Reflection Chamber Emulation system (RCE) has been developed in order to create a natural harmonic early reflection surround space for acoustic recording.

The system allows you to recreate a controlled standing waves flow on certain frequencies thus creating a real harmonic early reflection surround space.
The chamber is pointed at the sound source and than miked with an inverse-M/S technique or using one of the Renaissance X-Techniques. This recording will be tracked on 2 separate recorder tracks. During the mix stage these tracks will be decoded (with the X-mat if used in X-techniques or in MS matrix if used in inverse MS) and then encoded as surround channel in the Dolby Surround format.

The RCE has been developed to get a natural 3D environment during the Dolby Surround encoding process for the RENAISSANCE SFX library. The RCE environment has the peculiarity to be harmonic and for this reason it is best suited for music acoustical recordings.

Tracks produced using RCE techniques will give you very good results also in 5.1 productions, simply decoding them with a Prologic decoder and addressing the S channel to mono Ls and Rs. As a matter of fact the natural harmonic content of the early reflections generated by the RCE, can be further processed for example with a stereo reverb processor just using its late reflections on the Ls and Rs surround channels.

The psychoacoustic character of the spatialization generated by the RCE tech is extremely natural and "musical", generating a pleasant surrounding sense into the listener without distracting motions, thus guaranteeing a solid musical background where to build up dialog and fxs.

A separate track is also generally provided for the LFE channel. Such track will be generated from the original recording extracting the lowest tonal band with a proprietary technique called LFX (see later).
The RCE has been used for the first time producing CD 10 and 11 (Drama strings and Strings Construction Set) of the RENAISSANCE SFX library with excellent results. More applications of this technique will follow in the future.


Structure:
The chamber is composed of 2 planes at 90 degrees X,Y and 2 planes at 30 degrees on the Y plane (used to focus the sound source on the X plane).
The RCE has been build in plexiglass due to its reflective characteristics.
The width of X plane l1 will set the frequency range available. Its lenght it will give us a number of bands.
l1 will determinate the frequency f at equal constant K.
K/f= l1 if K=341 M/S than 341/f=l1
Values are expressed in meters and Hz.
The Y axis will determinate the amplitude of the standing waves (volume).
Since the sound will be amplified by the microphones preamps, it is not relevant to measure an absolute SPL amplitude value, but it is rather important to establish a relationship among the components in order to calculate the summing frequencies that compone the generated spectrum.


Gates:
Gates are composed by a number of plexiglass strips. Their position on the X plane determinate the frequency of the standing wave for each band, while their high will establish the amplitude of that band. Depending the width of the X plane you can place any number of gates (=number of bands).
For bests results we recommend a minimum gate width of 5cm.
The Y plane will determinate the maximum wave amplitude (volume). Since it's important to establish a relationship of amplitude among the components of the RFE, we suggest to build different gates with highs that are multiple one of the others (i.e. 5 cm, 10 cm, 20 cm etc.).
On the X plane you can place freely the gates at any position so that you can calculate an exact frequency for that band.
Many different studies have been already done for calculating harmonics using the RCE. For example in the CD 10 it has been calculated a different harmonic table for each chord, while on CD 11 a different character has been given in the RCE for each kind of music texture.
We are actually studying many different applications of the RCE like live recordings, realtime sound processing etc.


Inverse MS:
Beside the X-Techniques a special MS technique has been developed for the RCE recording.
A figure 8 microphone (side) is placed around the focus of the RCE at about the half high of the Y plane. A highly directional microphone (i.e. a shortgun) is placed near coincident to the figure 8, but pointed to the direct source instrument that generate the base harmony (generally the bass).
The directional mic (Mid) during the MS decoding cancel the tonal sound weight that arrives at the figure 8, leaving a cleaner stereo early reflection image of the RCE.
Such image is then feed in the LR inputs of the Dolby Surround encoder, the phase difference is automatically encoded as surround channel preserving just the harmonics generated into the chamber.
The MS decoding is done with the X-mat in order to balance the phase of the figure 8 diaphrams against the directional mic. This balancing is necessary due to the gates positions on the RCE that might have different sizes on left and right sides of side microphone.
Using the inverse MS you need to mike the direct source independently (ORTF, XY etc.) in order to create the stereo front, while using the X-techniques you include the RCE as surround space like in a normal location recording. We suggest to use the inverse MS in studio recordings, while the X-techniques are best suited for live performances.


2000 - RCE is patent pending and belongs to Renaissance Sound Technologies. All rights reserved worldwide.