Stereo on an NES?

[Polygon]

I spotted this on Youtube the other day and I found it pretty interesting. He does some serious mods on an NES. It's not something I'd ever consider doing, but I was curious about at least one thing. In the video, one of the mods he does is wire the NES for stereo sound. Someone correct me if I'm wrong, but all NES output a mono signal. So wouldn't that make this mod pointless on an NES?

Also, he's concerned about fatigue on the 72 pin connector. Since he disabled the lock out chip, you don't even need to push the cart down anymore negating the wear on the connector. Regardless, it was pretty cool to watch and the end result is pretty cool too. This is just the first part in a three part video.


http://youtu.be/jdzZIeemumo

[Drixxel]

Skip forward to 9:52 (http://youtu.be/jdzZIeemumo?t=9m53s) and Ben Heck offers a partial explanation in this very video. Apparently NES audio is mixed down into a single channel en route to the audio out on the side of the console but exists with stereo separation if you pull it directly from the sound chip. What I wonder is how pronounced the stereo separation is, and how much control sound programmers have over channel panning.

EDIT: Ah, okay, I actually listened to the video this time, there's no such programming of channel panning. 3 sound channels come off one pin, the other 2 come off another so basically you could divide the channels between left and right in a 3/2 split. Ben points out how some folks recommend blending the mixed down mono audio into the signal, presumably to fill the center channel with something as you'd be getting weird hard panning otherwise.

[Polygon]

That's very interesting as I thought the source was mono from the cartridge. I'm interested to try this one, but I wonder if it's worth the time. If you would really hear any decent separation. I have enough NES lying around I could try it on one.

[Drixxel]

Well, hmm, just to be clear, the sound data is stored on the cartridge, but it's the sound chip in the NES that generates the audio from that. You'd be creating an unintended stereo effect by performing this mod, since you're basically rewiring how the audio signal, intended to be heard in mono, is pulled from the console. The stereo separation is going to be hard L/R panning with 3 channels going to one speaker and 2 channels to the other, so... imagine the bass coming completely from the left, percussion coming completely from the right, etc. It's not going to be a thoughtfully arranged stereo field with leads phasing around, sounds would be lumped into left or right and that's where they'd stay.

[wingzrow]

All that work and he plays it on a 16:9 LCD instead of a CRT in 4:3.

That aside, that's some pretty amazing stuff.

I wonder what he would charge for one of those?

[bb_hood]

but I wonder if it's worth the time. If you would really hear any decent separation.


Thats what I thought. Would it be any better than splitting the mono signal and sending it to 2 sets of speakers through a mixer?
Neat project though

[Drixxel]

Thats what I thought. Would it be any better than splitting the mono signal and sending it to 2 sets of speakers through a mixer?
Neat project though

It wouldn't really be better or worse, just... different. This mod would at best be giving you a simulated stereo where the 5 channels that would otherwise be mixed together to create the mono sound have been arbitrarily assigned to either left or right. After a bit of reading, I see that pulse 1 & 2 (lead voices) come out of one pin and triangle/noise/PCM (bass & SFX) feed from the other pin, so just try to imagine how that split is going to sound unless some effort is made to soften the hard panning.

Now, if there was a way to isolate each individual channel rather than the 3-and-2 divide you get by tapping into those two pins off the sound chip, a clever modder could go on to do something way cooler.

[Satoshi_Matrix]

The NES cannot do true stereo, but only pusdo stereo. The NES/Famicom has five sound channels:

two square waves [sometimes called Pulse waves] which act as the leading interments
one triangle which acts as a supportive instrument
one noise which acts as bass
one sample (PCM) which plays short voice, instrument or sound effects

A very good video for learning more about the sound channels of the NES can be found here:
http://www.youtube.com/watch?v=la3coK5pq5w


Ben is correct in saying that the sound channels come from two sources on the 2A03, but they are NOT stereo. The System was never intended to be stereo and thus no games were programmed for it. Most modern Famiclones include two audio RCA jacks, but they only serve as dual mono across both stereo channels.

It is possible to modify an NES or Famicom for pseudo stereo by assigning three of the five audio channels to one stereo channel and the remaining two to another, but this rarely beneficial to the audio experience as again, NES games were not intended to ever be stereo. Some of the games where separating the sound channels across stereo channels does help include Castlevania 3, The Legend of Zelda, Super Mario Bros. 3, and most Sunsoft games, but by and large the vast majority of games plays on a pseudo stereo NES sound no better than a stock console.

[Greg2600]

I thought the wooden box he put it in was really cheesy.

[Polygon]

Thanks guys! After reading these posts I'm not going to bother doing this. I'll just stick with my Y-splitter.

[Tanooki]

The NES is a weird one alright with audio considering it's capable internally but outputs in mono. I have a top loader I picked up that was very custom modded over a year and a half ago. It has the RCA jacks and the LED mod you see, but it also has a stereo mod with a wheel knob in back. Basically what it does is split the audio channels as stated in this thread already with 3 going one way and 2 the other, but not 100% as you still hear a bit of the other from the other side and that's from playing with the wheel. You can just make it dual mono all the way one way, and a total split all the other way on the wheel with 3 one way and 2 the other, but if you find that sweet spot spinning it, the sound splits over the two creating what I feel is a pretty nice effect.