The original thread here was a bit vague on what the purpose of the actual plugin was, so I thought a thread with a more specific title might be helpful for people that could use a bus inside the track view. If nothing else, it might just make it visually more convenient to have tracks and their related busses all in the same track folder.
 
The idea is very simple. All the plugin does is present a "sidechain" input to Sonar. This makes the input available to any track or bus's output, or any track or bus's sends. The plugin then mixes this sidechain input with the main signal going through the plugin. The end result is that you can:

• Send the output or send(s) of one or more tracks into another track. The destination track(s) then becomes a "track bus".
• Send the output or send(s) of a "track bus" into yet another track. So you can create a complex chain for a signal where it can go through as many "track busses" as you want. I tested this by having many cascading "track busses" and it all works.
• One can also put an FX bin with a Sidechain Mixer into the PC (move the FX bin to the top), and use that "track bus" to do PC processing with.
• Insert multiple FX bins along various points along the PC so that you can insert signals from different tracks at different points. Not sure if it can be useful, but it works. You can also add multiple Sidechain Mixer plugins into the FX bin of a track or bus as a way to insert different signals at different points along the FX chain (once again, useful?).
• Feed the output of an actual bus back into any other track.

 
As an example, I have a "Vocals" track folder containing a track called "Clean Vocals". This track then has multiple sends that each go into the sidechain input of all other "track buses" in the same track folder. The outputs of all those "track busses" then go into a final "track bus" that serves as the main bus for the track folder. Now you can do all of your parallel processing right in the same track folder without needing to do it in a real bus. For instance one of the track buses is a "sizzle bus", based on Craig's tip #50.
 
All of the Craig Anderton tips involving a bus can be done inside a track folder without using an actual bus. For example:

• Week 2: The Biggest, Baddest Drum Reverb Sound Ever. One can now skip the required bounce step here. I used the CW Pitch Shifter on the two reverb-only track busses, not sure if there is a better option here.
• Week 50: The “Sizzle” Bus. I created the sizzle bus as just part of another parallel processing track bus.

 
You can find the plugin here. To use: 

• Unzip the files.
• Copy the 32-bit and/or 64-bit files somewhere into your VST3 folders.
• Let Sonar do a scan.
• The plugin shows up under Plugins > Audio FX > VST3 > Sidechain Mixer (or wherever you put it).
• Drag/drop the plugin into the FX bin of the track that you want to convert to a bus.
• Set the output of any other track to "Sidechain Mixer(Input 2)-[track bus name].
  
  

  Some points: 

• If you solo the track bus, Sonar will not solo the tracks feeding into the track bus. To get around this, solo the whole folder, or group the solo buttons together. Use Ctrl+Click to toggle individual buttons in a group. Note there is no need to group the mute buttons since they will work as expected.
• You need to set PC to Post-FX if you want the signal to go through PC.
• You only need one plugin per track bus. You can send the outputs and/or sends of as many tracks and/or busses to the same sidechain input as you want, and Sonar will mix them together before sending it into the plugin.
• If the 1st input into the plugin is mono, it will cause all other inputs to the same plugin to be mono as well. To work around this, make sure at least the 1st input is from a stereo source.
• I only tested the 64-bit version so let me know if the 32-bit version doesn't work.

I've already taken to adding multiples of these into tracks, each in their own fx chain so I can automate the fx chain's output volume for mixing.  You guys ferreted out a couple of neat ideas there!

 
SilkTone, thanks for this.
 
Is the link you provide in this thread to the same version of your plugin as in the original thread ?
 
Are you satisfied with it the way it is or do you foresee updating it at some point ?
 

swamptooth
I've already taken to adding multiples of these into tracks, each in their own fx chain so I can automate the fx chain's output volume for mixing.  You guys ferreted out a couple of neat ideas there!

Yes it is still the same version as in the original thread. Other than improve on the corny graphics, there isn't much else to change really. It is the most straightforward plugin I ever made (mix 4 inputs down to 2), so unless someone reports a problem with it I don't foresee spinning a new version.
 
The only change I can think of is a way to possibly deal with the situation where the first input is from a mono track. In that case, it forces all subsequent inputs to mono as well (as pointed out in the original thread and confirmed by Noel). I was thinking that if I give it 5 inputs instead of 4, there could be "Stereo" input as well as a "Mono" input. So you would feed all your mono tracks into the Mono input only, and all your stereo tracks into the Stereo input. I'm not sure whether this will work around that issue or not, but I might give it a try at some point.

Re the idea mentioned above... I played with 1 Stereo + 1 Mono sidechain input, but came to the conclusion that it doesn't make a difference. If your 1st input is mono, Sonar will still force all other inputs to mono, regardless of whether the 1st input is going into the dedicated "Mono" sidechain input.
 
It's not a big issue really, just make sure your first input isn't mono. So therefore the version linked to above is still the latest.

How about if you have one in a prochannel fx bin and another in a regular track fx bin?

swamptooth
How about if you have one in a prochannel fx bin and another in a regular track fx bin?

That will work fine. It is only a problem when you mix mono and stereo inputs going into the same plugin. In fact, you could place two SideChain Mixer plugins back-to-back into the same FX bin and feed only mono inputs into the one, and only stereo inputs into the other.
 
I would think this is really a bug in Sonar. If any plugin has a stereo sidechain input, all other inputs would be forced to mono if the 1st one happens to be mono. Now probably there aren't many/any other plugins right now that care about whether the sidechain input is stereo or mono (other than Sidechain Mixer now), but there could be (I don't think the Sonitus plugins care). I imagine Sonar does this as a performance optimization (albeit minor), but ideally it should look at all inputs and if at least one is stereo (not just the 1st one), treat the input as stereo. After all, the plugin did present the sidechain input as stereo.

TOO COOL - thanks so much for this! :)
 
Bob Bone
 

Now all we need is to be able to work out how to feed the signal into a tracks input rather than fx bin. I appreciate that it's probably not an easy thing to do???

mudgel
Now all we need is to be able to work out how to feed the signal into a tracks input rather than fx bin. I appreciate that it's probably not an easy thing to do???

That would have to be on a Cakewalk level, I would bet.