We revisit the Sinclair ZX Spectrum +3 we fixed a few weeks ago and we attempt to improve the quality of the sound output. We compare the sound the AY chip produces on the Spectrum +3 to the Spectrum +2. We record some test sounds and compare the sound waves produced on the two computers.

We look at the sound amplifier circuit on the +3 and attempt to make sense out of it. We look at the AY signal and the amplified signal with an oscilloscope. Then we model the amplifier on a circuit simulator and attempt to fix the clipping problem.

Finally, we make a few minor changes to the +3 sound amplifier and run some tests.

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Links: Original Spectrum +3 amplifier circuit: http://tinyurl.com/vmtcsaq Fixed amplifier circuit (similar to Spectrum +2): http://tinyurl.com/qu4kx68

Music: Glider Rider https://spectrumcomputing.co.uk/entry/2054/ZX-Spectrum/Glider_Rider Astro Marine Corps (AMC) https://spectrumcomputing.co.uk/entry/295/ZX-Spectrum/Astro_Marine_Corps Cybernoid https://spectrumcomputing.co.uk/entry/1196/ZX-Spectrum/Cybernoid

BASIC programs: http://retrolab.gamesfromwithin.com/files/RL26SpectrumP3Sound/Sound1b.tap http://retrolab.gamesfromwithin.com/files/RL26SpectrumP3Sound/Sound3.tap

Additional music by nene https://opengameart.org/content/theme-song-8-bit

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#zxspectrum #sinclair