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

[esp]

@marqs @Zoomer88
I tapped the Mega Drive’s audio before the amp and routed it to the headphone jack; the distortion is gone.
I recommend doing that anyway unless you plan on using headphones with the Mega Drive, since the audio has less noise.
I’m not familiar with model 2s, but if they do output line level stereo through the minidin I don’t see why they would have an issue with distortion.

[jonlad]

Is it possible to decrease gain on the AV1 input?

[marqs]

@Zoomer88: yes, I’m aware that Model 1 DIN audio output is mono, but didn’t know that many available rgb cables were wired to use headphone output which is not a good idea in general. There’s no point in installing audio mod for v1.6 board, but you may try adding a simple lpf filter or just a load resistor on the scart block.

@jonlad: audio (pre-adc) gain adjustment is on the list of upcoming features, but it is primarily meant for balancing audio level between sources/profiles and probably won’t help here as you can already adjust the level of headphone output – right?

[Gummi]

I’d bet Retro Gaming Cables and Retro Console Accessories sell more cables that use the headphone output for audio than without. The fully shielded cable from RGC isn’t even available without it.

[Zoomer88]

@gummi True that

@marqs Soldering iron for me is like a gdi ion canon. No way I’m gonna touch that black magic sorcery. But you are correct – lowering Genesis volume slider doesn’t eliminate the distortion unfortunately. What’s intersting is is that only OSSC exhibits this issue. No other appliance has problem with such a signal (several different TVs from sony and lg as well as Yamaha and Denon AVRs – all have no problems with it.

Not to mention that said output is near perfect on my console – no noticeable interferences (well, aside from that VDP noise, but it’s picked up way earlier afaik and no amount of audio circuitry bypass will help to avoid it. Even so, it’s really faint, almost negligible).

[jonlad]

So our only option is to mod the MD or mod the cable, which works fine with any other device?

[marqs]

Or add the antialias filter on ossc board, which apparently works fine with any other console as is 🙂

[Damn-Deal-Done]

Hello.

I experience the same issue. Digital artifacts/distortion (high pitch chirping) of the audio signal.

OSSC 1.6
RetroGamingCables headphone out scart cable.
Sega Mega Drive VA1 NTSC-J

Scart to TV is fine. Scart to OSSC is horrible.

This is disappointing since this is my most used console.

[Damn-Deal-Done]

Does anyone have a real solution to this problem? It must be a widespread problem since headphone out scart cables are pretty much the de-facto standard.

“try adding a simple lpf filter or just a load resistor on the scart block” How is this achieved?
“add the antialias filter on ossc board” How is this achieved?
“I tapped the Mega Drive’s audio before the amp and routed it to the headphone jack” How is this achieved?

These are not really solutions or understandable for people that are not electronics experts. Are any of these guaranteed to fix the audio?

Would the MegaAmp2 and a mini jack line out on the rear of the console fix this problem?

Thanks

[jonlad]

I’m guessing the reply by Marqs above is our real solution.

[BuckoA51]

I’ll keep looking into this for a definitive answer!

[Damn-Deal-Done]

That’s awesome. Cheers.

Just wondering. Are you involved officially with OSSC?

[BuckoA51]

Yes, I’m the website owner 🙂

[marqs]

Has anyone tried a 3.5mm Y-splitter adapter/cable to connect headphones simultaneously? I wonder if that CXA1034 headphone amp just needs low-impedance load to behave properly.

[BuckoA51]

I’ve managed to confirm this here with a Megadrive 1 and stereo SCART cable. Affects 1.6, doesn’t affect 1.5.

[Author]

Posts