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SNES S/PDIF...

Started by zedrein, April 03, 2010, 07:29:55 AM

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zedrein

April 03, 2010, 07:29:55 AM Last Edit: April 03, 2010, 07:33:27 AM by zedrein
I've got a few technical questions about the materials necessary to do this mod properly (found in the wiki)...if that's all right with y'all.

1.) WIRE: What wire gauge/type is going to be most suitable for point to point wiring in this instance? I'd imagine solid conductor and small gauge wire is going to be easier to work with versus the stranded or larger gauge stuff, but will it still maintain that digital signal properly? I don't want to go with the ease-of-use route if it's going to somehow adversely affect the audio transmission/reliability or fidelity.

2.) CONNECTORS: I am leaning towards using a RCA type connector (as opposed to the TOSlink fiber optics connector) because the SNES chassis already has the proper "port" for that connector already in place where the RF out is. I know there is debate out there among audiophiles about which standard will sound better (which is strange because they both transmit digital and not analog information) but I'd like to know if there are some amongst you that think going one way or the other will be better sonically. Also, depending on which standard I go with what is going to be the best brand to purchase for securely mounting the connector to the SNES case? At the local electronics store they have a few nice gold plated connectors, but they look like they'd be difficult to mount flush onto the inside of my console, and my neurosis won't allow me to have electrical components just floating around inside there.

3.) RESOURCES: I am getting pretty used to people telling me "Bro, ____ only costs a few bucks, trust me!" but when I actually get a hold of this stuff it usually ends up costing significantly more. So, if you massively intelligent folks would direct me to your favorite online electronics retailer that has reliable components at reasonable prices, I'd surely appreciate it. At the end of the day I'm still a dude with barely a working knowledge of basic electronics, but I still desire to make these old "retro" consoles that I still love so much better than I remember them, and I need all the practical help that I can get.

As usual, thanks for your time! I hope to get this thing off the ground soon as I will then have a Super NES plugged into a suitable RGB display AND crystal clear audio!

Hojo_Norem

Quote from: zedrein on April 03, 2010, 07:29:55 AM
I've got a few technical questions about the materials necessary to do this mod properly (found in the wiki)...if that's all right with y'all.

1.) WIRE: What wire gauge/type is going to be most suitable for point to point wiring in this instance? I'd imagine solid conductor and small gauge wire is going to be easier to work with versus the stranded or larger gauge stuff, but will it still maintain that digital signal properly? I don't want to go with the ease-of-use route if it's going to somehow adversely affect the audio transmission/reliability or fidelity.

If you imagine the amount of conductor used in the circuit traces on the PCB I dare say you should be ok using that.

Quote
2.) CONNECTORS: I am leaning towards using a RCA type connector (as opposed to the TOSlink fiber optics connector) because the SNES chassis already has the proper "port" for that connector already in place where the RF out is. I know there is debate out there among audiophiles about which standard will sound better (which is strange because they both transmit digital and not analog information) but I'd like to know if there are some amongst you that think going one way or the other will be better sonically. Also, depending on which standard I go with what is going to be the best brand to purchase for securely mounting the connector to the SNES case? At the local electronics store they have a few nice gold plated connectors, but they look like they'd be difficult to mount flush onto the inside of my console, and my neurosis won't allow me to have electrical components just floating around inside there.
Digital is digital is digital.....  The medium might be different but the information is exactly the same.  An optical link is practically immune from EM interference but the cable itself can have problems with tight corners but coaxial is cheaper to setup and if you need to switch between multiple digital sources then any regular half decent AV switcher will do the trick.
Quote
3.) RESOURCES: I am getting pretty used to people telling me "Bro, ____ only costs a few bucks, trust me!" but when I actually get a hold of this stuff it usually ends up costing significantly more. So, if you massively intelligent folks would direct me to your favorite online electronics retailer that has reliable components at reasonable prices, I'd surely appreciate it. At the end of the day I'm still a dude with barely a working knowledge of basic electronics, but I still desire to make these old "retro" consoles that I still love so much better than I remember them, and I need all the practical help that I can get.
Thats a hard one to answer.  True that the parts on their own don't cost that much, its the shipping that can put the price up especially if you are ordering just one one part.  I always try to make the order worth the while by ordering other things I may need at the same time (spare soldering iron tips, various connectors, etc) and it's allays a good idea to buy more than you need of any parts you need (not counting the real expensive parts of course).  I can't really recommend a supplier without knowing where you hail from.  Over here in the UK I tend to use a combination of Rapid Electronics for small orders, Farnell for bigger ones (they have a £20 minimum for credit card orders, but thats also their threshhold for Farnell's free shipping) and at a pinch I might try CPC (same company as Farnell but they carry a slightly different inventory) and lastly Maplin if I'm wandering around inside their store.
Formerly 'butter_pat_head'

zedrein

Thanks for the reply. I asked about wire specifically because I've read that a conductor that doesn't maintain a proper 75 ohm impedance can make for a unreliable signal. But if there is someone here that has had luck with this mod regardless of wire then I suppose there's no real reason to worry. I just want to get this thing done properly.

zedrein

May 12, 2010, 01:17:53 PM #3 Last Edit: May 12, 2010, 01:20:44 PM by zedrein
Ugh, got the mod done and found out my damn receiver won't accept the extremely weird 32 kHz sampling rate. I know that I'm potentially asking too much on this one, but...can someone drop me some actual digital recordings from a SPDIF modded SNES? I figure there are loads of digital audio interfaces out there that have proper inputs for recording from a number of digital sources including the SPDIF format, and I'd sure love to hear how great the files would sound from a real life SNES...can you make a young boys' wish come true?

Hojo_Norem

Quote from: zedrein on May 12, 2010, 01:17:53 PM
Ugh, got the mod done and found out my damn receiver won't accept the extremely weird 32 kHz sampling rate. I know that I'm potentially asking too much on this one, but...can someone drop me some actual digital recordings from a SPDIF modded SNES? I figure there are loads of digital audio interfaces out there that have proper inputs for recording from a number of digital sources including the SPDIF format, and I'd sure love to hear how great the files would sound from a real life SNES...can you make a young boys' wish come true?

Shame about you receiver not liking the SNES's slightly-not-32Kz signal.  I do have a couple of short recordings I made for another thread on the board.  I made them by hooking the SNES's digital audio into my soundcard's CD digital audio input.
Formerly 'butter_pat_head'

zedrein

Thanks for that! I can honestly say that I did hear a difference, but it wasn't as massive as I might of thought, although I'm sure a true sound test would require a real SNES here at my home through a compatible receiver and good speakers switching between analog and digital... thanks again for digging that up!

zedrein

September 20, 2010, 06:30:44 AM #6 Last Edit: September 20, 2010, 06:35:33 AM by zedrein
DAMMIT! As I was executing this mod with dangerous precision on my first model SNES deck I must have somehow hit the SPC 700 and ruined the damn thing! Funny thing is that there are no "solder burns" to speak of on the chip...maybe the sheer heat of the iron rendered my chip useless? As there is really no way to use a socket on the chip are there any other options to keep me from burning the thing up? I know used SNES consoles are fairly cheap, but I can't really afford to keep going through them at such an alarming rate. Also, I cannot find any new Cirrus Logic CS8405 digital transmitter chips for under $13 US, will it matter which alternative I go with? I want to get a good quality transmitter that converts the SNES' (not quite) 32000 kHz signal perfectly as possible but that doesn't brake the bank.  

zedrein

November 09, 2010, 06:52:36 AM #7 Last Edit: November 14, 2010, 03:23:39 AM by zedrein
Sorry to be a pain in yall's bum, but I cannot find a DSP chip that will reformat all the raw digital audio of the SNES' sound chip into something a commercial receiver can decode and amplify (and, yes, my new AVR can receive non-standard sampling rates in case you were wondering). The original document that detailed this mod said to use Cirrus Logic's CS8405A-CS, but that chip is no longer manufactured and the new version, CS8415A, cannot purchased for under $13 US unless you are buying in quantities of more than 1,000!!! I clicked on the "request a sample" link on Cirrus Logic's own site and (when the page actually loads) it prompts me to enter a legitimate business e-mail account which I am not in possession of. DigiKey, Avnet, and Newark are all sites that supposedly carry this chip, but not without the strings attached that I already mentioned...please help me in finding a comparable alternative or a resource where I can find this IC inexpensively.

acem77

I found a way to get around the nonstandard 32khz you need to supply another clock.
my sony works ok with the nonstandard 32khz signal, my denon does not:(
the problem is  my denon replaced my sony when the sony lost some channels.
I since fixed the sony but i dont want to go back to it as my main unit...

after using another clock the snes worked on my denon but now there is a some jitter/static/crackle(not sure what the right term is) :(
it can only be heard in some tone ranges. 80% time it sound nice,
but i want it to be perfect.

Not sure if the clock is off a bit? I tried a trim cap but still no luck.
It could be noise in the circuit Lots of long wires/antennas :P








Hojo_Norem

March 23, 2011, 04:32:52 AM #9 Last Edit: March 23, 2011, 04:40:37 AM by butter_pat_head
Quote from: acem77 on March 22, 2011, 06:59:40 AM
I found a way to get around the nonstandard 32khz you need to supply another clock.
my sony works ok with the nonstandard 32khz signal, my denon does not:(
the problem is  my denon replaced my sony when the sony lost some channels.
I since fixed the sony but i dont want to go back to it as my main unit...

after using another clock the snes worked on my denon but now there is a some jitter/static/crackle(not sure what the right term is) :(
it can only be heard in some tone ranges. 80% time it sound nice,
but i want it to be perfect.

Not sure if the clock is off a bit? I tried a trim cap but still no luck.
It could be noise in the circuit Lots of long wires/antennas :P


The problem with the jitter is because of the external clock.  As the SNES's output is not quite 32KHz as we know, the act of supplying a standard 32KHz clock will result in the S/PDIF encoder skipping/duplicating audio bits of audio data.  The only way I can see to get it perfect it to somehow resample the audio to something higher like 44.1KHz in real time.

EDIT:

Just did a bit of googling and it looks like the Cirrus Logic CS8420 might do the trick.  It can act as the S/PDIF encoder so everything is done on the one chip.  I have no clue how good it will sound however...
Formerly 'butter_pat_head'

acem77

thanks for the info, this may come in handy :)
I finally got the snes working great on my denon, I had to change the clock generator block.
the only system with issues left is the jaguar, some tones are tinny sounding/echoing.

zedrein

Acem, was that digital audio all you ever hoped for? Please relay to us the glorious details!

acem77

Quote from: zedrein on April 11, 2011, 12:45:48 AM
Acem, was that digital audio all you ever hoped for? Please relay to us the glorious details!

Yes!
Id compare the jump in audio quality as RGB video is visually.
With some good speakers and a digital receiver the sound is way more filling and defined.
You start to hear things you never noticed before.
This is the same for any of the systems that can be digitally modded.
With the psx sounding the best for audio cds, even better than the ps3.

imparanoic

i have a nakamichi av10 av amplifier in the lounge, not sure if it can accept non standard 32khz digital feed, i have also psone and snes, can any one quote me a spdif conversion  cost in uk? 

elizle

Ok, so I am trying this out and I'm not having any luck. I am using this http://www.mouser.com/catalog/specsheets/totx177l(f,t).pdf and I can't get the emitter to light up on it. I just used my multimeter. VCC is 5V, ground is reading 0V and Signal is like 0.1V or something like that, I don't remember exactly. Do I need a capacitor between VCC and Ground like it shows in the datasheet? Does anyone have this done with optical? A picture is worth a thousand words. I got some sound to come out, but it was crackly using a 3.3V Toslink emitter and I had some resistors on VCC and I was assuming that that was the problem, but now I'm getting nothing.

jamisonai

I put the cap between the VCC and ground just to be safe, and because I saw a few people from another forum do so for the Saturn s/pdif mod, which uses the same chip.  Its just supposed to smooth out any voltage spikes going to the chip.  It shouldn't really affect performance.  Insofar as your emitter issue, just check the datasheet to ensure you're connecting it properly.  If all else fails, check it with an RCA plug to see if you get sound through Digital Coax.  I have never used toslink, but I have seen others use them with the Saturn s/pdif mod without issues.   

bernhs

June 21, 2012, 01:48:12 PM #16 Last Edit: June 21, 2012, 01:50:34 PM by bernhs
Quote from: zedrein on November 09, 2010, 06:52:36 AM
Sorry to be a pain in yall's bum, but I cannot find a DSP chip that will reformat all the raw digital audio of the SNES' sound chip into something a commercial receiver can decode and amplify (and, yes, my new AVR can receive non-standard sampling rates in case you were wondering). The original document that detailed this mod said to use Cirrus Logic's CS8405A-CS, but that chip is no longer manufactured and the new version, CS8415A, cannot purchased for under $13 US unless you are buying in quantities of more than 1,000!!! I clicked on the "request a sample" link on Cirrus Logic's own site and (when the page actually loads) it prompts me to enter a legitimate business e-mail account which I am not in possession of. DigiKey, Avnet, and Newark are all sites that supposedly carry this chip, but not without the strings attached that I already mentioned...please help me in finding a comparable alternative or a resource where I can find this IC inexpensively.

hello  im speak french

It seems to me that  you can use the CS8415A but the pin to used on the spc700 ,Will be different!

i have too the CS8415A into my dvdplayer Philips lx3950w.

If somebody succeeds with this chip, there will be certainly better  audio quality.

It's a pity there  is not of datasheet on the spc-700



duo_r

Hi modded mine last night. Everything works fine with the system however no digital audio. I am using CS8406 and everything appears to hooked up right. How can I tell if my receiver doesnt like the signal or not working?

I dont have an oscope.

RGB32E

Quote from: duo_r on May 09, 2013, 01:15:43 AM
Hi modded mine last night. Everything works fine with the system however no digital audio. I am using CS8406 and everything appears to hooked up right. How can I tell if my receiver doesnt like the signal or not working?

I dont have an oscope.

What are you connecting the SPDIF to?  Are you using coax or optical?  Is it a Denon recevier?  Cheapie external DACs usually make for a good test system, and are typically very flexible.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=180-997

I use one of these to test a digital audio mod.

duo_r

Thanks so much for the reply that is a fantastic idea. I tried both optical and coax with no success on Two Yamaha and one older Dennon. I have an Onkyo but no remote to switch to digital.

Think this would work?

http://www.monoprice.com/products/product.asp?c_id=104&cp_id=10423&cs_id=1042302&p_id=6884&format=2

I also saw even cheaper ones on eBay.

RGB32E

Anything that claims 32kHz would likely work.

duo_r

I got my Onkyo to work yesterday on selecting digital input but no sound. That's 3 different brand receivers tested. I will try this as a last resort if it doesn't work ill assume something is wrong with the setup.

RGB32E

I should mention that the CS8406 seem to be very ESD sensitive, as I've had one just not work, and another crap out after 15 min.  However, my first one I attempted is still working just fine.  I'd suggest building another one even though the price of the chip is $7.

duo_r

Where are you getting yours? I got one more chip I could swap in. What brand receivers are working for you?

RGB32E

I order CS8406 ICs from DigiKey.  I'm not using a receiver.  I use an external DAC - Cambridge Audio DacMagic 100.

duo_r

Ok got the DAC today. No sound I am going to swap the chip.

RGB32E


duo_r

June 04, 2013, 02:15:13 PM #27 Last Edit: June 04, 2013, 02:18:06 PM by duo_r
Might try the new chip tonight, thanks for the help man you are really helpful for fellow modders! You helped years ago create my first RGB AMP years ago. :-)

duo_r

Ok swapped in 2nd chip, I also cleaned up my board on how I had the ground / 5v connections.  Well nothing worked. I used the DAC and no sound. Normal sound works.

Checked everything ensured connections to the DSP were good and no shorts. I am at a loss is it possible the DSP is toast on the digital sound somehow?

I used coax and yes I had the proper resistors installed.

Of all the mods I have done this one has been a pain.... lol

RGB32E

Well that sucks!  Maybe you need someone else to do it for you.  What PCB revision of SNES were you using?

duo_r

Yeah it sucks be nice if someone could test the circuit. I will post the model later.

RGB32E

Did you give up?

I have a number of extra SNES systems.  I could just do the mod for you!

duo_r

About to I have 1 chip left.  :o