SNES analog audio upgrade

[Jamisonia]

You can get infinitely better shielded cables if you install simple RCA jacks then use well shield interconnects. Of course getting it digital is perfect.

[Cronozilla]

I would go as far to say the first party cables likely aren't shielded at all. At best there might be some wire wrap technique to keep some stray signals out (very unlikely). But most bundled wires don't insulate at all, they merely have shrink wrapping on them.

It's the reason why Sony's cables come with the pack at the connector end, it's a magnet to help create an EM field to block some signals. It's better than nothing.

The best thing you could do while keeping it analog is actually busting open the connector, getting new shielded composite cables, and soldering those in.

Otherwise, you go optic, since ... shielding is unnecessary, just darkness. But ... I was speaking purely from a "If you don't want to mod you console but still want better audio and video signal try this" position. "Best" isn't really part of what I was talking about.

[Drakon]

I'm currently waiting on parts for the next step of this project. This stupid cheap ebay spdif to analog converter creates this annoying hiss sound for some reason. This's really annoying because either I have high quality audio with a hiss or noticably lower quality audio with no hiss. According to tiido the digital signals in the snes are i2s (which I can confirm is correct after I looked up what i2s standard is). I'm wiring up a straight i2s to analog circuit. I'm using the same dac that some guy supposedly used to upgrade the cheap ebay spdif to analog pcb I got. Except in this case I'm wiring the dac straight into the snes since it has the right signals for it. I'll still leave my cirrus logic chip wired up if I ever want spdif.

[Jamisonia]

I'd say s/pdif is the way to go, then buy a good external DAC that you can use for multiple devices. Going cheap with the DAC is really limiting the potential of this mod. Of course don't fall down the DAC rabbit hole either.

[Drakon]

I'd say s/pdif is the way to go, then buy a good external DAC that you can use for multiple devices. Going cheap with the DAC is really limiting the potential of this mod. Of course don't fall down the DAC rabbit hole either.

I'm still leaving the spdif hardware in my snes. This just saves extra needless conversions.

[Ziggy]

I'm now planning on doing the digital audio mod since I was able to get a new receiver with digital inputs. So that being the case, I've been reading up more on the mod. I was reading the datasheet (something I always suggest doing) for the CS8406 and noticed something that I don't believe was mentioned in the original mod guide or anywhere else I've read about the mod. The IC has unused "test" pins. They should be grounded, but I don't see a note to do that in the guide.

Test Pins (Input) - These pins are unused inputs. It is recommended that these pins be tied to a supply (VL or GND) to minimize leakage current. The CS8406 will operate correctly if these pins are left floating, however current consumption from VL will increase by 25 uA per TEST pin that is left floating.

So yeah, it works perfectly fine if you don't ground them, but then the IC consumes more current.

[Drakon]

I'm now planning on doing the digital audio mod since I was able to get a new receiver with digital inputs. So that being the case, I've been reading up more on the mod. I was reading the datasheet (something I always suggest doing) for the CS8406 and noticed something that I don't believe was mentioned in the original mod guide or anywhere else I've read about the mod. The IC has unused "test" pins. They should be grounded, but I don't see a note to do that in the guide.

Test Pins (Input) - These pins are unused inputs. It is recommended that these pins be tied to a supply (VL or GND) to minimize leakage current. The CS8406 will operate correctly if these pins are left floating, however current consumption from VL will increase by 25 uA per TEST pin that is left floating.

So yeah, it works perfectly fine if you don't ground them, but then the IC consumes more current.

Here they tied it into vcc:



http://gamesx.com/wiki/doku.php?id=av:snes_sp_dif

This's how I wired mine.

[Ziggy]

Yeah, I saw that pic after I posted. The guide on gamesx seems to be a cut n paste of the original guide, plus those two extra pics at the bottom. I don't know what the source of that pic is (from a forum post I assume). I just crossed referenced the pic with the datasheet real fast and it seems to make sense.

One thing I don't see though is the datasheet's recommendation for the power supply (VD and VL pins). The CS8406 has two different power supply pins, diagram 6 shows them being supplied independently. Also, tying a cap to ground on each power line to reduce interference.

I'm not sure what the difference would be though. If all the pins that need 5v get tied all together, or if you supply VD and VL independently. Maybe no difference at all. But the cap seems like a good idea.

The VD and VL supplies should be decoupled with a 0.1 uF capacitor to GND to minimize AES3 transmitter induced transients.

[Drakon]

I gave the datasheet a thorough read through a while back and I don't remember any wiring being wrong or strange.

[Jamisonia]

Ziggy just take a look and the GamesX, original Alpha-II version. The GamesX is just good because it updates the mod for the new version of the Cirrus Logic chip.