Review #3 (OP Amp, Cable)

The Music Telegraph | Text 2019/03/08 [16:23]

Review #3 (OP Amp, Cable)

The Music Telegraph| 입력 : 2019/03/08 [16:23]

▲ Microphone pre amplifier circuit (OP amp circuit diagram)

© Toyskids



 

Review #3 (OP Amp, Cable)

 

 

OP Amps

 

1. Unity gain = 0 dB gain (1:1 ratio)

 

a) Summing Amp

- Combine several input signals into one composite output signals

- Found in console masters

 

b) Distribution Amp

- One signal in, multiple outputs

- Found in headphone cue systems

 

c) Impedance matching Amp

- Any Z in, constant output Z in:

1) Condenser Mic pre-amp => 200 Ω out (to a Mic input)

2) In an Active Direct Box => 200 Ω out (to a Mic input)

3) After patch bay inputs => 600 Ω out (to line input)

 

 

 

2. Non-unity gain or Amps

 

a) Console Mic pre-amp

: 60 dB gain -> brings Mic level to line level

: Trim pot or gain control

 

b) Line-Amps

: To boost signals already at line level

1) In line inputs (line trim)

2) EQ: +15 dB boost

3) Fader

 

 

 

Audio Cables

 

1. Balanced Line

- Up to hundreds of feet of cable run with Lo Z

- 3 conductors:

1 hot (+)

1 cold (-)

1 shield to ground

 

e.g. XLR connector:

- pin 1 = ground

- pin 2 = hot

- pin 3 = cold

 

 

 

2. Unbalanced Line

- 2 conductors:

1 hot (+)

1 cold (-), which is also for shields

- Used with Hi Z equipments

- Maximum 25 ft of cable run

 

 

 

 

Protection

- ‘Surge suppressor’ to prevent spikes from damaging equipment

 

 

Voltage regulator

- Keeps voltage with +/-5V of operating voltage

 

 

Power conditioner

- Removes “dirty” (noisy) AC line buzzes (inherent noises of electronic devices) and static hum

 

 

UPS

- Uninterruptible Power Supply

- Back-up battery for computer

 

 

 

 

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