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Aaron Mitchell
Here are my notes for Lesson 4:
Chapter 4 Section 1:
- Path of guitar soundwaves:
- Vibrations from guitar goto the pickups or "The guitars microphones"
- Pickups convert vibrations to low level electric voltage
- Goes to amp, amp boosts the current
- Goes to microphone placed in front of amp, coverts back to low level electric voltage
- Goes through a microphone preamplifier, increases voltage from mic level to line level
- Goes to analog to digital converter
- Goes to protools
- Goes to digital to analog converter
- Then you can listen to it again
- Signal flow = The path a signal takes, from beginning to end
- Standard audio connectors:
- Two conductor connectors:
- NL2 (Speakon)
- Double Banana
- Unbalanced 1/4" TS (Tip-Sleeve)
- RCA
- BNC
- Three conductor connectors:
- XLR
- Balanced 1/4" TRS (Tip-ring-sleeve)
- TRS MIL
- TT/Bantam
- 1/8" Mini
- Multi-pin connectors:
- ELCO
- DL
- D-SUB/DB25
- CAT 5
Review Questions:
XLR: 3 "pins" Blue end and black "Hollow" end
RCA: Normal connection for cable tv
TRS: Silver with black end, has 2 rings on front
- Analog Cables:
- Speaker wire
- Coaxial
- Singles conductor wire with conductive shield
- 2 conductor wire with conductive shield
- Multi-Conductor
- Analog = "Low voltage electricity
- Common voltage levels:
- Microphone level = -60 db
- Instrument level = -30 db
- "Consumer" line level = -10 db
- "Pro" line level = +4 db
- Balanced connections allow signals to travel a longer distance without degrading, as well as offering a higher degree of noise isolation
- (A+noise)-(-A+noise) = A+noise +A-noise = 2A
- Balanced connections are 6 db louder than unbalanced connections
Review Questions:
- Microphone level is "-60 dbu
- Pro audio level is "+4 dbu
- A unbalanced connection has three conductors and transmits a signal out of phase which eliminates unwanted noise that could be picked up on a cable run: False
Unbalaced cables:
- RCA cables: mostly used for consumer grade audio components, unbalanced line level signals (-10 db or lower) Pin in center is hot, outer prongs connect
to ground
- Instrument cables: used for electric guitars, and keyboards, (-30 db to -10 db). 1/4" plug, divided into two parts, the tip and the sleeve, tip is positive,
sleeve is ground
- Speaker cables: Larger gauge wires, designed to carry high voltage signals, often thousands of watts, from amps to loudspeakers. Speaker cables can be
fitted with speakon, banana, or unbalanced 1/4" connectors. One conductor carries the hot signal, the other carries the negative signal. No ground need with speaker
wires because the signal voltage is so much greater than any noise that would be inducted and because the signal will not be amplified.
- BCN cables: Consist of coaxial cable, central conductor surrounded by tubular insulation and a braided conductive shield which is covered with a rubber jacket
and a BNC connector. Pin in center carries hot signal, while outer cup connects ground. Distance between hot and cold are constant throughout the cable which makes them
ideal for use with antennas.
Balanced connections:
- XLR cables: "Mic cables", Pin 1 = Ground, Pin 2 = Hot, Pin 3 = Cold. Signal flows from female end to male end of the cable.
- TRS cables: "Balanced 1/4" or TRS (Tip, ring, sleeve), tip = hot, ring = cold, sleeve = ground
- TT cables: Similar to TRS cables, half the size of a TRS cable, and tip is more rounded. Use in mostly studio patch bays. Same pinout as TRS, Tip = hot, etc.
- Snakes: Large cables, allow for multiple isolated signal to be sent through them simultaneously.Often have multi-pin connector on at least one end.
Multi-channel balanced audio cables:
- ELCO cables: Can carry up to 28 channels of balanced audio (84 Wires), connects through one single connector. It is common practice to wire an ELCO connector to
support 24 channels, leaving some of the connector unpinned.
- DL cables: simliar to ELCO but different shape and uses a latch to be threaded instead of a screw. Recommended to be connected only a dozen or so times in its life.
DL is the format used by solid state logic
- D-sub or DB25 cables: This has the same description as the DL cables, this needs to be fixed.
Digital cables and connectors:
- Light pipes: Use fibre optics to transmit digital information. Support multiple formats and protocals, including: ADAT, SMUX, SMUX 2, and S/PDIF
- S/PDIF: Supports both stereo and 5.1 surround at sample rates as high as 192k. Uses RCA connector, and 75 ohm coaxial cable, but can support S/PDIF as well.
- AES: Uses XLR type connector and a 110 ohm cable to send 2 channels of digital audio. Supports sample rates high as 192k.
- TDIF: Tascam Digital interconnect format, uses DSUB cable to send and receive eight channels of digital audio simultaneously. Signals can travel to and from the
the device over one single cable.
- BNC cables:Used to send digital clocking signal called word clock which allows the digital audio devices to sync together. Also used to transport digital audio
in a format called MADI.
- MADI: Uses BNC cables or light pipes to carry vmulti channel digital audio. "AES 10 standard". Can transport as many as 64 channels of digital audio over a single
cable using serial digital transmission.
- mLAN: Uses a firewire 400 type cable and incorporates several features of the firewire standard into its protocol.
- Digi link cables: Used to send digital audio between the protools HD cards and the converters
- Firewire 400: Standard protocol supported by most computers, can support hundreds of channels of high-resolution digital audio.
- Thunderbolt: faster transfer speed than firewire
- USB: Standard computer protocol, not recommended to send more than two channels of digital audio at a time over usb. MIDI info. can also be sent over usb.
- CAT 5: "RJ45 or Ethernet": can be used for digital audio, no current AES standard exists for the purpose at this time. Used to connect digital audio systems using
a proprietary protocol called Dante. Can also be used to connect many models of protools controllers.
Review Questions:
- Unlike other types of cables which carry voltage, "Digital" cables transfer information in the form of binary code.
- The "Audio engineering society", is an organization which has helped to standardize and document audio formats and digital audio protocols.
- "MADI" is a protocol which was developed by AMS neve SSL and AES. It uses BNC cables or light pipes to carry multi channel digital audio.
- Patch bays: Server two important functions, providing a centralized hub where all analog audio connections can be made, and dictating the default signal flow of the studio.
- Most common types of connector types and configurations are: 96 point TT and 48 point TRS, both commonly found in single space 19" rack panels.
Fully normalled: A fully normalled connection is broken when patch cable is inserted into either the top or the bottom jack.
Half normalled: Only patching into the bottom jack will break normal.
Parallel: Normal can not be broken.
Open: No connection between top and bottom rows.
Split: One set of inputs or outputs feeds both the top and bottom row, with the top row mirroring the bottom.
Review Questions:
- "Patch bays" server two important functions, providing a centralized hub where all analog audio connections can be made, and dictating the default signal flow of studio.
- A "Fully normalled" patch bay connection is broken when a patch cable is inserted into either the top or the bottom jack.
- With a "Half normalled" patch bay, only patching into the bottom jack will break normal.
