ZX Spectrum: Experimenting with 1-Bit Sound

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Release party: DiHalt 2026 summer Compo: Demo Platform: zx spectrum Ranked: 2nd

Will post an update after I get back to my parent's home, where I have these beauties that launched me into computer science: https://imgur.com/a/GKrA0vX

Questions like: How many channels can a mod file[1] have? Does that number of channels this file has change depending on whether it is being played back with monophonic or stereophonic (or some other arrangement of) speakers? What happens to the count when one or more individual samples within that mod file contain polyphonic data (chords!), themselves?

It also leads to rhetorical statements, such as: When I play a film that has a soundtrack with 8 (ie 7.1) discrete audio channels on a stereophonic pair of speakers with a sane playback chain, I'm definitely still hearing all 8 of those channels. The same happens if I extend that stereophonic system to greater number of output channels, by adding surround speakers (quadraphonic!) or whatever.

Or maybe I take one earbud out and put it back in its charging case, and through the magic of active electronics, good software, and wireless comms, the output deliberately collapses to being monophonic.

However it happens, I've still got an 8 channel of film soundtrack in my ear(s).

And of course, it also works the other way: If the electronic musical keyboard in front of me is said to support 10-voice polyphony, then that's a hard limit on the number of notes it can produce at once regardless of the number of audio output channels.

Multichannel and polyphonic are pretty bendy terms, I think. Maybe that flexibility was wrong at some point, but they've been flexible in this way for so many decades that it definitely seems right to accept the overlapping uses as being correct.

[1]: https://en.wikipedia.org/wiki/MOD_(file_format)

Delta-sigma modulation generates an inefficient encoding of the audio signal, with much more bits than necessary.

Converting a delta-sigma encoded bit stream to a PCM (pulse-code modulation) stream (e.g. with 24-bit or 16-bit samples at a sampling frequency of 48 kHz or 44.1 kHz) is a method of data compression.

On the other hand, delta-sigma modulation is more efficient for both analog-to-digital and digital-to-analog conversions, in the sense that for a given quality of the conversion it is much easier and much cheaper to make ADCs and DACs with delta-sigma modulation than with pulse-code modulation.

Because of this, for audio signals, normally delta-sigma ADCs and DACs are used at the analog inputs and outputs, but the delta-sigma bit stream is converted by digital filtering to PCM for data storage or for audio processing.