Jump to content
IGNORED

FPGA Based Videogame System


kevtris

Interest in an FPGA Videogame System  

682 members have voted

  1. 1. I would pay....

  2. 2. I Would Like Support for...

  3. 3. Games Should Run From...

    • SD Card / USB Memory Sticks
    • Original Cartridges
    • Hopes and Dreams
  4. 4. The Video Inteface Should be...


  • Please sign in to vote in this poll.

Recommended Posts

Sorry it didn’t work out better. I bought an NES30 with a NES Classic Edition Retro Receiver from either eBay or an Amazon seller (can’t recall).

 

I don’t think that’s it though. If you look you will see that it wasn’t the only controller they discontinued. They discontinued ALL of their look-alike controllers and introduced a new line of look-similar controllers. If you try to find documentation, support, firmware updates, etc for the SNES30, NES30, etc you won’t find it. They don’t even have a single picture of these anywhere on their site. If you REALLY dig you will find that them renamed as “N30” and “SN30 Legacy.”

 

It’s pretty clear that they were suddenly concerned with having designs too similar to Nintendo’s and concerned with having trademarks like “NES” and “SNES” in their product names... for whatever reason.

 

Right, but that's also a clue: they replaced the SNES30 with the new SN30, but they didn't replace the NES30 with anything. The N30 Pro replaces the NES30 Pro, rather than the quite different NES30. I suspect that there just wasn't much customer interest in something that was the shape of an NES controller but had ABXY and shoulder buttons. You don't get the nostalgia of an NES controller because it was too different, but you get all of the sharp-angled discomfort.

Edited by Guspaz
  • Like 1
Link to comment
Share on other sites

Kevtris, if you don't mind me asking: Why did you go with a hard limit of 254 on the SNES color output? I notice your ramp starts at decimal 7 for the first non-black color and ends at 254-254-254 for pure white. Higan goes from 8 to 255 in comparison. The menu font for the Super Nt is set at 255-255-255, so of course the system is capable of using full range. Just thought it was curious.

 

Also do you know if there's any sort of high-pass filtering going on in the Super Nt when it comes to MSU1 audio? We've been (me and Qwertymodo) have been doing some comparative sound test recordings of MSU1 played from revision H SD2SNES hardware in real SNES consoles like the Junior and 1CHIP, and noted there seems to be more filtering going on in the Super Nt than these systems. I've got more testing to do myself to make certain of this, but I'd thought I'd ask to see if you know anything about how the cart audio is managed in the Super Nt compared to real SNES consoles.

 

Cheers!

Edited by Karbuncle
Link to comment
Share on other sites

Funny how some people claim because Kevtris' work is closed source that means he isn't helping the community or preserving video games.

 

 

If you're referring to me thats not what I said in the slightest. I don't think anyone said that actually.

I did say that I didn't think Analogue's goal was to preserve video games as they're a company with the ultimate goal of making $, so maybe that confused you.

Link to comment
Share on other sites

 

If you're referring to me thats not what I said in the slightest. I don't think anyone said that actually.

I did say that I didn't think Analogue's goal was to preserve video games as they're a company with the ultimate goal of making $, so maybe that confused you.

I was talking about Byuu.

  • Like 1
Link to comment
Share on other sites

Kevtris, if you don't mind me asking: Why did you go with a hard limit of 254 on the SNES color output? I notice your ramp starts at decimal 7 for the first non-black color and ends at 254-254-254 for pure white. Higan goes from 8 to 255 in comparison. The menu font for the Super Nt is set at 255-255-255, so of course the system is capable of using full range. Just thought it was curious.

 

Also do you know if there's any sort of high-pass filtering going on in the Super Nt when it comes to MSU1 audio? We've been (me and Qwertymodo) have been doing some comparative sound test recordings of MSU1 played from revision H SD2SNES hardware in real SNES consoles like the Junior and 1CHIP, and noted there seems to be more filtering going on in the Super Nt than these systems. I've got more testing to do myself to make certain of this, but I'd thought I'd ask to see if you know anything about how the cart audio is managed in the Super Nt compared to real SNES consoles.

 

Cheers!

I fixed the -1 thing (pretty sure... lol) it was because I was multiplying by 0xff instead of 0x100 in the scaler at some point. This turns 0xff into 0xfe, and 0x8 into 0x7. i.e. 100h = 1.00, 80h = 0.5, etc. yeay for fixed point math. The SNES itself was outputting what you'd expect, so I knew it wasn't that, so I checked the video chain in the scaler and some lerps wouldn't do 1.00 and only 0xff (0.996). That's been fixed.

 

The MSU-1 audio is coming out of a DAC on the cart, and the DAC is totally missing its filter, at least on the rev h sd2snes. I opened mine up and looked, and the DAC output normally has an RC lowpass filter, but it is missing. The audio is being buffered by a fairly fast op-amp and nothing else. To do a proper job of it, that op-amp could've been turned into a two pole active lowpass filter to clean the audio up and remove most of the ultrasonic components.

 

I could hear some aliasing from my ADC due to this. The proper fix would be to add the lowpass to the sd2snes itself (indeed earlier versions have this filter but no buffering, and the filter was replaced by an op-amp in buffer mode). There's going to be some lowpassing going on inside the SNES audio path itself, but you're not going to be digitizing the SNES audio very often, but instead just running it through a TV/monitor/stereo system which will pass any ultrasonic not stripped out by the SNES audio circuit and you won't be able to hear it.

  • Like 1
Link to comment
Share on other sites

Funny how some people claim because Kevtris' work is closed source that means he isn't helping the community or preserving video games.

 

Just so no one misses the importance of what happened here if a product gets released that damages oem stuff plugged into it then that is probably going to get a really negative response and also kill a lot of accessories no longer in production. Just giving out a few footnotes to prevent that is like if Voultar had been able to help the SSD3 team correct their board before the release. Can you imagine how different the response would be to the SSD3 right now if that happened?

 

Or the Gamecube HDMI adapter, which we know cost at least one known youtuber their gamecube.

www.youtube.com/watch?v=wvd-73clV6E

 

 

Anyway, when it comes to preservation of video games there's always two goals:

1) Preserving the original hardware, so the original software can be played as it was designed.

2) Preserving the software source code, so it can be re-engineered for newer hardware while preserving the original experience.

 

 

What hasn't happened, at least for most pre-N64 era games, is that game companies didn't save a lot of their development stuff, especially during the NES/SNES era. Case in point: https://wiki.superfamicom.org/space-funky-b.o.b. found on eBay, but provides some interesting insight on how SNES at least one SNES game was put together.

 

Now, I do think it's unreasonable to ask game companies to release the source code to all of their games, especially if they have an interest in re-publishing the games themselves, but I think it's not reasonable to just sit on IP perpetually and do nothing with it. If they have the source code, and the game isn't worth the effort of fixing and putting on steam, then by all means publish the source code you have, and let someone else take a crack at it with a license that says you won't sue them for releasing a new game engine. That would even allow the original publisher/developer to get some money out of it by selling "the original" asset/engine package for use with the third party engine (a la scumm) or just putting it out there for free if they have no interest in maintaining a store to buy it from.

 

The interesting thing that has happened in the last 3 years or so is that the Japanese market has realized they can sell all their PC games to the English market, even with mediocre localization efforts by a third party on steam (and no I'm not talking about SquareEnix this time.) So if we had a FPGA+SoC platform that GoG, Steam or some other online store could integrate with (eg enter your steam/gog id on the FPGA+SoC box, and it will give you a list of games you own that can be played on it, and what core is used for it.) More tech savvy people will just pop the SD card out and put whatever they want on it, and that doesn't need to change. So a FPGA machine that can do all the 8 and 16-bit (eg PC9801, MSX, etc) hardware, instantly opens additional markets for it. That could be our "cartridge-less" universal model.

 

And as I said before, yes software emulation is usually "good enough", but usability is lacking. I think we're almost there with the Super NT/SD2SNES, but it could really use a "more info" panel that shows the original box art and manual (something that the WiiU Virtual console does) and be able to pause the game and look at the manual.

 

But, cart before the horse. Maybe we don't need just one piece of hardware that does everything, because that has never been true (look at how many times this hasn't been true, from smartphones to kitchen appliances, usually one piece of kit replaces several others, but doesn't do anything of them well.)

Link to comment
Share on other sites

The next step in convenience would be a console that syncs to a folder on your PC through WiFi. Drag and drop the roms in there. Firmware updates could be automatic. No SD card needed.

How about built in scraping of box art from the games database. This would actually look cool using the SNES's limited resolution and color palette. I guess someone would have to figure out a way for the SNES to decode JPEGS on the fly, or else create a new database of binary image data that could be interpreted by the SNES.

Maybe built in Bluetooth for 5 controllers. No retro receivers needed.

Call me in 10 years when I can get something like that that's not running retro pie. :D

Link to comment
Share on other sites

I think people are also missing the point on the preservation angle. It's all well and good to have a system completely documented, emulated/simulated with near 100% accuracy and to have every ROM dumped. But as we've seen with the huge popularity of the SNES Classic, some care needs to be taken into creating a method to get people to easily PLAY THE GAMES. We all walk around with computers capable of decent SNES emulation every single day, but people are ready and willing to pay money for a seamless package that allows them to play their SNES games with controllers on an HDTV. I've played more SNES since I've gotten my Super NT than in the whole last 2-3 years. The Super NT is preserving people's WILLINGNESS and ABILITY to easily play SNES games.

well said. earlier this week i got off my arse and fixed the sram batts in yoshi island and smrpg. and starting fresh playing through these games again on my super nt. i debated the snes mini or real hw and chose the later. though the mini consoles with their curated game collections are nice, they are more or less shelf fodder at this point. i was at work last friday and all i could think about was coming home and playing yoshi and smrpg, 25+ years old games with freshly installed cr2032s.

 

my retrofreak and retrobit generations are going up in marketplace soon. im done with software emulation, save for my portapi mame cab, if i ever pull myself away from the super nt long enough to reinstall it. :D

Link to comment
Share on other sites

I had heard about the ZX-UNO but not the other two.

 

I hope I am not stepping on some toes but I would like to give them some protips on the Collectorvision board.

 

It should have ESD protection on the two controller ports, keyboard port, and RGB/audio outputs. The original Coleco had a big problem with the controller ports failing due to ESD. Also, the audio looks like it is just some RC filtered PWM from the FPGA. A real audio DAC isn't very expensive and would sound a whole lot better. Ditto for the video DAC. I see what looks like 3 bits of weighted resistors but not a DAC. I don't see any pullup resistors on the inputs either, unless they (and possible ESD protection) is on the bottom. Also, DDR/SDRAM would be a lot cheaper and 32 times bigger (i.e. 16mbyte vs. 512K) for the RAM.

Thanks Kevtris.

 

I always welcome others opinions especially when they are as knowledgeable as you.

 

The image from the linked post is actually a little out of date.

The controllers, keyboard, and a few other ports that have been added are running through a gtl2000dgg,118 level converter which is rated for ESD suppression and "hot insertion". So I think it should be fine on ESD protection,

The VGA port was modeled after the F18a's video output, but I have actually decided to remove the analog video and audio and just do HDMI only to keep costs down.

 

I had gone back and forth about SRAM vs SDRAM or doing both, but decided to go with the SRAM since it was already implemented and working.

Link to comment
Share on other sites

Hey guys, longtime lurker and first time poster!

First off, just wanna say thanks to Kevtris for all the hard work on his systems. I have the NT mini and I absolutely love it. I've ordered my SuperNT in the second batch and hope to have shipping confirmation tomorrow like Analogue said. After following this thread I'm a little anxious and want to know if someone can kind of help me with video settings? Maybe some type of newbie guide? Everything that has been discussed here with scaling, scanlines, & gamma is way over my head. Is there someplace to start? Or should I just play around and see what looks good to me? Thanks for any help.

Link to comment
Share on other sites

Personally, I am starting to know this feeling well. I've been working on Stella for almost 18 years at this point, and at times it's starting to get to be a chore. Open-sourcing anything does definitely have its pro's, but there are some con's too. In particular, it wears you out after a while, not seeing much money (or sometimes interest), but still a constant demand for support.

Maybe it's time to take a break for a year. Or step back and pass the torch..?

Link to comment
Share on other sites

Thanks Kevtris.

 

I always welcome others opinions especially when they are as knowledgeable as you.

 

The image from the linked post is actually a little out of date.

The controllers, keyboard, and a few other ports that have been added are running through a gtl2000dgg,118 level converter which is rated for ESD suppression and "hot insertion". So I think it should be fine on ESD protection,

The VGA port was modeled after the F18a's video output, but I have actually decided to remove the analog video and audio and just do HDMI only to keep costs down.

 

I had gone back and forth about SRAM vs SDRAM or doing both, but decided to go with the SRAM since it was already implemented and working.

I don't trust/believe them on their ESD capability having been burned by that before. I would still put TVS diodes on those signals. The cartridge port is fine but the controllers/keyboard/video/audio should really have it.

 

Going hdmi only is a decent method and does save all the stuff for analog use. You could make an hdma to analog adapter if people really had to have the analog out.

 

SDRAM is harder to implement but it is a lot cheaper. If volume isn't too high there might not be a real need to change it from sram though.

Link to comment
Share on other sites

Even if I do not open source my core work, I *have* released multiple documents on how various videogame systems work that I have personally reverse engineered. These documents are valuable in their own right if you wish to know something about how those previously undocumented or underdocumented systems work. Pretty sure there will never be a homebrew scene for such fringe systems, but not at least it'd be theoretically possible. I am planning on releasing my SNES technical notes when I get a chance to clean it up, too. I found several previously unknown and underdocumented things during my research for the project.

I completely agree with all that you said. I also think contributing documentation on original hardware is perhaps even more important than open sourcing FPGA cores.

 

Regarding open hardware though, I believe it's an area that has a future by the existing work done and the possibility of crowdfunding (for production of proven designs). The MiST platform was pretty successful from an end-user standpoint (judging by number of cores ported to it and existence of clones) so I don't see it going away. It benefited in part from previous open projects such as Minimig or OneChipMSX, so I expect it will evolve. MiSTer is not exactly a replacement since the hardware can't be soldered without special hardware if you try to avoid the subsidized FPGA boards.

 

Regarding MiSTer, there is already work being done to support other boards (like the DE0) which means it isn't locked to a single item. And I also suspect the market for these boards is far larger than retro computing enthusiasts... I wonder if sales for MiSTer even register on their radar. So I think it's an interesting approach, nobody will make money out of it, and the devs know it. :)

 

I completely understand though that developers can't expect to make any money, and that's also why it's harder to find skilled people willing to 100% complete a core. Some are getting there, at least.

 

We already are in a pretty good spot with "no fuss cartridge" experiences (i.e. console replacement) being covered by your work and Analogue, and retro computing covered by open solutions. More fitting since a lot relies on user data (user disks, hard drive, OS configuration, etc.)

Edited by Newsdee
Link to comment
Share on other sites

 

Right, but that's also a clue: they replaced the SNES30 with the new SN30, but they didn't replace the NES30 with anything. The N30 Pro replaces the NES30 Pro, rather than the quite different NES30. I suspect that there just wasn't much customer interest in something that was the shape of an NES controller but had ABXY and shoulder buttons. You don't get the nostalgia of an NES controller because it was too different, but you get all of the sharp-angled discomfort.

That's why it doesn't make sense they pulled it for too closely resembling an NES controller. It had extra buttons and the ABXY buttons weren't even oriented the same as the original controller and they had letters molded into them. I feel like there are plenty of 3rd party nes controller that look more like originals than the 8bitdo version. They may not have sold very well and that might be why they removed them but they seem different enough from the original. The original SNES 30 looked very much like the original though so I can see why they changed it.

 

Edit - I mean I agree with you why they probably did. I don't think it was because it too closely resembled an NES controller.

Edited by Toth
Link to comment
Share on other sites

1. I played through Chrono Trigger to the point where Chrono, Lucca and Marle are sent to 2300AD, which is past the "Chrono is thrown in jail" point. I encountered no crashes or freezes. I did save and load a couple of times and tried rapidly switching to the menu and back more than once and I couldn't get the game to misbehave.

 

So after some back and forth with GH, and investigating; it seems the bug I am seeing on Chrono Trigger with the SD2SNES and Super NT is related somehow to the save game file that was on there since the last time i played through. When erasing that and creating a new one, loading even after power cycling, I can not get the game to crash.

 

I've tested the problematic save file on both my snes mini (that the file was created on) and an earlier model SNES and I can not get the game to crash using this save file on either machine.

Edited by ErebusMaligan
Link to comment
Share on other sites

That's why it doesn't make sense they pulled it for too closely resembling an NES controller. It had extra buttons and the ABXY buttons weren't even oriented the same as the original controller and they had letters molded into them. I feel like there are plenty of 3rd party nes controller that look more like originals than the 8bitdo version. They may not have sold very well and that might be why they removed them but they seem different enough from the original. The original SNES 30 looked very much like the original though so I can see why they changed it.

 

Edit - I mean I agree with you why they probably did. I don't think it was because it too closely resembled an NES controller.

 

Nintendo's trademark is on the button layout primarily, and pattern.

nes-classic-logo-800x300.jpg

 

To be fair, the rectangular corners are hard on the hands. With the SNES I find instead the bottom of the controller pushes into the middle or ring finger depending how tight you grip it, hence why the PSX and later all have grips that double as spaces for the vibration motors. However the XBOX360 controller misses the mark a little as well (battery operated is too heavy, D-pad is useless (has "hat" style movement which is fine for menus, but awful for 2D game's))

 

The SNES is a bit more obvious

fzb48z.jpg

 

angled start and select buttons, background around the ABXY buttons.

Edited by Kismet
  • Like 1
Link to comment
Share on other sites

That's why it doesn't make sense they pulled it for too closely resembling an NES controller. It had extra buttons and the ABXY buttons weren't even oriented the same as the original controller and they had letters molded into them. I feel like there are plenty of 3rd party nes controller that look more like originals than the 8bitdo version. They may not have sold very well and that might be why they removed them but they seem different enough from the original. The original SNES 30 looked very much like the original though so I can see why they changed it.

 

Edit - I mean I agree with you why they probably did. I don't think it was because it too closely resembled an NES controller.

Yes, but the graphics and size/shape did not leave any room for interpretation or doubt that they were selling a product based on Nintendo’s iconic design. Same patterns and colors. Also, the product name itself had “NES” in it (since retconned to “N30”).

 

They made a clean break between the old replica product line and the new and there was a distinct shift away from how similar their products looked. I mean: Why else did they ditch slanted Start/Select on the new SNES controllers?

 

Remember when 3rd-party Wii Remotes suddenly got really weird toward the end of 2007 and early 2008? Nyko went from a round A button to a square A button! That was because of Nintendo threatening them for looking too similar. They made a deliberate effort to look different. It was pretty well documented and reported.

 

There’s really no mystery here. 8bitdo’s color and design schemes were too close for comfort. Even if they can be distinguished with all the extra buttons, letting them use the color and design scheme could cause issues when Nintendo needs to go after a straight-up infringing counterfeit/replica that doesn’t have all those extra buttons. I’m not saying that there were threats, requests, or even friendly talks between Nintendo and 8bitdo. It could be that 8bitdo hired a lawyer who told them that they were too close for comfort and they changed on their own, but it was definitely changed for that reason. No question.

Edited by CZroe
  • Like 1
Link to comment
Share on other sites

 

Nintendo's trademark is on the button layout primarily, and pattern.

nes-classic-logo-800x300.jpg

 

To be fair, the rectangular corners are hard on the hands. With the SNES I find instead the bottom of the controller pushes into the middle or ring finger depending how tight you grip it, hence why the PSX and later all have grips that double as spaces for the vibration motors. However the XBOX360 controller misses the mark a little as well (battery operated is too heavy, D-pad is useless (has "hat" style movement which is fine for menus, but awful for 2D game's))

 

The SNES is a bit more obvious

fzb48z.jpg

 

angled start and select buttons, background around the ABXY buttons.

They got rid of the ring around the SNES D-pad too.

 

Anyway, those are Nintendo’s recent filings regarding the controller design and it’s intended as the logo for the Classic Edition consoles. There is more to it than those. Heck, Nintendo once had exclusive use of the D-pad designed but that expired sometime in the 2000s.

  • Like 1
Link to comment
Share on other sites

Found a minor Super NT bug that may already be fixed in the yet unreleased development version of the firmware. In Super Star Wars, during the Mode 7 land speeder sections (level 2 is the first example), the game will randomly pause and unpause very quickly. It doesn't happen all that often so it's not a big deal, but it does seem to happen one or two times every time I play through the level. My guess is that something about the way the game polls for controllers on this level is tripping up the Super NT. Maybe similar to Monopoly?

Link to comment
Share on other sites

There’s really no mystery here. 8bitdo’s color and design schemes were too close for comfort. Even if they can be distinguished with all the extra buttons, letting them use the color and design scheme could cause issues when Nintendo needs to go after a straight-up infringing counterfeit/replica that doesn’t have all those extra buttons. I’m not saying that there were threats, requests, or even friendly talks between Nintendo and 8bitdo. It could be that 8bitdo hired a lawyer who told them that they were too close for comfort and they changed on their own, but it was definitely changed for that reason. No question.

 

IMO, if I were 8bitdo:

 

1) Release a "dogbone" NES pad. Nintendo doesn't currently use that design, and it won't be confused for the top-loader NES. Yes, there is probably not that much market for 4 button (S/S/B/A) controller, but that's one less confusing thing to use with the NT Mini or RetroUSB AVS. This would be sufficient for such games, but...

 

2) Release a "dogbone" SNES pad keeping the button colors but taking a cue from the XBOX 360 controller and having the semi-transparent letters in the button. To further not stomp on the trademark remove the "background plate" around the ABXY button and stick it around the angled start and select. (You might say putting the button label in the button is a bit backwards, and I'll agree, but you need to have the button spacing/layout the way it is or it just doesn't work.) Also note that the US controllers have concave X and Y buttons, which I think is a tactile improvement, and wish other controllers did that. The SFC controllers do not have this, and the fact that the XY and AB are the same colors required US games to always refer to the letter while JP/EURO games could refer to the color.

 

What 8bitdo missed out here was selling removable plates for the front of the controller. Remember removable faceplates from early nokia phones? Plus faceplates would allow people to get blank plates and just print stickers to go on them if they wanted to customize it.

 

Like my opinion really is that 8bitdo got a cease&desist for all products with NES, SNES in them and anything with the US trademarks, hence why the SN30 and SF30 are still available, these look like SNES pads but are XInput style controllers with the dual analog and dual shoulder buttons, plus additional wii/home button.

 

edit:

The other thing that I'd like to see, and perhaps someone who has one of the color-matched Super Nt controllers could confirm, is to use the same or similar-enough textured plastic that Nintendo used and not that shiny-cheapy plastic that virtually all crappy aftermarked joysticks are made from.

Edited by Kismet
  • Like 1
Link to comment
Share on other sites

 

IMO, if I were 8bitdo:

 

1) Release a "dogbone" NES pad. Nintendo doesn't currently use that design, and it won't be confused for the top-loader NES. Yes, there is probably not that much market for 4 button (S/S/B/A) controller, but that's one less confusing thing to use with the NT Mini or RetroUSB AVS. This would be sufficient for such games, but...

 

2) Release a "dogbone" SNES pad keeping the button colors but taking a cue from the XBOX 360 controller and having the semi-transparent letters in the button. To further not stomp on the trademark remove the "background plate" around the ABXY button and stick it around the angled start and select. (You might say putting the button label in the button is a bit backwards, and I'll agree, but you need to have the button spacing/layout the way it is or it just doesn't work. Also note that the US controllers have concave X and Y buttons, which I think is a tactile improvement, and wish other controllers did that. The SFC controllers do not have this, and the fact that the XY and AB are the same colors required US games to always refer to the letter while JP/EURO games could refer to the color.

 

What 8bitdo missed out here was selling removable plates for the front of the controller. Remember removable faceplates from early nokia phones? Plus faceplates would allow people to get blank plates and just print stickers to go on them if they wanted to customize it.

 

Like my opinion really is that 8bitdo got a cease&desist for all products with NES, SNES in them and anything with the US trademarks, hence why the SN30 and SF30 are still available, these look like SNES pads but are XInput style controllers with the dual analog and dual shoulder buttons, plus additional wii/home button.

 

If they rerelease the Mini in some capacity, a pack in (or exclusive run) dogbone, with just the A and B buttons, would be awesome. I love me some dogbone and really don't want to play NES any other way.

Link to comment
Share on other sites

I fixed the -1 thing (pretty sure... lol) it was because I was multiplying by 0xff instead of 0x100 in the scaler at some point. This turns 0xff into 0xfe, and 0x8 into 0x7. i.e. 100h = 1.00, 80h = 0.5, etc. yeay for fixed point math. The SNES itself was outputting what you'd expect, so I knew it wasn't that, so I checked the video chain in the scaler and some lerps wouldn't do 1.00 and only 0xff (0.996). That's been fixed.

 

The MSU-1 audio is coming out of a DAC on the cart, and the DAC is totally missing its filter, at least on the rev h sd2snes. I opened mine up and looked, and the DAC output normally has an RC lowpass filter, but it is missing. The audio is being buffered by a fairly fast op-amp and nothing else. To do a proper job of it, that op-amp could've been turned into a two pole active lowpass filter to clean the audio up and remove most of the ultrasonic components.

 

I could hear some aliasing from my ADC due to this. The proper fix would be to add the lowpass to the sd2snes itself (indeed earlier versions have this filter but no buffering, and the filter was replaced by an op-amp in buffer mode). There's going to be some lowpassing going on inside the SNES audio path itself, but you're not going to be digitizing the SNES audio very often, but instead just running it through a TV/monitor/stereo system which will pass any ultrasonic not stripped out by the SNES audio circuit and you won't be able to hear it.

 

 

Borti and I are in agreement that the amp effectively replaces the filtering circuit such that it it not needed, especially since the signal is being sent to internal SNES mixing/filtering anyway. However, testing has revealed that the sound output is nearly perfectly intact in a SNES junior when compared to digital playback in Higan. See the two graphs below showing the sound signature of the same track in both:

 

NxIYJZK.pngUnlZjdZ.png

 

Now compare the same playback in the Super Nt:

 

JLhIG6Q.png

 

Note the filtering in the upper rage seems much more aggressive. These pic are courtesy of Qwertymodo, but I'm going to be comparing direct capture results on my own SNES systems. I'm using a revision "F" SD2SNES that I upgraded with the sound amp myself as seen below:

 

UdqlY4I.jpg

 

I will be doing a volume diagnostic test using the following:

 

1. Revision "APU" Super NES

2. Revision "1CHIP-03" Super NES

3. Revision "Junior" Super NES

4. Super Nt. revision 4.3

 

I'll also be measuring relative volume levels between all 4 devices to determine what setting the "Cart Volume" should be ideally set at for the Super Nt. I'll let you know how it all turns out, but for now, I thought those sound spectrum images were interesting to compare against.

Edited by Karbuncle
Link to comment
Share on other sites

 

 

Borti and I are in agreement that the amp effectively replaces the filtering circuit such that it it not needed, especially since the signal is being sent to internal SNES mixing/filtering anyway. However, testing has revealed that the sound output is nearly perfectly intact in a SNES junior when compared to digital playback in Higan. See the two graphs below showing the sound signature of the same track in both:

 

NxIYJZK.pngUnlZjdZ.png

 

Now compare the same playback in the Super Nt:

 

JLhIG6Q.png

 

Note the filtering in the upper rage seems much more aggressive. These pic are courtesy of Qwertymodo, but I'm going to be comparing direct capture results on my own SNES systems. I'm using a revision "F" SD2SNES that I upgraded with the sound amp myself as seen below:

 

UdqlY4I.jpg

 

I will be doing a volume diagnostic test using the following:

 

1. Revision "APU" Super NES

2. Revision "1CHIP-03" Super NES

3. Revision "Junior" Super NES

4. Super Nt. revision 4.3

 

I'll also be measuring relative volume levels between all 4 devices to determine what setting the "Cart Volume" should be ideally set at for the Super Nt. I'll let you know how it all turns out, but for now, I thought those sound spectrum images were interesting to compare against.

I recognize that picture from Facebook. :) You might recognize mine:

76d9fce656114e192433a2c878cfc476.jpg

 

c2a6e77e8432f78d1de2875a0469c8ae.jpg

(click for full-res)

 

Glad to see yours is going to better use than mine! ;) Wish I could help but my hearing sucks.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...