The XO4 is a 4-in 8-out audio management system from XTA, in collaboration with Funktion One, offers advanced processing capabilities and improved performance along with extra features as standard.



  • 4 inputs and 8 outputs - native processing now runs at 96k resulting in wider bandwidth (over 30kHz).
  • Flexible routing matrix - in addition to standard fixed configurations such as 4 x 2 way (standard configs are still implemented), any output may be fed from any input or the sum of inputs. Edit buttons show routing instantly when pressed.
  • Extended processing capabilities - 9 (previously 5) full bandwidth parametric bands available on every output, all switchable between PEQ, high and low shelving responses.
  • Input EQ is now offered as standard - 8 bands of fully parametric EQ on each input channel.
  • Further extended processing capabilities - crossover filters on each output now offer 48dB/Oct. responses, on top of the previously available 1 to 4dB/Octave options. A gentle 6dB/Octave roll-off response is also now included.
  • Legendary XTA program limiters with automatic and manual time constant facilities.
  • New additional ''D-Max'' limiter with look ahead processing allows attack time of standard limiter to be optimised for best audio quality, whilst still being able to set a ceiling on the maximum output of any channel.
  • Delay memory allows for up to 650mS from any input to any output - extra fine delay resolution on outputs for driver alignment, in 30nS (0.1mm) steps!
  • Extended memory capacity - user memories now extended to a maximum of 55 which may be Input data, X-over data or both.
  • Library manager software available for design of OEM presets - design your crossover live whilst connected to the unit, and lock out any parameters as required to stop end user adjustment/viewing. No practical limit to the number of presets that may be stored (over and above the user memories).
  • Improved converters - lower noise and improved distortion figures.
  • AES Input accepts AES rates from 32k up to 192k via a sample rate converter. Front panel indication of AES selection and AES lock status.
  • AES Output (available special order as a product enhancement) sample rate fixed at 96k.
  • Familiar 226 style user interface with enhancements including menu shortcuts and quick access triple press editing to get the job done quickly. ALL functions are available though the front panel interface - NOTHING is just a remote facility.
  • Bigger 2 x 24 character display with new low profile buttons.
  • Auto switching power supply works across the world on all voltages. 
  • XO4A - Audiocore compatibility (Not available in the standard XO4), control up to 32 processors remotely via 3 Pin-XLR standard signal cable, using RS485 (wireless adaptor available).


DP4 Remote application offers the possibility to remote control up to 32 XO4A Loudspeaker Management Systems from your iPhone® or iPod Touch® or iPad®.  DP4 Mini is also available as a shrunk down application that allows read only access.

Funktion One XO4 Audio Management System

  • Inputs:  4 electronically balanced
    Impedance: >10k ohms
    CMRR: >65dB  50Hz - 10kHz


    8 electronically balanced
    Source Imp: <60ohms
    Min. Load: 600ohm
    Max. Level: +20dBm into 600 ohm
    Frequency Resp: ±0.5dB 20Hz-20kHz
      -3dB @ 32kHz
    Dyn. Range: >116dB 20Hz-20k unwtd
    Distortion: <0.02%@1kHz +18dBm
    Maximum Delay: 650 mS 
    Min Step Size: 0.3 µS
    Input Gain: +6dB to -40dB in 0.1dB steps
    Output Gain: +15dB to -40dB in 0.1dB steps and mute
    Parametric Equalisation**
    8 Sections per Input, 9 Sections per Output 
    Filter Gain:  +15dB to -30dB in 0.1dB steps 
    Freq. Range: 19.7Hz - 32kHz, 1/36 octave steps
    Filter Q / BW: 0.4 to 128 / 2.5 to 0.008
     (Sections switched to shelving response)
    Low Frequency:  19.2Hz - 1kHz
    High Frequency: 1kHz - 32kHz
    Shelf Gains: ±15dB in 0.1dB steps
    High and Low Pass Crossover Filters
       1 of each high & low pass filter per output
      Bessel / Butterworth 6/12/18/24/48dB per octave
      and Linkwitz-Riley 12/24/48dB per octave
    Look ahead output limiters:
    Threshold:  +22dBu  to -10dBu
    Attack Time: 0.3 to 90 milliseconds
    Release Time: 4/8/16/32 x Attack time
     Automatic time constant facility also included
    'D-Max'' clip limiters:
    Threshold:  +2 dB to +12 dB above standard limiter
    Release: Slow/Medium/Fast/Automatic
    Display:  2 x 24 Character LCD
    Input Meter:  2 x 4 point, -24dB to digital clip
    Output Meter  8 x 4 point, -24dB to +4dB into limit
    Inputs:  3 pin female XLR
    Outputs:  3 pin male XLR
    External:  9 pin DEE connector (RS232)
     3 pin XLR I/O (RS485)*
    Power:  3 pin IEC
    Power: 60 to 250V ±15% @ 50/60Hz

     3.3kg Net, (4.7kg Shipping)

    7.25lbs Net, (10.3lbs Shipping)

    Size: 1.75''(1U) x 19'' x 11.8''
     (44mm x 482mm x 300mm) excluding connector
    Latency: 1.5mS (analogue in - analogue out @ 96kHz)


    Only operational when AudioCore compatibility option has been included 
    ** Extended EQ Pack adds the following response types: Band pass; Notch; All pass; Phase; Elliptical Hp/Lp; VariQ (Resonant)
    Due to continuing product improvement the above specifications are subject to change.


Product Rating

“By far the best service I’ve ever experienced. I was importing a product to Canada and the whole experience was quick, easy and seamless. These guys really care about running a good business. Not to mention the price was cheaper than the stores here even after importing. Definitely will do more business in the future.” 

—  Philip Manzon

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