Audio Week 3 (Patchbay, cables, connectors)

Patchbay

1) from point A to point B: out to in (never into out) i. Output is normally top row and input is bottom. Sometimes they're next to each other. ii. Send = output, return equals input (ex. Inserts, AUX) 2) A panel that enables us to use all of these different pieces of gear. A patchbay contains accessible patch points. (Jacks) that correspond to the various inputs and outputs of these devices. (Console, external effects and monitoring devices) you can even have patch points hat connect to different production rooms. * it exists so that you don't have to reach around the back of every piece of gear and stretch cables across the floor every time you want to use them 3) Color coding includes White for inputs, green for multitrack returns (output), red color for channel insert sends

Ground

A.k.a. shield, chassis, or earth; (third prong on a plug) used to allow electricity to travel safely down to the earth and reduce the risk of shock or electrocution

TRS (balanced cable) (Tip ring sleeve)

A.k.a. stereo quarter-inch carries audio between various equipment

Balanced cable

Carries +4 DBU and -55 DBU; low wattage • The term "Balanced" means there is both a hot (+) and cold (-) wire inside the cable that are utilized to complete the circuit path and carry audio from end to end • there is also a third wire inside that is comprised of metal hairs that are simply wrapped around, or braided around the 2 audio carrying wires • noise reduction: common mode rejection (another reason why they're called "balanced") -as audio travels through the cable, the hot and cold wires are flipped out of phase by 180° (if we listened at this point we would hear nothing except maybe interference) -as interference (RFI/EMI) presents itself at this point, it attaches to the audio and travels along with it to the other end -by the time audio arrives at the other end and is flipped back into phase with itself (by the input transformer of the receiving device) for listening, any noise that was present on the way is now canceled out 180°

Unbalanced cable

Carries -10dBu; High wattage • there is only one audio carrying wire that allows the hot (+) signal to travel through • ground has two operations: not only does it protect the electricity traveling through, but it also acts as cold (-) to complete the circuit path Noise reduction: • The only way to avoid noise in an unbalanced line is to provide a thick shielding against it • there are many layers of rubbery plastic, a cottony paper sheath & of course the material a ground shield is made from that all help protect the audio traveling through from interference • more than 16ft would add more noise to the sound

XLR ( balanced cable) (Mic cable)

Carries pro line or Mic level signal to console, to multitrack, etc

EMI

Electromagnetic interference - comes from electronic equipment, most often refrigerators, and fluorescent lights. - to eliminate you must: Limit grounds by using power strip, utilize outlets that are separated from the rest of the buildings' AC lines - indicated with orange outlet. The last resort would be using a ground filter

One patch

Output is not normalled to the input. When no plugs are inserted, each I/O connection entering or leaving the panel is independent of the other and has no electrical connection. E.g.) outboard gear input and output

RFI

Radio frequency interference - comes from cell phones, TV stations, radio stations - to eliminate you must: Convert to a balanced line, use higher quality shielding in an unbalanced cable, and reposition player in the room

Half-normalled

The internal connection is broken when patching at the input only. You would use this when splitting the signal to other locations without interfering with the current internal "Normalled" connection E.g.) Multitrack output - Ch. line input

Fully normalled

The internal connection is broken when patching at the input or output. E.g.) Studio Mic line - Ch. mic input *only fully normalled connection in B

Speaker cable

This cable contains two heavy gauges with parallel wires that carry amplified signal from amp to speaker - ON-SHIELDED DO not confuse with instrument cable or with other shielded cable's - connector associated with unbalanced/speaker cables: TS (Tip sleeve)

Bantam (balanced cable) (mini TRS)

Used to carry audio from place to place in the patchbay a.k.a. mini TT (telephone type)

Noise

Usually described as the addition of unwanted sounds (White Noise) due to RFI and EMI; a.k.a. interference which is usually a problem in studios as it latches onto audio running to AC cabling and thereby becomes amplified with audio signal

Normalled

When no plugs are inserted, each I/O connection entering the panel is electrically connected