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Author Archives: Nigel Redmon
Sampling theory, the best explanation you’ve ever heard—Part 1
I’ll start by giving away secrets first: Individual digital samples are impulses. Not bandlimited impulses, ideal ones. We know what lies between samples—virtual zero samples. Audio samples don’t represent the source audio. They represent a modulated version of the audio. … Continue reading
Sampling theory, the best explanation you’ve ever heard—Prologue
I’ve been working on a new video, with the goal of giving the best explanation of digital sampling you’ve ever heard. The catch is I started on it three years ago. I’m not that slow, it’s just that I’ve been … Continue reading
Amp simulation oversampling
In tandem with our last article on Guitar amp simulation, this article gives a step by step view of the sampling and rate conversion processes, with a look at the frequency spectrum. From guitar to digital The first two charts embody the … Continue reading
Guitar amp simulation
In this article, I’ll sketch a basic guitar amp simulator. For one, questions on the topic come up often, and also, it will be a good example of a typical use of working at a higher sample rate. The most … Continue reading
Posted in Aliasing, Digital Audio, Sample Rate Conversion
3 Comments
About coefficient conventions
It’s been asked many times, so it’s worth an article explaining the conventions used on this site for transfer functions, and why they may differ from what you see elsewhere. People run into this most often with biquads: I use … Continue reading
Posted in Biquads, IIR Filters
7 Comments
Evaluating filter frequency response
A question that pops up for many DSP-ers 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
27 Comments
Filters for synths—the 4-pole
The last post noted that the two most popular synthesizer filters are the 2-pole state variable, and the 4-pole “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
6 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 time-varying … Continue reading
Posted in Digital Audio, Filters, IIR Filters, Synthesizers
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