Immersive Sound is big news at the moment. With expanded surround workflows being integrated into Pro Tools HD and major broadcasters only accepting and distributing 5.1 mixes, the role and use of "upmixer" plug-ins has become increasingly relevant.

When discussing the merits of various upmix plug-ins with other post-production engineers, I've found that there is a large variety of preference and that this largely depends on the nature of the material being used. Different upmix plug-ins have varying capabilities - some are limited to 5.1, others can accommodate "height" for immersive audio formats and others offer the ability to check the resulting downmix within the plug-in.

So we thought it would be good to run a blind listening test with the community. We want to find out which upmix plug-ins the community prefer, purely by listening to the results, without being swayed by knowing which brand's plug-ins have been used. We want to get as much feedback as possible, from as many people as possible, so are putting this out to anyone who wants to take part, rather than selecting a small sample of "experts".

How Do I Take Part?

Simple - just click on the link at the end of the story, to download a specially compiled zip file. This file, once unzipped, will contain two folders, firstly you will get our special Pro Tools Expert Surround Alignment video to help you hear the examples in the best conditions.Secondly, a folder with a Pro Tools session containing four pieces of music and one feature film mix segment, that have been upmixed to 5.1. For each example, the format will be -

• Original Stereo File
• 5.1 Upmix of that file for each upmix plug-in
• Stereo "LoRo" downmix of the 5.1 upmix for each upmix plug-in

For each example and each plug-in, I have adjusted the parameters and where available, the presets, to give as accurate a representation tonally, for the 5.1 upmix vs the original stereo. I have done this to more accurately represent an average workflow.  

In the case of the feature film example, you will also receive the video that accompanies the audio. By giving you the original, upmix and downmix, we would like you to compare all three, on both technical and aesthetic grounds. We have used the Avid Downmixer plug-in set to a modified version of the ITU preset.

For the LoRo downmixes, although the standard ITU specification does not include the LFE channel in the fold-down, we have decided to include it, as the downmix is more representative of the 5.1 that way. The way we see it, if the upmixer adds a low-frequency extension, on its standard settings, then that should be reflected in the downmix settings. We have applied the same downmix settings to ALL the upmixes.

Be Exclusive With Your Solo

We've supplied you with a Pro Tools 12HD session with all the originals, upmixes and downmixes neatly laid out. You might need to point Pro Tools in the correct direction for the media, but simply navigate to the "EXAMPLES" folder and it should find it all. One thing we would definitely recommend, is to switch your Solo Mode to "X-OR", so that you have less chance of damaging your loudspeakers, and more importantly your hearing!

Of course, should you wish to use an alternative DAW to Pro Tools, simply drag the WAV files in the "EXAMPLES" folder into that DAW.

The Poll

Once you've listened through all the examples, as many times as you like, please come back to fill out this poll but you only get one choice per example. 

The Big Reveal

Once we have a statistically valid number of responses, we will reveal which examples were made using which, the results of our poll and also provide important technical analysis of the resulting upmixes and downmixes, in terms of their compatibility and transparency.

Download The Specially Compiled Demo File

So what are you waiting for? Click this link to download the file to get started! Be aware that the file is nearly 6GB so make sure you are on a capable unmetered internet connection.