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Stereo Tool 7.83 - Help - True Bass

True Bass section

Lost harmonics generator.

True Bass attempts to generate harmonics that either weren't recorded properly (due to for example a highpass filter, a bad microphone) or appear to be missing.

It can generate bass at a specific frequency, which matches the rest of the signal. True Bass was designed to only generate bass that sounds like it should always have been there.

Some examples: Input: Square wave, 50 Hz, with the base frequency (50 Hz) filtered out - only 150, 250, 350, 450 Hz etc. remain. True Bass will recreate a 50 Hz tone in this situation:



However, if instead of a square wave, we feed it a sine wave at 150 Hz, it will [b]not[/b] generate a subharmonic:



True Bass panel

  • Enabled
    Enables True Bass.

Place in chain panel

Determines where True Bass is located in the processing chain.

  • Before multibands
    Sets the place in the processing chain where True Bass is performed.

    For consistency, it's best to place it before the Multiband Compressor, or if you use 2 Multiband compressors, at least before Multiband 2.

    The effect on the audio is bigger if you place it after the multiband compressors, but you risk getting too loud bass in some cases, and the clipper can easily be overdriven if that happens.

Band 1 panel

First True Bass filter.

  • level
    The amount of effect that True Bass has.

    Using level 100% matches the 'natural' effect of the filter. Using more can give unnatural effects.

Controls panel

True Bass audio controls.

  • Peak frequency
    The frequency around which this True Bass filter works.

    The filter drops off pretty steeply to higher frequencies, but also to lower ones.

  • Look at frequencies upto
    Input frequencies to look at to generate harmonics.

    If this frequency is set very high, asymmetrical sounds such as voices can cause rumbling effects. If it is set too low, if only one harmonic is seen the filter will not do anything (see the images of a square wave and sine wave above), a too steep filter will make the filter "think" that a square wave which' ground frequency is gone is actually a sine wave.

  • Upper slope
    Steepness of the lowpass filters.

  • Drop steepness (relative to 300%%/oct)
    Rolloff steepness of the effect of the filter below Peak frequency.

  • Pre-ringing filter level
    Amount of pre-ringing allowed.

    Since the subharmonic frequency is lower, it can sometimes start before the original bass sound started. This sounds very strange. This setting determines how much pre-ringing is allowed. Setting it too low will also remove reconstructed bass harmonics if they are a lot louder than the original.

  • Assume voices are above
    Assume that voices start above this frequency.

    Voices (and other asymmetrical sounds) can cause rumbling bass in the output. If there's very little content below this frequency, the effect of True Bass is reduced. This avoids having weird bass harmonics during news broadcasts, for example.

  • Allowed voice rumble
    Amount of voice rumble that is allowed through.

Band 2 panel

Second True Bass filter.

This can be used to boost bass at multiple frequencies.
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