The 4 Channel Ambiophonic Transcoder has a listing that allows you to select both inputs and outputs such as a CD player and an external reproduction system.
The Ambiophonic Transcoders have a center sound boost control to allow Ambio reproduction to sound more like the stereo loudspeaker triangle which doubles the lower frequency sound level for mono or central sound sources. This accommodates stereophiles who prefer this boost. An optional high frequency bypass feature avoids processing high frequencies where no audible crosstalk exists avoiding unpredictable HF level and polarity errors for some arrangements or settings.
VST plugin implements the full RACE protocol including adjustable bypass frequencies. Included is a calibrate mode that provides a left-to-right panning noise signal facilitating the setting of the cancellation controls. Click here to download the plugin (note the plugin is contained in a zip file).
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").
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.
How
good can stereo be? Try Ambiophonics and see. You can enjoy free Ambiophonics enhancement of CDs/DVDs/games
using your PC and soundcard or (better) external A-D-A converters. Optionally
using multi-channel converters, expand to 360° surround sound for
multi-channel music, movies, or games (with or without ambience convolution).
Choose either a) Recursive Ambiophonic Crosstalk Eliminator (RACE),
which turns your PC into an Ambiophonic DSP engine, or b) Choueiri multi-band
crosstalk cancellation (BACCH) using convolution. Not "virtual,"
these solutions preserve spatial information distorted by crosstalk
with ordinary stereo speakers.
This is the simplest and easiest to use RACE program configured for use in AudioMulch. You must install AudioMulch in your computer, learn how to use it, and then download the free .amh file into the program. The AudioMulch screen is shown below with some installation notes. You must be able to get a digital input to the sound input of the program and get its output to your sound card or built-in speakers.
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Using a browser capable of displaying formatted XML such as Firefox or Internet Exporer, click here to display the file in a browser window. Save the formatted XML as RACE.amh.
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Download and install AudioMulch www.audiomulch.com. Open RACE.amh in AudioMulch. Your screen should look similar to the image below.
(See Tutorials-Understanding and Installing an Ambiophonic System for further advice on adjusting the program parameters.)
Ambiophile Edgar Choueiri, professor of applied physics at Princeton University, has developed an improved crosstalk cancellation method that is an alternative to RACE in Ambiophonic sound reproduction. While RACE can attain ILD values of up to 10 dB the Choueiri program is capable of reaching ILD values as high as 20 dB. In music reproduction and in concert halls, ILDs seldom approach 10 dB and so RACE is adequate for use in Domestic Concert Halls. But if you want to localize sounds very close to the head (well in front of the loudspeakers) as are found in many scary recordings made using dummy heads, but using loudspeakers rather than earphones, then one needs a crosstalk cancellation method that can deliver very high values of ILD.
BACCH bandsplits L & R signals and optimizes regularization of crosstalk cancellation of each before recombining with direct signals. BACCH is not adjustable so the listening configuration is fixed as follows: distance from speakers = 170 cm; speaker separation = 50 cm but the distances can be scaled as long as the angle to the listener remains the same.
It is beyond the scope of this site to specify all the ways that an impulse response can be convolved. One needs to be able to feed the sound signal into the input of convolver which essentially uses the impulse response to operate on each input sample and feed the result to the convolver output. The Impulse Response is in the form of wave files.
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Download BACCH ver3 (2x2 .wav file filter for convolution);
Configuring Surround Speakers for Concert Hall Ambience
One principle of Ambiophonic sound reproduction is that the frontal stage generated by RACE should be complemented by concert hall ambience generated from real concert hall impulse responses and fed to virtually any number and location of surround speakers. At the present time, there is only one affordable method to do this known to the author. One downloads the IR-L VST plugin from WavesAudio and clicks on Plug Ins on the top menu and purchases IR-L. IR-L is a program that operates under the same AudioMulch program that processes RACE software (see above).
Using a browser capable of displaying formatted XML such as Firefox or Internet Exporer, click here to display the file in a browser window. Save the formatted XML as Ambience_Only.amh and open it in AudioMulch. It is also possible to load RACE.amh in the same AudioMulch window, providing additional functionality. Some 100 hall impulse responses can be obtaned from Waves Audio, Ltd. and loaded into the various instances of the IR-L VST plugin. The image below shows 7 different impulse responses being used to drive 14 surround speakers. Diversification is the name of the game, and so different but related impulse responses should be selected for each of the plugins. See the Recording Concert Hall Acoustics for Posterity paper elsewhere on this site for further information.
