5.2.5™ ENCODER

Circle Surround®

USER'S MANUAL

C. E.

Your Circle Surround 5.2.5 Encoder has been tested and complies with the following Standards and Directives as set forth by the European Union:

� Council Directive(s): 89/336/EEC

• Standard(s): EN55013, EN50082-1

This means that this product has been designed to meet stringent guidelines on how much RF energy it can emit, and that it should be immune from other sources of interference when properly used. Improper use of this equipment could result in increased RF emissions, which may or may not interfere with other electronic products.

To insure against this possibility, always use good shielded cables for all audio input and output connections. Also, bundle audio cables separately from the AC power cables. These steps will help insure compliance with the Directive(s).

For more information about other Rocktron products, please see your local dealer or one of our importers closest to you (listed on the enclosed warranty sheet).

Introduction The 5.2.5 Advantage The Circle Surround Encoder

Front Panel Rear Panel Quick Setup Advanced Setup

Encoder Interfacing Production Techniques

Mixing / Panning Considerations Outboard Signal Processing Devices Compressors, Expanders, Limiters and Gates Reverberation and Ambience Processors Stereo and Multiple Microphone Considerations Pre-Production Considerations Music Production Drama Productions Advertising Productions

Specifications

CONTENTS

Are you recording in Circle Surround®?

If you are producing material in Circle Surround, RSP Technologies highly recommends that the material be marked that it was recorded in Circle Surround, either by the authentic Circle Surround logo, a simple "C

S", or "Recorded in Circle

Surround". This notifies the general public that the greatest listening enjoyment can be derived by playing the recorded material back through a Circle Surround Decoder (or any device providing Circle Surround decoding circuitry).

Should you wish to identify your material as having been recorded in Circle Surround, please contact RSP Technologies for trademark approval at the address or phone number below.

RSP Technologies 2870 Technology Drive

Rochester Hills, MI 48309

Phone: (810) 853-3055 Fax: (810) 853-5937

E-mail: info@rsptech.com

1. INTRODUCTION

RSP Technologies Circle Surround® system is a powerful multi-dimensional matrix surround sound format designed for exclusive-audio as well as video-sound applications. Circle Surround creates a listening environment which places the listener "inside" music performances, and dramatically improves both hi-fi audio and conventional surround-encoded video material. Unlike other popular matrix "surround" systems, Circle Surround provides true-stereo rear channels to greatly improve separation and image positioning—adding a heightened sense of realism to both audio and A/V applications.

The 5.2.5 Advantage

With 5.2.5, Circle Surround is now the only matrix surround system in the world that is capable of encoding up to 5 indepenent signals down to a stereo L

T/R

T signal, with the ability to then decode the signal back into 5 individual

channels with greater than 30dB of channel separation. In addition, Circle Surround also decodes all other surround-encoded material, and creates a surround environment from any stereo source. This greatly improves separation and image-positioning—increasing the sense of realism when viewing films, and adding a new dimension when listening to music.

The complete Circle Surround system is comprised of three components—the Circle Surround 5.2.5 Encoder, the Circle Surround 5.2.5 Decoder and the Circle Surround 5.2.5 Controller. Utilizing the complete system allows audio engineers to place any voice, instrument or sound effect at any predetermined location in the 360o radius enveloping the listener, and provides features like these:

Music Mode unlocks the music from both encoded and non-encoded sources. This patented technology retains the original artistry of the recording while extracting ambient information that envelopes the listener.

Video Mode uses a dynamic center channel and techniques developed for the music mode to maintain the stereo soundfield—even in the presence of dominant center channel information that causes other systems to collapse into mono. Patented multi-band steering technology allows the 5.2.5 processor to decode full bandwidth stereo surround channels from programs encoded with only a mono surround track.

5.1 Channel-like performance from the patented Independent Channel Decoding with 59dB of separation between the L-C-R and opposing surround channels. Full separation and imaging is maintained during the presence of dominant center channel information. Program sources can be broadcast, DSS, laser discs, audio and video cassettes, compact discs or vinyl records.

Full Bandwidth, Stereo Surround Channels use a patented multi-band steering technique that provides 29dB separation between the left and right surround channels. Only 5.2.5 matrix technology provides the ability to present different signals to the surround channels simultaneously.

Advanced Steering Logic retains soundstage imaging—even with an active center channel—with no fuzziness or image-wandering experienced with other matrix decoders. There are no undesirable artifacts from heavy-handed steering or DSP that add delays or reverb not intended by the recording artists or sound designer.

Backward Compatibility with 4-2-4 matrix systems. Programs encoded with other matrix systems can be played back and sound better than the original decoders.

The Circle Surround Encoder

The Circle Surround 5.2.5 Encoder provides the ability to encode five channels of information into a conventional two-channel (L

T/R

T) output. This is accomplished by utilizing the relative amplitude and phase relationships of the

five input signals and effectively encoding them to a left total/right total output storage or transmission signal.

The left, center, right, left surround or right surround will be processed to provide the proper phase and amplitude relationship to the left and right outputs. The Circle Surround 5.2.5 Decoder will then decode these signals and send each to its proper speaker location.

The Circle Surround encoding process is completely compatible with all popular surround formats, as well as two-channel stereo and single-channel mono reproduction equipment.

This user's manual will detail various applications for the Circle Surround 5.2.5 Encoder. Please keep it for future reference.

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2. FRONT PANEL

(1) POWER switch and LED indicator The POWER LED will be lit when power is applied to the unit and the power switch is in the ON position.

(2) 5.2.5 / 4.2.4 select switch This switch determines whether the 5.2.5 Encoder operates in 5-channel or classic 4-channel mode.

(3) channel LED indicators These LEDs indicate signal presence (>-20dB below nominal) and clipping for each input (left, center, right, left surround, right surround and low frequency effects).

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3. REAR PANEL

(1) 25-pin INPUTS connector This balanced XLR connector provides inputs for all channels. The pin configuration for this connector is shown below. Preferred cable assemblies are available are available from Hosa Technology, Inc. (714) 522-5675.

INPUTS connector pin configuration

(2) 9-pin TO CONTROLLER connector This 9-pin connector accepts signals from the Circle Surround 5.2.5 Controller.

(3) 9-pin METER OUTPUTS connector

This 9-pin connector provides outputs to drive a meter for each channel.

(4) LEFT TOTAL and RIGHT TOTAL Output connectors (XLR) These XLR connectors provide the servo balanced left and right encoded outputs of the 5.2.5 Encoder.

(5) POWER jack This 4-pin DIN jack accepts power from the 9VAC adapter supplied with the unit.

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4. QUICK SETUP

Several different configurations are possible when interfacing the 5.2.5 Encoder to a mixing console, allowing you to configure the system to best suit your production requirements. It is common to connect the main Master Left and Right output to the Left and Right inputs on the Encoder, then connect Center, Left Surround and Right Surround to the sub master group outputs. An alternative connection would be to connect Left, Right, Center Left Surround and Right Surround to five separate sub group outputs.

TO CONTROLLER connector pin configuration

METER OUTPUTS connector pin configuration

Figure 1

Figure 1 illustrates a quick setup interfacing sub-group outputs to the Encoder. The Left and Right outputs from the Encoder are then connected to a master 2-track recorder, as well as to the inputs of a Circle Surround 5.2.5 Decoder.

Although the Circle Surround 5.2.5 Encoder is compatible with all popular surround decoders, it is essential to

monitor the production through a 5.2.5 decoder during the mixdown process to monitor the positional aspects of the production. When this is not performed, the full potential of the image-positioning capabilities of the system cannot be monitored.

Figure 2 illustrates incorporating the Circle Surround 5.2.5 Controller and Panner to the system.

IMPORTANT! Note:

Due to the fact that 5.2.5 matrix technology is proprietary to RSP Technologies, the Circle Surround 5.2.5 Decoder is the only surround decoding system capable of decoding five independent channels from 5.2.5 encoded material.

It is therefore very important that material encoded in 5.2.5 mode is monitored through a Circle Surround 5.2.5 Decoder during the encoding process. The use of any other surround matrix decoder to monitor a 5.2.5 mix will result in unpredictable and possibly unintended results when the finished mix is played back through a Circle Surround 5.2.5 Decoder. Any mix encoded in 5.2.5 will provide compatible and stable playback performance with any other 4-channel matrix decoder (with the exception that the surround channel will be restricted-bandwidth mono).

However, material encoded in 4-2-4 mode can be monitored with any standard matrix decoder during mixdown.

Figure 2

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5. ADVANCED SETUP

The Circle Surround® 5.2.5 Encoder is a 5-to-2 matrixing system, accepting five independent signals and encoding them into a stereo (L

T/R

T) signal. Each input (L, C, R, LS, RS) utilizes a specific amplitude and phase relationship

relative to each of the other inputs.

Figure 3 is a simplified block diagram of the basic encode process*. Here LT and R

T are the total encoded outputs of

left, center, right, left surround and right surround, with their corresponding phase relationships. Blocks F and F-90o are all-pass networks providing a flat response with respect to amplitude, but incorporate a frequency-dependent phase response. (Such phase shifts are required in order to provide an interior-position mixing capability and smooth panning between channels.)

Figure 3

Simplified Block Diagram In 5.2.5 mode, each surround input (S

L and S

R above) is fed into its respective channel's output at .707, and its

opposite channel's output at .549. When the system is switched to 4-2-4 mode, each surround input is fed into both outputs at .707.

* The Circle Surround encode process described herein is the subject of one or more currently pending United States and foreign patent applications. Any use of this technology apart from the device described in this manual, without the expressed written permission of the patent holder, is strictly prohibited and will be pursued to the fullest extent of the law.

Figure 4 (below) is a block diagram illustrating the encoded separation relationships between the L, C, R, LS and RS channels produced by the 5.2.5 Encoder. Although the separation between adjacent channels is only approximately -3dB (as shown in Figure 4), the advanced steering logic circuitry incorporated into the Circle Surround 5.2.5 Decoder greatly enhances the separation between these channels. The presence of this condition makes the Circle Surround encoding format highly compatible with other conventional logic and non-logic decoding systems.

When encoded information is played back on a conventional two-speaker stereo system, left and right information remains accurately assigned while center information is assigned to both channels. Surround information will also appear in both channels at a reduced amplitude.

Single-channel systems will produce all channels with the exception of the surround signals. The material in the surround channels will produce fade-ins and fade-outs that create an imaging effect not unacceptable to the listener.

Figure 4 Encoding Separation (without steering)

Encoder Interfacing

When the Encoder is interfaced with the mixing console, several configurations may be considered to best suit your production requirements. One method is to connect the left and right main outputs of the mixer to the Encoder's Left and Right inputs. Then connect sub-group outputs to the Center, Left Surround and Right Surround inputs of the Encoder, as shown in Figure 5 below.

Arrows pointing toward LS and RS depict the surround information relationship only.

Figure 5

Figure 5 also illustrates the use of the LFE (Low Frequency Effects) input. This input allows for all channels of an existing 5.1 mix generated for a digital surround encoder to be fed directly through the 5.2.5 Encoder from a digital

multi track recorder. In addition, it also provides an input for a dedicated low frequency effects channel from the mixing console.

Note: There is no internal filtering provided at the LFE input. A dedicated low frequency effects channel must be low-pass filtered prior to connection to this input, otherwise the signal will appear at the center channel location.

If better separation is required, connect separate sub-group outputs to the Left, Right, Center, Left Surround and Right Surround inputs on the 5.2.5 Encoder. In this configuration, any channel may be assigned to any particular Encoder input. If the mixer's Sub Assign switches on each channel select two sub-groups at a time (i.e., 1 to 2, 3 to 4, etc.), then that particular channel may be panned from Left to Right or Center to Surround.

The most common approach is to assign various console sub-group outputs to Left, Center, Right, Left Surround and Right Surround inputs on the 5.2.5 Encoder. If the console is capable of panning between any two group outputs, only four group outputs will be required. (If this is not possible, the Circle Surround Controller, which interfaces four signal-steering joysticks to the Encoder, is recommended. Feeding a direct or sub-group output from the mixing console to the Controller will send the signal to the Encoder and direct the signal anywhere in the mixing space based on the position of the joystick.) Since most consoles do not have this capability, but do have panning between odd and even groups, it is necessary to assign more than one group to the same Encoder position. Once this is done, the L

T and R

T outputs of the Encoder are returned to a Pre-Master Fader insert point on the mixing console to allow

master fader control of the encoded program. (The performance of the Encoder will be dependent upon the tracking capabilities of the Fader controls on the console (otherwise, the L

T and R

T relationship cannot be guaranteed. An

example of this is shown in Figure 10.)

Some mixing consoles provide greater flexibility by providing quad panning (Left Front, Right Front, Left Surround and Right Surround). Consoles such as these are equipped with both left-to-right and front-to-back panning controls. These panning controls allow for continuous Circle Surround panning when used in conjunction with the 5.2.5 Encoder.

If the mixing console only has left and right panning, Circle Surround encoding is still possible if the mixing console is equipped with auxiliary sends and Pre and Post fader controls for individual channels. To interface this type of console to the Encoder, connect the left and right outputs to the Left and Right inputs on the Encoder, and connect an auxiliary output to the Encoder's Left or Right Surround input. With this configuration (and the Auxiliary Send control set up in a post-fader mode), the input signal can be panned from left to right, and partially into the surround position (this is due to the left and right pan control still producing an output). If it is desired that the signal go completely to the surround position, the Auxiliary Send control should be set up in a pre-fader mode. In a pre-fader mode, the fader can be turned down—attenuating the left and right pan control. If additional flexibility is desired over image-positioning, connect the auxiliary send to an input of the Circle Surround Controller and use the joystick to position the signal.

Sub-group outputs inserted into the inputs of the Circle Surround Controller are processed with the relative phase and amplitude depending on the joystick position. This signal is sent to the Encoder through a 9-pin D-sub cable. The use of joysticks for panning provides greater positional control not previously possible (i.e. panning from Left to Surround, Right to Surround or Left, Center, Right to Surround). In addition, when the Controller is connected to the Encoder via the 9-pin D-sub cable, the main L, C, R, LS and RS inputs on the 5.2.5 Encoder are still operational.

More than one Controller may be connected to an Encoder. Figure 6 shows a configuration interfacing four Controllers to a single Encoder by connecting the EXPANDER OUT D-sub connector of one Controller to the EXPANDER IN of the next Controller. The ENCODER OUTPUT of the last Controller in the chain connects to the

TO CONTROLLER of the Encoder. Stacking Controller units in this fashion allows for the use of up to four Controllers before noise may impair the performance of the system. The main inputs on the Encoder (L, C, R, LS, RS, LFE) remain operational in this configuration—providing further patching capabilities.

Figure 6

In addition, more than one Encoder can be used at a time during a production, with their outputs combined to form a final L

T and R

T. Previously encoded material will be passed through the left and right inputs of the second Encoder

without alteration and initiated into the new production. Once the Circle Surround encoding process has been generated, its integrity will be preserved as long as the relative amplitude and phase relationship between the channels has not been significantly altered during the production or playback.

Figures 7 through 10 illustrate further configuration examples utilizing the complete Circle Surround system.

Click to view:

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6. PRODUCTION TECHNIQUES

Mixing / Panning Considerations

If difficulties should occur regarding localization interactions between two or more sound elements, panning one of the signals toward the interior position and reducing its amplitude will typically eliminate such interactions. As experience in mixing in Circle Surround is developed, more complex, discrete-sounding mixes can be produced.

Circle Surround program mixes are totally backwrd-compatible to stereo and mono, as well as with other matrix systems.

Outboard Signal Processing Devices

Circle Surround places no unique restrictions on the use of signal processing gear such as limiters, compressors, gates, equalizers and reverberation equipment. In general, single-channel input signals can be processed as desired. However, after a L

T and R

T program has been produced, any further processing must be equally applied to both L

T

and RT, as separation of L, C, R, LS and RS is dependent upon phase and amplitude. Applying different equalization

to LT and R

T will cause the program signals to become more diffused and spread across the front speakers. Because

dissimilar equalization implies a phase-shift between channels, images will tend to spread toward the rear position.

� Figure 7 - Aux outs to Controller/Main & group outs to Encoder � Figure 8 - Main & group outs to Controller and Encoder � Figure 9 - Same as above with CR monitor outs to Decoder � Figure10 - Alternate version of Figure 9

IMPORTANT! When encoding material in 5.2.5 mode, it should be noted that placing a non-correlated, stereo signal hard to the left and right surround positions, without any portion of that stereo signal present in any other channel of the 5.2.5 Encoder, should be avoided. This particular condition can cause unpredictable steering upon playback through the Circle Surround 5.2.5 Decoder. However, the desired effect can be achieved by simply feeding a small portion of the stereo signal to the left and right front channels, as the 5.2.5 Decoder will steer the signals to the respective surround channels—provided they are dominant in the surround channels by at least 15dB in the mix. Further experimentation and continued experience with the unit will increase the user's familiarity with this technique. Note that the above only applies when panning a non-correlated stereo signal in 5.2.5 mode, and that any given single signal can be panned completely to the left or right surround position without producing undesirable effects. The condition described above does not apply when operating the system in 4-2-4 mode.

Compressors, Expanders, Limiters and Gates

In amplitude-related signal processing, these devices are typically implemented for signal clean-up, dynamic range control and program signal effect. The application of these devices in Circle Surround is very similar to conventional stereo and mono applications, as they are typically used on individual production signals or sub-mixes, as opposed to a complete mix. If devices such as these are desired to be used on a completed mix, consideration should be given to maintain equal L

T and R

T gain reduction, or modification in the decoding process will occur.

Reverberation and Ambience Processors

Signal processing devices which create various ambience effects offer a variety of mixing opportunities when used in a Circle Surround production. By returning the outputs of such devices to front and surround channels, certain ambience effects can be created that envelop the listener.

Circle Surround provides an advantage in that this difference material can clearly be heard as surround material, and can be more readily identified and repositioned. Several different techniques can be applied, such as changing the processor characteristics or panning its output toward the center position. Panning the outputs of such devices hard-left and hard-right will produce a reverberation effect that will envelop the listener. This effect will predominantly come from the surround channels. Then, as the signals are panned away from hard-left and right, this effect will gradually begin focusing toward the front until they are panned center. When panned center, the reverberated signals will be focused in the center channel speaker only.

Stereo and Multiple Microphone Considerations

When two or more microphones are used to pick up a single source, it can be said that stereo microphone techniques are being applied. In general, such techniques are performed intentionally by applying a variety of spaced pair, near coincident and coincident mike arrangements. In some multi-microphone recording applications, various instruments unintentionally bleed into mikes placed for other instruments. This undesirable condition is often unavoidable when applying stereo microphone techniques. When recording in Circle Surround, the net result of applying such techniques is that the decoding process, responding to the relative amplitude and phase conditions of these paired signals, will position them between the front and surround speakers.

In order to achieve the desired results, it will be necessary to have as much control as possible over the relative amplitude and phase relationship of these microphones through both their selection and placement. The 5.2.5 Encoder can be used in such applications for precise spatial positioning in the final mix. As a precautionary measure, the microphones and cables should be checked for polarity by speaking into two microphones simultaneously. If the microphones and cables are in phase, both signals should be heard from the Center channel speaker only. If this is not checked, signals could potentially appear in the surround channels unintentionally.

In stereo microphone applications, the correlation between mike output signals decreases as the distance between the mikes increases—resulting in ambient-like sounds appearing in the interior and surround positions. These results are not typically representative of the performance in acoustic space, nor consistent with the ambient objectives of the production. More acceptable results are obtained through the use of coincident or near-coincident mike arrangements.

Typically, x-y or mid side stereo microphones with cardioid and bi-directional side patterns are well suited for Circle Surround production. By observing the resulting left and right polar patterns produced by combining various levels of mid and side signal sources, sounds in front of the microphone will be decoded uniformly across the front speakers. If the signal is panned dead-center, it will emanate from the center channel. If the signal source is off-axis of center, then the signal will pan to the left or right depending on the position of the Pan control. (If the signal is panned hard-left or hard-right, it will appear in the left rear or right rear, respectively.) Sounds to the rear of the microphone will be decoded to the rear surround channels.

Pre-Production Considerations

In the pre-production phase of a project, it is beneficial to establish an audio objective based on the capabilities of Circle Surround. Because Circle Surround provides three additional channels (C, LS, RS) compared to traditional stereo, it must be decided what to place in these channels. First conceive imaging objectives, then determine how to achieve those based on the advantages and limitations of the interfacing scheme of your system to Circle Surround.

In television sports productions, for example, several audio elements are involved—such as music, announcing, crowd ambience and sounds resulting from sports action. The most common imaging objective for such a production is to create a sense of being at the actual event, with all-around crowd ambience and the announcer panned to the center. Music in such productions is generally mixed with a wide frontal sound and a noticeable interior ambience. Realistic crowd noises can be created by positioning at least four crowd microphones, with one group panned between left and interior position and right and Interior position, and another group in a similar position but panned further back toward the surround positions.

Action sounds are generally panned to the center to avoid listener confusion as the camera(s) changes view.

Music Production

Music production applications typically fall into one of two categories—popular and classical. Creating a unique sense of acoustic space is a major part of popular recording, whereas capturing the sense of the performance space is important to classical music productions.

When mixing with Circle Surround in popular music applications, it is good to start by mixing the sound elements toward the front (L, C, R) positions with the outputs of effects toward the interior position. Instruments panned hard-left or hard-right will tend to be panned toward the surround channels.

After the mix is generally roughed in, further refinements can be made to the front and surround positions. In live production applications, refinement of the mix can be made during rehearsals (whereas a post-production environment offers more opportunities to optimize the mix). A live audience can be integrated into the mix in a similar fashion as is described for a television sports production.

When mixing a classical music production, it is good to start by using a stereo microphone for overall ensemble pick-up, with its mid side ratios selected to spread the musicians across the left, center and right speakers. In addition, directional microphones should be placed in the performing space with their null points in their patterns aimed at the ensemble to capture the ambience of the hall. The outputs of these microphones should be panned hard

left and hard right, as the ambience information will then be panned to the rear speakers. In situations where the performance space is acoustically undesirable, the inclusion of the hall ambience microphones would be inappropriate, as outboard digital reverb devices could be used in their place. These devices would be driven by the ensemble microphones, with their outputs panned left/surround and right/surround to achieve the desired ambient effect.

Drama Productions

Drama productions are typically produced in a similar fashion as motion picture productions. These productions submixes for dialogue, music and effects, and combine these in the final mix for the master. When using the Circle Surround format, individual dialogue, music and effect L

T and R

T mixes are developed for later remixing into a final

release.

If the production has not yet been encoded individually, LT and R

T mixes can also be developed by using a single

Encoder in conjunction with a Circle Surround Controller, whech has four joysticks for positional control. The design of the Encoder allows for more than one Controller to be interfaced with a single Encoder—thereby providing as many channels as is needed for the production.

Advertising Productions

Due to the almost standard stereo transmission of television broadcast, product and industrial advertising can be effectively delivered to consumer's homes in the Circle Surround format. With the exploding number of home audio systems providing the ability to decode such productions, the Circle Surround process offers additional mixing capabilities to producers of such commercials to increase the impact of their productions.

The mixing environment for these productions is similar to the mixing techniques already discussed, where the final mix is being created from individual dialogue, music and effects sub-mixes. The important element in these productions is that of good mono capability, and the ability of the production to get its point across—even if one channel is lost in the transmission. With the precise control of relative amplitude and phase with the Circle Surround encoding process, these concerns are more easily dealt with when compared to conventional two-speaker stereo production methods.

Industrial promotional productions, although commercial in nature, are typically created for specific playback environments (such as special rooms and dedicated audio systems using playback from high-performance video tape and disc formats). Many of these productions are now being produced using High Definition Television formats. The Circle Surround format provides an advantage for these productions in that the completed mix can be easily played back on conventional two-channel systems. The full potential of Circle Surround can be set up for maximum impact in the final mix of the production.

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7. SPECIFICATIONS

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Maximum Input Level Maximum Output Level

Input Impedance Output Impedance

Distortion Dynamic Range

Power Consumption XLR Configuration

+23dBu +23dBu

22k ohms less than 150 ohms

.002% THD typical (A-weighted) over 110dB typical (A-weighted)

9VAC/2A adaptor pin 1 = ground pin 2 = hot (+) pin 3 = cold (-)