Thank you for the explanation, Tiido! ^^ I once read about this weird amp configuration in some Sega forum, but lost track about it.
The reason I mentioned it, is, because the default connection to the TV set was RF (antenna cable),
which gave a different sound than the headphones output. So that's why it came to my mind.
Some games apparently were meant to sound right via RF modulator (-which I thought was fed by the mono amp, too-) in first place,
so they may not sound nice/as intended if played back "unfiltered" (-akin to the dithering "issue", where some games don't look right if not played via RF or Composite-),
while other games perhaps sounded better/as intended in stereo via headphones jack.
Anyway, I never really had a chance yet to install that clear sound mod into one of my MD1 models. 🙁
Edit: I'm sorry for the bad writing. I have difficulties to put my thoughts into words.
In essence, I was trying to say, that the filtered sound should be taken into account when making the card.
I don't mean that the sound should be low-quality by design, but maybe there should be some testing with existing MD soundtracks
before finalizing the card. Maybe then a simple low-pass filter can be added, if necessary. It could be enable/disable by a simple port write perhaps.
Maybe implemented as a simple flip-flop. Some early devices, like the Amiga or SB Pro also had fixed filters, I recall.
Edit: That being said, these are just ideas that come to mind. They are in no way binding, of course.
I think this a facinating project, no matter how the final card will come out in detail. 😀
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