Category Archives: Digital Audio

WaveTableOsc optimized

Posted on April 28, 2019 by Nigel Redmon

The wave table oscillator developed here in 2012 is pretty lightweight, but I never took a close look at optimization at the time. An efficient design is the number one optimization, and it already had that. I was curious how … Continue reading →

Posted in Source Code, Wavetable Oscillators | 6 Comments

Wavetable signal to noise ratio

Posted on September 22, 2018 by Nigel Redmon

In our wavetable series, we discussed what size our wavetables needed to be in order to give us an appropriate number of harmonics. But since we interpolated between adjacent table entries, the table size also dictates the signal to noise … Continue reading →

Posted in Digital Audio, Oscillators, Wavetable Oscillators | Leave a comment

Sampling theory, the best explanation you’ve ever heard—End notes

Posted on September 21, 2018 by Nigel Redmon

A few words before moving on to other topics… We’ve looked at why digital sample represent ideal impulses, and why any point between samples represents a value of zero. And, as a result, audio samples don’t represent the audio itself, … Continue reading →

Posted in Digital Audio, Sampling Theory | Tagged | 2 Comments

Sampling theory, the best explanation you’ve ever heard—Part 3

Posted on August 25, 2017 by Nigel Redmon

We look at what Pulse Amplitude Modulation added to our analog source audio. What did PAM add? Earlier, we noted that the PAM signal represents the the source signal plus some additional high frequency content that we need to remove … Continue reading →

Posted in Digital Audio, Sampling Theory | Tagged | 5 Comments

Sampling theory, the best explanation you’ve ever heard—Part 2

Posted on August 17, 2017 by Nigel Redmon

In this article, we explore the origins of sampling. Discrete time For many, discrete time and digital sampling are synonymous, because most people have little experience with discrete time analog. But perhaps you’ve used an old-style analog delay stompbox, with … Continue reading →

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Sampling theory, the best explanation you’ve ever heard—Part 1

Posted on August 16, 2017 by Nigel Redmon

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 →

Posted in Digital Audio, Sampling Theory | Tagged | 4 Comments

Sampling theory, the best explanation you’ve ever heard—Prologue

Posted on August 15, 2017 by Nigel Redmon

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 →

Posted in Digital Audio, Sampling Theory | Tagged | Leave a comment

Amp simulation oversampling

Posted on May 27, 2017 by Nigel Redmon

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 →

Posted in Digital Audio, Effects, Guitar Amp Simulation, Sample Rate Conversion | 4 Comments

Guitar amp simulation

Posted on May 26, 2017 by Nigel Redmon

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

Posted on January 4, 2017 by Nigel Redmon

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