OMG, guys. I can't believe how professional and extensive discussion on this topic started here! At the beginning it was just my innocent question about whistling in the STe audio output and now things are being solved here that I no longer understand at all. Unfortunately, I'm not an electrician. B...

On the STE one, I do hear (and you can hear in the audio) when it starts doing memory test, you can hear the "dashes" on the screen as the come up.. I need to find me headphone adapter and try that again... Yes. That's the same as mine STe. I hear doing memory test the same way (my file C...

If it's any help as a reference, the TT's audio output (twin phono) is a great bus monitor. You can hear all the memory accesses as a twerping "hiss" and it's amplified by the internal pre-amp as if you turn the sound volume down in the control panel the "hiss" decreases also. S...

exxos wrote: ↑Tue Apr 24, 2018 9:30 pm OK finally got it recorded..
This is pure PC noise... after 10 seconds I start graphics tests...

The interesting thing is that you don't have the peaks at 2600Hz and 15000Hz. Your hiss sounds a little different than mine.

No, I didn't run memory test software yet... but I have this feeling that the more RAM access, the worse noise is in the audio out. No matter if it is a direct stereo output or monitor audio (pin 1). So, the question is why and if there is a possibility to defuse this noise and interferences. And w...

Have you run memory test software and checked the audio noise ? Can't remember if its been talked about before, though I think some noise is RAM access noise. So more RAM access, the worse the noise should get.. No, I didn't run memory test software yet... but I have this feeling that the more RAM ...

Maybe I figured out an interesting thing. Hiss is not the same when in color or mono mode. In color mode, the peaks are about 2600Hz and 15000Hz, in mono mode 2600Hz and 6700Hz. I recorded the same situation in both cases. The scratches in the beginning are memory test of TOS 2.06 during boot, the s...

I've noticed that one chip on the left of the processor is missing on my board compared to other STe mainboards. Does anybody know, what is it good for? Its the blitter... Its integrated in the large SMT chip to the left on later machines. Thanks very much for your answer. I had a little bad feelin...

I've noticed that one chip on the left of the processor is missing on my board compared to other STe mainboards. Does anybody know, what is it good for?

And here are the pictures after recap and some other little improvements (for example, LMC mixer audio fix). More here: - https://www.exxosforum.co.uk/atari/last/STEDACFIX/index.htm ("STE LMC MIXER AUDIO FIX") - http://forum.8bitchip.info/hardware-16/fixing-ste-microwire-'mixer'-error/ (&q...