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LA Audio MPX10 Operation Manual

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MULTI PROCESSOR
OPERATION MANUAL

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  • Page 1 MULTI PROCESSOR OPERATION MANUAL...
  • Page 2 Version - V1 April 2000 Page 2...

  • Page 3: Table Of Contents

    CONTENTS Page Introduction Installation Inspection and un-packing Operating environment CE standards Power requirements Signal levels External connections Warranty 10-15 Description of controls Input section Noise Reduction and Compressor section Equaliser section Output section 16-21 Applications Input Compressor Expander Equaliser Output Circuit description Inputs Expander and Compressor...

  • Page 4: Introduction

    Noise Reduction, 4 mode Auto Compressor and Equaliser in a compact 1U case. The MPX10 is an ideal front end for direct to tape or hard disk recorders and as a superior analogue input stage for digital work stations. The MPX10 is equally at home in sound reinforcement applications where it can provide feedback suppression, vocal levelling and comprehensive tone shaping.
  • Page 5 Page 5...

  • Page 6: Installation

    2 . 1 I N S P E C T I O N A N D U N P A C K I N G The MPX10 has been carefully packed at our factory in a carton designed to withstand handling in transit. Should the unit appear to have been damaged in transit notify your dealer immediately and do not discard any of the packing.

  • Page 7: Signal Levels

    An incorrect fuse could cause damage to the unit and may constitute a fire hazard. If you carry your MPX10 from one country to another it is very important to ensure the voltage is compatible. For your information the unit can be internally rewired for use in 230V, or 110-125V countries - contact your dealer for information.
  • Page 8 INPUT SECTION: M I C R O P H O N E XLR Pin 1 Screen (Signal ground) Pin 2 Hot (+ve) Pin 3 Cold (-ve) This is a low impedance (1.2k ), low level input designed to give the correct loading and sensitivity for dynamic type microphones.
  • Page 9 This connector provides an unbalanced line level output from the Mic/Line/DI preamplifier. Plugging a jack into this connector does not effect the signal path through the MPX10. Source impedance is 100 which is suitable for driving loads of 1k and greater.
  • Page 10 Commonly used to insert an equaliser into the sidechain to produce frequency conscious compression such as de-essing. Because each section of the MPX10 has Input and Output break jacks it is possible to plug the EQ of the MPX10 into the Compressor sidechain to allow more advanced Frequency Conscious Compression.
  • Page 11 O U T P U T jack Hot (signal +) Sleeve Screen (signal ground) An unbalanced output from the Compressor section. Page 11...

  • Page 12: Output Section

    EQUALISER SECTION I N P U T jack Hot (signal +) Sleeve Screen (signal ground) Unbalanced input to the EQ section. Half-Normalled to the output of the Compressor section O U T P U T jack Hot (signal +) Sleeve Screen (signal ground) Unbalanced output from the EQ section.
  • Page 13 To receive service under this warranty it is 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.

  • Page 14: Description Of Controls

    I N P U T S E C T I O N G A I N control This control adjusts the sensitivity of the MPX10's input amplifier. GAIN has different ranges depending on which input is selected - +10dB CCW (counter clockwise)
  • Page 15 N O I S E R E D U C T I O N & C O M P R E S S O R S E C T I O N NR (Noise Reduction) on the MPX10 is provided by a downward expander which operates exactly opposite to a compressor.
  • Page 16 level falls the more the gain is reduced. Expander response is soft knee around the onset of attenuation which combined with a low ratio (2:1) and slow decay (similar to 'release' on a gate) time ensures transparent operation. The fast recovery (similar to 'attack' on a gate) time ensures that leading transient edges are not lost.
  • Page 17 Threshold. This is referred to as Limiting. The ratio curves shown in Fig 4.3.1 are Hard-knee where the change in gain is abrupt. The MPX10 has a Soft-knee control system which provides a gradual change between compression levels. A T T A C K & R E L E A S E switch...

  • Page 18: Equaliser

    LMF control This control sets the amount of cut or boost for the LMF (Low Mid Frequency) section. The Gain range on the MPX10 is ±15dB. The diagram on the following page shows the effect of different cut and boost settings.
  • Page 19 Varies the 'Q' (bandwidth) of the cut or boost region. A low Q, CW (clock wise) affects a wide band of frequencies whilst a high Q, CCW affects a very small band. The Q control on the MPX10 has a range of 0.3 (3 octaves) to 12 (1/12th octave) - see the following diagram.
  • Page 20 H M F control Sets the amount of cut or boost for the HMF (High Mid Frequency) section. F R E Q U E N C Y control This control varies the cut or boost centre frequency for the HMF section. Control range is 500Hz, CCW to 20kHz, CW.
  • Page 21 O U T P U T control The OUTPUT adjusts the final level from the MPX10. It can be used to level match between equipment connected to the MPX10. Adjustment range is -20dB to +20dB. G A I N R E D U C T I O N meter The led meter displays the applied gain reduction (GR) in dBs.

  • Page 22: Applications

    5.0 APPLICATIONS Using the MPX10 to record direct to tape, rather than through a mixing console and associated cabling, will result in a cleaner, less cluttered recorded sound which has more definition. 5 . 1 I N P U T...
  • Page 23 Signal levelling Signal level variations can occur when the distance between the vocalist and microphone changes. The MPX10 compressor can be used to level out the result of poor microphone technique, producing an even sound. Set RATIO to around 4:1 and adjust THRESHOLD for a gain reduction of 6 to 10 dBs at maximum signal level.
  • Page 24 'ess' frequencies. This method can also be used to tune-in to a particular fret buzz on a guitar. The Millenium EQX20 or the EQ section of the MPX10 is ideal for this application.
  • Page 25 5 . 4 E Q U A L I S E R The MPX10 offers High and Low shelving equalisers and two fully variable parametric Mid sections. In general the shelving EQs are easy to use and have a smooth, musical character.
  • Page 26 A U D I O S W E E T E N I N G a n d P R E C I S I O N E Q U A L I S A T I O N The following are a few practical examples which should be treated as clues, with personal taste, source sounds and material you are creating deciding the final settings.
  • Page 27 M I X I N G C O N S O L E Patch any or all of the sections of the MPX10 into a channel or Group insert on your console to add Expander, Compressor and EQ processing to your signal path.

  • Page 28: Circuit Description

    Gain Threshold Compressor Detector Sidechain Threshold Ratio Auto Gain reduction Bypass Filter Input 2 x Mids Gain Freq Output -10dBV Input Output +4dBu Output Level Fig: 6.0.1 Block diagram of the LA MPX10 showing the main signal paths Page 28...
  • Page 29 6 . 1 I N P U T S The Mic input has a dedicated amplifier stage which is optimised for low noise, impedance matching and common mode rejection. This amplifier is protected against RFI and excessive input levels. The GAIN control for this stage is ganged to the Line amplifier to ensure maximum signal headroom.
  • Page 30 C O M P R E S S O R The Threshold control sets a DC reference level above which compression can start. This is compared to the RMS voltage and when this exceeds the reference the difference is forwarded to the Ratio control. RATIO The difference voltage from the Threshold stage is amplified or attenuated depending on the setting of Ratio.
  • Page 31 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. The outputs of the Expander and Compressor sidechains are combined and drive both the VCA control port and the Gain Reduction meter.

  • Page 32: Inputs

    7 . 0 S P E C I F I C A T I O N S INPUTS electronically balanced, 1.2k , XLR-F, pin 2 = hot LINE electronically balanced, 20k , 1/4" TRS, Tip = hot unbalanced, 0.5M , 1/4" jack, wired Tip = hot OUTPUTS Type Ground sensing, balanced impedance...
  • Page 33 Weight Unit = 2.2kg, Shipping = 2.85kg LA Audio reserves the right to alter any feature or specification without prior notice E&OE. Page 33...
  • Page 34 Page 34...

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