Dolby Surround Mixing Manual Part No.
Dolby Surround Mixing Manual Dolby Laboratories, Inc. USA Headquarters Dolby Laboratories, Inc. 100 Potrero Avenue San Francisco, CA 94103-4813 Telephone 415-558-0200 Facsimile 415-863-1373 UK European Licensing Liaison Office Dolby Laboratories Wootton Bassett Wiltshire SN4 8QJ England Telephone (44) 1793-842100 Facsimile (44) 1793-842101 Far East Dolby Laboratories International Services, Inc.
Dolby Surround Mixing Manual Table of Contents List of Figures .................................................................................................................vi List of Tables.................................................................................................................viii Chapter 1 Introduction ................................................................................................ 1-1 Chapter 2 Technical Guidelines .............................................
Dolby Surround Mixing Manual 3.6 3.5.1 Internal Switches—CAT 344 information ........................................ 3-8 3.5.2 Center Speaker Switch .................................................................... 3-9 3.5.3 Wake-up State ............................................................................... 3-10 3.5.4 Local/Remote Fader ...................................................................... 3-10 3.5.5 EPL Switch ................................................................
Dolby Surround Mixing Manual 7.5 7.6 7.7 7.8 7.9 7.10 Dolby Surround Game Mode Encoding ....................................................... 7-2 Modification Principle ................................................................................... 7-3 Application Information ................................................................................ 7-4 SEU4 Game Mode Alignment......................................................................
Dolby Surround Mixing Manual List of Figures Figure 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9 2-10 2-11 2-12 2-13 2-14 2-15 2-16 2-17 2-18 2-19 2-20 2-21 2-22 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-12 3-13 3-14 3-15 3-16 3-17 3-18 3-19 3-20 4-1 4-2 4-3 Description Page Dolby Model SEU4 and SDU4 ..................................................................... 2-1 Typical Room Layout ...................................................................................
Dolby Surround Mixing Manual 4-4 4-5 7-1 7-2 7-3 7-4 7-5 7-6 7-7 8-1 8-2 Standard X-Curve ........................................................................................ 4-4 Modified X-Curves........................................................................................ 4-4 Phase Shifter and Positioner ....................................................................... 7-2 Signal Flow for Game Encoding ..................................................................
Dolby Surround Mixing Manual List of Tables Table 3-1 3-2 7-1 Description Page EPL Connections ....................................................................................... 3-12 Delay Switch Settings ................................................................................ 3-14 Dolby Surround Game Encoding Options....................................................
Dolby Surround Mixing Manual Chapter 1 Introduction Dolby® Surround is a format that enables the production and delivery of multi-dimensional soundtracks for television, cable, consumer video, compact disc, video game and other stereo media. Once created, Dolby Surround soundtracks can be recorded, broadcast and reproduced in the same manner as any conventional stereo programs, including compatible monophonic playback.
Dolby Surround Mixing Manual Chapter 2 Technical Guidelines 2.1 Equipment from Dolby Laboratories The equipment described below exists in two versions. The newer one has much greater immunity to RF interference, and as sold in Europe with a single power line voltage, is compliant with the EMC standards of the European Union. Operationally the two versions are analogous, and this manual applies to both. Older units have a “gold” finish to the tray and top, the more recent ones a “silver” finish.
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines Both the SEU4 and SDU4 are available for purchase from Dolby professional product dealers and for rent from several studio equipment rental houses. 2.2 System Information 2.2.1 Room Layouts The various room possibilities for working with Dolby Surround encoding all conform to a basic standard. They all require the typical Left and Right speakers we have grown accustomed to for stereo production.
Dolby Surround Mixing Manual 2.2.2 Chapter 2 - Technical Guidelines Control Rooms In order to achieve even Surround channel dispersion, Dolby Laboratories recommends that a room layout such as the one shown in Figure 2-3 use two Surround speakers. Figure 2-3 Sound Field Pattern with Two Surround Speakers For rooms similar to Figure 2-4, four Surround speakers better serve both the mix engineer working in the front of the room and the clients listening in the back.
Dolby Surround Mixing Manual 2.2.3 Chapter 2 - Technical Guidelines Remote Trucks Remote trucks producing live shows offer a challenge for Center channel speaker placement. The desired Center channel speaker position is usually either occupied by equipment and video monitors vital to production, or by the window to the main production area. In the latter case a Center channel speaker would block the line of sight to the director.
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines consumer level to correct channel imbalances introduced during transmission or tape duplication. Also, consumer decoders do not normally have enough time delay for studios or a simple way to compare Mono, Stereo and Surround compatibility. While suitable for small listening rooms, never use consumer decoders in control rooms as part of the mixing process. 2.3 Additional Equipment Required 2.3.
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines MONITOR L C R S S Figure 2-7 Incorrect Soffit and Center Speaker Placement The Surround speakers can be smaller bookshelf-type speakers. The actual frequency response of the Surround channel is 100 Hz to 7 kHz so large speakers for bass reproduction and extended range tweeters for ultra-high frequencies are not necessary.
Dolby Surround Mixing Manual 2.3.2 Chapter 2 - Technical Guidelines Center Channel Speaker The Center channel speaker is used to anchor dialogue and other sounds to the screen. In conventional two-speaker configurations, the listener can only hear a balanced mix when seated exactly in the center or sweet spot, Figure 2-8. This configuration provides a good phantom image. Figure 2-8 Listener in Sweet Spot If the listener moves to either side of this sweet spot the mix becomes heavy on that side.
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines This produces an eye/ear conflict, since the visual and audio images don’t match. The addition of a Center speaker ensures that the center information, such as dialogue, stays locked on the screen no matter where the listener is seated, as shown in Figure 2-10. Figure 2-10 Defined Image Also, since most engineers are used to mixing with a phantom center, it is easy not to realize how much mono or center information a typical mix contains.
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines Figure 2-12 Ideal Setup—All Speakers Above Screen Figure 2-13 Ideal Setup—All Speakers Below Screen The goal is to place the high frequency drivers (tweeters) in a straight line. This may require turning the Center speaker upside down or sideways, as shown in Figure 2-14. Make sure that the high frequency driver is oriented for the correct dispersion characteristics if you place it in any position other than its normal one.
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines only option for the Center channel. The Dolby SDU4 allows for the smaller Center speaker, with its reduced low frequency capabilities, by redirecting the Center channel low frequency information below 100 Hz to the Left and Right speakers. For further information on implementing this function, please see Part 3.6.1 Bass Splitting Modification. 2.3.
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines Figure 2-16 Vertical Location of Surround Speakers in Control Room 2.3.6 Audio Consoles The console’s flexibility greatly affects surround mixing capability. While it is possible to create a Dolby Surround mix on a console with as little as a stereo bus and one auxiliary send, the ability to do complex mix moves is virtually nonexistent. A console with film-style panning allows the greatest flexibility for desired sound placement.
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines shown in Figure 2-18. A few manufacturers have installed patch points in the proper place for this purpose. If you have this feature, follow the console manufacturer’s instructions for installing the decoder. If you do not have this feature, some wiring or modifications may be required.
Dolby Surround Mixing Manual FROM SDU4 OUTPUT L FROM BUSS OUTPUT L FROM MACHINE OUTPUT 1 FROM SDU4 OUTPUT R FROM BUSS OUTPUT R FROM MACHINE OUTPUT 2 FROM SDU4 OUTPUT C FROM BUSS OUTPUT C FROM MACHINE OUTPUT 3 FROM SDU4 OUTPUT S FROM BUSS OUTPUT S FROM MACHINE OUTPUT 4 Chapter 2 - Technical Guidelines L TO MAIN MONITOR AMPS TO “B” MONITOR AMPS R TO MAIN MONITOR AMPS TO “B” MONITOR AMPS C TO MAIN MONITOR AMPS TO “B” MONITOR AMPS S TO MAIN MONITOR AMPS TO “B” MONITOR AMPS Figur
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines When producing home video releases, experience has proven that lowering the overall mixing room level to as low as 79 dB results in a mix with better dialogue levels. When mixing at 85 dB, mixers hear low level dialogue easily in quiet control rooms, but consumers lose some of the quieter passages due to the higher ambient noise levels in homes.
Dolby Surround Mixing Manual Chapter 2 - Technical Guidelines Figure 2-21 Tektronix 760 Phase Scope Display of Center Channel Information The Left, Center and Right channels will appear across the top and the Surround channel will appear at the sides. Information that is in all channels will appear somewhat circular as in Figure 2-22. Individual channel information appears on the appropriate vectors.
Dolby Surround Mixing Manual Chapter 3 System Installation 3.1 Signal Routing Audio Connections 3.1.1 Inputs and Outputs The audio inputs and outputs of both the SEU4 and SDU4 use electronic floating balanced circuits and do not use ground as reference. They should be wired as you would an item with input/output transformers. In particular both signal pins (2 and 3) of the XLRs must always be connected.
Dolby Surround Mixing Manual Chapter 3 - System Installation We strongly recommend that all audio interconnections employ twin-core shielded cable. At the SEU4/SDU4 end, irrespective of the nature of the equipment at the other end, connect the inner wires to pins 2 and 3, and the shield to the shell of the XLR, not to pin 1. Leave pin 1 opencircuit.
Dolby Surround Mixing Manual Chapter 3 - System Installation Note: Some equipment (not from Dolby Laboratories!) has balanced non-floating outputs on XLR connectors. Although they are described as balanced, they consist of two independent unbalanced outputs with respect to a signal ground, bearing equal audio signals of opposite polarity (resembling a center-tapped output transformer with the tap connected to signal ground).
Dolby Surround Mixing Manual 3.2.2 Chapter 3 - System Installation Basic Recording Setup with Film Panning Console The most versatile console setup uses a console with film-style (LCRS) panning. These consoles can pan from left to center to right and from front to back. This pan pot system can place sounds quickly and easily. These consoles will have left, center, right and surround outputs for connection to the encoder. The output of the encoder follows a flow similar to the above example.
Dolby Surround Mixing Manual Chapter 3 - System Installation L L R R Lt L L Lt R L L C Rt R R Rt C R S Output 1 Output 2 Monitor Section Monitor In Monitor Out S SEU4 RECORDER SDU4 L R L R CONSOLE Figure 3-5 Signal Routing—Console with Monitor Section The only caution here is that the console monitor level must be set and the decoder level calibrated. Once this is done, do not move the console monitor level control.
Dolby Surround Mixing Manual Chapter 3 - System Installation L L L R R Lt L L C Rt R R S Output 1 Output 2 CONSOLE L Output 1 R Lt R Rt C Output 2 L R SEU4 S SDU4 TO BROADCAST CHAIN Figure 3-7 Signal Routing—Live Broadcast 3.3.4 Live Broadcast Setup with Fail-Safe Because of the addition of patch points to insert the Dolby® Surround encoder in the final outputs of the console for typical live broadcast applications, many mixers have adopted the use of a failsafe connection.
Dolby Surround Mixing Manual Chapter 3 - System Installation units are in the monitoring chain, not the recording chain. Such monitoring can also be used when tracking a music session that will be mixed later in Dolby Surround. L L R R Lt Lt R C C Rt Rt C S S CONSOLE L S SEU4 SDU4 Figure 3-9 Signal Routing—4-2-4 Monitoring 3.4 Dolby Model SEU4 Setup Normal operation of the SEU4 requires no modifications to the unit as it comes from the factory.
Dolby Surround Mixing Manual 3.4.2 Chapter 3 - System Installation External Processing Loop (EPL) Loop Switch The SEU4 can be used with an external processor inserted in a loop before the final output stages of the unit, Figure 3-11. In normal operation, this loop is unused. The processor is placed after the encoder outputs and before the next device in line such as the stereo master fader on the console. The EPL loop output is a separate output with its own level controls.
Dolby Surround Mixing Manual Chapter 3 - System Installation Figure 3-12 CAT 344 Card Switches and Jumpers 3.5.2 Center Speaker Switch When using the SDU4 with a Center speaker, the switch should be in the yes position, Figure 3-13. This is the recommended configuration.
Dolby Surround Mixing Manual Chapter 3 - System Installation Troubleshooting Tip: If a Center speaker is not in use and left and right information can be heard, but center information can’t be when in either the Dolby Surround mode or Mono mode, the Center speaker switch is probably set to the yes position. This causes all of the center information to be fed to the center output of the decoder (which, in this case, is an open unconnected output).
Dolby Surround Mixing Manual Chapter 3 - System Installation Figure 3-16 Remote Fader Switch Detail Troubleshooting Tip: If the volume control on the unit does not seem control the monitor level, check the remote fader switch. The unit will output audio at full volume with the switch in the remote position and no pot attached. 3.5.5 EPL Switch As with the encoder, the decoder contains an EPL switch as shown in Figure 3-17.
Dolby Surround Mixing Manual Chapter 3 - System Installation Table 3-1 EPL Connections Pin Signal 1 Ground 2 Loop Send Surround 3 Loop Send Right 4 Loop Send Center 5 Loop Send Left 14 Loop Return Surround 15 Loop Return Right 16 Loop Return Center 17 Loop Return Left Later units (“silver” finish) only have the sends, usable for level monitoring; the loop returns are omitted. The switch on the Cat.No.344 module must therefore always be left in the factory default off position.
Dolby Surround Mixing Manual Chapter 3 - System Installation Figure 3-18 Detail of Jumper Modification for Bass Splitting 3.6.2 Time Delay Calculations In addition to the switches mentioned above, a rotary switch sets the time delay to the Surround channel, as shown in Figure 3-19. On older units, the switch is behind the removable front panel cover. On newer units, the switch is visible through the round hole in the front panel.
Dolby Surround Mixing Manual Chapter 3 - System Installation Table 3-2 Delay Switch Settings Setting 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Delay 20 ms 30 ms 40 ms 50 ms 60 ms 70 ms 80 ms 90 ms 100 ms 110 ms 120 ms 130 ms 140 ms 150 ms 3-14
Dolby Surround Mixing Manual Chapter 4 System Setup 4.1 Encoder Alignment Correct electronic alignment is a must for proper surround mixing. Perform the following steps on initial installation of the equipment and verify system integrity from time-to-time. 1. If it isn’t already, connect the unit to an audio path. See Section 3.2 for further information. If using the effects processor loop, switch it out for the following alignments. You will be instructed when to switch it back in.
Dolby Surround Mixing Manual Chapter 4 - System Setup Figure 4-1 Adjusting the Center Input Trim Control 9. Apply the 1 kHz reference tone to the Surround channel input. 10. Adjust the Surround channel input trim to light both green LEDs. Again, do not adjust the Lt or Rt output trims. The left and right meters on the device being fed by the encoder, console or recorder, should both read -3 dB and the signal should be 180° out of phase. 11.
Dolby Surround Mixing Manual Chapter 4 - System Setup 2. Adjust the left and right inputs, as shown in Figure 4-2, to light both green LEDs. The inputs are now aligned. Figure 4-2 Adjusting the Right Input Trim Control 4.2.2 Output Levels To adjust the outputs to the speakers, set the volume control to the reference position, about 2 o’clock on the scale, and use the built-in noise generator to send pink noise to each speaker.
Dolby Surround Mixing Manual 4.3.1 Chapter 4 - System Setup ANSI/SMPTE 202M X-Curve When in large mixing rooms, defined as greater than 5300 cubic feet or 150 cubic meters, use the X-curve as defined by the ANSI/SMPTE 202M standard. This curve is flat from 63 Hz to 2 kHz and then falls off at 3 dB per octave from above 2 kHz. See Figure 4-4. There is also a 3 dB roll off on the bottom end, with 50 Hz being down 1 dB and 40 Hz down 2 dB.
Dolby Surround Mixing Manual 4.3.3 Chapter 4 - System Setup Recording Studios—Music Mixing There are perhaps more arguments over what equalization should be used in a recording studio than any other place. Most studio designers have an opinion about what the curves should be and how they relate to what is ultimately heard by the end user. Find out what initial curve your room designer used to set up your facility for music mixing.
Dolby Surround Mixing Manual Chapter 5 Mixing Techniques 5.1 Announcers and Dialogue Traditionally, dialogue is placed only in the Center speaker to tie the on-screen sounds to the picture. When a Center speaker is used, all center-panned dialogue appears to come from the screen regardless of the listener’s position. If the dialogue comes from the Left or Right speakers, the stereo image differs depending on the listener’s position. This is highly undesirable.
Dolby Surround Mixing Manual Chapter 5 - Mixing Techniques is now directed to a single point source, the Center speaker, we perceive it as all center. To correct this in the mix, make the image slightly wider than normal for a two-channel stereo mix. Do not eliminate the Center speaker in the control room and use the phantom monitoring mode. While this may produce a more familiar sound in the control room, it does not satisfy home listeners who have a complete home theater system.
Dolby Surround Mixing Manual Chapter 5 - Mixing Techniques in the Surround channel. This results in out of phase or inverted information in the stereo pair, which XY stereo microphone techniques typically produce. While this may sound pleasing by itself and no encoding seems necessary, this is an unpredictable process that should not be relied upon. Adding another element to the mix, such as a voiceover, could easily change the mix’s phase characteristics of the mix and alter the decoding process.
Dolby Surround Mixing Manual Chapter 5 - Mixing Techniques inconsistencies between the two stereo channels. The viewer usually recognizes the problem as Surround channel ambience pumping in response to the dialogue. This is particularly noticeable during live sporting broadcasts when there is crowd noise in the Surround channel. 5.9 Proper Surround Level and Content When is there enough surround content? This decision is usually left up to the taste of the producer and engineer mixing the project.
Dolby Surround Mixing Manual Chapter 5 - Mixing Techniques designed to be used with their own decoders are another issue. The real question is how many consumers are going to be able to hear the mix with the proper decoder. Dolby Surround is the de facto standard matrix surround system worldwide. If a listener has a surround decoder, it most likely is a Dolby Surround decoder. 5.
Dolby Surround Mixing Manual Chapter 5 - Mixing Techniques heard in the Surround channel instead of paying attention to the action on the screen, you have a problem. Too much surround information may also make dialogue intelligible.
Dolby Surround Mixing Manual Chapter 6 Live Broadcast Applications 6.1 Transmission Path Considerations Because fiber optic and satellite transmission lines are standard services at sports arenas and stadiums, this part of the signal chain is usually repeatable and predictable. Frequency response and headroom are consistent from event to event. Most of the early problems encountered in Dolby Surround broadcasts were related to signal processing added by the station.
Dolby Surround Mixing Manual 6.5 Chapter 6 - Live Broadcast Applications Headroom The amount of available headroom depends on the final distribution medium. In broadcast transmission applications 6 dB of headroom above reference level is the usual limit. For transmission paths between venues and satellite uplinks, 10 dB may be available. VHS tape hi-fi tracks have about 12 dB of headroom. CDs, laser discs, and digital video recorders have 20 dB of headroom.
Dolby Surround Mixing Manual Chapter 7 Video Games and Multimedia 7.1 Introduction Dolby® Surround has become a popular tool for video game and multimedia developers. There are several ways to include Dolby Surround in a video game, and each depends on the game’s platform. Control of the sound’s spatial position in response to the game player’s input is often desired. There are several techniques that can be used to achieve this in the game itself.
Dolby Surround Mixing Manual Chapter 7 - Video Games and Multimedia By adding an inverter, multiplication by –1, to the game audio tool kit, it is possible for a sound to be placed at any of the four cardinal points. If the level of one of the two output signals can be attenuated, it is possible to move the sound across the front or down either side toward the Surround channel. This degree of sound positioning is often adequate for many situations in game play.
Dolby Surround Mixing Manual Chapter 7 - Video Games and Multimedia Dolby Surround Game Mode is designed to assist computer game developers with creating sound effects and elements that can be used within the game and spatially placed within the sound field by the game while being played.
Dolby Surround Mixing Manual Chapter 7 - Video Games and Multimedia Once the F and S signals are prepared, they are recorded in two channels of the game soundtrack. To create the final surround encoded outputs, the F and S components are blended together during game play using the simple mixer shown in Figure 7-4. Lt F PAN OR LEVEL Rt S LEVEL Figure 7-4 Game Mixer 7.7 Application Information Game mode encoding is only useful for the generation of sound files for use in video games and the like.
Dolby Surround Mixing Manual 7.8 Chapter 7 - Video Games and Multimedia SEU4 Game Mode Alignment If the encoder has been aligned for normal operation, no changes to alignment will be necessary for game mode. If the encoder has not been aligned, you can either set it up following the normal operation, with the unit in the normal mode, or follow the procedure below which is valid only for game mode. 1. Make sure the unit is in the game mode.
Dolby Surround Mixing Manual Chapter 7 - Video Games and Multimedia L R PAN PAN t t PAN INPUT MODULES GAIN GAIN P H A S E P H A S E FRONT INPUT GAIN P H A S E SURROUND INPUT Figure 7-6 Positioner Function Via Audio Console The left (F) signal is panned from left to right for the front channel information. The right (S) information that is in phase should be assigned to the Left channel, the Rt information that is inverted polarity should be assigned to the Right channel.
Dolby Surround Mixing Manual Chapter 7 - Video Games and Multimedia Figure 7-7 shows how the various sound elements may join together in the final game. The final audio output is a complete surround mix in the Lt/Rt encoded form, which is output from the sound card. It is then the task of the Dolby Pro Logic® decoder to extract the multichannel sound field for reproduction over several speakers, or to be further virtualized for playback over a conventional pair of speakers.
Dolby Surround Mixing Manual Chapter 8 Theory of Operation 8.1 Encoder Figure 8-1 is the block diagram of a Dolby® Surround encoder. φ L C _ -3 dB φ R BP Filter Half B NR -3 -3dB dB Rt φ S Lt Figure 8-1 Dolby Surround Encoder The encoder adds the center channel input C, attenuated by 3 dB, to the left and right input signals, L and R. The results are sent through all-pass networks providing frequency-dependent phase-shift and fed to the left and right total outputs, Lt and Rt.
Dolby Surround Mixing Manual Chapter 8 - Theory of Operation methods. For this reason, signals panned to the center of the left/right bus will appear in the Center channel output after decoding, not the Left and Right channels. Figure 8-2 is a block diagram of the Dolby Surround Pro Logic® decoder.
Dolby Surround Mixing Manual Chapter 9 Miscellaneous Information 9.1 Contacting Dolby Laboratories In addition to its headquarters in San Francisco, Dolby has several other offices around the world. All offices are equipped to provide information on soundtrack production and encoding. You may contact Dolby from anywhere in the world via the following email addresses: Address Use info@dolby.com trademarkagreement@dolby.com info@dolby.com info@dolby.
Dolby Surround Mixing Manual Chapter 9 - Miscellaneous Information CFE PRO Japanese Liaison Office Roppongi Office Saski Building 18-9 Roppongi 3 Chome Minato-ku, Tokyo 106-0032 Japan Phone (81) 3-583-84515 Facsimile (81) 3-589-0272 Dolby Laboratories International Services, Inc. Japan Branch Fuji Chuo Building 6F 2-1-7, Shintomi, Chuo-ku Tokyo 104-0041 Japan Phone (81) 3-5542-6160 Facsimile (81) 3-5542-6158 9.
Dolby Surround Mixing Manual 9.4 Chapter 9 - Miscellaneous Information Dolby Surround Software Lists To inform consumers of programs, CDs, games and videos available with Dolby Surround encoding, Dolby Laboratories maintains listings on the Dolby Web Page (www.dolby.com) and in print. To keep these lists current, studios and engineers producing Dolby Surround encoded programs are encouraged to inform us of their titles for inclusion on these lists. Send program information to info@dolby.com.
