Retrotink pass-thru + OSSC resulting in audio noise

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Hi there.
So I’ve purchased the Retrotink2x along with the VGA output adapter in order to use it in pass-thru mode together with my OSSC.
However, I’ve noticed that this results in pretty annoying audio noise.

When plugging Retrotink2x directly in my tv, used in any mode, no problem.
When outputting Retrotink2x in 2x mode to OSSC, no problem. When switching Retrotink2x to pass-thru -> noise.

The console isn’t the issue, as this also happens with nothing at all plugged in. So I’ve got just the test screen, 2x mode, everything silent. Switch to pass-thru -> noise.

Any ideas? Is this a common issue?
Thanks.

[nmalinoski]

Have you tried bypassing the RT2X and connecting audio directly to the OSSC?

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Will test that tonight, but assuming that won’t give any problems.
When noise occurs, unplugging the VGA output adapter’s breakout audio cable results in no noise (and no sound, of course)

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Have tested. As expected, no problems when sending audio directly to OSSC.

Although this is a workaround that works, it’s not ideal in my setup. Also I’m wondering what causes this, and if everyone is having this issue, or if my unit is faulty in some way?
And would there be a way to fix this?

[nmalinoski]

At this point, I would think it’s one of two issues. Either the HDMI->VGA adapter doesn’t like being fed 15kHz signals, or the RT2X somehow introduces audio noise when passing-through 15kHz modes.

Testing passthrough solely on the RT2X might be a little difficult if you’re connecting directly to a TV that doesn’t support 240p/480i over HDMI; however, if you have an AVR, that should still play audio, even if your TV can’t display the video mode.

One way you could test the HDMI->VGA adapter:
1. Connect composite output from the console to green/Y of AV2 on the OSSC;
2. Connect HDMI output of OSSC to the HDMI input on the converter;
3. Connect the 3.5mm TRS output from the converter to an AVR, speaker system, or plug in headphones;
4. Turn on everything;
5. On the OSSC, configure 240p and 480i for passthrough and set input to AV2-YPbPr.

If you still get audio noise then, I’d blame the HDMI->VGA converter.

[bmp02]

When connecting the RT2X directly to my tv in pass thru mode, 240 is interpreted as 480i and there is no audio noise.
Does that tell you anything?

And regarding your other test option, when speaking of the “converter”, you mean the HDMI->VGA adapter right?
Thanks.

[nmalinoski]

When connecting the RT2X directly to my tv in pass thru mode, 240 is interpreted as 480i and there is no audio noise.
Does that tell you anything?

It gives us another data point demonstrating that it’s not the RT2X at fault.

And regarding your other test option, when speaking of the “converter”, you mean the HDMI->VGA adapter right?

Yes, that’s the device I’m referring to.

It’s a converter; I misspoke (mistyped?) when I referred to it as an adapter. Adapters are passive devices that do not modify the signals they receive, like a gender changer or a componentless SCART to BNC cable; whereas the device you have has active circuitry to change the digital signals to analogue signals, which makes it a converter.

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Have performed your test a few hours ago (which resulted in no noise), but ran into much bigger problems which resulted in not being able to use the RT2X anymore at all this evening. Must say the RT2X feels extremely unstable to me.

Steps I took:
First the test. Used my headphones, heard some crackling sounds at first (nothing like the noise described before), then everything became perfectly silent.
Then wanted to do a second test. Unplugged console as it doesn’t seem to make any difference at all to the noise problem. RT2X hdmi to converter, converter not plugged in to OSSC, headphones in 3.5mm jack audio breakout socket. Everything silent. As soon as I plug in the VGA to the OSSC, the audio noise is back, unplug, noise gone, plug back in, noise is there (can’t remember if OSSC was switched on or off).

Then the RT2X image disappears and I can’t get it back. Have unplugged all cables and restarted everything several times, but OSSC does not sync up to the RT2X output at all. I must mention this has happened several other times this week.
I then plug the RT2X hdmi directly into my tv, no image. Unplug all cables, restart, no image. Unplug hdmi from my tv and plug back in, image for 4/5 seconds, then it’s gone again.

And that’s the last of RT2X I’ve seen this evening. Both OSSC as well as my tv have not recognized the image coming from RT2X at all for the past few hours.

As said, this has happened before (not that long though), and from experience I tend to expect that tomorrow it’ll work fine again. But it feels totally random and unstable. No clue what’s going on here…

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Oh hey it’s back again! Weird weird

[mikechi2]

It sounds like most of your audio problems is related to the HDMI->VGA converter. Here are the tools I used, which work well:

I would never recommend having the 2X digitize the audio, then having another adapter convert it back to an analog signal only to be digitized yet again for the OSSC.

Double check the microHDMI cable. I find that 8/10 cases where the picture stops without reason was due to a faulty cable/connector.

[bmp02]

Thanks for the reply Mike.
Just checked your video, and although I might order that HDMI->Component box, I’m a little hesitant as it will make the cable mess behind my tv even bigger, which I’m not really looking forward to 🙂

I understand that it’s not ideal to digitize audio and convert it back again, however if it works it is the neatest option for me atm, and considering the converter was bought with the RT2X, I think I might expect it does work well enough.
Since I assume you’ve tested every possible combination by now – What happens if you use it in the same setup like me (RT2X in pass thru mode -> HDMI2VGA converter with audio breakout -> OSSC). You don’t get that noise? It’s definitely loud enough not to miss it, and a big immediate change when alternating RT2X between 2x and pass thru modes.

Regarding the HDMI cable, it’s a pretty expensive and sturdy one, have never had any issues with it. But it would be the next logic step to check what happens if I change it for another one indeed. Might also be the adapter plug that came with it. Will try and find another one and check.

Another question – What’s the reason for not including a power switch on the RT2X board? I have installed one in the cable now, so not a problem anymore, but it felt like the main missing piece.
Thanks.

[mikechi2]

You’re welcome and no problem at all. I definitely hear you on the cable mess. I didn’t like the component box at first because it also needs a power cord (unlike the VGA one) but I find that the component box has been more reliable and produces a better picture due to the OSSC LPF.

I actually haven’t tried your setup. I’ll see if I can dig up the VGA converter and give it a shot. I guess I always plugged the audio directly into the OSSC or PC (for captures).

Yeah, I can see why you might think a lack of power button is a bit odd. Maybe I’m weird but I guess I never turn off my stuff…

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Did you already manage to check for noise with the VGA converter setup?

Also, anyone from VGP reading here? I assume when you’re selling this combo, you will at least have tested it yourself. So would love to hear about that.

Then regarding the RT2X being unstable. I have tested again last night with a different HDMI cable, but made no difference as expected.
I have connected straight to my tv, switched it on with no console attached, leaving test screen to test. After a minute or so, connection is lost, it sometimes flashes a few times and then it’s gone. Restarting won’t help. Waiting for 5 minutes and then restarting brings the image back for a minute, then it’s gone again.
So it’s not the HDMI cable, and it’s not my tv either. Because when connected via VGA converter to OSSC, also OSSC loses connection with RT2X regularly.

Only possible issue I can think of would be the included HDMI adapter plug (HDMI 2 micro HDMI). I don’t have any of those plugs or any micro HDMI cables around so can’t test that. But honestly don’t really expect that to be the issue.

Altogether – This is definitely not working, would like to get a decent solution.
Thanks.

[BuckoA51]

I tested the VGA adapter with what systems I had on hand, mostly the C64. I didn’t extensively test the audio since it makes more sense to bypass the VGA adapter and plug the audio direct into OSSC.

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Thanks for your reply.
Console type doesn’t matter, you could easily test with no console plugged in at all. Only RT2X to OSSC and that’s it.
Could you test and tell if my VGA converter is the problem, or if this is normal behaviour (which should then be mentioned at the RT2X buying page imo).

And more important at this moment, since my RT2X is constantly losing connection with both my OSSC as well as tv (also even when no console plugged in), how can we solve that?

Thanks.

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