LA Audio GOC20 Operation Manual Download Page 16

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Page 16

7.0 SPECIFICATIONS

INPUTS

Type

electronically

balanced

XLR-F

+4dBu, wired pin 2 = hot ()

1/4' TRS jack

-10dBV, wired Tip = hot

Impedance

20k

Ω

Maximum input

+20dBu

Sidechain

unbalanced, TRS jack, >10k

Ω

OUTPUTS

Type

Ground

sensing

XLR-M

+4dBu, wired pin 2 = hot ()

1/4" TRS jack

-10dBV, wired Tip = hot

Impedance

100

Ω

Max. output

+20dBu

Sidechain

unbalanced TRS jack, <100

Ω

PERFORMANCE

THD

< 0.05%, 6dB compression

Noise

-87dBu

Frequency response ±1dB, 20Hz to 20kHz

GATE CONTROLS

THRESHOLD

-50dB to +20dB

RANGE -80dB
ATTACK <1mS
RELEASE

30mS to 3S

COMPRESSOR CONTROLS

THRESHOLD

-30dB to +20dB

RATIO

1:1

20:1

ATTACK

Fast = 5 - 70mS, program dependant

Slow = 10 - 100mS, program dependant

RELEASE

Fast = upto 0.5S, program dependant

Slow = upto 2.5S, program dependant

GAIN

-20dB

+20dB

POWER SUPPLY

Mains voltages

220VAC, 60Hz, 6VA

Europe

115VAC,

60Hz,

6VA

North

America

220VAC,

60Hz,

6VA

ROK

Mains connector

Standard IEC receptacle

MECHANICAL

Dimensions

1.75" (44mm)H x 19" (482mm)W x 6.5" (165mm)D

Weight

Unit = 2.2kg, Shipping = 2.85kg

LA Audio reserves the right to alter any feature or specification without prior notice E&OE

Summary of Contents for GOC20

Page 1: ...DUAL COMPRESSOR NOISE GATE OPERATION MANUAL Version 1 April 2000 ...

Page 2: ...section Page 9 10 5 Applications Page 11 5 1 Compressor applications Page 11 12 Limiting PA systems Preventing tape and digital overload Signal levelling Fattening bass drum sounds Bringing sounds forward in the mix Vocal de essing 5 2 Noise Gate applications Page 12 13 Reducing background noise Tightening percussion sounds Improving mic separation Feedback avoidance Modifying signal decay 5 3 Oth...

Page 3: ...d and Release Fast attack Stereo linking Gate threshold LED Side chain insert for connection of an external equaliser Balanced inputs and outputs on XLR and TRS jack connectors The two Compressor sections feature Soft knee compression Two Auto Attack Release modes Variable Threshold Ratio and Gain Gain reduction metering Stereo linking Side chain insert for connection of external equaliser Balance...

Page 4: ...wer transformers motors mobile telephones or radio transmitters The unit should only be connected to a power supply of the type described in 2 4 POWER REQUIREMENTS or as marked on the unit The unit must be earthed for safe operation Disconnect the mains supply before removing any cover 2 4 POWER REQUIREMENTS There is a mains fuse located inside the unit which is accessed by removing the cover This...

Page 5: ...mpressor section allows 20dB to 20dB of level adjustment which should allow the GCX20 to interface to most equipment types Signals in excess of 20dB will cause the unit to distort 2 6 EXTERNAL CONNECTIONS The input and outputs of the GCX20 are balanced on both XLR and 1 4 TRS jack connectors For balanced input and outputs connections to the unit should be wired as follows XLR 4dBu Pin 1 Screen Sig...

Page 6: ...en Ring Send Tip Return Plugging into the GCX20 s side chain automatically breaks the signal path to the side chain circuitry This path must be completed by the external connected equipment The side chain in out signal path affects both the Compressor and the Gate response ...

Page 7: ...necessary to return the unit to an LA Audio authorised service centre or to the factory with a dated receipt as proof of purchase After repair the unit will be returned to you free of charge Limitations This warranty does not cover damage resulting from accident or misuse The warranty is void unless repairs are carried out by an authorised service centre The warranty is void if the unit has been m...

Page 8: ...t fully CW Short release times used with long decay sounds such as bass guitar can cause the gate to repeatedly close and open chatter To avoid this effect lengthen the RELEASE time A more sensitive THRESHOLD setting will also reduce the chances of chatter Short Release settings will give an abrupt ending to gated signals which may sound un natural on signals such as vocals string sounds etc N B T...

Page 9: ...TIO control Ratio defines the amount of compression applied to the input signal once it has exceeded the Threshold level A Ratio setting of 2 1 for example means that for every 2dB that the input exceeds the Threshold the output will increase by 1dB The following graph shows the relationship between input and output levels for various Ratios INPUT OUTPUT 1 1 2 1 4 1 10 1 20 1 THRESHOLD 0dB 0dB Fig...

Page 10: ... to the average level of the input signal and is the normal setting for most signal types Fast transient signal peaks will pass unaffected Using FAST attack the compressor reacts more to signal peaks and will control all but the fastest transients SLOW mode has been tailored for mixed program material FAST mode is suitable for solo instruments GAIN REDUCTION meter The led meter displays the applie...

Page 11: ...nto clipping producing unpleasant and damaging distortion In this application it is necessary to apply high degrees of compression at a high Threshold level Set the RATIO to 10 1 or 20 1 Set the THRESHOLD to minimum sensitivity fully CW Reduce the THRESHOLD until around 15 20dB of compression is achieved around 3dB below the amplifier clipping point N B Compressing program material with a high ene...

Page 12: ...or other lead track in a multitrack recording Use a gentle RATIO of around 2 1 and a THRESHOLD of approximately 20dB to achieve gain reduction of no more than 6dB Restore the compressed signal to its original level using the GAIN control NB Avoid over compression as this may produce a dull sound It is better to apply gentle compression twice passing the signal through both GCX20 compressors than a...

Page 13: ...for reducing mic leakage is identical to those above for tightening drum sounds although the settings of THRESHOLD and RELEASE for acoustic and vocal mics will vary from the drum kit mic separation ones Feedback avoidance Feedback can occur in live PA environments when signals from main or monitor speakers is allowed to enter open microphones Good engineering and microphone techniques will reduce ...

Page 14: ... The RMS detector produces a DC voltage level proportional to the RMS value of the incoming signal This voltage feeds both the Gate and Compressor side chains The level of signal leaving the VCA is controlled by the sum of the Gate and Compressor sidechains and the GAIN control 6 3 GATE THRESHOLD The Gate Threshold control adjusts the reference level for the gate This reference is compared with th...

Page 15: ...tenuated depending on the setting of Ratio This control voltage defines the amount of compression once Threshold has been exceeded ATTACK RELEASE Attack and Release are based around two time constants An initially short time which reacts to lower level and or short duration signals and a longer time constant for higher levels and or longer duration STEREO In stereo mode the RMS voltages are combin...

Page 16: ...z to 20kHz GATE CONTROLS THRESHOLD 50dB to 20dB RANGE 80dB ATTACK 1mS RELEASE 30mS to 3S COMPRESSOR CONTROLS THRESHOLD 30dB to 20dB RATIO 1 1 to 20 1 ATTACK Fast 5 70mS program dependant Slow 10 100mS program dependant RELEASE Fast upto 0 5S program dependant Slow upto 2 5S program dependant GAIN 20dB to 20dB POWER SUPPLY Mains voltages 220VAC 60Hz 6VA Europe 115VAC 60Hz 6VA North America 220VAC 6...

Page 17: ...COMPRESSOR 2 GATE 2 40 0 30 10 16 50 10 FAST SLOW RELEASE GAIN REDUCTION GAIN REDUCTION MASTER dB t dB t A U D I O Dual Compressor Gate 0 10 10 20 2 6 20 0 10 10 20 30 20 THRESHOLD THRESHOLD RELEASE 1 FAST GATE SLOW STEREO DUAL 20 GAIN RATIO dB 1 dB ATTACK BYPASS BYPASS LINK 20 15 10 6 4 2 COMPRESSOR 1 GATE 1 40 0 30 10 16 50 10 FAST SLOW RELEASE 0 10 10 20 2 6 20 0 10 10 20 30 20 THRESHOLD THRESH...

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