Chapter 4 Notes - Posted on 2017-01-12 by Nicholas Casas

Chapter 4 Notes

• Signal Flow: The path a signal takes from beginning to end. As sound engineers we must know how to hold the integrity of a signal flow and make sure to adjust important factors on every aspect.
• NL2 (Speakon), Double Banana, Unbalanced 1/4 Tip Sleeve (TS), RCA, BNC
• Three-Conductor Connectors: Three separate isolated conductors intended to connect to specific wires. XLR, Balanced 1/4" Tip-Ring-Sleeve (TRS), TRS MIL, TT/Bantam, 1/8" mini.
• Multi-pin Connectors: Have many isolated signals that are sent simultaneously through one connection. Each pin is soldered or crimped to a corresponding wire. Often used in places where many channels of audio are being sent in and out, and where having individual connections for each channel would be impractical. ELCO, DL, D-SUB/ DB25, CAT 5
• Different cables can have the same connectors, but have entirely different functions.
• ANALOG CABLES: Speaker Wire, Coaxial, Single conductor wire with conductive shield, two conductor wire with conductive shield, multi-conductor.
• Analogue cables mainly have low voltage electricity.
• MICROPHONE LEVEL: -60 db
• INSTRUMENT LEVEL: Between -30 db and -20 db
• Consumer Line Level: -10 Pro line level :+4 db
• Speaker level signals are measured in watts and have a lot of current. Larger gauge wires are employed in the cables used for speaker level signals.
• Certain analog "unbalanced" connections have two components, hot and ground. I.E. Guitar and amplifier.
• "Balanced" connections have three components: hot, cold, and ground. I.E. mic and preamp.
• Balanced connections allow signals to travel a longer distance without degrading, as well as offering a higher degree of noise isolation
• It is possible to connect an unbalanced output with a balanced input, but because the input amplifier will be missing the signal for -A the output will be 1A instead of 2A
• Instrument Cables: Carry instrument level signals from instruments like electric guitars and keyboard (-30 to -20). They have 1/4 inch plug divided into the tip and sleeve.
• Tip is positive and sleeve is ground.
• Speaker Cables use larger gauge wires and designed to carry high voltage signals from amps to loud speakers.
• Speaker Cables can be fitted with speakon, banana, or unbalanced 1/4" connectors. One conductor carries the hot signal and the other carries the negative. There is no ground for speaker wires because the signal voltage is so much greater than any noise that would be inducted and the signal won't be amplified.
• BNC Cables: Coaxial cable, a central conductor surrounded by tubular insulation and a braided conductive shield covered with a rubber jacket, and a BNC connector. The in in the center carries the hot signal while the outer cup connects the ground. Coaxial cables are ideal to use with antennas because the distance between hot and cold are constant throughout the cable. They can be used for unbalanced audio connection.
• XLR Cables: "Mic Cable"; Has 3 separate pins that are used to carry hot, cold, and ground. pin1= Ground, pin 2=hot, pin 3=Cold. Signal flows from the female end to the male end of the cable.
• XLR OUTPUTS ARE MALE; XLR INPUTS ARE FEMALE.
• TRS "Balanced 1/4": Tip is hot, Ring is cold, and sleeve is ground, which is used to send balanced line level signals.
• TT: Tiny Telephone, or Batnam Cables; Similar to TRS. More rounded tip and over half the size of TRS. Used for studio patch bays. Have the same pinout as TRS.
• Snakes: Large Cables containing many wires and allow for multiple isolated signal to be sent through them simultaneously. Often have a multi-pin connector on one end.
• ELCO Cables: Can carry up to 28 channels of balanced audio (84 wires) and connect through one single connector. Used for large format mixing consoles.
• DL Cables: Capable of carrying up to 28 channels of balanced audio through a single connector. Has a latch that is turned 90 degrees to lock the male pins to the female pins. The pins are fragile, so each DL connector is recommended to be connected a dozen or so times in its life. DL is used by Solid State Logic.
• D-sub/DB25: can support up to 8 channels of balanced audio through a single connection.
• Light Pipes/ADAT Cables: Use fiber optics to transmit digital information. An LED in a device's output sends light traveling through the fiber and is picked up by a receiver at the other end. ADAT, SMUX, SMUX2, AND S/PDIF
• Light pipes have a limited bandwidth, meaning they can only transfer a limited amount of info per second.
• ADAT can transmit up to 8 channels of DA over one pipeline at sample rates of 44.1k or 48k.
• The sample rates can double, but the number of channels supported is halved.
• SMUX can support 4 channels at 88.2 and 90 and SMUX 2 can support two channels at 176.4 or 192k
• S/PDIF is a digital audio protocol that supports stereo and 5.1 surround at sample rates as high as 192k. S/PDIF uses an RCA type connector and 75 ohm coaxial cable. They can also use light pipes.
• AES/EBU: Use XLR connector and a 110 ohm cable to send 2 channels of DA. D-Subs and ELCO are used with multi-conductor wire to make multi channeled snakes. They support sample rates as high as 192k. Can be used for mic cables.
• Tascam Digital Interconnect Format: TDIF; Uses DSUB cable to send and receive eight channels of DA simultaneously. They are bidirectional which means the signal can travel both ways.
• BNC Cables: Used to send digital clocking signals "word clock" allowing the audio devices to sync together. 1's and 0's are sent in sequences called words. word clock ensures that both devices are locked to the same position in sequence. Used to transport DA in a format called MADI
• MADI: Uses BNC or light pipes to carry vmultichannel DA. recognized as the AES 10 standard. Can transport 64 ch. of DA over a single cable using serial digital transmission.
• mLAN: Uses a fire wire 400 type cable and incorporates several features of the fire wire standard into its protocol. Used to allow computer-based DAWs to communicate with mLAN-complaint hardware.
• Digi Link: proprietary format belonging to Avid. Digi links are used to send digital audio between the protools HD cards and the converters.
• Firewire 400: Enough bandwidth to support hundreds of channels of high-res. DA
• Thunderbolt: Supports faster transfer speeds than Firewire.
• USB: Standard computer protocol used to connect many types of peripherals. MIDI info can be sent through USB. Not recommended to send more than two channels of DA at a time through USB
• Cat 5, RJ45, Ethernet Cables: can be used for DA although no current AES standard exists for the purpose at this time. CAT 5 cables are often used to connect DA systems using a proprietary protocol called Dante.
• Patch Bays: Serve two vital functions; providing a centralized hub where all analog audio connections can be made and dictating the default signal flow of the studio.
• Two most common are 96 point TT and 48 point TRS, both of which are most commonly found in single space 19" rack panels.