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Transcript
Metropolitan Community College Audio Video Production Engineering Part 1 Audio Sound and Hearing The Human Ear Outer Ear Middle Ear Inner Ear Courtesy of Dr. John S. Oghalai Used by permission Courtesy of Dr. John S. Oghalai Used by permission Courtesy of Dr. John S. Oghalai Used by permission Noise Induced Hearing Loss Base level 85 dB for 8 hrs Each 3 db increase 1/2 time “A” weighting measurement Most sensitive at 4 KHz 40 yrs @ 85dB = NIHL 8% 2 1 3 In phase 0 4 8 5 7 6 2 1 3 90 degrees out of phase 0 4 8 5 6 2 1 7 3 180 degrees out of phase 0 4 8 5 7 6 N Magnetic Field S 0 - Direction of Travel Magnetic Field + . 0 - + Direction of Travel Direction of Travel 0 Magnetic Field + + Magnetic field around wires Polarity changes as current direction changes Review Week 1 Output Moving coil attached to Diaphragm N S Dynamic Microphone Diaphragm Diaphragm (front plate) Back plate (fixed) Output Spacer Capacitor Microphone How Speakers Work http://electronics.howstuff works.com/speaker5.htm Block Diagrams Used to make complex circuits or systems easy for the user to comprehend and use Block Diagrams Most common symbol is a square or rectangle Triangles often used Interconnected by lines Block Diagrams Direction of lines important INPUTS – top and left OUTPUTS - bottom and right Use arrows when not standard Tone Li nk Board Room F.S. Li nk STA 2-1A STA 2-3A STA 2-5A none 5-4 Rem out Spkr Mi c Rem i n 5-28 5-3 Ech o Cancel #2 AGC 3- 6 AGC 3- 5 75 76 AGC 3- 7 2-15 2-16 2-39 2-40 2-37 2-38 2-34 2-35 2-36 2-32 2-33 2-29 2-30 2-31 2-27 2-28 1-48 2-25 2-26 1-46 1-47 1-44 1-45 1-41 1-42 1-43 1-39 1-40 1-36 1-37 1-38 1-34 1-35 1-32 1-33 1-29 1-30 1-31 1-27 1-28 5-27 Punch Block ACR 2-2 ACR 2-4 ACR 2-6 ACR 2-9 Phone Bri dge 74 1-25 1-26 OC C ACR 2- 8 STA 2A STA 1A Sat 2 M ont. Sat 3 Si erra TV Studi o A STA 2-7A UN O 1 UN O 2 UN O 3 QS DETAIL of ACR Connections 2-13 2-14 Gtw y out sel D emod PBS IR D 2-6 2-7 2-8 2-4 2-5 STA 1-9A 1-24 STA 1-10A 2-1 2-2 2-3 1-22 1-23 1-20 1-21 1-17 1-18 1-19 2-10 2-11 2-12 VP-2 VP-2 VP-2 STA 2-1A STA 2-3A STA 2-5A 1-15 1-16 VP-2 STA 2-7A 1-12 1-13 1-14 STA -A 1-10 1-11 See Detail 2-8 STA -A - - VCR 2 TCR M atri x 10 MC R Mi c Quad Spli t VCR 1 ESU-2 AS ESU-2 BN ESU-2 BS ESU-2 EC Bri dge 3 U NO 1 U NO 2 U NO 3 OCC Bri dge 1 Bri dge 2 Gatew ay N ET III SRP 116 FRC 108 SOC 516 STA 1-5A FOC 16 VBrick VBrick STA 1-3A STA 1-4A VP-2 VP-2 1-8 1-9 1-6 1-7 EVC 103 EVC 106 FOC 206 VP-2 N ET II STA 1B STA 1-1A STA 1-2A 1-4 1-5 1-1 1-2 1-3 EQ A B OC C STA 3-4B ACR 3- 3 STA 3-9B Bridge Detail VU Meter 40 37 38 39 35 36 32 33 34 30 31 28 29 25 26 27 23 24 20 21 22 18 19 15 16 17 13 14 11 12 8 9 10 6 7 4 5 1 2 3 ACR 3- 1 ACR 3- 2 STA 3-9A Equal izer A B Tone Audio Monitor 3-1 3-25 3-2 3-26 3-3 3-27 4 3-4 3-28 STA 1-1B VP- 2 FOC 206 5 3-5 3-29 STA 2-7B VBr ick FOC 16 3-6 3-30 3-7 3-8 3-31 3-32 STA 2-3B STA 1-4B VBr ick VP- 2 FRC 108 SOC 516 STA 1-5B VP- 2 SRP 116 3-9 3-33 Test Mon EVC 103 1 1 RS1 Test Mon 1 2 2 RS2 EVC 103 2 EVC 106 3 3 RS3 EVC 106 3 FOC 206 4 4 RS4 FOC 206 FOC 16 5 5 RS5 FOC 16 FRC 108 SOC 516 6 7 6 7 RS6 RS7 FRC 108 SOC 516 6 7 SRP 116 8 8 RS8 SRP 116 8 Gateway 9 9 RS9 NET III 10 10 EVC 103 10 OC C 11 OC C 11 EVC 106 11 STA 3-8A Bridg e 74 12 FOC 206 12 STA 3-8B Bridg e 75 13 FOC 16 14 FRC 108 3-11 3-35 3-12 3-36 3-13 3-37 STA 2-7B DV-2 Gateway Bridg e 1 12 Bridg e 2 13 Bridg e 3 14 UN O 1 15 15 SOC 516 UN O 2 16 16 SRP 116 UN O 3 17 EXP 17 ESU -2 EC 18 Quad Spli t 1 19 Quad Spli t 2 20 Quad Spli t 3 21 Quad Spli t 4 22 VCR 1 23 VCR 2 Streaming 24 4-25 4-2 4-26 4-3 4-27 4-4 4-28 29 4-5 4-29 30 4-6 4-30 4-7 4-8 4-31 4-32 4-9 4-33 4-10 4-34 4-11 4-35 4-12 4-36 4-13 4-37 4-14 4-38 4-15 4-39 4-16 4-40 25 26 27 28 Gtwyi n sel 31 32 Modul ator 1 33 Modul ator 2 34 Dupe Rack 35 TV Studi o A 36 Board R oom 37 F.S. Link 38 39 Link 1 4-1 40 Future 9 EVC 106 Gateway RS10 NET III 4-42 MX Out 3-43 3-20 3-44 3-21 3-45 3-22 3-46 1 3-10 3-34 STA 3B 3-14 3-38 STA 3-5A 3-15 3-39 3-16 3-40 3-17 3-41 RS14 Bridg e 3 2 RS15 UN O 1 3 RS16 UN O 2 In #5 3-19 3 4 Quad Spli t in 1 Quad Spli t in 2 Quad Spli t in 3 Quad Spli t in 4 UN O 1 STA 2-3B VP- 2 UN O 2 STA 2-5B VP- 2 UN O 3 5 6 RS18 ESU -2 AN 6 3-18 3-42 7 3-23 3-47 STA 1-9B 3-24 5-1 3-48 5-25 STA 1-10B 8 9 RS24 VCR 2 Gateway Mod ch - 10 NET III Mod ch - 11 Bridg e 1 Dupe Rack 12 Bridg e 2 Studi o A 13 UN O 3 Board R oom 14 QS mi x 8 9 ESU -2 AN 10 Mi c 11 12 Non-TCR Rooms 15 VCR 1 16 MC R mi c AM 16/12 ( #2) Audi o Matri x EXP 17 Preset #1 Bridg e 3 VP- 2 RS17 UN O 3 RS23 VCR 1 NET III STA 2-1B 5 7 Test Mon EVC 103 TCR Rooms AM 16/12 ( #1) Audi o Matri x Preset #1 2 4 In #1 Spkr out Echo C XL Rem i n Rem 5-2 out Spkr VCR 1 VCR 2 5-26 Metropolitan Community College Master Control Audio Block June 22, 2001 rev. 9/16/01 Craig C. Carls on, NCE Functional Drawing of a typical VCR and TV RF In V AV In L R Tuner TV/Video or Input switc h Play VCR VCR TV Record VCR TV Mod RF Out RF In V TV/VCR s witch (auto VCR when play is selected) L R AV Out V AV In L R Tuner TV TV/Video or Input switc h Picture Sound Amplifiers Electronic devices used to increase an electronic signal level Many types and kinds Amplifier Characteristics Gain Impedance input/output Balanced input/output Unbalanced input/output Audio Amplifier Types Pre amplifier Buffer amplifier Line amplifier/DA Power amplifier Pre Amplifier Frequently used in low level applications Phonograph cartridge Microphone Intercom Buffer Often used to isolate one circuit from another and to match impedances Line Amplifier/DA Often used to increase drive capability Split signals to feed several different pieces of equipt. Usually no change in level Power Amplifiers Usually used to increase current capability to drive speakers and headphones Decibel Unit of measure Bel Based on ratio Used for both Acoustic and electrical applications dB formulas Power dB = 10 log (P1/P0) Voltage and Acoustic dB = 20 log (E1/E0) dB as Unit of Measure Requires a reference 3 and 10 rule (power) 6 and 20 rule dB Standards dB-SPL Acoustic sound Pressure Reference 0.0002 Dynes/sq cm dB Standards 0 dBm = 1mw>600 Ohm load (.775 V) 0 dBu = .775 V 0 dBv = .775 V 0 dBV = 1 V dB Standards 0 dBW = 1W 100W amplifier is 20dBW 1000W amplifier is 30dBW SPL Meter Microphone Amplifier Meter A Weighting filter inverse of equal loudness contours B & C Weighting high end of equal loudness contours dB Meter Specialized AC Meter with scale calibrated in dB VU Meter Much the same as dB meter Calibrated 0VU = _dB Response peak to average Analog, LED, Electronic display Review Week 2 Wiring Characteristics Impedance and Resistance Impedance for AC circuits Resistance for DC circuits Both measured in Ohms Balanced Wiring Unbalanced Wiring Input + Output Audio Class of Service Microphone level (-50 dB) Line level (0 dB) Speaker level Video (1V Noisy) RF (Saturates Amplifiers) Data (HF Noisy) Cable Characteristics Conductor size (AWG) Number of Conductors Twist or no twist Shielding Insulation type Review Week 3 Equipment Interconnect Power Grounding Earth/Chassis Signal Grounding Patch Panels 1 25 From Equipment (Outputs) T o Equipment (Inputs) Normalling Jack Pair 24 48 The right way to do it. Courtesy Rane Corporation (RaneNote 110) Used by permission Courtesy Rane Corporation (RaneNote 110) Used by permission Transformer Isolation Courtesy Rane Corporation (RaneNote 110) Used by permission (A) Off the Shelf cable (B) 6dB sig. loss Courtesy Rane Corporation (RaneNote 110) Used by permission Courtesy Rane Corporation (RaneNote 110) Used by permission Courtesy Rane Corporation (RaneNote 110) Used by permission Review Week 4 Mix Bus Common point where multiple signals are combined Summing point Attenuators Used to reduce signal level Many types Gain controls do not do the same thing Magnetic Tape Back coat Plastic base Binder Magnetic coating Magnetic Tape Several different coatings Iron oxide Chromium dioxide Cobalt Doped Metal Magnetic Tape Properties Not covered in this class Coercivity, Retentivity, Sensitivity, Print through, Dropout, and many more Recording Process Recording is non-linear at audio frequencies Bias current is needed to make recording linear Bias adjustment depends on type of tape Bias Frequency Around 100 KHz Applied to Erase Head Modulated by Audio Review Week 5 Digital Audio A to D Process Storage D to A Process A to D Process Sampling Rate How many times per second is the analog signal looked at CD is 44,100/Sec 32 KHz Broadcast Sampling vs Frequency Sampling rate needs to be twice the frequency of the highest audio frequency needed Analog Signal Sample Points Sample Rate Anti-aliasing A low pass filter us used to limit high frequencies prior to sampling Quantization The Value of each sample Two 8 Bit words (16 bits) yields 65,536 graduations (used for each CD channel) Modulated #132 1 Clock 2 4 8 16 32 64 128 The D to A Process Demodulation Error Correction D to A Conversion Sample and Hold Low Pass Filter Demodulation Restores the recorded signal to original ones and zeros Error Correction Compensates for errors introduced during the recording process D to A Conversion Electronic process that converts digital numbers (samples) into analog voltage (current) Sample and Hold Circuits that remove “Switching Glitches” that appear after D to A processing Low Pass Filtering A circuit that does the final smoothing of the analog signal and removes any high frequency noise Wiring Considerations Most digital connections use standard XLR connectors wired the same as balanced audio Do not bundle/run with audio cabling Wiring Considerations Most MIDI hardware uses DIN-5 pin connections Pins 4 & 5 carry digital signal Pin 2 is shield 50 ft maximum length