Bad audio quality through SCART from Genesis (using headphone out) – OSSC 1.6

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Viewing 15 posts - 61 through 75 (of 89 total)
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  • #19126
    BuckoA51
    Keymaster

    Thanks, I’ll give that a try as soon as possible.

    #19128
    marqs
    Participant

    @James-F there is no analog circuitry or load before PCM1862 audio ADC except a 100K pull-down to prevent floating.


    @BuckoA51
    so the mono output was no better? That somewhat contradicts with esp’s post, although in that case signal was tapped before buffer and op-amp. Is there some particular game where distortion is most apparent? The modified VA1 here should sound close to your VA5 but I have hard time hearing any notable distortion after pre-amp gain fix (Sample 4).

    #19136
    James-F
    Participant

    I think this 100k should have sufficed.

    Page 56, PCM1862
    The analog inputs also require coupling caps, does the OSSC has them?

    #19166
    marqs
    Participant

    @James-F Yes, it has them.

    #19167
    James-F
    Participant

    Very well then.
    So it’s the CXA1034PM that is whacky, and using a simple headphone output splitter like you’ve suggested fixes the problem without modding the cable.
    The only problem is noise from the headphones, might as well mod the cable if audio quality is top priority. 🙂

    MD1 phones

    #19437
    James
    Participant

    Anybody know if you still get this issue if you are mixing the audio from the headphone jack into a mega cd and then using the cd’s RCA connectors through a 1.6 OSSC?

    Or does the mega cd apply the appropriate load to the CXA1034PM as it’s getting mixed with CD’s audio?

    #19484
    marqs
    Participant

    Good news!

    I found a problem in PCM1862 initialization. The default ADC clock divider value appears to be different than specified in the datasheet, resulting to too high ADC clock. Setting the divider manually to correct value seems to fix the MD sound issue based on short testing.

    #19485
    Damn-Deal-Done
    Participant

    That’s awesome. So does this mean it can be done with firmware only?

    #19487
    BuckoA51
    Keymaster

    I was just going to pick up my modded RGB cable tomorrow too 🙂

    #19489
    jonlad
    Participant

    If it’s a firmware fix, then this has just made my Friday!

    #19490
    Zoomer88
    Participant

    Yay! Great news indeed!

    #19516
    BuckoA51
    Keymaster

    Just solder 1k resistor between pin 2 & 4, and pin 6 & 4.
    Note that Pin 2 and 6 wired to the tip and ring of the 3.5mm plug, pin 4 is ground.

    Ok so we tried that and it didn’t seem to make much difference, sound was still noticeably worse on 1.6 than 1.5 + Audio board.

    Perhaps there’s two issues here that we’re running into, hopefully Markus’ fix will finally solve it.

    #19517
    James-F
    Participant

    Strange, for me a load of 1k has the effect as plugging headphones in parallel.
    Anyway, great that this is solved by firmware.

    #19619
    BuckoA51
    Keymaster

    Beta testing firmware 0.80a here and now the audio from my VA5 Megadrive is identical through both 1.5 with audio board and 1.6.. so I think this one is solved…so in conclusion

    If you have VA0 or VA1 console, solder 1k resistor between pin 2 & 4, and pin 6 & 4 on your SCART cable.

    if you have a VA0 or VA1 or VA2 console, try the firmware update first and if you still have problems, see this thread:- http://www.sega-16.com/forum/showthread.php?27397-VA2-Preamp-fix

    everyone else just needs to update to 0.80a which should be out very soon.

    #19621
    jonlad
    Participant

    This is great news – thank you

Viewing 15 posts - 61 through 75 (of 89 total)
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