Cubase Pro 8.5 / 9 VST3 Sidechain not showing on mono tracks


I just noticed that VST3 sidechain has a big bug in both Cubase Pro 8.5 and 9.

Create a new empty project, create 5 empty (MONO) tracks, insert VST3 plugin on each track, activate the sidechain icon => erratic display of sidechains in send menu.

I tried with following plugins (be sure you use vst3 versions):

  • steinberg compressor
  • plugin alliance lindell 254 compressor
  • fabfilter pro q2
  • fabfilter pro ds
  • waves vocal rider

Only steinberg plugins showup in the list correctly. Other vendors is completely erratic: sometimes it shows up and sometimes you have to activate another plugin to have another appear.

Can anyone confirm please ?


As I investigated a bit further it seems that if you use stereo tracks sidechain works normally. Only if you use mono tracks then you have the bug on sidechaining not showing up in the send list. I updated the thread title to reflect this.

I concur with this. I didn’t think it was a bug as I always thought it was a third party thing but wondered why some/most didn’t have a side-chain button when loading the mono plugins.

Let’s see if others chime in with the same issue.

I have the same problem in one of my projects I’m currently working in, so I started Googling and found this thread.

So to test, I opened up a new project and I made:

  • 1 Stereo Audio track
  • 1 Mono Audio track
  • 1 Stereo Group
  • 1 Mono Group

On each of the tracks, I’ve place a Neutron Equalizer with the side chain function enabled.
But now, I can send signal to all the other Neutron Equalizer’s.

In the project which made me Google, I couldn’t send from a Stereo Group to a Neutron Equalizer on a mono Audio Track. I could send to a Cubase Compressor on the same Mono Audrio Track from the Stereo Group within the same project.

I’m on Cubase 9 pro.

Any suggestions?

Besides the obvious ?
use stereo tracks only, or asking the plugin developer for a bug fix ?

I don’t see anything obvious since it’s working in a new project but not in an older project which I’ve already been working on. Do you see anything obvious?

Why ask the plugin developer when it works in a new project, but not in an older project?
Extra info: both the old and new projects were started in the same configuration.

I have a feeling it might has something to do with a Windows update, but I’m not sure.

Obvious is not for everyone. I opened a ticket with Waves support and their answer is “since it happens with other vendors plugin it comes from the host not the plugin” …

That was a fast conclusion Waves made there. Could be true, or something else, like a design fault on their part.
In my experience most plugin developers have a hard time with VST3

Could be, of course. But what are the odds that 3 separate highly skilled editors (Waves, Plugin Alliance & Fabfilter) end up with the same specific bug ? Occam razor would tend to point at Cubase not the plugins …

Worth investigating on Steinberg side if you ask me …

Oh wow, I noticed this same thing on a project I was working on recently and thought I was going crazy. I opened a Waves C1 instance but there was no sidechain icon. Just kinda shrugged and used one of the Cubase compressors instead.

Even if this isn’t a host issue, which I’m guessing it actually is, then Steinberg should work together with these third parties to fix it, because if something goes wrong for multiple companies then something has to be done about it.