Interconnections, signal flow, busses, and patch bays
Contents
1. RING 2 SLEEVE Inputs arc always XLRF outputs are always XLRM TT Bantam cantent ect our 8 8 Balancing a Signal Take a positive and negative 180 degree phase inversion of a signal Sum the signals han divide in half 3 signal noise signal noise 4 signale As a procedure 1 aise 5 signal 6 signal 8 9 Cable Internals Conventional Two Conductor One braided wire with shield used as second conductor ground Called guitar cable instrument cable 8 10 Cable Internals Conventional Three Conductor Two braided wires with shield used as second conductor ground Called Mic cable pair 8 11 Cable Internals Star Quad 5 conductors 1 ground 2 positives negatives Four braided wires with shield as fifth conductor BLUE ung 48 SHIELD CONNECTOR Typical 2 conductor mic cable Canare Star Quad cable 8 12 Converting from Balanced to Balanced Use a cable bes adapter not recommended 8 13 Converting from Unbalanced to Balanced DI Box Never use an adapter or a cable Ditcet Injection Box convere 10 dBu to 4 dBu and balance signal PAD allows super hot such as piayarto bo p MERGE FUNCTION tens nd fu jacka pacco mixer do sam sieroo signals lo moro2. handle rwo or more channels per cable Unbalanced Balanced Fiber Optie 8 16 Digital Cables Examples SPDIF Coaxial looks RCA DIGITAL AUDIO OUT ADAT Lightpipe channel optica MADI optical or coaxial up 10 64 channel 8 17 Snakes Bundle cables in a single insulation 8 18 Power and DC Phantom Power Altemating current AC 120 voles RMS in 60 Hz sine wave current DC not a sine wave Transformers rectifes and smoothes AC into DC Phantom power 48 Volt DC transmitted on signal lines ofa balanced cable 8 19 The Mixer and the Patchbay Mixer signal control processing combinacion and routing Combines fundamental tools used in almost every signal processing context Patchbay signal routing Offers tools that have evolved into conceptual paradigms may be hardware may be software 8 20 The Mixer Primary Components A mixer ean be seen as having primary components Channel strips A number of commonly used routing and processing tools bundled together Should be called a track stip may be applied o one or more channels Physical mixers made of numerous 4 12 16 32 64 channel strips Busses signal destination a repository thar signals lead in to output may go to another channel physical output May be called mains or main bus groups sub groups or auxiliaries aux sends aux 8 21 Channel Strip B
3. Chapter 8 Meeting 8 Interconnections Signal Flow Busses and Patch Bays 84 Announcements Audio materials for frst Processing Report due 7 Match audioProcReport Lzip About Bangle readings Need schlep crew of three for Wednesday at 3 10 at my office Need volunteer solo musicians for Wednesday who can bring instruments 8 2 Quiz 8 3 Pro Audio and Consumer Audio Standard operating level and signal to noise ratio Cables Price 84 Cables Wires conductors carry voltages or grounds Shielding meso level of protection Insulation outer level of protection Connectors and Jacks provide easy interface can be male or female F 8 5 Signals Voltages and Grounds Analog sound can be represented as changing voltage Grounds are a point of zero voltage or safety a path for faulty currents Ground loops grounds with differing electrical potentials on the same connection nor exactly a ground May result in a 60 hum 8 6 Analog Cables Types Unbalanced Two conductors one signal one ground SOL 10dBV High impedance Length Limit 25 fect Balanced SOL 4 diu Low impedance Length Limit 1000 fect Active and transformer balanced 8 7 Analog Cables Connector Examples E bel AL SLEEVE 4 Figure TS Plug Phono SLEEVE SLEEVE RING SLEEVE SLEEVE RING Im
4. Tris saves valuable inputs on mier INPUT and THRU jacke connect them the and te the insturont agito FULL BOTTON PAD improves isolation he 101 moving around on busy stages XLR palace 5000 mea 1000 fer without aprecian nano EOOK END DESIGN creates proteste zona aei PARALLEL SPEAKER ori opten a second Pat av pars BIZ gutar speaker GROUND LIFT cisconnects me ground path to tha transtormar tha SiR ouput POLARITY REVERSE hs re polarty for pin 2 on ine MLR Transformer isolation removes ground hum noise 164 Schema for a Sani DI bes Used to connect guitars bases keyboands guitar bass amp direct outs turntables deum machines synths er cetera into pro audio inputs Can be used in forward and reverse to extend the run of an unbalanced signal 8 14 Analog Cables More Examples Mini Stereo 3 conductors used for 2 unbalanced channels Y or insert cable 3 conductors used for 2 unbalanced signals prosessor men pipere RETURN fom processor 7 Figure E Insert Plug ord insert able Banana Designed for amplified signale Speaker Wire Speakon Designed for high warage amplified signals Mea A sevi hs content ie entes ra Cru 8 15 Digital Cables Types Always
5. asics Amplifiers processors and distributors bus assignment Common vertical orientation is not che same as signal low 8 22 Channel Strip Components Input o selector Preamp trim ine mie lev switch pad phase Insert serial processing slot Low cut filter Auxiliary sends for parallel processing fader controlled bus assigament and dynamics serial processors Shelves and parametric eq Dynamic effects such as compressors limiters gates and expanders Mute and solo control Fader Panning and bus assignment Bus assignments may be stereo or multichannel gt May use panning to assign to one channel ofa stereo bus 8 23 Channel Strip Example Mackie 1604 Vertical orientation is not the same as signal ow Channel strip C66 TONEY T Y MR pts mem ier aes os 1000 evo ne Al rg reserved Thie contant ace Signal Bow 0 M 1 Commen emere mer emat sc cu edu 8 24 Channel Strip Example Mackie Onyx 2408 Channel strip 8 25 Channel Strip Example SSL AWS 900 Channel 8 26 Channel Strip Example SSL Channel stip Se reservet uch m ar creative 827 Busses Channels may ourpat 10 or more bus Other channels may take a bus as an inpur Used fo
6. hs does Eargle say possible with a microphone and low capacitance cable Which type of condenser might we expect ro have larger self noise a small or a large diaphragm Whar are rhe advantages of using an clecret material in the design ofa capacitor microphone How dies a piezoelectric microphone work What are some applications MIT OpenCoursoWaro 21 380 Music and Technology Recording Techniques and Audio Production Spring 2012 For information about cing these materials or our Terms of Uso visit htp ocw miadullams
7. presented on bottom From rear connect from other devices on top connect inputs to other devices on bonom Three common figurations normal haf normal and de normal 8 33 Patch Bay Normal normal conncetion is default connection that does not require a patch normal conncetion flows from the rear top ro the rear bottom front panel pateh is Can be half normal or full normal difference is what happens when a cable is inserted into the front top half normal inserting a cable into front top does not break the normal connection the signal is sent rwo places at once full normal inserting a cable into front breaks the normal connection the signal is sent one place out the front 8 34 Patch Bay Denormal Open What you see is what you ger No internal normal connection front simply connects to rear are still over inpues 8 35 Patch Bay All formats HALF NORMALLED NORMALLED gt 21 Image by MIT OpenCourseWare 8 36 MOSS Diagrams Secondary Patchbay Points 49 56 isolated 20000000 8 37 Reading Eargle Chapter 3 The Pressure Microphone Hos capacitor pressure microphones affected by temperature Ts it possible that a microphone pad can change frequency response Whar cable lengt
8. r grouping and processing related channels Used for distibuting sub mixes to other processors aurputs 8 28 Busses Main Outs Sub Outs Control Room Main Outs final ourpur destination a physical output may be stereo or multiple channel Sub busses to alternative physical ourputs Room bus designed ro deliver audio to the engineer not the main outs 8 29 Busses Grouping 8 30 Busse Assign a number of channels to a group channel Use the group channel for shared processing or fader contral Then assign the group to the main output Auxiliaries Channel strip bus assignment with a rotary fader Used for ercating sub mix different from the channel fader position Ona physical mixer physical ourpur might be labeled ausiliary or auxiliary send On aa viral mixer auxiliaries tracks thar receive a bus as input Used to provide a different mix to monitors or outboard processors Can be pre or post fader je 3 E rave cont iene fer nomtn ge m 8 31 Patch Expose and outputs in one place Can refer wa standalone device ar to the section afa larger device Bring i o from the rear ofall devices to front panel interface Example se nie 8 32 Patch Bay Concepts Vertical pairs matter Out over in from outputs are represented on top inputs are re
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