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Using JRiver to Create a 3D Domestic Concert Hall

This guide shows you how to produce a full width front stage plus concert hall ambience as described by Ralph Glasgal in The Science of Domestic Concert Hall Design article. The use of JRiver is an alternate solution allowing more audiophiles to experiment using their existing audiophile system. Convolution, when properly implemented as described here, brings the acoustic characteristics of St. Cecilia hall to your listening room. You will hear the full 2.2 seconds reverberation of the hall. It recreates concert hall ambience using specially recorded 360 degree impulse responses (IRs) of the St. Cecilia concert hall. In this guide, I will show you how I implemented these IRs using JRiver. My solution may not be the best but it opens the door to unlimited possibilities for tweaking the sound to match your preferences and can provide a lifetime of sound to enjoy You can read more about the importance of convolution at the ProAudiofiles site.

Requirements:-
1) PC with i5 and above. 8GB RAM Memory. Please see OS requirements for JRiver. However, AmbiophonicsDSP VST plugin works with Windows OS only. For other OS, you have to use the MiniDSP with the Ambiophonics plugin.
2) USB DACs. One is required for every IR. In my case, I have convolved IRs for left and right speakers placed at 60, 75, 90, 105, 120, 135, 150 and 165 degrees. Therefore, I am using 8 DACs for surround ambience alone. My choice was the PCM 2704 DAC which can be bought for about $10 from Ebay. AudioQuest Dragonfly is another good choice for better sound quality. You can use any DAC brand but it is advisable to use identical DACs for all the surround speakers. The most cost effective solution is to use cheaper ones for the convolution channels and a better DAC for the main front speakers. I use Mytek 192 DSD DACs for the main front channel and the PCM2704 for the rest. You can also use multichannel audio interfaces such as RME, MOTU 24AO or Focusrite to replace the DACs.
3) One stereo amplifier for each DAC. You can use small amplifiers as the convolved surround speakers need not be played loud. I use Line5 A960 amplifiers (50Watt @ 4 Ohm) which can be bought for about $50. You can also use multi channel amplifier.
4) One pair of speakers for each amplifier. The quality of the surround speakers is not crucial although better ones require no additional PEQ to tame any frequency response errors that may be audible. I use small HT speakers bought used.  Extended bass response is not mandatory for hall ambience reproduction.
5) Powered USB Hub such as TPLink UH700 or Anker 10-Port USB 3.0 Hub. All your USB DACs must be connected to a hub to maintain easier synchronization including additional hubs.
6) AmbiophonicsDSP from http://electro-music.com/article.php?t=37687. If you prefer higher resolution files, you may use a MiniDSP with the Ambiophonic plugin. These products are for use in the front and rear direct sound channels within JRiver or external to it and preferably connected after a preamplifier.
7) SIR 2 from http://www.siraudiotools.com/sir2.php . You can also use JRiver’s built in DSP convolver but it requires modification of the original IRs and is time consuming. It is best to get a convolution engine that can process true stereo impulse response for 3D ambience.

Step 1
In JRMC, create Zones for the convolution speakers. I will use a 90 degree IR as an example.
i) Click Player > Add Zone > Name [Zone 90 degrees] Copy - None > OK
Each IR contains hall reflections from the left and right of the stage but both are destined for the same surround speaker.  Do the same for the rest of the IRs. Each Zone must use both Lsp and Rsp files. If you intend to use all 24 IRs, then you need to create 12 Zones which will be fed to 12 right and 12 left convolved surround speakers. You will need one DAC for every zone. In my case, as I have described in (2) above, I use eight DACs for 8 zones.


Chart 1

Step 2
i) Plug in your first DAC for a surround pair to the USB hub.
ii) Click Tools > Options > Audio > Zone to configure > Choose Zone 90 degrees > Audio Device > click arrow > click More > "N" USB DAC [Direct Sound]. (or the appropriate driver for your DAC such as ASIO or WASAPI).
IMPORTANT :- JRMC will automatically assign an unique number/identity each for the identical DACs. The number will remain the same unless you disconnect the USB DAC from the USB Hub or computer port.
iii) Click Tools > Options > Audio > {after you have configured the DAC} > Device settings > Buffering > 0.05 seconds. This value may change and is DAC dependent for skip free play. You need to experiment to decide what's best for your system. Start with the lowest number. I use 0.05 second with SIR 2 convolver but with JRiver's in-built convolver I needed about 0.1 second of buffer.
iv) Make sure you disable "Play from Memory" in JRMC as this can affect synchronization between DACs.


Chart 2

Step 3
After you have completed Step 2, you now need to use JRiver's DSP functions to include the IR files. For Zone90degrees
i) Click Tools > Options > Audio > DSP & Output format > tick Output format > Since the PCM2704 DAC is only capable of an up to 48 kHz sampling rate, I set all to 44,100 Hz.The convolution speakers' resolution is not critical as the sound that comes from those speakers is sound walls with extended delay and decay rates as well as losses in high frequency energy. Choose the sampling rate according to your DAC's specification.
ii) Tick Audio Leveling. This feature is important to maintain constant volume level of the convolution speakers.
iii) Click Tools > Options > Audio > DSP & Output format > Manage plug-in > add SIR 2.

Step 4
You have to follow SIR 2 instruction to how combine both Lsp and Rsp Impulse response to create a true stereo Impulse response. This is the easiest part of this guide.


Chart 3

Ambiophonic Transcoder and iPad/iPhone Player from Xivero

Click on the images below to find out more about these new products from Xivero.

 

 

Ambiophonic App for Android
Neutro Music Player
Click here to read about the Neutron Player with built-in Ambiophonic capability.
Enjoy wide-stage 3D sound in the background while running multi-media sources such as games and videos.

VST plug-ins available

This VST version of RACE has two controls for recursive delay and attenuation parameters to adjust for a variety of speakers, listening room geometries, and recordings.with unusual stage properties such as 40 foot pianos. As with other RACE implements, needed for surround are two instances running of the VST plug-ins and hardware that supports 4.0 or 5.1 input and 4.x output. (Note: a 5.1 center input must be mixed into L & R front channels by setting the player to "no center").

Ambiophonic DSP

AmbioDSP vst plugin

This is a very sophisticated version of RACE which includes a variety of novel adjustments to cope with unusual recordings, loudspeaker arrangements, or just personal preferences.  A user guide and ordering information can be obtained by going to www.filmaker.com/products.htm   Some non-vanilla RACE algorithms include Pop, Electro/game, Jazz/acoustic, Classical/movie, Wareing, and Bypass.  Wareing is an example of nonrecursive crosstalk cancellation and was used extensively before RACE became feasible.  A Zentrum control allows central soloists to be made louder or softer and a Space control boosts ambient content if desired.  There are also memory locations to allow custom configurations to be stored and recovered.  Two instances of this plugin can be used in surround sound applications or to enhance stage width and realism even when playing 2.0 media.

Ambiophiles tools

DIY Ambiophonics & PanAmbio surround

Recursive Ambiophonic Crosstalk Eliminator (RACE) -- turn your PC into an Ambiophonics DSP

You must install AudioMulch on your computer, learn how to use it, and then load the free .amh file into the program. The AudioMulch screen is shown below with some installation notes. Using a digital input or a .wav file, direct the AudioMulch output to your sound card, built-in speakers or cd burner.

* Using a browser capable of displaying formatted XML (XML with tags) such as Internet Exporer, click here to display the file in a browser window. Save the formatted XML as RACE40.amh or any suitable name with an .amh extension.

* Download and install AudioMulch www.audiomulch.com. Open your .amh file in AudioMulch. Your screen should look similar to the image below.

AudioMulch screen
(See Tutorials-Understanding and Installing an Ambiophonic System for further advice on adjusting the program parameters
.)

Configuring Surround Speakers for Concert Hall Ambience

One principle of Ambiophonics sound reproduction is that the frontal stage generated by RACE (and optionally enhanced by Envelophonics) should be complemented by concert hall ambience either recorded as a rear pair and reproduced from 4.0 media using RACE in the rear (Panambiophonics) or generated from real concert hall impulse responses.  In the case of 2.0 (and most 5.1) media such as LPs and CDs using hall IRs is the only available option.   Indeed modern 3D hall impulse responses can be used to produce very natural spatial channels for virtually any number and location of ambience speakers.  An impulse response can be thought of as a recording of what happens to a single sample of sound launched from the stage and then bounces around in the rest of the hall. 

In the diagram below, AudioMulch a low cost digital audio workstation, and Voxengo (registration payment required for this version) can be combined to produce hall ambience for virtually any number of hall ambience loudspeakers using one ordinary PC or Mac computer.  The output is normally via a single USB cable which then needs to be demultiplexed into digital or analog signals for power amplifiers and speakers.  At this time such Multichannel Audio Digital Interface (MADI) equipment is only to be found in professional recording engineer catalogs.  The RME ADI-6432/MADIface USB is one example of such hardware.  Neither the speakers nor the amplifiers need be full range or expensive.  Even as few as two is better than none.  But the process of creating a domestic concert hall is not for those lacking computer or DIY skills.

AudioMulch screen

 

Thanks to Prof. Angelo Farina, and Dr. Justus Verhagen, 3D impulse responses are available for La Scala, The Sydney Opera House, and St. Cecilia.  These are 96/24 IRs and cover both an entire circle in the horizontal plane and a selection of elevations.  Provided below is a set of IRs from St. Cecilia, reverb time 2.2 seconds, for every 15 degrees in a circle at an elevation of 23 degrees but with some at the rear elevated by 60 degrees.  So if you put a speaker at 90 degrees to the right you would feed it a right stereo input convolved with the 90 degree IR. The IRs are .wav files and can be loaded into Voxengo which itself is a VST plugin that can be used in many programs.  It is not feasible to put the entire set of IRs for all the halls on this site but if you wish additional IRs please send an e-mail to glasgal@ambiophonics.org 

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