Sinclair ZX80 / ZX81 / Z88 Forums

Hi all

I hope you don’t mind my sharing with you the latest mod I have done on my ZX Spectrum +2 (grey) This mod was relatively easy to do and I have included every single step in my blog

https://alleged-geek.blogspot.com/2021/ ... g-fix.html

at the end of the blog entry I have included a Youtube clip which compliments the blog entry and more importantly has sound )

https://www.youtube.com/watch?v=Zx2vTIMSwKk

If you have any question or queries please feel free to message me either here, or my blog or on my Youtube channel.

Best regards,

Steve

I've just made something similar to a 128 Toastrack.
R115 from de AY to mic is originally 10K. In other sites they recommend to use 2.2K or 1.65K I tried 1.5K with insuficient result. then I soldered mounted in parallel another 1K resistor resulting in 600ohm ..
Then I raised r35 from the ULA to mic from 10K to 22K.. and now sond levels are pretty even.
Matching them by lowering to much the ULA levels (raising the resistor) will make you rise the volume and may make some background noise audible..
If you have the original 10K resistor from AY sound I would recomend to mount in parallel a 560ohm resistor avoiding to desolder the original..
(Some people prefer to maintain the original aspect and some other prefer to touch it the less posible)
Nice article at your blog by the way...

Edit..
An easy way to test is running from 128 BASIC

10 PLAY "C"
20 BEEP 0.5, 0
30 GO TO 10


tones are some how different, perhaps someone can match them, but volume levels are easily comparable