【 Weak current College 】 5.1 surround sound room process design---Power By 【 China power house network 】

China national radio at the end of 2004 the concert started recording control room renovation project, stereo audio control room for surround sound audio control room, the room was put into use. Was responsible for organizing the implementation of the reconstruction works of the author about surround sound audio control room technology design, equipment selection, summarized, is expected to carry out surround sound technology peers provide reference.

China National Radio Music Hall audio control room was mainly used for recording stereo programs, to meet the surround program recording needs, Taiwan's decision will be adapted to produce surround programmes, while compatible stereo broadcasts of audio control room.

General design considerations

Currently 5.1 surround sound audio control room in one of the few, the design information for reference. We designed the main consideration in several areas:
1. process to ITU-RBS.775-1 standard as a basis for design.
2. acoustic meets the recording control room acoustics technology requirements such as the reverberation time in RT60 = 0.3?. 1s (63Hz ~ 8kHz), room noise not higher than NR-20, etc.
3. function: large Orchestra of surround sound pick-up, multi-track recording, surround sound mixing and mastering coarctation of production; recording large organ surround sound music; throughout the recording process for digital signal storage and handling; surround sound and stereo compatible and on the same program for surround sound and stereo real-time comparison; real-time monitoring of concert hall farm, with convenient internal communication and communication functionality; audio control room, sound amplifying equipment room, master room and audio repositories can exchange data (analog and digital); the use of lifting the handset, Rod floor type microphone stand and high quality micro capacitor microphone recording large Orchestra and stage performances, the effect in ensure the recording of that performance visuals; the engine room, the audio signals sent to the adjacent surround hearing room to listen; this room, the audio signals sent to concert venue for listening and monitoring; multiple remote sessions; receive cable TV signal, and so on.
According to the above, we use the entire system is divided into the control room inside and outside the engine room control (i.e. Concert Hall Interior) in two parts.

Internal process design Hall

Control room design is divided into the outside process technology electric box and microphone.
Process design of electrical boxes
In the Concert Hall stage at the front, middle and back side of the left, the set of three to box, divided into technology-powered box, return to the send box and microphone cartridge, a total of six group. Each group of five microphone jack, two electrical outlet boxes and two way to send output. Besides rig also on both sides of the mouth with a AV socket box to provide foreign TV signal of replay and conventional Studio Studio monitor, so you can conduct the concert hall sound source playback and remote TV network meeting.
Microphone point design
The internal microphone Music Hall is divided into two parts of the stage and hanging, optionally add a wireless microphone.
(1) hanging microphone section
Considering hanging microphone distances, signal power by farm lighting, and other factors, the hanging microphone microphone within the roof line to metal tube closed and be a good grounding to minimize interference. At the microphone amplifier section moved to the roof, the microphone pickup weak signal-in-place zooming and encoded into digital multi-channel serial code stream (i.e. the MADI signal), through two 75 Ω coaxial cable back to the control room. MADI signal transmission distance of coaxial cable to the theory, practical rejection line 50m length 40m, has guaranteed the hanging microphone signal transmission quality. The phone box of MADI cable can be used in its 56 channel last channel mixer on the microphone of the control signal to enable the microphone level, interface and phantom-powered remote control. Lifting the receiver point according to the modern Orchestra concert seating location hanging. In order to meet the practical microphone pickup of different needs, in the band in front of a line-shaped hanging directional microphones, as AB pickup standard primary microphone; in addition, the command behind hanging famous DECCA Tree microphone arrays; also prepared a set of ATMOS5.1 surround microphone, as the single point of surround sound pickup.
AB standard microphone forms, mainly to take into account the standard stereo audio AB in the sense of space and the fusion of comparative advantages. Reservations-microphone recording form AB, on the one hand, you can continue to maintain a system of recording mode AB merits; on the other hand, the various recording format structure, you can use it as a supplement to the main and auxiliary microphone. DECCA Tree microphone array is tested, for DECCA company parties spoke highly of pickup standard, has been focus of research experts, in its basic structure of the T-word derived from a variety of audio format, you need to be selected on the basis of the actual situation. The hanging of the main microphone arm is still uses the T-Word microphone arm, but the difference is in the low 6 only installed on the handset: the front is a pair of stereo microphone, MS system with a panoramic view of the stage; distance side pickup 0.5m install two forward-shaped capacitor microphone, as the surround reverb source; in front of the T-Word gallows side installation and Center angle of about 135?, heart-shaped capacitor microphone as surround sound reverberation source in the rear. T words gallows used ultra-fine wires and through a rocker arm movements, if you are picking up the regular stereo sound source that can be easily replaced by DECCA Tree recording standard or large AB, AB, MS, ORTF format, etc. ATMOS5.1 surround microphone pickup system originates from Germany r surround sound preamplifier for analog circuit design, can provide today all surround sound audio system. It uses a fixed microphone "great" font face, through cable and accessory microphone preamplifier. The microphone amplifier using motor control of electric central control knob to gain control, you can ensure that only the microphone gain 5 synchronous adjustment, you can also directly in the microphone amplifier for surround microphone gain adjustment,Busbar distribution and output, audio-visual e-broadening, subwoofer signal extraction and conditioning, surround sound and stereo conversion and listening, and so on, for field records, the disadvantage is that the recording scene needs a microphone stand and other equipment.
The front of the main microphone stand is located in the middle of the stage 4 only microphone can use dedicated hanging shelf with XY or ORTF format into two stereo microphone to pick up the band deep voice. The hanging racks directly using the phone line for hanging in the microphone line end winding fine wire, to control the receiver to the pitch angle. Chorus above set 4 heart-shaped microphone, override the choir voices. In lifting the handset set point, the use of inadequate stage microphones.
Distance from the stage above the swimming 5m 5m, set at the edge of a set of four heart-shaped or 8 font microphone composition of surround sound background pickup microphone, microphone toward the wall on both sides for the concert hall, used to pick up directly to the sound outside the reflections and mixed sound.
(2) the stage microphone section
Stage microphone signal and not delivered directly to a mixer with microphone-amplifier, but through shielded metal pipe back into your room, then through the control room of Canon jumper frame jump received microphone amplifier input. The advantage is that you can flexibly jump stage microphone access ports to facilitate uniform planning, to troubleshooting; easy MIDI instrument to control desk for the shortest distance to access sound mixer, to improve the transmission signal to noise ratio.
(3) wireless microphone section
8-channel wireless microphone receiver directly installed in the recording control desk behind, as in the following field tests, the received signal stability is good, that you do not have to install an external receiving antenna.
All the microphone settings and sound mixer channel delay and sound like Locator, you can achieve accurate positioning of the sound source, avoid obvious echo phenomenon.

Control room design of internal processes and functions

Regional settings and major equipment distribution
Concert control room internal is divided into production areas, areas and equipment cabin. Production area to recording, listening to the circumference, 5.1 constitute control room inside the core of the recording. Control desk is located in the recording back, as a signal to the center of intersection, and Director of platform. In addition to the mixer amplifier, host, host, and so has the effect of fan noise device placement in small rooms, almost all of the tape recorder, amplifier, etc., are all installed in the control table and desk, sound mixer ear for ease of operation and maintenance, and repair work, all devices of analog and digital audio signals to/received in line to the jumper on the disc, and then by jumper up complete mixer and audio signals switch between devices.
Speaker settings
In order to achieve 5.1 surround sound recording and listening, indoor acoustics and sound settings with reference to the standard, ITU-RBS.775-1 adopts five DYNAUDIOM3 za, a sub-woofer. Taking into account the needs of future expansion, set aside another bass speaker locations. 5 only listens to the sound of the bottom margin is set to high, so that speakers of 1m high frequency units on some points (sitting) recording of the ears (about 1.2m). 5 only speakers and a sub-woofer all point to the recording of the seat, and recording the distance of the seat, as all take 2.9m embedded installation, this can prevent comb ponders the wave effect, extend the scope of listening, but also makes space compact. In view of this concert hall was mainly as a classical music recording, we have adopted a standard surround speaker (i.e. the angle and the center of the angle of 120. ) To install.
Sound mixer settings
This concert hall with full digital audio mixing console Neve, specifically to: physical faders 30 road; audio interface total 36-channel analog input for stage microphones, wireless microphones, recorders, and effects equipment analog line outputs; 32-channel analog output for device simulation line input, control room monitor, audio content, such as returning to send; 24 channels of AES/EBU digital input/output for digital input/output; two on the MADI input/output interfaces for one 56 road Pyramix audio workstations and ceiling 24-channel microphone interface box MIOS interface. In addition to the MADI and listen on the interface, all digital and analog interface and control desk for the jumper is attached to the disc. Mixer while only 30 road physical faders, but can carry a total of 4 levels of 120-channel faders, hierarchical control set to respectively: channel level (such as microphone input channel) control, tape recorder level (such as multitrack tape return channel of) control, auxiliary channel (AUX primary output channel) control and external device channel (such as a tape recorder and auxiliary equipment of the return signal) control, etc.
Jumper wheel design
My desk concert control room is Switchcraft96 road, jumper, total use 4: simulation of the two, number one, concert halls and an external (Ministry of sound reinforcement machine room, master, hearing rooms, library, etc.) signal switching a; the upper part of each of 48 holes set to signal to the hole, lower 48 holes set to signal to the hole, and analog and digital signals to cable received 48 holes on, corresponding to the line received under 48 holes (i.e. 49 ~ 96 holes). Considering the continuity of digital signal processing, in the normal working hours to device digital input/output for the main audio link, so that all digital signal input/output via jumper up to constant Tung are exchanged in the form. Adopted in the form of atmospheric fluxes can save significant jumper, if required, then use jumper jump to signal. In the jumper on also sets and cable hole, you need to extend digital or analog signal output port. Will DVD players and set-top box audio interface is arranged in jumper up to provide TV signal source and meet the Watch works. 4 jumper disk as the exchange of internal and external signals, control operations, the hearing room, sound amplifying equipment room repositories to/to set the line to standby. For future expansion, in preparation for the Concert Hall of wiring, pre-Internet network cables, and sound reinforcement signal switching of cable computer room and network cables, and database connectivity cable, and can be used with ISDN audio signal transmission 3 rootTelephone cables.
Recorder selection
In the disc recording media popularity today, to the workstation as the main body of records forms become mainstream. For the master tape recorders, we use a PC-based workstation Pyramix. Make this choice, the fact is taken into account for this workstation is compatible with today's almost all audio formats, and include the Apple platform, PC-based platform for data exchange on various workstations; you can use the MADI interface, a coaxial cable can transmit 56 channels of digital signals, the wiring on cost-effective; powerful, cost-effective, easy-to-upgrade; reduction in recording, mixing is done, you can output a variety of formats of audio data into a portable hard drive or burn into CD data.
In order to be able and available to various recording carriers supporting the use of the control room is also equipped with a DSD 8 track tape machine, DAT recorders, laser recording/playback, cassette recorders, MD recorders, and surround sound DVD, etc.
Effects of matching
As the surround and stereo compatible control room, the effects should also meet production surround sound and stereo needs with analog and digital specialty interface. We choose to add surround sound reverberation of TCM6000 as main effects, it can achieve a variety of room conditions surround reverb incentive, you can surround material master post-processing, mono or stereo surround sound conversion and noise reduction, dynamic processing, and so on. In addition, you select a Lexicon of PCM-91/81, Rainbow of Thai DSP7500 etc effects as secondary producers of equipment.
Monitoring equipment considerations
In order to master the concert hall farm, we introduced two high definition plasma TV as a control room monitoring unit of functionality. From on-site monitoring camera's video signal, digital set-top box TV signal, the signal of a dual-head video card and a DVD player all the received signal, plasma color TV with remote, you can freely switch screen can be found in the image overlay video source for picture-in-picture effects, you can do 4 picture while monitoring.
Surround sound box arrangements in care of the human ear height, also is the vision of the person, it will be on two plasma TV mounted on top of the front speakers, overlooking the rear corner main care Director area perspective. Workstation's main screen using another desktop LCD displays, so that recording can focus on the work of the recorder, plasma color TV interface can provide Station mixing console interface and multitrack digital signal level meter display, both practical and beautiful.
Concert hall room renovation complete, invited several industry experts carried out the actual evaluation, and conducted a Germany played organ experts surround sound audio experiments, from actual use, the room is highly convenient and ideal acoustic effects, surround sound positioning accuracy significantly, recording is very good, experts from Germany and the famous recording.