Atari 2600 stereo mod - actually making a significant difference to audio content or not?

[TheRealOC]

Hi all, 

 

I'm just writing up the wiki entry for the Atari 2600's audio capabilities https://consolemods.org/wiki/Comparison_of_game_consoles_by_sound_capabilities#Second_generation_of_consoles

 

And I wanted to expand a bit on my notes, which currently just note that a stereo mod exists, but doesn't go into any detail at all. 

 

Now my assumption would have been that if I'm playing an Atari 2600 game on a stereo-modded console, and the game was not programmed with stereo audio in mind, then the resulting audio experience is not going to be significantly different from the original mono audio output - because while the stereo mod will split the audio channels into Left and Right, the actual audio content within the game would remain unchanged. 

 

At best, I would have thought that the 2600 console would output duplicate or mirrored sounds through both the left and right channels, and maybe the mod might provide some sense of spatial separation (giving a slightly wider audio experience) but would not dramatically alter the audio output which would remain as it was originally designed, with mono effects and music - and lacking the immersive stereo effects found in newer games specifically programmed for stereo audio

 

*** 

 

All that being said, I then came across this post by @82-T/A ("Atari 2600 - Stereo Mod?"), and here's what I took away from it:

 

* The original design of the Atari 2600 included provisions for two built-in speakers, one for each sound channel. Early games like Combat were programmed to utilize this setup, with each player's sounds coming from the corresponding speaker. However, Atari eventually scrapped the built-in speaker idea, possibly for cost reasons, and opted for mixing the audio into the TV signal.

 

* The stereo mod for the Atari 2600 involves tapping into each sound channel on the motherboard and routing them to separate left and right audio channels. This allows for the potential of stereo sound effects in games that were designed with stereo in mind, but these are largely going to be homebrew game that were designed after official games stopped coming out.

 

* Some games, like Combat, were mentioned as having certain sounds always come from a specific side of the speakers, representing each player's actions. However, these games were not necessarily designed for audio directionality or true stereo effects.

 

* The stereo mod can provide a stereo audio output from the Atari 2600, but the actual impact on games that were not programmed for stereo audio will vary. Some games may exhibit stereo-like effects, while others may still sound similar to their original mono output.

To me, the overall consensus seems to be that while the Atari 2600 can be modified for stereo output, true stereo effects and directionality in games were limited to a few early titles. However, the modded stereo output can still enhance the audio experience slightly and provide a wider soundstage, even for games that were not originally designed for stereo audio. I don't have access to a stereo modded 2600 console; can anyone more knowledgeable confirm if that's a fair assessment, so I don't put misinformation on the wiki?

 

Thanks!

 

@Thomas Jentzsch @macdlsa @SpiceWare @Turbo-Torch @atari2atari

 

[Thomas Jentzsch]

Seems pretty correct to me. Also, quite some games try to utilize the two channels as good as possible by giving priorities to the sound effects. A higher prioritized effect will overwrite the current lowest prioritized effect. And this will cause the effects come from random sides on a stereo modded console.

 

Note: Even Combat wouldn't have worked with stereo as we understand it, because the tanks or planes switches sides. Therefore the sound of the tank on the right, may come from the left speaker and vice versa. However the lately discovered prototype Sonar made heavy and correct use of stereo. The game doesn't ever work without stereo.

[TheRealOC]

Thanks @Thomas Jentzsch

 

Very difficult to summarize all that information in a short wiki note - but here's what I came up with

 

"Stereo" mods exist which split the TIA's two audio channels into left and right audio; however although this provides an enhanced audio experience for Atari 2600 users, true stereo effects are limited. Early games like ‘Combat’ were designed with the assumption that the 2600 would have two separate built-in speakers for each player’s sounds. However Atari removed this feature, and most of the library outputs music/effects in mono.   The stereo mod for the 2600 allows for potential stereo sound effects in newer homebrew games designed with stereo in mind. However, games without stereo programming may exhibit stereo-like effects or remain similar to their original mono output. Some games prioritize sound effects, causing them to come from random sides on a stereo-modded console. A prototype game called Sonar did demonstrate proper stereo utilization however.

 

Here's a screenshot:

[+SpiceWare]

That doesn't look good at all if you're not on a 16x9 display, such as an iPad:

 

 

or if you don't use the full width of a wide-screen monitor for your browser. My browser is usually about 4:3:

 

 

as I tend to have other windows open along side my browser.  As such I suggest you review your layout on 4:3 displays, and split out any longer notes to a new page that's linked to via a brief comment. That would also let you add additional images, such as the following photos I took and posted in this reply of another topic covering 2600 stereo. Feel free to use them.

 

 

6-switch cover reveals location speakers were going to be at

 

Lower section of the heavy sixer has supports for the speakers. These do not exist in the later light sixer models.

 

Photos were taken a long time ago, so are a tad blurry due to slight camera movement when I took them. I could take better photos if you'd like, though I need to remember where my heavy sixer ended up

[+SpiceWare]

Atari homebrews I'm aware of that feature stereo sound are:

• A-VCS-tec Challenge
  The spear level of A-VCS-tec Challenge is programmed in stereo, so you can hear if the spear is coming from the left or right side. When reaching the middle of the screen, it's switched. Additionally the spear sound is getting louder when coming closer to the player.
   
• Medieval Mayhem
  Features: ... Stereo Sound ...
   
• Skeleton+
  If your Atari 2600 has been modified for stereo output, Skeleton+ takes advantage of this to help you locate Skeletons in the maze!

[TheRealOC]

56 minutes ago, SpiceWare said:

That doesn't look good at all if you're not on a 16x9 display, such as an iPad:

 

 

or if you don't use the full width of a wide-screen monitor for your browser. My browser is usually about 4:3:

 

 

as I tend to have other windows open along side my browser.  As such I suggest you review your layout on 4:3 displays, and split out any longer notes to a new page that's linked to via a brief comment. That would also let you add additional images, such as the following photos I took and posted in this reply of another topic covering 2600 stereo. Feel free to use them.

 

 

6-switch cover reveals location speakers were going to be at

 

Lower section of the heavy sixer has supports for the speakers. These do not exist in the later light sixer models.

 

Photos were taken a long time ago, so are a tad blurry due to slight camera movement when I took them. I could take better photos if you'd like, though I need to remember where my heavy sixer ended up

Yikes, okay I definitely need to consult with the mods to fix that. Thanks for pointing that out. 

 

I will put a citation to all these threads in the relevant section of the wiki article 

[TheRealOC]

50 minutes ago, SpiceWare said:

Atari homebrews I'm aware of that feature stereo sound are:

• A-VCS-tec Challenge
  The spear level of A-VCS-tec Challenge is programmed in stereo, so you can hear if the spear is coming from the left or right side. When reaching the middle of the screen, it's switched. Additionally the spear sound is getting louder when coming closer to the player.
   
• Medieval Mayhem
  Features: ... Stereo Sound ...
   
• Skeleton+
  If your Atari 2600 has been modified for stereo output, Skeleton+ takes advantage of this to help you locate Skeletons in the maze!

@SpiceWare Stupid question... I don't have an original 2600 unit with the stereo mod, but I do know a guy who owns a Retron 77 that I might be able to borrow for testing.

 

I assume the stereo mixes on those games should work in the same way over a Retron's HDMI output (whether it was using a Harmony cart or original cartridges)? 

[+SpiceWare]

6 minutes ago, TheRealOC said:

@SpiceWare Stupid question... I don't have an original 2600 unit with the stereo mod, but I do know a guy who owns a Retron 77 that I might be able to borrow for testing.

 

I assume the stereo mixes on those games should work in the same way over a Retron's HDMI output (whether it was using a Harmony cart or original cartridges)? 

 

It might as the Retron uses an older version of Stella. I don't know if they enabled stereo or not. There is a community built version of Stella for the Retron:

 

 

It has more features, uses the standard Stella interface so should expose the stereo/mono setting, and lets you put lots of ROMs on the SD card to run without requiring an actual cartridge.

 

Do note that newer versions of the Retron don't work well with the community build, something to do with faulty DRAM:

 

 

The Retron doesn't use the cartridges like a real Atari does - it dumps the cartridge to a ROM image, then runs that image. Because of that it won't run games from the Harmony's menu.  It might work if you flash a single game to the Harmony, though do note the Retron's dumper only supports a subset of Atari bankswitching formats, and even those it doesn't always correctly detect. The dumper is a stand alone module with no apparent way for the community to reprogram for better support.

[+MrZarniwoop]

In case you are interested, this is a simple audio buffer circuit for stereo from NTSC Atari 2600 posted by Tim Worthington who created the 2600RGB.

[+Nathan Strum]

I have a stereo-modded 2600, and I've often found it distracting playing games *not* designed for stereo. There may be a heavy reliance on one channel or the other, just depending on how the game was programmed, so the sound can seem lopsided at times. That said... I'm planning on keeping the stereo mod, because sometimes I like hearing the different channels and *how* the programmers used each of the sound channels when programming their games. But apart from the homebrews that specifically utilize it, the stereo mod doesn't particularly enhance gameplay. And if you want a wider soundstage from a mono source, most modern sound systems/TVs have modes that can fake it.

[+x=usr(1536)]

It's probably also worth mentioning that only NTSC systems had two discrete sound channels.  PAL and SECAM systems were one-channel only; sound was mixed on the TIA into a single channel.

 

Just my personal opinion, but given that it's not true stereo and the channels can't pan between each other using the default hardware, it's an interesting artifact of the system's design but not much more.  Nothing wrong with the fact that it's there, but it's not terribly practical out of the box.

 

Now, a dual TIA setup on the other hand...  That could get interesting, and for more reasons than just audio.

[TheRealOC]

23 hours ago, SpiceWare said:

 

Do note that newer versions of the Retron don't work well with the community build, something to do with faulty DRAM:

 

Does the DRAM in the Retron 77 console have any identifiable serial numbers that distinguish older revisions from the newer revisions that may have compatibility issues?

 

Or would it just be a case of trying to get any woodgrain Retron 77 from eBay and crossing your fingers?

 

Edited May 17, 2023 by TheRealOC

[Thomas Jentzsch]

Unfortunately there is no way to tell before trying. AFAIK the initial batch worked well, so maybe look for a used one. 

Edited May 17, 2023 by Thomas Jentzsch

[+Yurkie]

On 5/16/2023 at 8:31 AM, Thomas Jentzsch said:

Seems pretty correct to me. Also, quite some games try to utilize the two channels as good as possible by giving priorities to the sound effects. A higher prioritized effect will overwrite the current lowest prioritized effect. And this will cause the effects come from random sides on a stereo modded console.

 

Note: Even Combat wouldn't have worked with stereo as we understand it, because the tanks or planes switches sides. Therefore the sound of the tank on the right, may come from the left speaker and vice versa. However the lately discovered prototype Sonar made heavy and correct use of stereo. The game doesn't ever work without stereo.

Your comment triggered this question. If there where a way to play .mp3 with the Harmony would the stereo play correctly? With the Stereo mod that is.

 

[dwh]

On 5/16/2023 at 7:48 AM, SpiceWare said:

Atari homebrews I'm aware of that feature stereo sound are:

• A-VCS-tec Challenge
  The spear level of A-VCS-tec Challenge is programmed in stereo, so you can hear if the spear is coming from the left or right side. When reaching the middle of the screen, it's switched. Additionally the spear sound is getting louder when coming closer to the player.
   
• Medieval Mayhem
  Features: ... Stereo Sound ...
   
• Skeleton+
  If your Atari 2600 has been modified for stereo output, Skeleton+ takes advantage of this to help you locate Skeletons in the maze!

The number three was rattling around in my brain for the number of stereo games. Just couldn't remember which ones...thanks for the reminder.

Of course, now we have to add the prototype Sonar, unofficially anyway.

[dwh]

On 5/16/2023 at 7:41 AM, SpiceWare said:

That doesn't look good at all if you're not on a 16x9 display, such as an iPad:

 

 

or if you don't use the full width of a wide-screen monitor for your browser. My browser is usually about 4:3:

 

 

as I tend to have other windows open along side my browser.  As such I suggest you review your layout on 4:3 displays, and split out any longer notes to a new page that's linked to via a brief comment. That would also let you add additional images, such as the following photos I took and posted in this reply of another topic covering 2600 stereo. Feel free to use them.

 

 

6-switch cover reveals location speakers were going to be at

 

Lower section of the heavy sixer has supports for the speakers. These do not exist in the later light sixer models.

 

Photos were taken a long time ago, so are a tad blurry due to slight camera movement when I took them. I could take better photos if you'd like, though I need to remember where my heavy sixer ended up

I just had my revision 12 four-switcher open to clean it. That heavy sixer was really made to last. The molded speaker holders are so cool. Surprised no one here have made a mod of the heavy sixer with the speakers in it.

[Thomas Jentzsch]

14 hours ago, Yurkie said:

If there where a way to play .mp3 with the Harmony would the stereo play correctly? With the Stereo mod that is.

I don't see any reason why it should not do so.

[Rob Mitchell]

On 5/18/2023 at 12:35 AM, dwh said:

That heavy sixer was really made to last. The molded speaker holders are so cool. Surprised no one here have made a mod of the heavy sixer with the speakers in it.

Thought about it years ago .. then I got the Coleco Combat tank game which has two speakers built-in .. the LR effect is not that great.