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Hi z = Line level Low z = Mic Level Direct Box changes impedence from line level to mic level. High / Low Impedance. A high impedance circuit tends to have high voltage and low current A low impedance circuit tends to have relatively low voltage and high current. Connecting Devices.
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Hi z = Line level • Low z = Mic Level • Direct Box changes impedence from line level to mic level
High / Low Impedance • A high impedance circuit tends to have high voltage and low current • A low impedance circuit tends to have relatively low voltage and high current
Connecting Devices • I'M CONNECTING TWO AUDIO DEVICES. IS IT IMPORTANT TO MATCH THEIR IMPEDANCES? WHAT HAPPENS IF I DON'T?
Connecting Devices • When you connect two devices, one is the source and one is the load. • The source is the device that puts out a signal. • The load is the device you are feeding the signal into. • The source has a certain output impedance, and the load has a certain input impedance. • It’s important to match the output impedance of the source to the input impedance of the load
Matching Impedance • If the source impedance equals the load impedance, this is called "matching" impedances. • It results in maximum POWER transfer from the source to the load.
low-Z source to a high-Z load • Suppose the source is low Z and the load is high Z • There is no distortion or frequency-response change caused by this connection. • When you plug a low-Z source (microphone) into a high-Z input you get a weak signal. That's because a high-Z input is designed to receive a relatively high voltage from a high-Z mic or instrument, and so the input is designed to have low gain. So you don't get much signal amplification.
high-Z source to a low-Z load • If you connect a high-Z source to a low-Z load, you might get distortion or altered response • For example, suppose you connect an electric bass guitar (a high-Z device) into an XLR-type mic input (a low-Z load). The low frequencies in the signal will roll off, so the bass will sound thin.
high-Z source to a low-Z load • We want the bass guitar to be loaded by a high impedance, and we want the mic input to be fed by a low-impedance signal.
Low z – High z mics • Most mics are low Z, and all mics with XLR (3-pin) connectors are low Z. • A low-Z mic can be used with hundreds of feet of cable without picking up hum or losing high frequencies. • A high-Z mic will lose highs and pick up hum if the cable exceeds about 10 feet • If your mixer has XLR inputs, they are low-Z balanced.
Balanced connections • A ¼” balanced connection uses three wires • Tip Signal + (Positive) • Ring Signal - (Negative) • Sleeve (Ground ) • TRS
Balanced connections • An XLR balanced connection uses three wires • Pin 1 (Ground ) • Pin 2 + (Positive) • Pin 3 - (Negative)
Balanced connections • The balanced connection has the advantage that it rejects noise and interference that may be picked up on long cable runs
Unbalanced • An unbalanced connection uses two cable wires • Signal • Ground
Types of Cabling • ¼ unbalanced line/instrument cabling • XLR balanced cable used for microphone and line level connections • RCA unbalanced line level/ phono connections • Speaker cable, various gauges depending on the application • AC Cabling • Patch bays are not common in live sound • Mutipins ( Snakes, outboard racks, consoles ) • Inserts ( Tip, Ring, Sleeve, unbalanced x 2 )
Insert Cable • Pg. 294 • Gives you an unbalanced input and output from a tip ring sleeve connector on the console • Eq’s, Compressors, Gates, Effects for a single channel • English an American consoles may be wired differently • If no signal is present flip input and output on the device being inserted
Speaker Cables • Can be used with ¼” , Banana Plug or Speakon connectors.
¼” Speaker Connector • Tip Positive + • Ring Negative – • Do not use for instruments may cause buzz • Vice Versa ( Do not use Instrument cables to run speaker, may short amplifier, causing failure or damage )
Banana Plugs • 2 conductor connector positive and negative • Fit into binding terminals on amplifiers • Tab is usually wired to the negative terminal • Can be piggy backed, connected to each other • Recently outlawed in Europe
Speakon Connectors • Three different types • NL2 • NL4 • NL8
Speakon Connectors • Industry Standard • NL2 ( Two Pin Connectors ) +1 -1 • Used for Single Speaker Connections • NL4 ( Four Pin Connectors ) +1 -1, +2 -2 • Used for two Speaker Connections ( Bi-Amp) • NL8 ( Eight Pin Connectors ) +1 -1, +2 -2, +3 -3, +4 -4 • Used for 3 or 4 way Speaker Connections
Speakon Connectors • No universal wiring configuration • Check amplifier specifications for pin wiring configuration
Adaptors • Adaptors are available for every possible application
RCA Adaptors • RCA to ¼” • ¼” to RCA • Fem RCA to Fem RCA
AC • Alternating current • Standard circuits are 115 volt 15amp 60Hz • 1 amp = approximately 100 watts • Rule of thumb Maximum amount of power you can draw from one 15 amp circuit is approximately 1500 watts