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Noise gate section

Removes background noise, including 16-bit quantization noise.

The noise gate removes background noise, which is mainly useful for older recordings. But even for recent CD's it helps to let it work very gently, because quantization noise (the number of bits on a CD is not infinite) can be increased a lot by processing which makes music sound harsh. Gentle Link error '10083' and Noise gate level per band solve this.

Noise gate panel

General Noise Gate settings

  • Noise gate
    Turns the Noise Gate on.

Settings panel


  • Total noise removal
    The maximum amount of noise to be removed.

    This can be fine-tuned for different frequency ranges in Noise gate level per band.

Filtering per band panel


Noise gate level per band panel

Fine-tuning of the amount of noise to be removed per frequency range.

  • Relative band {} noise removal
    The maximum amount of noise to be removed per frequency range, relative to Link error '10083'.

  • Band 1

  • Band 2

  • Band 3

  • Band 4

  • Band 5

  • Band 6

  • Band 7

FM hiss panel


FM Hiss (removes FM hiss in the INPUT signal) panel

Removes FM stereo hiss on the input (!) signal.

If you need to rebroadcast audio from another radio station, and reception is not optimal, this filter can remove the FM stereo hiss without touching the rest of the sound. The sound stays stereo. Even quite severe stereo hiss can be nearly completely removed.

  • FM Stereo hiss removal
    Enables the FM Stereo hiss remover.

FM panel


  • FM median pos: Ordered histogram position that determines noise level
    Controls hiss vs. tone detection.

    A lower value means that sounds are more easily detected to be noise - a too low value will reduce not only stereo hiss but also other stereo sounds.

    A higher value means that even hiss is not detected properly anymore, and noise removal will not work at all anymore.

    Hint: Use the Difference checkbox to hear if what is removed is really only the stereo hiss.

  • Multiply median at most with
    Controls hiss vs. tone detection in combination with Multiply median at most with.

    Higher values mean that sounds are more easily detected as noise.

  • Reduction strength of estimated FM hiss level
    Determines how much FM hiss can be removed, compared to the measured hiss level.

    This normally needs to be set a bit above 100%, because otherwise the hiss is not always completely removed. If it is set too high, other sounds might be damaged as well.

  • History size (Response speed)
    The amount of time that hiss detection uses.

    If this time is short, FM stereo hiss will be removed nearly immediately when it becomes present. However, the detection of noise vs. tones and the level detection is less accurate. With longer times, it takes longer for the filter to kick in but it has less effect on the sound and removes the FM hiss a bit more accurately (or actually, the Reduction strength of estimated FM hiss level setting can be reduced a bit).

  • Rough/smooth: Median position in ordered history histogram
    Controls how to combine the measurements in History size (Response speed).

    The histogram of measured noise levels over History size (Response speed) is ordered, and then the value at this position is used as the noise level.

    If the FM stereo hiss is very constant, use a low value. This reduces incorrect FM stereo hiss detection. If for some reason the stereo hiss is not constant and changes rapidly, you might need a higher value.

    Set this value as low as possible until you notice that it starts to miss hiss.

Phase issues panel



Azimuth correction section

Reparation of AZIMUTH (phasing) errors.

AZIMUTH errors are often present in tape recordings, and also on some cheap CDs. Phasing problems causes playing a recording in mono or through a surround system to result in very ugly artifacts. But even normal stereo playback may sometimes sound a bit unpleasant. The phasing offset is automatically detected and removed by this filter.

This filter only works properly if the sounds at the left and right channel are similar. If this is not the case for a longer period, the azimuth correction will slowly be reduced.

Azimuth panel


  • Auto-detect and fix Azimuth errors
    Enables AZIMUTH correction.

  • Azimuth limit
    Maximum tape head displacement (assuming cassette tapes) to be detected and resolved.

    0 disables this filter. Suggested value: 40 μm.

  • Azimuth change speed
    Maximum speed at which the filter follows detected phasing errors.

    This slider controls how fast the azimuth correction can change if the measured displacement is differs from the correction that is taking place.

    Use a very low value ( 0.1 m) to correct for a constant azimuth correction.

    Use a higher value (~ 0.4 m) to also correct for rapid changes.

    To avoid getting too much effects from measurement noise, use the lowest possible value where the blue line (the actually performed correction) can keep up with the red dots (the measurements).

Single instrument phase errors panel


  • Limit maximum phase offset

  • Limit maximum phase offset below

  • Fully move to center if above

Phase inversion panel


  • Auto-detect and fix input phase inversion

  • Flip if phase offset stays above

  • Status

Difference panel


  • Difference (combined)