7800 "Stereo" Mixing Circuit?

[darkknuckles]

So I'm looking to get my 7800 upgraded to S-Video in the future and I've been looking online on the options for the audio. It looks like the 7800 is dual mono which is fine, but I found a schematic that suggests one could possibly have "Stereo"

 

http://farm3.staticf...2b6d04040_b.jpg

 

http://www.flickr.co...ius/4196279930/

 

It also shows the "Enhanced Audio" circuit from the cart connector being connected as well. My question is would this particular circuit produce two descrite sounds on seprate speakers creating a "Stereo" effect or is it the same sound coming through different pins on the TIA.

[Rybags]

There's several scenarios for audio coming from a 7800 (including the new XM module)

 

- bare bones TIA.

- Pokey via cart or XM module.

- Pokey as above + TIA.

- combination of Pokey, TIA and YM2151 audio from XM.

 

AFAIK no existing or planned software uses stereo. The problem is you have 3 somewhat different chips that can produce audio and the only realistic scenario where you'd use stereo would involve the YM chip on the XM module.

 

Of course there's the want for all audio going through 2 speakers on modern TVs or if piping thru a home theatre, but you can generally use a splitter or set the device to play the left channel on both speakers.

 

ed - looks like the YM2151 can do stereo, although I don't know if the XM module is configured to take advantage of this.

Edited July 9, 2012 by Rybags

[darkknuckles]

There's several scenarios for audio coming from a 7800 (including the new XM module)

 

- bare bones TIA.

- Pokey via cart or XM module.

- Pokey as above + TIA.

- combination of Pokey, TIA and YM2151 audio from XM.

 

AFAIK no existing or planned software uses stereo. The problem is you have 3 somewhat different chips that can produce audio and the only realistic scenario where you'd use stereo would involve the YM chip on the XM module.

 

Of course there's the want for all audio going through 2 speakers on modern TVs or if piping thru a home theatre, but you can generally use a splitter or set the device to play the left channel on both speakers.

 

ed - looks like the YM2151 can do stereo, although I don't know if the XM module is configured to take advantage of this.

 

That's intresting to say the least, being there's so many options for sound for the 7800. Ask for XM project, I'd like to think some programmers may implement Stereo for a whole new dimension of classic Atari sounds.

 

That being said looking at the original schematic for the 7800 the two audio lines from PINs 12 and 13 from the TIA do join quickly and then with PIN 18 from the cart port which would be POKEY I believe joins alittle down the line.

 

I'm just curious if they are the same audio signal before they get joined or are they "noise 0" and "noise 1" or "noise" and "music" channels. Because if they are, which they should be, then one could seperate them by connecing straight to the pins and have different sounds on two speakers. Of course games without music would benefit the most since you would have different sounds coming from different speakers. Kind of like the 2600 was supposed to do by having two speakers in the case.

 

Now with the upcoming XM, one could use the two channels of audio from the TIA and have them as seperate left and right noises while the YM2151 can be music mixed in Mono or Stereo. And why not add a center channel using the POKEY, so 5 channels of audio to work with could easily be turned into a stereo mix. Just brainstorming there alittle bit, just to hear that Missile Command sound go from speaker to speaker in a Stereo mix would be kind of cool.

Edited July 10, 2012 by darkknuckles