Interesting suggestion, you also must take into account that many mono films played in theaters which had back/sides surrounds speakers (they were mono to save money on prints and mixing). So mixing down the tracks to 1.0 is botching the intended sound, period. (I repeat, unless one channel has laser rot and there is no other option). Those mono tracks were two channels, and often played not just on the front, but also on the sides/rear. Most people didn't noticed they were mono.

There were 2 reasons why films continued to be released in mono once Dolby Stereo became established: avoiding the Dolby license fee, in which case the soundtrack was academy mono, or because of a creative decision to keep the audio mono ie Woody Allen, in which case the movie could still be released in mono but Dolby encoded.
Later Ultra Stereo was an option, there was no license fee payable so a lot of indie features used it (and it was compatible with Dolby systems)

So I did a little test by encoding some mono tracks into DTS-HD MA 3.0 (no volume attenuation, simply copying the 1.0 stream into all 3 channels) and I have to say I was impressed by how much better it sounded compared to 1.0 and 2.0 mono. It might be helpful to reduce the center channel a couple db, but I'd have to play around with it more.
Really curious to see what other people think, especially anyone with a good home theater setup. But I think this could be a very viable option for audio projects. If anyone wants to check out any of the test tracks I made shoot my a PM.

It sounds great!

Fan preservers needs to understand how stereo mono sound imagery work. You don't put 1 channel dead center because it will sound dead.

You open up the music and soundspace by switching the left and right channels a bit off center.

Look at Audacity when you have mono tracks. See that little G to D switch which you can play with?

That's how these were done on analog consoles back then (again, we're speaking here mono mixes released as stereo).

So if you downmix a mono track to 1.0, or delete one channel, you are effectively doing the contrary of what fan restoration is supposed to do, you are messing up the sound image balance.

I suggest unless a track has one channel rotted, that future releases of mono tracks are untouched input 2.0 to output 2.0. After all the point if preservation, and you don't preserve anything if you destroy the soundfield image.

Now going back on the list, that's a lot of tracks, but the goal should be fan preservation.

Sorry, but I don't see any proof showing that the very minor fluctuations between dual mono tracks is not just due to the imperfection of older analog gear. The tracks were mixed as a single channel, and if you process the difference between channels with ffmpeg you'll see the difference in db on average is not enough that you could even hear. Now what your equipment is doing with it is a whole different story. If you are on a PC then there is software running that will reformat whatever is playing to fit the system audio settings, and of course modern receivers with way more channels have to figure out how to deal with it in their own way.

No, I mean you bypass the "final mix" thing. Mono mixes may have one channel of data, but they are spread to create a wider soundfield.
That's how final mixing is done. You are literaly throwing off the final mix stage if you mess with this.
That's why all these early releases sound better as 2.0 than when downmixed to your center field, where the whole dynamics are gone and it's sound nosy.
I rather let anyone custom deleting one channel if they want, but to do a preservation by throwing one channel off is wrong. Period.

On the topic of LD tracks specifically, I was watching this:
https://www.youtube.com/watch?v=_cl7Fd9bdXo

And at 23:42 he mentions a crosstalk issue between the video and right audio channel. I'd assume this wouldn't affect the digital track at all, but is it possible that somewhere in the analogue to digital mastering process this issue is what causes minor discrepancies in dual mono LD tracks?

The crosstalk referred to in the youtube video is basically interference between the video and audio signal once it is mastered onto disc. Basically a laserdisc is an FM signal with 3 separate 'channels' ie video, digital audio and analogue audio (which can be split again into left/right). CX encoding reduced the noise floor of analogue audio considerably, without it analogue audio on laserdisc has a kind of vinyl 'surface noise' made worse by dust and scratches on the disc, as well as pressing imperfections or rot. I don't think it's the cause of the 'issue' here

Some receivers like my Onkyo have a full mono mode which plays back mono content in every channel.

(2022-07-15, 12:52 AM)captainsolo Wrote: Some receivers like my Onkyo have a full mono mode which plays back mono content in every channel.

Does it disable your eq/crossover settings when using it? That's a problem using any modes like that on Denon and Sony AVRs I've used.
And does it play back on every channel or just the fronts? In the tests I did I preferred having the sound come primarily from the front soundstage, with neural-x making minimal use of the surround channels.