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Search Results for: filter
Evaluating filter frequency response
A question that pops up for many DSPers working with IIR and FIR filters, I think, is how to look at a filter’s frequency and phase response. For many, maybe they’ve calculated filter coefficients with something like the biquad calculator … Continue reading
Posted in Biquads, FFT, Filters, FIR Filters, IIR Filters
22 Comments
Filters for synths—the 4pole
The last post noted that the two most popular synthesizer filters are the 2pole state variable, and the 4pole “Moog style”. And we started with the state variable—simple, popular, and delivering multiple filter outputs (lowpass, bandpass…) simultaneously. Here, we’ll follow … Continue reading
Posted in Digital Audio, Filters, IIR Filters, Synthesizers
5 Comments
Filters for synths–starting out
We haven’t developed a synth filter here yet… Filters we’ve presented Biquads. While they are useful for many simple cases of filtering, they are not a good choice for analog synthesizer emulation. Most notably, they are poorly suited to timevarying … Continue reading
Posted in Digital Audio, Filters, IIR Filters, Synthesizers
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A onepole filter
Here’s a very simple workhorse of DSP applications—the onepole filter. By comparison, biquads implement two zeros and two poles. You can see that our onepole simply discards the zeros (the feedforward delay paths) and the second pole (feedback path): We … Continue reading
Posted in DC Blocker, Digital Audio, IIR Filters, Source Code
30 Comments
The digital state variable filter
The digital state variable filter was described in Hal Chamberlin’s Musical Applications of Microprocessors. Derived by straightforward replacement of components from the analog state variable fiter with digital counterparts, the digital state variable is a popular synthesizer filter, as was its … Continue reading
Posted in Digital Audio, Filters, IIR Filters
17 Comments
WaveUtils updated
WaveUtils needed only a minor change for compatibility with the WaveTableOsc update—addWaveTable changes to AddWaveTable. But I added something new while I was at it. The original wave table articles advocated minimizing the number of tables necessary—one per octave—by allowing … Continue reading
Posted in Source Code, Wavetable Oscillators
10 Comments