Bass Enhancer CAO

Compact audio playback systems may experience a noticeable reduction in bass fidelity during music reproduction. Bass enhancer extends the physical limitation of loudspeaker playback range by generating the virtual Bass. Bass Enhancer helps to enhance the perception of existing bass content.

Speakers have physical frequency range in which audio is reproduced well. Frequencies lower than this range are highly attenuated by the speaker. Bass enhancer first extracts the low frequency signal below the speaker cutoff frequency. Then, Bass enhancer adds the harmonics generated for each frequency component in the low frequency signal to original signal. These added harmonics are in the speaker physical frequency range and the signal is perceived as the lower frequency. This is also called virtual bass.This is equivalent to extending the lower limit of speaker’s frequency range.

Bass Enhancer CAO has stereo input and output.

Bass enhancer CAO uses below audio objects:

1. Bass enhancer audio object
2. Parameter Biquad
3. Delay
4. Compressor
5. Matrix Mixer

Bass enhancer audio object: Bass enhancer audio object produces three channel audio output with stereo input (Left and right channel).

The three output channels of bass enhancer AO are:

a) high pass filtered left channel

b) high pass filtered right channel

c) harmonic signal

Harmonics are generated for each frequency component below speaker cutoff frequency. These harmonics are added to the original high pass filtered left and right channel to reproduce the enhanced perceivable bass.

ParameterBiquad: Parameter Biquad  AO is used to shape the harmonics generated for the bass.

Delay: Delay AO is used to adjust the delay to compensate for phase delay.

Compressor: Compressor AO is used to limit the dynamic range of the harmonics generated by Bass Enhancer AO. In addition “Make-up” gain parameter of the compressor is used to control output level of Harmonics.

It is not mandatory to use Compressor AO.

Matrix Mixer: Matrix Mixer AO is used to combine the harmonics with high pass filtered left and right channel to produce bass enhanced stereo output.

On the main panel, tuning and control parameters are accessible as follows:

• InputGain: Controls stereo input gain. This can be used to apply gain to stereo input signal.
• CrossOver: Speaker cutoff frequency. This tuning parameter is used to set the speaker cutoff frequency below which speaker is unable to reproduce the sound. Harmonics are generated for each frequency component below speaker cutoff frequency.
• Dist odd: Odd harmonics level control. The harmonics generated will have odd and even harmonic components. This tuning parameter is used to control the level of odd harmonics.
• Dist even: Even  harmonics level control. This tuning parameter is used to control the level of odd harmonics.
• Threshold: Limit level of harmonics. This compressor tuning parameter is used to limit level of harmonics generated. When signal  level reaches this values compression is activated.
• Attack:  Attack time constant. This time constant determines amount of time required to compress the signal to target value.
• Release: Release time constant. This time constant determines amount of time required to restore the signal to its original value once signal level drops below Threshold.
• Ratio: Amount of the Compression applied to harmonic signal when harmonic signal level exceeds Threshold
• Delay Left ch:   Delay control for high pass filtered left channel. This control is used to delay Left channel to time align with harmonic signal
• Delay Right ch: Delay control for high pass filtered right channel. This control is used to delay Right channel to time align with harmonic signal
• Harmonic Gain: Control harmonic output level. This control is used to adjust the output level of harmonic signal.
• Presets: Different tuning sets and Bypass. Tuning sets have values for Low, Moderate and Strong bass generation. Preset also has tuning to bypass(bass off).
• Biquad: Biquad panel to shape the harmonics. The biquads can be tuned to shape harmonics.
• Mixer: Panel to control the mixer gains.