Software Listing of Author : "Jeff Tackett"
- Bass / Treble Shelving Filter
- License: Shareware
- Price:


Derive coefficients for a shelving filter with a given amplitude and cutoff frequency. All coefficients are calculated as described in Udo Zolzer's DAFX book (p. 50 -55). Usage: [B,A] = shelving(G, Fc, Fs, Q, type); G is the logrithmic gain (in dB) FC is the center frequency Fs is the sampling rate Q adjusts the slope be replacing the sqrt(2) term type is a character string defining filter type Choices are: 'Base_Shelf' or 'Treble_Shelf' Typically this filter is used for multi-band equalization of audio. For example a 3-band equalizer (Bass/Mid/Treble) might use: Bass = Bass shelving Filter Mid = Peaking Filter Treble = Treble shelving Filter
- Publisher: Jeff Tackett
- Date Released: 22-02-2013
- Download Size: 10 KB
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- Platform: Matlab, Scripts
- Comb Filter
- License: Shareware
- Price:


Returns IIR coefficients for a Nth order Comb Filter Usage: [B,A] = COMB(order, scalar); ORDER is the number of samples delayed prior to add SCALAR is the coefficient that will be applied to the delayed signal path at the final summation block. Note, there are two types of comb filters. A DC-blocker and a DC-passer. To get a DC-Blocker (tooth at DC), pass in a -1 for the scalar. To get a DC-Passer (+6dB at DC), pass in a +1 for the scalar. By default, if the scalar is not passed, a DC-Passer is assumed.
- Publisher: Jeff Tackett
- Date Released: 16-04-2013
- Download Size: 10 KB
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- Platform: Matlab, Scripts
- Digital Resistor-Capacitor (RC) Filter
- License: Freeware
- Price: 0.00


Returns equivalent IIR coefficients for an analog RC filter Usage: [B,A] = RC_FILTER(r, c, fs, type); R is the resistance value (in ohms) C is the capacitance value (in farrads) FS is the digital sample rate (in Hz) type is a character string defining filter type Choices are: 'high' or 'low' This function uses a pre-calculated equation for both of these circuits that only requires the resistance and capacitance value to get a true digital filter equivalent to a basic analog filter. The math behind these equations is based off the basic bilinear transform technique that can be found in many DSP textbooks. The reference paper for this function was "Conversion of Analog to Digital Transfer Functions" by C. Sidney Burrus, page 6. This is also the equivalent of a 1st order butterworth with a cuttoff frequency of Fc = 1/(2*pi*R*C);
- Publisher: Jeff Tackett
- Date Released: 26-06-2013
- Download Size: 10 KB
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- Platform: Matlab, Scripts
- ISO 226 Equal-Loudness-Level Contour Signal
- License: Shareware
- Price:


This function will return a 29-point equal loudness contour for your desired phon level. The frequencies evaulated in this function only span from 20Hz - 12.5kHz, and only 29 selective frequencies are covered. This is the limitation of the ISO standard. In addition the valid phon range should be 0 - 90 dB SPL. Values outside this range do not have experimental values and their contours should be treated as inaccurate.(Limitation due to standard) If more samples are required you should be able to easily interpolate these values using spline(). *For more information regarding this method refer to ISO 226. ------------------------------------------------------------ Usage: [SPL FREQ] = ISO226(PHON); PHON is the phon value in dB SPL that you want the equal loudness curve to represent. (1phon = 1dB @ 1kHz) SPL is the Sound Pressure...
- Publisher: Jeff Tackett
- Date Released: 13-04-2013
- Download Size: 10 KB
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- Platform: Matlab, Scripts
- Peaking / Notch IIR Filter
- License: Shareware
- Price:


Derive coefficients for a peaking filter with a given amplitude and bandwidth. All coefficients are calculated as described in Zolzer's DAFX book (p. 50 - 55). This algorithm assumes a constant Q-term is used through the equation. Usage: [B,A] = peaking(G, Fc, Q, Fs); G is the logrithmic gain (in dB) FC is the center frequency Q is Q-term equating to (Fb / Fc) Fs is the sampling rate The typical usages is multi-band equalization where each band has it's own peaking filter.
- Publisher: Jeff Tackett
- Date Released: 20-06-2013
- Download Size: 10 KB
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- Platform: Matlab, Scripts