Routing REAPER through Harrison Mixbus using Soundflower

A step by step guide to help you incorporate Harrison into your REAPER workflow.

This requires the installation of Soundflower originally developed by Cycling 74 for use with Max MSP. Soundflower is available here and is now developed by Matt Ingalls. A few things to add, in case they aren’t clear in the video, I have my individual instruments setup in folders in REAPER and each parent master send is turned off. These are sent to one of the of the four stereo busses, labeled Drums, Bass, Vocals and Guitars, which I then send to Mixbus.

The Soundflower routing can get a bit fiddly, so I hope that it is clear here. REAPER has alias names for Soundflower channels whereas Harrison doesn’t, which is why I don’t show the name mappings in the video.

At the end of the video I solo some tracks in Harrison, but not REAPER. If you want to solo in REAPER you must remember to include the Mixbus return track in your soloing otherwise you won’t hear anything.

Just remember that when routing between the two DAWS to turn your monitors or headphones down in case you route something incorrectly and get feedback that could potentially damage your hardware, or your ears!!!

If you want to do this on a PC then follow this link. This technique uses Rearoute, an ASIO driver that comes with the REAPER install.

REAPER Harrison Comparison

In the pursuit of fairness I pulled two versions of the same mix in REAPER, one a straight REAPER bounce and the other running through 4 stereo mixbusses with the tape saturation drive set at 0 and level matched them to -16LUFS.

As you can see here the two files do not completely null, which could be down to additional harmonic content added by Harrisons’ tape saturation as well as other non-linearities from the audio engine, which is internally dithered, ramped, and gain ­staged so that sound quality is preserved as close to analog as possible.*

Here are the two comparison tracks in full for you to listen to. The differences are extremely subtle, some may say negligible, but that is for you to decide.

I would agree that this is quite a laborious process for such tiny changes, but you also get access to the Harrison EQ and Compressors, which I didn’t use in any of these examples but do sound great. Mixbus 32C has an updated engine too and includes the 32C EQ.

I do find some of the Mixbus features to be lacking however, and the track management for me is not intuitive (yet), as most DAW’s allow you to freely drag tracks at will. Also, utility busses are not delay compensated which makes little sense to me.

Hopefully some of these issues will be ironed out in future updates.


The tracks I use in the video demo are free from Produce like a Pro and the song is called ‘Wasting Away’ by Alexx Calise.  The comparison track is called ‘Vintage’ by the artist Pablo and is a free download. You can grab the raw tracks from David Glenns page here.I would suggest you check out both of these subscription services. The tutorial videos for each monthly track are worth the admission price alone and you get a mountain of free content. Also, you can use these tracks for your resumé to attract new clients.

*There are a lot of similar comparisons online, most famously the one from Spectre Sound Studios. One video shows a REAPER bounce and a Harrison bounce nulling, but it is worth pointing out that in that particular example the mix exported from Harrison is not running through the mixbus saturation stage.