No-cut SNES digital audio mod:

[FBX]

My prototype boards came in today. I soldered one up, installed it on my spare APU SNES (polishing a turd, I know), and the sucker works beautifully! First try, rock solid, and I even had to do fine-pitch leg soldering (which I hate) in order to wire up the SNES APU audio chip. This is yet another aspect that makes the 1CHIP model superior: All digital audio lines can be accessed through vias.

At any rate, eye candy of my first ever no-cut SNES digital audio mod:







The RCA jack was just a cheap spare I bought from amazon, but I like the nylon discs they have so you can install these without even so much as leaving a scratch on the SNES plastic. On the mod board, I tented all the vias underneath (including the optical output terminals), but I'm like Bob in that I feel better covering the back with a sheet of electrical tape, so I did that anyway. I then took another piece of electrical tape, inverted it, and looped it to make it double-sided sticky. Then I used it to mount the mod board to the SNES main board. It works great for my needs, but I imagine other modders might use a dab of hot glue.

So this is the prototype of course, but the final production boards will look very similar. I'm only making a few cosmetic changes, but the layout and size will stay the same. I'll post back when I have more news.

-FBX

[Lawfer]

Interesting, so aside from the fact that you don't need to cut out the shell to make room for the connector, any other notable differences between the regular digital audio mod?

I notice there is an additional chip called "DA101JC DA1734", what's it for?

[FBX]

Interesting, so aside from the fact that you don't need to cut out the shell to make room for the connector, any other notable differences between the regular digital audio mod?

I notice there is an additional chip called "DA101JC DA1734", what's it for?

No user-end differences that can be detected. The DA101JC is the pulse transformer for the coaxial output (which is needed for no-cut modding through the RF port). Aside from that, I have my own assigned pinouts of the CS8406 that slightly differ from Borti's work. I chose them based on the datasheet and the vertical arrangement of the CS8406 in this board. Which brings me to an important point: There is a wiring chart on the back of these boards that must be followed exactly because the pad assignments are different than already available mod boards.

My next project is going to be incorporating MSU-1 and SGB audio for a "Deluxe" version of the board, although that's going to make that version 4x more complex. I'll be using metal standoffs to elevate the board using the screw hole left behind by the RF box. It might even allow me to put internal jacks on the board itself that fit through the RF port holes. But this project is likely going to take me several months to work on, so I'm not going to expect to have it done any time soon. I've got a lot of measuring to do, prototype board fitting, and of course laying out the components for ADC because MSU-1 audio and SGB audio are forced into analog signals due to how the lines are routed in the SNES.

[Lawfer]

My next project is going to be incorporating MSU-1 and SGB audio for a "Deluxe" version of the board, although that's going to make that version 4x more complex. I'll be using metal standoffs to elevate the board using the screw hole left behind by the RF box. It might even allow me to put internal jacks on the board itself that fit through the RF port holes. But this project is likely going to take me several months to work on, so I'm not going to expect to have it done any time soon. I've got a lot of measuring to do, prototype board fitting, and of course laying out the components for ADC because MSU-1 audio and SGB audio are forced into analog signals due to how the lines are routed in the SNES.

MSU-1?? Oh, borti's board can't do MSU-1, so you are saying your's will? How many games support MSU-1 so far btw?

And what's SGB? Super Game Boy maybe?

[Ikaruga11]

Amazing work, FBX! When will this be finished? I'll definitely purchase a few of these.

[FBX]

MSU-1?? Oh, borti's board can't do MSU-1, so you are saying your's will? How many games support MSU-1 so far btw?

And what's SGB? Super Game Boy maybe?

No current digital audio boards can handle MSU-1 or Super Game Boy, because those lines are analog only. It goes like this:


S-APU/DSP >>> Digital-to-Analog audio converter chip (DAC for short) >>> S-MIX chip, which combines the stereo analog lines coming from Cart pins (MSU-1 and Super Game Boy audio) as well as stereo lines from from the expansion port on the bottom of the system (Broadcast Satellaview used these lines in Japan) >>> caps and resistors >>> Multi-AV port.

So the digital audio mod boards currently available work by intercepting the data lines in the S-APU/DSP chip, and this is why MSU-1 and SGB audio don't come through on them. So you'd think that all it would take is a small ADC chip to convert analog into digital and pipe those lines through the mod board, but converting analog into digital is many times more complex than converting digital to analog. For example in the SNES, it merely takes one single chip the size of a pea to convert the digital sound into analog stereo lines. In order to convert those lines back to digital, you need the ADC processing chip, a crystal clock chip, a hex inverter chip, a digital processing chip, about 30 or so various caps and resistors, and likely a linear power regulator that changes 5V to 3.3V. It's a bunch of shit in other words, and that's why it hasn't been tackled yet. I'm going to take up the challenge myself though, as my next project.


Anyway, I'm going to be asking some friends for help on mass production of the current boards and selling them online. I'll post here the details on where to get them when we've got it all set up.

-FBX

[darcagn]

Interesting, so aside from the fact that you don't need to cut out the shell to make room for the connector, any other notable differences between the regular digital audio mod?

I notice there is an additional chip called "DA101JC DA1734", what's it for?

No user-end differences that can be detected. The DA101JC is the pulse transformer for the coaxial output (which is needed for no-cut modding through the RF port).

About 4 years ago I bought a CS8406 and did this exact mod myself (no cut, coax output where RF was) with a generic SOIC/DIP adapter board. It works great and doesn't need any extra components... so what's the DA101JC for?

[Josh128]

What is the benefit of digital audio out on the SNES?

[Blair]

FBX, are you focusing on coaxial output because of concerns with S/PDIF jitter?

[Lawfer]

FBX, are you focusing on coaxial output because of concerns with S/PDIF jitter?

Isn't Toslink better?

[FBX]

FBX, are you focusing on coaxial output because of concerns with S/PDIF jitter?

Isn't Toslink better?

Other way around. TOSLINK is more and more prone to jitter the longer the cables, whereas Coaxial doesn't have this problem.


@Blair only reason I added coaxial was to make the "no-cut" option available on these boards. As in the pic I posted, the existing RF port hole was used without cutting it.

What is the benefit of digital audio out on the SNES?

Same benefit of hooking CD players or other digital media up with digital cables: Improved sound quality and no analog noise in the lines. It really does make a difference. I've been releasing soundtracks I ipped from various SNES games using this mod, and people have noticed it sounds effectively 'perfect'.

[bobrocks95]

What is the benefit of digital audio out on the SNES?

The main advantage is the elimination of any audio buzz from analog output. I don't remember anyone saying it was a big quality jump beyond that.

[FBX]

What is the benefit of digital audio out on the SNES?

The main advantage is the elimination of any audio buzz from analog output. I don't remember anyone saying it was a big quality jump beyond that.

It depends on the hookup comparison. It's going to sound MUCH better than standard AV cables, but if you were to isolate the analog audio lines inside the SNES and output them via shielded wires directly into a recorder, the gap in quality would be much smaller. But as you said, the main advantage is zero analog noise while transmitting the data to the receiver.

It works great and doesn't need any extra components... so what's the DA101JC for?

The CS8406 datasheet specifies the use of a pulse transformer for isolating the digital output to the coaxial jack. I'm also using the transformer to invert the negative lead from the TXN pin of the CS8406 as well.

[Lawfer]

FBX, are you focusing on coaxial output because of concerns with S/PDIF jitter?

Isn't Toslink better?

Other way around. TOSLINK is more and more prone to jitter the longer the cables, whereas Coaxial doesn't have this problem.

Even if the cable is 1m long and uses glass fibers?

From what I am reading Coaxial cables are susceptible to RFI (radio frequency interference) or EMI (electro-magnetic interference), if there are any existing 'hum' or 'buzz' problems within a system (e.g. a ground loop), a coaxial cable may transfer that noise between components. Unlike coax, Toslink cables are not susceptible to RFI/EMI noise or signal loss over distances, because it is light and not electricity carrying the information.

[FBX]

From what I am reading Coaxial cables are susceptible to RFI (radio frequency interference) or EMI (electro-magnetic interference), if there are any existing 'hum' or 'buzz' problems within a system (e.g. a ground loop), a coaxial cable may transfer that noise between components. Unlike coax, Toslink cables are not susceptible to RFI/EMI noise or signal loss over distances, because it is light and not electricity carrying the information.

That's what the pulse transformer is for (one of the reasons anyway). You can technically get away without one, but it prevents AC hum from getting into the line and deteriorating the signal (at least that's my understanding of how it works).

As for optical, it's perfectly fine for short distances, but you're better off using properly shielded coaxial cable for long line runs.

[borti4938]

No user-end differences that can be detected. The DA101JC is the pulse transformer for the coaxial output (which is needed for no-cut modding through the RF port). Aside from that, I have my own assigned pinouts of the CS8406 that slightly differ from Borti's work..

How many pins differs from the use of TX-? Two: changing MCLK from 256*fs to 256*fs... There is not that much one can do different here. So it's still the same

[Edit]
Don't missunderstood me here. I just want to clarify for the others that there is no new technique in here. It's still the digital audio from the SNES. What's complete new and great here is the possibility to use RCA without any extra components off the board.
[Edit end]

Anyway, I'm going to be asking some friends for help on mass production of the current boards and selling them online. I'll post here the details on where to get them when we've got it all set up.

Really I cannot understand that but that's your choice...
[Edit]
If I saud this I'm really just surprised at this stage. Just want to prevent you from investing a lot of money and effort for setting up a sale if there are still some quite obvious things which can be improved.
[Edit end]

Here are the reasons why I'm surprised:

• [Edit]Comment removed as missleading - I haven't took the right words[Edit end]
• I don't see the use of the footprint for the optical transmitter in your setup. Due to the transformer the PCB is quite heavy and put a lot of downforce to the output jack as the PCB still sits above.
• The PCB still looks like a prototype as like as mine. (Just my personal opinion)

I guess have to spend some time in refactore my own design and realize the ideas I have.

Nevertheless, a great first project to start with PCB design. One can see that you put a lot of effort into it.

[FBX]

I followed the datasheet to the letter, which concerned not only those two pins, but also the diagram suggested in the sheet that both pins 23 and 24 should be decoupled together on the same power line. I'm sure I mentioned that when I wrote to you my concerns about those differences in the datasheet from your board. My efforts were to see if I was missing something obvious or if it were truly as simple as following the datasheet, which turned out to work perfectly fine doing it this way. The datasheet also suggested the pulse transformer as well as the 374 Ohm and 90.9 ohm resistors, which is what I have on the board in the pics. Lastly, the optical transmitter is an optional feature for those that prefer using it. I edited the device file in order to leave the underside tented such that the board can operate either way (or both at the same time).

But really this board is just a run-up to my bigger project of fully incorporating MUS-1 ans SGB audio. As I mentioned in this thread, it requires a lot more work to convert analog into digital, but I've been studying for several hours a day and I've just about got the logistics worked out. That's my main focus moving forward, and I'm going to see it through even if nobody is interested.

Edit: And by the way, the transformer is very light. It weighs about the same as the CS8406 if even that much.
Edit 2: Just got out the DA101JC and the CS86046. The CS8406-CSZ is about twice the weight of the transformer, so there are no issues with stress on the board at all.

[tjstogy]

I still don’t understand how this mod is helpful- instead of relying on the dac in the snes you are now using the dac in whataver amplifier you use... ie It might come out digital from the snes end, but it will still be converted to analog in the receiver

[borti4938]

@FBX:
I hope you haven't got me wrong. I don't mean to be rude

Just as I said in the PM, the connection diagram is just a diagram and I understood it in the way that it was the closest point to connect the logical pin 24 to Vcc. The data sheet clearly says that only the power supply pins VD and VL are recommended to have decoupling caps.

Also I recognised and mentioned the use of TX- Sorry if it was too short. High respect on that idea of utilising both TX+ and TX-

I haven't expect the transmitter to be that light. Ok, my fault!

By the way, just give me a day to show my idea of how to design the digital audio board with RCA output.

[FBX]

I still don’t understand how this mod is helpful- instead of relying on the dac in the snes you are now using the dac in whataver amplifier you use... ie It might come out digital from the snes end, but it will still be converted to analog in the receiver

We would never have bothered with digital audio applications and equipment if it were that simple. It actually does make quite a bit of difference using a clean transmission like digital audio from one device to the next. The fact that it ultimately gets converted to analog through the speakers isn't the point. You avoid noise in the transmission lines, you get to digitally preserve soundtracks (which the rips I have already made doing this are VERY appreciated on the ffshrine forums), and you get to cut the number of lines from 2 down to a single line (or in the case of stuff like 10.2 surround, many lines into one). The main reason though goes back to the clean transmission of the data to the receiver and/or recording application. If you want a demonstration, check out this track from Axelay recorded directly from digital output:

https://filetrip.net/dl?iXX8XRxhto

Analog can't reach that level of clarity. You can get close, but it will never be quite as good no matter how much money you spend on shielded cables.

[tjstogy]

Don’t get me wrong I think it’s an awesome idea, I just would have to hear them back to back. Your results will vary on the quality of the external dac you are using. Maybe the snes dac sucks? But again, maybe it doesn’t. The audio quality scene has just as many “snobs” as those in the video quality
Scene— and by saying “it’s better cause it’s digital” doesn’t inherently mean anything. Unlike video quality which is either perfect, or it’s not- audio is much more rooted in personal preference. How many people prefer vinyl to lossless digital downloads? (Tons, And vice versa...)

That being said, hopefully someone could make some proper comparisons. Your recording sounds good- but in the audio world it’s almost illegal to upload anything without listing the exact equipment used to record. What programs, what dac, what cables etc etc. And importantly what did it sound like before?

Also- Borti, if you’re able to output to RCA- is it feasible it could also be integrated into the multiout?

[Lawfer]

I guess have to spend some time in refactore my own design and realize the ideas I have.

What will you be improving?

That's my main focus moving forward, and I'm going to see it through even if nobody is interested.

Any plans on doing a N64 digital audio output in the future?

[bobrocks95]

Don’t get me wrong I think it’s an awesome idea, I just would have to hear them back to back. Your results will vary on the quality of the external dac you are using. Maybe the snes dac sucks? But again, maybe it doesn’t. The audio quality scene has just as many “snobs” as those in the video quality
Scene— and by saying “it’s better cause it’s digital” doesn’t inherently mean anything. Unlike video quality which is either perfect, or it’s not- audio is much more rooted in personal preference. How many people prefer vinyl to lossless digital downloads? (Tons, And vice versa...)

That being said, hopefully someone could make some proper comparisons. Your recording sounds good- but in the audio world it’s almost illegal to upload anything without listing the exact equipment used to record. What programs, what dac, what cables etc etc. And importantly what did it sound like before?

Also- Borti, if you’re able to output to RCA- is it feasible it could also be integrated into the multiout?

Again I'd say it's a worthwhile upgrade if you have any buzz or AC hum from your analog cabling. Barring that, it's up to you to decide whether or not it's worth the effort- if the SNES already sounds good on your audio setup you may not get a lot of mileage out of this mod.

[Joelepain]

tjstogy your post is strange. It almost sounds as if you're saying "it's awesome but it's useless".

audio is much more rooted in personal preference

So if we follow you on that, let just say this mod if for people that prefer digital over analog...

How many people prefer vinyl to lossless digital downloads

The fact that people are blind by some kind of hype or nostalgia doesn't annihilate the fact that every serious comparison between Vinyl and CD say that CD destroys Vinyl in every possible way. And we're not talking about Hi-Res audio yet...

Maybe the snes dac sucks

We're talking about an almost 30 years old 200$ console made by Nintendo ! (hey, I love them, but cleary not because of their habit of beeing cheap on audio/video quality). I bet whatever 100$ Amp/Dac made in the last 25 years is better than this. Even the so hyped "professional-grade dac of the first ps1" is just "better than your average dac, but nothing to blow your mind" if you search for some comparison on internet.

What programs, what dac, what cables etc etc

And that's the whole point of digital ! it's useless to talk about all this, because technically what FBX uploaded should be bit for bit identical to whatever other snes digital audio mod in the world outputs, or what a cycle accurate emulator can produce.

Really, I don't what to be rude with you. It's just that your philosophical wondering about analog vs digital seems out of place on this forum.

[nmalinoski]

You avoid noise in the transmission lines, you get to digitally preserve soundtracks (which the rips I have already made doing this are VERY appreciated on the ffshrine forums), and you get to cut the number of lines from 2 down to a single line (or in the case of stuff like 10.2 surround, many lines into one). The main reason though goes back to the clean transmission of the data to the receiver and/or recording application.
...
Analog can't reach that level of clarity. You can get close, but it will never be quite as good no matter how much money you spend on shielded cables.

This is probably a ludicrous suggestion, because most home audio equipment can't use it, but would balanced analog audio-out also achieve noise reduction? If you tap the analog output, after the DAC, you could catch both internal and cart audio.

Then again, just imagine an SNES with two XLR ports on the back.

[FBX]

This is probably a ludicrous suggestion, because most home audio equipment can't use it, but would balanced analog audio-out also achieve noise reduction? If you tap the analog output, after the DAC, you could catch both internal and cart audio.

Then again, just imagine an SNES with two XLR ports on the back.

It's sort of on track with my eventual deluxe board idea. I've already spaghettied together the parts to test the idea and it works, but here's the train of thought: If you can intercept the audio directly from the two caps on the board just after the final output from the 'S-Mix' chip, and immediately digitize that signal, you'd get a pure and clean capture of the entire mixed stereo audio. I tested the theory out and sure enough, the 48Khz digital output of that mixed signal sounded clean with no audible distortion. So I got to thinking the ultimate digital audio board would have a single output and a small toggle switch (that fits through the channel selector for no-cut modding). You then have 48Khz clean ADC of the mixed stereo lines that include cart and ext audio, and with the flick of the toggle switch, you'd get the original digital-to-digital feed of the SNES music and sound. It's the best of both worlds in one mod board, and the toggle switch would make it easy for users to switch to their preference on demand.

[borti4938]

@FBX:
What about just applying the ADC to the audio lines of the edge connector and then digitally merging both audio streams together?

Then again, just imagine an SNES with two XLR ports on the back.

You can do that with the modding board shown here: just replace one resistor value (R1) and leave the other one open (R2) does the trick to have RCA+ and RCA- configured for a symmetric XLR port.

I guess have to spend some time in refactore my own design and realize the ideas I have.

What will you be improving?

The reason why I say it is still a prototype as like as my very first version is, how it fits in the SNES. You have a loose board which have to be fitted with glue. Nothing more holds the PCB (in my version the optical output) in place.

Most installations prefer to remove the RF output. So why not using this space. Also the SNES2 has the place for the RF although it was never came out with a RF output.

SSo here is my design idea:
For the RCA output:

Spoiler

PCB will be fixed using the large GND plane at the castallation vias. The RCA output is SMT style. The bottom layer is GND all over; so there is no need to isolate the PCB from bottom side. All signals are on the top layer.
My only concern is that it might be to high. My hope is of course that it won't be the case.

For the TOSLINK output:

Spoiler

To have it not only glued I introduced a mounting hole. At the big model SNES one has a mounting hole directly underneath which was for the RF and MultiOut. This reduces the amount of glue you need to fix the output. Finally it will be only to prevent the construction from rotating away while plugging in the optical connector.
On the SNES2 there is unfortunately such a hole unless you drill one. Highly risky, but... I'm not sure, there should only a large GND plane on top as well as on bottom side.

But even if you don't mount the PCB with a screw: the PCB layout is much much smaller than before The reason is simple: I also replaced the CS8406 with a DIT4096 from TI, which has a TSOP package instead of a SOIC.

Any plans on doing a N64 digital audio output in the future?

psssst

Also- Borti, if you’re able to output to RCA- is it feasible it could also be integrated into the multiout?

Feasable. Just do it and build your own cable for that. However as the MultiOut is fully populated you have to free two pins for that, e.g. Luma and Croma or the analog output pins.

[Lawfer]

The reason is simple: I also replaced the CS8406 with a DIT4096 from TI, which has a TSOP package instead of a SOIC.

So will it sound different/better than your original design/prototype?

psssst

Again I'd say it's a worthwhile upgrade if you have any buzz or AC hum from your analog cabling.

I can hear strange noises from time to time coming from my subwoofer that is connected with a coax cable to my receiver, sounds like "krrrk krrrrrrk krrrk", I don't however hear anything like that with analog audio from the Wii or GameCube (connected directly with RCA plugs to my receiver).

[tjstogy]

tjstogy your post is strange. It almost sounds as if you're saying "it's awesome but it's useless".

Not true- I've always thought it's been a great idea to obtain better audio fidelity from old systems (and this isn't the first digital audio output mod for the SNES). If you are bypassing the internal SNES DAC, then you are using an external DAC of some sort. Otherwise, you wouldn't hear sound.

audio is much more rooted in personal preference

So if we follow you on that, let just say this mod if for people that prefer digital over analog...

Doesn't exist. It's still in analog. Any time you are listening to sound through your speakers, a conversion to analog is being made- whether it's inside the SNES or outside of the SNES.

How many people prefer vinyl to lossless digital downloads

The fact that people are blind by some kind of hype or nostalgia doesn't annihilate the fact that every serious comparison between Vinyl and CD say that CD destroys Vinyl in every possible way. And we're not talking about Hi-Res audio yet...

Incorrect. I'm all for audio fidelity but my point in saying that was more to bring awareness that there is no "right way" when it comes to audio. A popular quote on audio is: "If it sounds good, it is good."

Maybe the snes dac sucks

I bet whatever 100$ Amp/Dac made in the last 25 years is better than this

You could very well be right! But let's demonstrate the differences, and explain what external DAC was used to reach each conclusion instead of saying "yeah, it's just better". (Especially if you're the one selling the boards..). It reminds me of the SNES RGB bypass methods- they keep on getting better and better. Why? Because people put different methods and chips through their paces to find which (incrementally) performed better. Same thing applies with audio. By saying the digital audio bypass is better is the same thing as saying "external DAC is better" (there are hundreds of external DAC's, so which one?).

What programs, what dac, what cables etc etc

Really, I don't what to be rude with you. It's just that your philosophical wondering about analog vs digital seems out of place on this forum.

[/quote]
It's ironic that you're saying I'm philosophically wondering about things and "out of place on this forum" when you have no idea what you're talking about yourself.... I pity your ignorance. (Really, I don't want to be rude with you.)

[borti4938]

The reason is simple: I also replaced the CS8406 with a DIT4096 from TI, which has a TSOP package instead of a SOIC.

So will it sound different/better than your original design/prototype?

No. The digital output signal will be the same. It's just a smaller IC, which is a) a bit cheaper, b) save some PCB area/cost and c) allows a neater installation