent this with a little send trick.
We want to just send only the kick from the kickloop to the bassline sidechain track channel, not the whole kickloop with claps. For this, we create a new track first (usually CTRL+T in Reaper or doubleclick on the empty track space) which we call “Router Group”. This track will have no own audio informations, it should just be used as a group track. So open up the Routing dialog and DISABLE “Master/Parent Send”. Now, the group is not sending it’s audio to the master track anymore!
Now we add another track as grouped track within the “Router Group” which we call “Kick send”. Now, change the send routing from the kickloop, don’t send it to the bassline track anymore but to the “Kick send” track. Delete the old send and add a new one.
At this point it’s a bit different, you leave the audio options for the channel at 
Audio 1 / 2 => 1 / 2” because it’s no sidechain track here. However, midi can be set to “None” anyway, just to prevent midi sends for any reason.
Now we have an exact copy of the kickloop on the “Kick send” track, which is not audible. So we add a new EQ instance here and turn the lowpass filter down to around 70Hz, so just the kick itself is left. At this point we route this edited kickloop back to the sidechain channel on the bassline track, to trigger the EQ!
Open the track routing options from the “Kick send” track and make a send like in part 1:
Add a send to “1: Am_120bpm_Bassline_1” and set “Audio 1 / 2 => 3 / 4” and “Midi NONE”.
Close the dialogue and open up the EQ from the bassline track - now it just reacts to the kick of the kickdrum loop, not to the (much louder) clap!
So, that’s a way how to shape the send content before using it on the sidechain channel!
*This is a guest post from Lopez who runs the label Electronic Anarchy and is involved in the develpment of Kirnu Cream