NOTE: this modular concept is far more creative than what you could do with a hardware mixer, or even sofware solutions that have built in aux busses. Indeed, you can choose exactly from WHERE you would like the audio to, be tapped to,the aux busses. For instance, if you have an audio input receiving a vocal, you could insert an EQ and a compressor, and depending on where in the chain you insert the Aux Bus Send, the sent signal will be compressed but not eq’d, not compressed or eq’d at all, or both. This opens up endless possibilies. (an Aux Bus plugin is transparent in the chain: its inputs are mirrored to its outputs, of course).

I included some additional real-world suggestions on the How-To page.


    This project was started because I wanted to get familiar with the C++ programming language, I was mostly doing Object Pascal before (Delphi). I wanted to learn the VSTGUI libraries too. Moreover, I needed Aux Busses myself, and there were some users on the Brainspawn Forums that had asked for them as well.

    A plugin existed that was close to what I wanted, but didn’t have a GUI so we needed to use a wrapper in Forte. Fortunately, it’s author was so kind to publish his code on KVR ( , so I took that as a starting point. It’s really ModulR who found the trick to achieve latency-free communication between instances, so the credit  for that is entirely his!


    Original Senderella code by Sean Person (ModulR). Thanks many!!

    Adaptation and GUI design by Dirk Offringa

    VST Plugin technology by Steinberg

    VST is trademark of Steinberg Media Technologies GmbH

    Important note: as of today, no license format has been agreed upon. The source code can be obtained upon simple request.


    This software is provided as is. No support will be provided, although I will try to figure things out if you drop me a mail :


    Please do not use this sofware without full understanding of audio paths. It’s easy to create feedback loops if you are a bit absent-minded, and damage to your speakers or other hardware, as well as to your valuable ears might occur in case of improper use. BE CAREFUL!


    Dirk Offringa, September 2005


    What’s this ?

    This is a set of 8 VST plugins, that can create up to 8 aux busses in any VST host.They are intended for use in hosts that do not natively feature auxiliary busses because of their modular design, such as Forte, the live audio workstation from Brainspawn (

    How does it work ?

    Each plugin can act as an Aux Send, or as an Aux Return. You need at least 2 instances to set up a bus. The Sender (Aux Send) sends audio to the Receiver (Aux Return) . Many senders can send audio to a receiver, just like in a hardware mixer.

    8 plugins are supplied, creating 8 different aux busses.

    Each plugin has the following controls:

    1: a level fader to control the output level to the bus (in send mode), or from the bus (in receive mode)

    2: a switch to change from send to receive mode (click on the led display)

    3: clicking on the logo at the bottom will display the “About” box.

Bus Receive

    How to use the Aux Bus Set

    A typical situation is as follows:

      You have a certain number of sources (audio inputs, softsynths), you would like to add some reverb to, in amounts that should differ from source to source. (If that was not the case, you could simply route all the audio to a bus with a reverb inserted, and tweak the dry/wet mix in the reverb).

      To achieve this, we must set up an Aux Bus that taps the audio and routes some of it to a reverb unit, and sends the processed audio to the main mix

      For instance, in Brainspawn Forte, take these steps:

      1: add a new bus with the same output assignment as your main output (generally Outputs 1/2) and name it “Aux Bus 1”.

      2: open the insert manager and insert an instance of the Aux Bus 1 plugin in the bus insert.

    • 3: open the plugin’s console, and click on the “mode” display to set the plugin in “receive” mode.



    4: set the slider full up (else nothing will come out of the receiver), so that everything looks as in screenshot 1.

    5: insert a reverb plugin AFTER the Aux Bus 1 plugin, so that incoming audio will be processed by you reverb, and the processed audio will be added to the main mix.

    6: Insert another instance of the SAME plugin (Aux Bus 1) into any number of input module inserts. The default mode is “Aux Send”, so nothing needs to be changed here.                      

    If everything went well, you now can feed audio from the input module to the aux bus by bringing the sender’s slider up, and you will hear the sound with the desired amount of reverb added through the main outputs.

    A typical Forte rackfilel could ressemble this one:


    We have 1 input, that has two aux sends: an instance of Aux Bus 1, and one of Aux Bus 2, both set to “send mode” . We have set up 2 Aux Busses, the first has an instance of Aux Bus 1 inserted, plus a Reverb plugin (not visible here); the second has an instance of Aux Bus 2 (not visible here), plus a Delay plugin; both instances are set to “receive mode”. All busses and modules are routed to the main output bus (Buss 1=>Analog1-2). Both the Reverb and the Delay plugin should have their Dry/Wet balance set to full Wet. You set the amount of reverb for the source (here: a brainspawn Audio Input) by tweaking the slider in its Aux Bus 1 plugin, and the amount of delay in the Aux Bus 2 plugin.

    These plugins run on Windows XP inside a VST host.

    UPDATE: It has been reported that on some systems the VST host will not recognise them unless the Microsoft .NET Framework is installed.



    Copy the folder “SolidSoundStudio Aux Bus Set” into your VST plugin directory, and restart your host. The host will find 8 new plugins: Aux Bus 1 to 8.