Category Archives: Widgets

Filter frequency response grapher

Here’s a tool that plots frequency response from filter coefficients. Hz linearlog 10log 2 Plot auto40 dB30 dB20 dB10 dB0 dB-10 dB-20 dB-30 dB-40 dB Max 60 dB80 dB100 dB120 dB140 dB160 dB180 dB Range a coefficients (zeros) b coefficients … Continue reading

Posted in Biquads, Filters, FIR Filters, IIR Filters, Uncategorized, Widgets | 7 Comments

Cascading filters

Sometimes we’d like to cascade biquads to get a higher filter order. This calculator gives the Q values for each filter to achieve Butterworth response for lowpass and highpass filters. Order: 234567891011121314151617181920 Q values: You can calculate coefficients for all biquad … Continue reading

Posted in Biquads, Filters, IIR Filters, Widgets | 9 Comments

Dither widget

Posted in Digital Audio, Dither, Widgets | Leave a comment

Pole-Zero placement v2

Pair Pole mag Pole angle Pair Zero mag Zero angle Sample rate (Hz) linearlog Plot A new pole-zero calculator An JavaScript remake of the old Java-based pole-zero placement applet—visit that page for tips on pole-zero locations for standard biquads. The … Continue reading

Posted in Biquads, Digital Audio, Filters, IIR Filters, Widgets | 11 Comments

Biquad calculator v2

Type:lowpasshighpassbandpassnotchpeaklow shelfhigh shelfone-pole lpone-pole hp Plot:linearlog Sample rate (Hz) Fc (Hz) Q Gain (dB) Here’s an update of the biquad calculator. It adds one-pole highpass and lowpass filters, and frequency, Q, and gain sliders. The sliders cover the range of … Continue reading

Posted in Biquads, Digital Audio, Filters, IIR Filters, Widgets | 59 Comments

Envelope generators—ADSR widget

Attack Decay Sustain Release Attack Curve Decay/Release Curve Plot:linearlog This is the widget I used in making the ADSR video. It’s a JavaScript recreation of my C++ source code.

Posted in Envelope Generators, Synthesizers, Widgets | 9 Comments

A biquad calculator

Something useful: a biquad filter coefficient calculator… Continue reading

Posted in Biquads, Digital Audio, Filters, IIR Filters, Widgets | 34 Comments

A closer look at upsampling filters

Interpolation type:NoneZero-order holdLinearSinc 1Sinc 2Sinc 3  Show impulse response Sweep! In this demonstration, we generate a sine wave sweep from low in the audio band to near the Nyquist Frequency, which is half the sample rate. You can view it … Continue reading

Posted in Aliasing, Digital Audio, Filters, FIR Filters, Impulse Response, Sample Rate Conversion, Widgets | Leave a comment

Building a windowed sinc filter

As promised, here’s our windowed sinc calculator for building a 2x oversampling filter:  Factor  Length  Rejection  Gain Notes: Use the Tab or Enter keys to effect changes (most browsers), or press Calculate. The frequency axis is in multiples of the … Continue reading

Posted in Digital Audio, Filters, FIR Filters, Impulse Response, Sample Rate Conversion, Widgets | 2 Comments

Pole-Zero placement

Use the new, improved pole-zero calculator—but be sure to read the “Experiments with standard biquads” section below for tips on placing poles and zeros for standard filters. Here’s a Java applet that illustrates pole-zero placement. It lets you design a … Continue reading

Posted in Biquads, Digital Audio, Filters, IIR Filters, Widgets | 7 Comments