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Version: Price: €79.00  Download

Windows Mac VST


With the Sonoris Meter, you can measure peak and loudness levels of audio signals, simultaneously at one scale. Besides a regular meter scale the Sonoris Meter supports the K-System, from Bob Katz, mastering engineer and founder of Digido masteringstudio. The end product closely follows the K-system specifications, including Leq(A) loudness metering and bandlimited pink noise monitor calibration.

The SMTR features an oversampling peakmeter mode. In this mode the SMTR catches intersample peaks that can cause ear fatiguing sound when audio is played on consumer CD players. Many CD players have inferior D/A converters with little headroom that will distort with samples above the clip level. These peaks occur when the audio is clipped (read squashed / limited) or otherwise digitally manipulated (eg. VSTi's). In oversampling mode the SMTR models the D/A conversion process and allows for maximizing the level but avoiding this distortion.

At the bottom of the interface a correlation meter can be found. This meter enables the user to monitor the phase relationship between the left and right channels.


  • Sample-accurate peak metering
  • K-System metering, closely following the K-System spec. , with three metering sets:
    • K12 for broadcast productions
    • K14 for home theatre, pop, rock, folk, etc
    • K20 for wide dynamic music
  • Regular, non K-system scale also available
  • High resolution metering of peak and loudness levels, on the same scale
  • Intersample peak metering mode
  • Correlation meter
  • Peakhold function with resetable indicators or 10 seconds hold
  • Loudness measurement methods: RMS/flat (AES-17) and Leq(A-weighted)
  • Pink noise output (left, right or stereo) for monitor calibration of 0dBr / 83dB
  • Adjustable number of consecutive overs before clipping
  • Resettable clipping indicators
  • Resettable clipping incident counters
  • Mousewheel support
  • All samplerates supported
  • Low CPU load
  • Settings can be saved
  • 64 bit resolution

The K-System

This page is not intended to fully explain the K-System and it’s backgrounds, but just the basics. For more indepth information, please read this article about level practices written by mr. Katz.

The K-System defines three metering scales, with different headroom. The systems are: K12, K14 and K20. The number defines the available headroom for the set. All measurements are in dBr, in contrast to standard VU or RMS meters. As the name says, it’s really a system. Every set depends on a calibrated monitor setting. For example, the K20 set has the standard 83dB monitor level at 0dBr, that’s –20dBFS. The K14 has 83dB at –14dBFS and so on. The main advantage is that you always work at the same monitor level, and the chosen set defines how much headroom there is available.

Typical uses for the three systems are:

  • K20: wide dynamic music / classical / "audiophile"
  • K14: high fidelity music for home listening, rock, folk, pop etc
  • K12: broadcast productions

Monitor calibration

Besides metering the Sonoris meter allows for accurate monitor calibration. By calibrating your monitors to a fixed level synchronized to a scale, the Sonoris Meter becomes a powerful tool allowing you to make more consistent masters with regard to loudness.

Calibration is simple, first select what channel to use for the calibrated pink noise (bandlimited 20Hz-20KHz or 500Hz-2KHz), L, R or both. The levels are calibrated to show 0dBr on any K-scale or -20dBr on the regular scale. You can calibrate your monitors at this level to show 83dB on a slow, C-weighted SPL meter using your monitor control. In stereo mode add 3dB. Mark the monitor control levels for each scale and you are done!

The 500Hz-2KHz noise signal can give a better and more stable reading on the SPL meter under some circumstances. Please try both options and see what works best for you.

RMS and Leq loudness measurement

RMS. This is the standard non-weighted implementation of RMS. Regardless of the samplerate, the bandwidth is 20 Hz to 20KHz (-0.1dB). The RMS calculation window is 1024 samples and metering ballistics are 600 msec. attack and release, as defined in the K-System specification. The 0dBr level is calibrated with –20dBFS pink noise.

Leq(A). This is the first implementation of a K-System meter with Leq. The definition of Leq is: "The level of a constant sound, which in a given time period has the same energy as a time-varying sound". Leq is also used in loudness meters for measuring aircraft noise or industrial noise over a long period. In the Katz proposal the Leq is measured over a 3 sec. interval. This is implemented in the plugin. The (A) stands for A-weighting filter. This filter approximates the loudness sensitivity of the human ear. In practice, you see a nice and rather slow meter, that translates the loudness very well.

Correlation metering

At the bottom of the meter you see a correlation meter that consists of a row of leds that range from -1 to +1. This meter shows the correlation between the signals of the left and right channels.

  • If the signals are in phase, the meter shows “1”.
  • If the signals are out of phase, the meter shows “-1”.
  • If the signals are completely uncorrelated, the meter shows “0”.

For normal stereo recordings, the meter should indicate a value between “0” and “1”. When one of the signals is absent, the meter shows “0”, because this is the neutral position. Negative values for a longer time indicate possible phase problems.


"There are hardware options such as VU meters, or LED offerings from Dorrough, Logitek, or Mytek. But Sonoris Meter is a plug-in that offers similar performance, allows on-the-fly scale changes, and generates calibration tones at a fraction of the price of the hardware units."

TapeOp, USA/UK/EU, 08-2009
logo Tapeop


"The Sonoris Meter is a flexible and affordable addition to my setup. The K-System and oversampling features help ensure consistent levels and accuracy."

Richard Morris
Mastering Engineer,
Richard Morris Mastering

"This is the one plugin that is used in every session."

Michael McInnis
Michael McInnis Productions


User Manual