Project Description

RTW 11900

8-channel PPM, loudness metering processor including surround sound analysis of 5.1, 6.1 and 7.1 (the RTW “House”) and SPL monitoring calibration. Rack-mounting (1U); VGA output.

  • On-screen representation of surround sound field of 5.1, 6.1 and 7.1 (the RTW “House”)
  • On-screen bargraph metering of 8 audio channels
  • Scale options include PPM and loudness units (LU or LKFS) conforming to ITU BS 1771
  • Loudness history display with user-definable time-axis
  • Additional meter displays of short-, medium- and long-term loudness integrated over time (user-defined period)
  • Simultaneous phase correlation display of all channel pair combinations
  • 2- or 4-channel “Lissajous” vectorscope displays


  • Accepts both analogue and AES3 inputs; with AES3 loopthrough outputs
  • Optional Dolby E and Dolby AC-3 decoding
  • Optional HD/SD SDI de-embedding
  • Internal stereo downmix algorithm, available for metering and as an output

Other features:

  • Dialnorm measurement
  • Built-in 1/3- and 1/6-octave spectrum analysis
  • Mic input for absolute SPL calibration
  • BLITS tone compatible (reader and generator)
  • Stopwatch
  • GPIO port
  • 1U 19” unit with VGA output for optional 8.4” TFT screen or user’s own display

This unit is also available as the RTW Model 31900*, which includes a surround sound monitoring controller with desk top remote.
* does not include stopwatch feature.


The RTW 11900 is a powerful and flexible 8-channel audio metering system intended for reliable monitoring of surround sound programme material in a professional environment such as broadcast, post-production or music recording. It provides the user with all the information necessary to achieve accurate sound level management when working in 5.1, 6.1 or 7.1 surround formats.

The processor occupies 1U of rack of space. The stereo or 5.1, 6.1 or 7.1 display output is in standard VGA format and may be connected to any suitable monitor, or to the optional Model 30010 8.4” LCD display, which has the additional advantage of duplicating the processor’s front panel controls.

The display layout and content may be configured in a variety of ways to suit the user’s operational preferences. As well as bargraph metering, a 2-dimensional analysis of the instantaneous surround sound field may be displayed (the renowned RTW “House” display).

Audio level monitoring is via large, clear on-screen bargraph meters. Meter types may be user-defined; these include standard PPMs and loudness meter scales conforming to the recommendations of ITU BS 1771 (both LU and LKFS units). In addition to metering of the individual surround channels, further meters may be placed on-screen, showing, for example, an internally-generated stereo downmix and overall programme loudness integrated over various timescales. The stereo downmix is also available as an output.

Phase correlation may be added to the analyser display, showing the phase relationship between every pair of surround channels. Dialnorm measurement is provided for subsequent inclusion with DolbyÒ metadata. Loudness history may also be displayed as a graph of loudness against time, the time axis calibration being user-definable. A further display option is an audio vectorscope, showing “Lissajous figure”-type phase relationships in 2- or 4-channel modes. Spectrum analysis is also included as standard, with 1/3-octave or 1/6-octave displays.

The 11900 accepts inputs in both analogue (balanced) and digital (AES3) formats. Various input configuration possibilities are available, allowing simultaneous analogue and digital sources to be metered, e.g. as in 5.1+2 operation. Two optional modules are available which greatly extend the unit’s input capabilities, allowing decoding of Dolby E/Dolby AC-3 datastreams, and de-embedding of eight channels from a HD/SD SDI video signal respectively.

The 11900 incorporates a BLITS-compatible test tone generator for channel identification and studio monitor level matching. A microphone input is provided to aid this, enabling measurement of room SPL. The generated tones are available at the unit’s 8 channel AES3 outputs, which normally provide an active loopthrough of the AES3 inputs when the generator is not in use.

Control of the display during on-air use is through large on-screen buttons and a standard USB mouse, or a USB touchscreen overlay may be used if preferred. Contact closures on the GPIO port also mimic these buttons, allowing interface with external controls. If the RTW 30010 is being used, the soft buttons below its display may be employed for this purpose. There is also a comprehensive menu system to allow the user to configure the primary setup parameters to his or her taste. Configurations may be saved as presets to facilitate rapid recall in a multi-user situation. An import/export facility for presets is also provided and the unit’s GPIO port may be used to recall presets, if wished.

The 30010 VGA display pictured does not come as standard with the 11900.

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