January 16, 2022, 03:06:01 am

NES stereo output mod

Started by keiffer01, August 22, 2007, 07:28:03 pm

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133MHz

Crappy Mspaint-drawing at your service! ;D

kite200

actually that's really good and easy to understand, can we get that stickied on the site in some misc section
ステキ

keiffer01

Yeah now it's easy to understand! ;D But I'm missing a few parts to start on the project...electronics store here I come! ;D

133MHz

EDIT: I made nice little text links to the files, but my crappy hosting doesn't allow MP3 hotlinking (though they allow it for images), so I had to remove them and break the links to avoid you from reaching their stupid 'Don't leech us' page >:(. So you have to copy the URL and paste it into your browser and remove the exclamation sign in http to hear them. Sorry.

Hi everybody!

I've been wondering how this mod would turn out. Electrically I think it will sound great, but really didn't want to punch more holes and solder more wires to my beloved NES without knowing how it would turn out. So I made some mock-ups with the computer (using Winamp w/NSF plugin and GoldWave) to approximate how this mod would sound like ;D.

I worked in WAV and converted the final products to MP3 (you know, the heaviest WAV is about 15 MB, overkill for the ones with teh slow internets) and found MP3 really destroys NES music >:(, but anyways here they are:

Headphones recommended!

Here's the worldwide known Super Mario Bros. Overworld Theme ;)
MP3 files, 96Kbps 44kHz CBR, 1 MB each:

* h!ttp://usuarios.lycos.es/dogbert/stereones/SMB Theme Joint Mono.mp3
SMB Theme in all its mono sound glory

The NES sound processor (built in on the CPU die) generates two square wave channels, a triangle wave channel, a white noise channel and a DPCM channel (for digital sound, not used in SMB). You can think of the square wave channels as two guitars, the triangle wave as an electric bass, the noise channel as a drum set and the DPCM as the vocals of the NES ;). The Famicom has an External Input on its cartridge connector so games with their own sound hardware (built onto the cartridge itself) could add extra sound channels by mixing them with the Famicom audio.

Both square waves come through Pin 1 of the CPU, triangle, noise and DPCM come out through Pin 2. They get mixed by some resistors and directed to the Audio out of your NES.

* h!ttp://usuarios.lycos.es/dogbert/stereones/SMB Theme squares.mp3
Here's how taking audio just from Pin 1 would sound like

Only the two square waves.

* h!ttp://usuarios.lycos.es/dogbert/stereones/SMB Theme triangle&noise.mp3
And here's Pin 2 output

Triangle and noise channels.

* h!ttp://usuarios.lycos.es/dogbert/stereones/SMB Theme Basic Stereo.mp3
'Basic' Stereo NES output mod

This is the common stereo mod, it just takes Pin 1 audio and routes it to the Left channel of your TV or stereo system, and Pin 2 audio to the Right channel. If you listen to it, it will sound stereo, but sounds a little 'dry' or 'weird' to me, like forced, and actually it makes me a little dizzy listening to it with headphones :D.

The Stereo NES output mod discussed here mixes back the mono sound onto the stereo channels by a variable amount (set by how much you turn the variable resistor's knob, so the square wave channels get a little from the triangle and noise, and viceversa), giving more 'life' to the sound, it sounds more like a real stereo song to me.

I simulated the stereo mod with the knob set at 20%, 40%, 60% and 80% of its travel:

* h!ttp://usuarios.lycos.es/dogbert/stereones/SMB Theme Stereo 20.mp3
NES Stereo mod, 20% mix
* h!ttp://usuarios.lycos.es/dogbert/stereones/SMB Theme Stereo 40.mp3
NES Stereo mod, 40% mix
* h!ttp://usuarios.lycos.es/dogbert/stereones/SMB Theme Stereo 60.mp3
NES Stereo mod, 60% mix
* h!ttp://usuarios.lycos.es/dogbert/stereones/SMB Theme Stereo 80.mp3
NES Stereo mod, 80% mix
(play with the balance on your volume control to note the subtle differences)

At 0% there will be no mix and it will sound like the basic mod (full stereo separation), and at 100% there will be full mixing, producing mono sound again (no stereo separation).

You can think of it like having a band, at 100% separation the two guitarists at the extreme left side; the drummer, bassist and vocals at the extreme right side. 
At 0% separation everyone in the center (mono)
and at some intermediate value just like a real band stage placement (a little mixed).

So the dual pot controls the stereo separation of the channels to suit your tastes and particular songs. These sound better uncompressed BTW.

And a bonus track ;D!
* h!ttp://usuarios.lycos.es/dogbert/stereones/chipndale_stereo.mp3
Some Chip 'n Dale song at 50% separation

Actually this is the first attempt I made, it's a little sloppy with the timing and such, but sounds pretty acceptable for me.

Any comments, suggestions, etc. I will be very glad to hear them :D.

UglyJoe

I'm pretty sure Notso Fatso will let you mix the NSFs directly in winamp.  That way you won't have to deal with Goldwave.

Also, the DPCM channel is used more for drum samples than vocals, I think.  Usually one of your square channels would be the "vocals" of the song.

133MHz

Yup, but when reading or hearing DPCM the things that come to my mind are those horrible digitized voices that some NES games have ;D