The Sinclair ZX Spectrum is an 8-bit home computer originally released in 1982. Various models of the Spectrum exist and the range was extremely successful especially in the United Kingdom and Europe. Most Spectrum models have RGB output making them potentially ideal for use with the XRGB or OSSC upscalers.
There were a total of eight different revisions of the Spectrum, the most popular being the 48k and 128k models. The model used for testing was a 128k ZX Spectrum +2A.
ZX Spectrum +2A (PAL, RGB SCART with raw sync)
XRGB-3 Specific settings
You will need to manually adjust the AFC settings to 4 to remove the warping effect at the top of the screen.
XRGB-Mini Specific settings
When using the Spectrum, It is highly recommended to set the sharpness to 0 at all times.
For a PAL Spectrum, you must set the mini to output 576p/50 if you want to use scanlines. You must also manually adjust the V_WIDTH to 29 in order for the scanlines to appear correctly.
Do not use the auto scaler in video mode, if you do, you will see excessive ringing on the image. Use either auto scaler in game mode or manually set the scaling options. Use V-SCALER at either 6 or 7 to avoid ringing. Use H-SCALER with a value between 5 and 7 for a sharper picture, or up to around 12 if you prefer a softer picture.
OSSC Specific settings
Adjusting the sync LPF and the sampling phase may be necessary to minimise picture jitter.
 World of Spectrum software archive and community forum