Audio – Clockworks Signal Processing: Recent Episodes
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ADI’s SigmaStudio tool for A2B topology set up can be controlled via a Windows COM API provided by Analog Devices. In this example we’ll create a small Python program to load an A2B configuration and then capture data from a temperature sensor connected to one of the nodes. This example is specifically focused on the […]READ MORE
During prototyping and development it can be convenient to be able to send or receive audio from a host PC (Windows or Mac in this case) for injecting signals or for monitoring -particularly if using SigmaStudio for A2B topology modifying routing to accommodate testing is trivial. miniDSP offers an easy to use board based on […]READ MORE
In testing some of the A2B hardware what appeared to be high jitter on the clocks was observed. While specialized scopes & software are available for making jitter measurements one was not available at the time measurements were needed. The basic idea is simple enough – measure the clock edges and see if they are […]READ MORE
Video from a presentation at Teardown 2019. Unfortunately the audio is out of sync with the video, and a little is missing off the front. This is a based on the work done for the AES paper and the background materials found here (including the audio files for experimenting with audible noise levels). It’s less […]READ MORE
Microsoft Excel probably doesn’t pop in to most people’s minds for doing spectral analysis, and that’s no surprise since it’s somewhat of a kluge to do it. But Excel is good to use for a quick sanity check when you are working in a different environment (in this case with Octave/Matlab .m files) and need […]READ MORE
This is the long delayed followup to the earlier post about power resistors as dummy loads and the nonlinearities found. After some further experimentation an 8 ohm load was built from four Riedon PF2270 series 2 ohm 200W thin film resistors (to give an 8 ohm load) and a surplus heatsink with fans. With 200W […]READ MORE
As part of some ongoing work earlier this year I needed to test the performance of a high performance 200W/channel class D amp (more on the amp in some future post). To get accurate SNR and THD+N measurements a low pass filter is needed in front of the measurement system as the high frequency switching […]READ MORE
This post is one of three related to the work done to measure resistor excess noise. A summary writeup and three other documents with experimental detail are provided to those interested in performing their own experiments. These long form reports were summarized in to AES eBrief 486 (open access), presented at AES 145 (Oct 2018, […]READ MORE
From the presentation at the Boston AES meeting held 27-Feb-18 at Shillman Hall, Northeastern University, Boston, MA. In addition to being a technical presentation aimed at anyone involved with audio, it also served as an example for students interested in submitting papers to upcoming AES events. Resistor noise presentation. Rnoise.r3.1 A pdf file made from […]READ MORE
This page provides .WAV files that can be combined with audio tracks to perform your own evaluation of the audibility of noise, both the unavoidable white noise and the excess noise (mostly low frequency) that is present in differing amounts based on the resistor technology. This is one of three posts related to resistor noise. […]READ MORE