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# WHAT IS IMPEDANCE - PowerPoint PPT Presentation

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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## PowerPoint Slideshow about 'WHAT IS IMPEDANCE ' - Philip

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Presentation Transcript

• Hi z = Line level

• Low z = Mic Level

• Direct Box changes impedence from line level to mic level

• 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

• I'M CONNECTING TWO AUDIO DEVICES. IS IT IMPORTANT TO MATCH THEIR IMPEDANCES? WHAT HAPPENS IF I DON'T?

• 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

• 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.

• 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.

• 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.

• 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.

• 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.

• A ¼” balanced connection uses three wires

• Tip Signal + (Positive)

• Ring Signal - (Negative)

• Sleeve (Ground )

• TRS

• An XLR balanced connection uses three wires

• Pin 1 (Ground )

• Pin 2 + (Positive)

• Pin 3 - (Negative)

• The balanced connection has the advantage that it rejects noise and interference that may be picked up on long cable runs

• An unbalanced connection uses two cable wires

• Signal

• Ground

• 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 )

• 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

• Can be used with ¼” , Banana Plug or Speakon connectors.

• 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 )

• 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

• Three different types

• NL2

• NL4

• NL8

• 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

• No universal wiring configuration

• Check amplifier specifications for pin wiring configuration

• Adaptors are available for every possible application

• RCA to ¼”

• ¼” to RCA

• Fem RCA to Fem RCA

• 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

• Powered Speakers

• Effects outboard equipment

• Instrument amps

• Keyboards

• Computers

• Consoles

• International Electrotechnical Commission

• Keep all cable runs tidy

• Do not run cables through the performance area

• Keep ac cabling and audio lines separate whenever possible to reduce noise

• Try not to run ac lines and audio lines parallel to each other to reduce noise

• Leave mic cable slack by the stand or instrument

• Do not leave mic cabling slack at the snake head or piled up on top of each other

• Leave speaker cable slack by the speakers not the amps

• Do not share ac power with lighting

• Use the proper length cable for the application whenever possible

• Use Sub snakes whenever possible to reduce clutter

• Use strain relief whenever possible

• Don’t tug on cables

• Wrap over under

• Pack up and wrap cabling in the reverse order of running them