YM/AY Soundcard with ZX True Tone (ZXTT) and AY-3-8910A, on the SAM Coupe

Two parts to the video, first is a live recording of a YM/AY Soundcard that&plugged into the SAM Coupe via the Bus Interface card, and it&using an AY-3-8910A with a date code of "8614&so manufactured in the 14th week of 1986, playing through an X-Mini Duo speaker. The second part of the video is the line out recording, sampled on a Zoom H1n Handy Recorder. So taking a look at the hardware I build, the first is the ZX True Tone (or ZXTT for short). This is an add-on module for Ed Brindley&YM / AY soundcard for the RC2014 DIY computer (and compatibles, plus it can be used on the SAM Coupe as this video shows!) and its purpose is to give the sound chip in the soundcard the exact clock frequency to the sound chip to have the correct pitch matching the AY in the ZX Spectrum 128K onwards. The tone of the YM and AY sound chips are all derived from the clock signal it receives. The ZX Spectrum&AY sound chip was fed with a 1.7734MHz clock which this module matches. There isn&much control of the clock on Ed&soundcard, as his circuit can provide a clock from either the main system clock divided by 2 or divided by 4, or on the Rev 6.1 card a separate oscillator module. If you are using the card to play ZX Spectrum tunes and the AY is fed a clock speed lower then the pitch of the tones will be lower, likewise if clocked higher then the pitch of the tone will be higher, so the tunes won&sound exactly right compared to a real ZX Spectrum. My ZXTT module replaces one of the chips on the...