Vienna Symphonic Library MIR Pro 3D & Vienna Power House

Screen 1: A 3D view of the author’s test project.

In a collaboration with tech pioneers GPU Audio, an add‑on to this multi‑impulse‑response [MIR] immersive audio reverb promises to take the strain off your computer’s CPU!

This latest update to VSL’s MIR Pro reverb brings the company’s lauded Multi Impulse Response convolution technology to the immersive audio environment, but the developers didn’t stop there. Also available, as a cost option, is Vienna Power House, an add‑on that promises to farm up to 50% of the processing out to your computer’s graphics processor, courtesy of technology from a company called GPU Audio. Given the heavy demands that immersive audio projects can make of a computer’s CPU, that really is an interesting prospect, and in this review, I’ll cover both MIR Pro 3D itself, and this novel CPU‑saving feature.

MIR Pro 3D Overview

Unlike in most reverbs, MIR Pro 3D’s processing takes place in a standalone room‑modelling app that runs alongside your DAW, but audio is routed to and from the app by instances of a plug‑in that are inserted on your DAW tracks in the usual way. You have a choice of two versions. The full version is called Vienna MIR Pro 3D, but considerably cheaper is Vienna MIR Pro 3D (24), which offers all the same features but limits the number of instruments/audio signals that can be placed on the virtual sound stage to 24.

Licensing is through iLok, and you’ll need a macOS (10.14 and up) or Windows (latest 64‑bit version of 10 or higher) DAW that hosts AU, VST, VST3 or AAX plug‑ins, as well as a graphics card supporting OpenGL 4.0 with at least 512MB of VRAM (more is recommended). VSL offer various system spec recommendations on their website, which change according to the scale of project you plan to undertake, but I tested the software on a 2022 M2 MacBook Pro with 16GB RAM, running macOS 14.5.

Upon opening the app, you’re prompted to select a ‘venue’ from one of the Room Packs that are installed. There are currently seven Room Packs available and you get one (of your choice) free with your purchase, but you can pay to add more and if you purchase more than one the most expensive of your selection comes free. Each Room Pack includes different rooms that the VSL team have captured meticulously and in incredible detail, such that you can place a source in various positions in a room, and even define the direction in which it’s pointing; there’s more on that side of things below.

Pack 1 is the famous Vienna Konzerthaus, and this includes 11,000 impulse responses captured in its four halls and foyer. Pack 2, Studios and Stage, has 24,000 impulse responses from Berlin’s Teldex recording hall, the Austrian Broadcasting Corporation building in Vienna, and two rooms from Austrian recording studio Weiler. Pack 3, Mystic Places, contains 4200 impulse responses captured in various Gothic churches. Pack 4, The Sage Gateshead, has 14,000 IRs from two large concert spaces in the North East of England. Pack 5 has 5000 IRs from the Pernegg Monastery in Austria. Pack 6 features 6000 IRs from VSL’s own 540 square‑metre Synchron Stage in Vienna, where many film scores by composers including Hans Zimmer, Rupert Gregson‑Williams and Laura Karpman, to name just a few, have been recorded. Finally, Pack 7’s responses were captured in two prestigious venues in Salzburg, the Grosses Festspielhaus and Karl Bohm Hall.

Venue selection is organised by venue type (concert halls, foyers and special places, mystic spaces or studios and sound stages), reverb time and location, so it’s pretty easy for you to find what you’re looking for even if you have several packs at your disposal. Multiple venues can be opened simultaneously and it’s easy to move instruments from venue to venue too, making it possible to audition different spaces quickly for creative reasons. Once you’re happy with your choice of venue, you insert an instance of the MIR Pro 3D plug‑in on any track in your DAW that you want to send to the virtual 3D space, and that signal will show up in the app, in the venue you’ve selected. You can insert the plug‑in on a mono or stereo track, and open it out in the app into anything from stereo to 9.1.6, including first‑, second‑ and third‑order Ambisonics.

The MIR Pro 3D Plug‑in

In the MIR Pro 3D plug‑in, simple controls let you to get things where you want them quickly. A meter display shows the level being sent to each output channel. The bypass, mute and solo options here are self‑explanatory, but there’s also a hide function that makes an instrument (or group of instruments) invisible in the MIR Pro 3D app venue display — useful when you’ve got 20 or 30 different instruments on a stage and the GUI is starting to become cluttered. There’s a dry/wet ratio (mix) control, as well as an overall output level control and a polarity inversion switch for the wet signal.

Screen 2: Audio is routed to/from the main MIR Pro 3D app from a DAW plug‑in, inserted in the usual way, and in this you have control over a number of basic functions, as well as instrument grouping.

Bottom left of the plug‑in pane is the room tone generator button, which plays background ambience for the selected venue. Simply throw up a spare track in your DAW, insert this and, hey presto, you get that little background hubbub ambience going on. This may strike you either as a gimmick or unnecessary attention to detail, but it’s actually very useful — often, when compiling live albums that play continuously from track to track, I’ve had to search for some ambience to play between some of the quieter moments because going down to ‘digital zero’ between tracks sounded wrong, and surprisingly disruptive. This feature, which VSL describe as a “natural dither”, overcomes that issue neatly.

In the centre of the plug‑in pane, at the bottom, you can assign each instrument to a group. When instruments are grouped together, changing one parameter adjusts that parameter for all instruments in the group. It’s not an all‑or‑nothing option, though, as you have control over which of the following parameters are linked: volume, rotation, width, dry/wet, position, bypass, hide, mute and solo. So, for a standard string section, you might group your violins together, and the same for your viola, your celli, and so on, and could then quickly place all instruments in a group on the stage, solo or mute them, or apply the same amount of effect.

App Basics

All these controls and more are also available in the main app. At the top of its GUI are the usual main menu and command bar, with preset management, a help button and a useful reset switch to return the selected venue to its default state. Below this lies the instrument channel list, a list of all the sources being sent to the app from your DAW, and, to help you keep control of your session, you’re given basic hide, bypass, mute, solo, volume and group assignment controls.

Screen 3: The default plan view shows the room layout, but you can also view the room in 3D (as in Screen 1), and in either view you can place both instruments and mics very precisely.

When multiple venues are open, they appear as tabs along the top of the page and in the instrument list. From that list, the instruments can be dragged and dropped into the various different venues. Screen 3 shows the Vienna Konzerthaus...