applied-acoustics-systems ultra analog ユーザーズマニュアル
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Parameters
as shown in Figure 8. The Cutoff knob is used adjust the center frequency and the Q knob sets the
bandwidth of the notch. Note that the center frequency is totally removed from the spectrum of the
output signal of the filter.
bandwidth of the notch. Note that the center frequency is totally removed from the spectrum of the
output signal of the filter.
4.3.5
Formant Filter
Amplitude (dB)
Frequency (Hz)
F1
F2
F3
Male Voice
Female Voice
Formant Frequencies
Figure 9: Frequency response of the formant filter.
The formant filter reproduces the filtering effect of the vocal tract in the human voice. By
changing the position of the tongue, the opening of the mouth and opening or closing the nasal
cavities one can change the filter applied to the glottal signal and thus produce the different vowels.
Measurements have shown that this filter can be modeled by three peaking EQ filters corresponding
to the three main cavities of the vocal tract as shown in Figure 9 and also known as formants. By
moving the parameters of these three filters (frequency, amplitude and Q-factor) one can cycle
between all the vowels. The effect of the Cutoff knob on the formant filter is to offset all the
formants by the same factor and it is used to switch between male voice (left position), female
voice (center) and child (right position). The Q knob is used to cycle between vowels. Note that
changing these parameters can be automated by using the different modulation signals.
cavities one can change the filter applied to the glottal signal and thus produce the different vowels.
Measurements have shown that this filter can be modeled by three peaking EQ filters corresponding
to the three main cavities of the vocal tract as shown in Figure 9 and also known as formants. By
moving the parameters of these three filters (frequency, amplitude and Q-factor) one can cycle
between all the vowels. The effect of the Cutoff knob on the formant filter is to offset all the
formants by the same factor and it is used to switch between male voice (left position), female
voice (center) and child (right position). The Q knob is used to cycle between vowels. Note that
changing these parameters can be automated by using the different modulation signals.
4.3.6
Filter Drive
As seen in the preceding sections, some filters can boost the signal in some regions of the spectrum.
Theoretically, with a high Q-factor the amplification can reach up to 50dB, but in real life, electronic
components will saturate before this level is reached and saturation will be introduced in the signal.
In other words, the output signal of a circuit can raise linearly up to a certain value but will then
begin to raise more slowly up to a value where the output is clipped to the maximum output value
allowed by the circuit. This effect is typical of the sound signature of vintage circuits and is
implemented in Ultra Analog through the Drive control as shown in Figure 10. There are 6 different
Theoretically, with a high Q-factor the amplification can reach up to 50dB, but in real life, electronic
components will saturate before this level is reached and saturation will be introduced in the signal.
In other words, the output signal of a circuit can raise linearly up to a certain value but will then
begin to raise more slowly up to a value where the output is clipped to the maximum output value
allowed by the circuit. This effect is typical of the sound signature of vintage circuits and is
implemented in Ultra Analog through the Drive control as shown in Figure 10. There are 6 different