Equalizer

ONLY Sound Items using the Windows Audio driver have access to the Equalizer.

The Equalizer (EQ) effect strengthens (boosts) or weakens (cuts) the energy of specific frequency band (frequency ranges: bass to low-mid to high-mid to treble).

Figure 1. Frequency Band

Functionality

Eight Band Equalizer
Band Frequency - Each band has a Center Frequency. Adjacent frequencies to the Center Frequency are affected by gain changes as well, but to a diminishing degree of effect (bell curve, Figure 1).
Band Frequency is Adjustable - The Center Frequency of each band can be changed as desired.
Equalize(EQ) DSP Effect - The settings of the Equalizer Tool (Figure 2) can be saved as a EQ DSP effect for future use. Saved EQ DSPs can be added to a DSP chain like any other DSP. You can also edit EQ DSP effects with the DSP Effects Editor (via Tools > DSP Effects > Manage DSP Effects).

Equalizer Limitations - Volume and Fading

Positive Equalizer Band values boost the gain on a given frequency band and therefore increase the overall volume output somewhat. Higher band values will lessen the effect of the Volume slider control and can interfere with Fade-In/Fade-Out to some degree.

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Locator: Sound List Editor > Tools > DSP Effects .

The Equalizer Tool is opened from the Actions menu or the Actions toolbar.

Equalizer menu items

Apply Equalizer To - You can control which playing sound items are affected by changes made in the Equalizer Tool. Clicking this menu item toggles the mode between the modes below.
- Selected Item Only - Changes are applied only the current selected Sound Item .
- All Sound Items - Changes are applied to all playing Sound Items.
Make Playback Equalizer Capable When - Equalizer is a DSP effect and incurs a modest amount of CPU processing. If you rarely use the Equalizer, the first option is better to avoid unnecessary processing. If you frequently use it, "Always" will simplify managing the effect.
- Only When Equalizer Tool is Opened - The Equalizer DSP is attached to a Sound Item only if the Equalizer Tool is opened when the Sound Item playback is started. If a Sound Item is already playing before the Equalizer Tool is opened, it will not be capable of Equalizer function.
- Always - The Equalizer DSP is always attached to any Sound Item when it is played.
Edit Equalizer Band Frequencies - Each Equalizer band is centered on a frequency. You can change the Center Frequency of any band. It is recommended that you keep them ordered from lowest to highest (but not required).
Reset Equalizer Band Frequencies to Defaults - Resets all Equalizer band frequencies to the SoundMill default values. Default values for Bands 1-8 are 100, 250, 500, 1000, 2000, 4000, 8000, 16000 (Hz).

About Equalizer Band Frequencies

The Band Center Frequencies are dependent on the sample rate of your input audio. If you change the frequencies, do not set any frequency higher than the Nyquist Frequency. If an EQ Band frequency exceeds the Nyquist frequency of an audio file, it will be clipped to the Nyquist value. The Sound Mill default EQ Band frequencies are set for 44.1K audio. So, if you mostly work with audio at much lower sample rates (ex. voice audio at 8KHz), you may want to adjust the EQ Band frequencies. The default high end Band (16kHz) may be too high for some audio hardware (graphics card or speakers) to make a perceptible difference to the ear. If so, try lowering it 1KHz at a time until you can hear a change. Also, realize there may be little or no high frequency samples in the audio file itself.

Terms

Sample Rate - Number of samples of audio carried per second, measured in Hz or kHz (one kHz being 1,000 Hz). Example: CD Quality audio has a sample rate of 44.1KHz
Nyquist Frequency - Half the audio sample rate. Example: If your input audio file has a sample rate of 44,100 Hz, the Nyquist Frequency is 22,050 Hz.

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Equalizer Tool

Frequency Band controls

Track Bar - Drag the Track Bar to change the Gain on a Frequency Band.
Center Band - Click this button to center the band to value 0.
Center All Bands - Sets all bands to the center (value 0). (left side middle of tool window)

Trackbar Changes by Keyboard

Small Change - Arrow keys (Up / Down).
Large Change - Page_Up / Page_Down keys.

Toolbar controls

Figure 2. Equalizer Tool

Equalizer Frequency Bands labels (Figure 2) above 1,000Hz are displayed rounded to the nearest tenth (ex 2.0kHz), however calculations are made with the precise frequency values.

Equalize DSP Effect

Equalize(EQ) DSP effect increases or decreases the gain on the frequency band (8 Bands). It can be used in DSP chains just like any other DSP Effect. You can save EQ DSPs with either 1) the Equalizer Tool, or 2) the DSP Effects Editor.

Parameters

Bands Gain - Band1 to Band8 - Valid Range: -30 to +30. Translates to -100% to +100%.
- +Range - Boosts/increases the gain on the frequencies in the band. (+30 Maximum)
- 0 - No gain. Passes the frequency band as it was recorded on the original audio.
- -Range - Decreases/cuts gain on the frequencies in the band. (-30 Minimum)

Language

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