Artisan Radio broadcasts (and will stream) in mono. FM broadcast quality is roughly equivalent to mp3 at 128Kbps stereo (or 64Kbps mono, which is what I use). Probably less.
I know that that will horrify audio purists. There are lots of audiophiles out there that swear by stereo as a listening experience. Although I bet that most people, particularly those on a computer or in a car or on a cell phone, effectively listen to a single speaker in mono.
There are lots of people that still encode mp3's in 320kbps (the maximum) and even higher with other codecs, or flac (lossless). Even when 128kbps is almost transparent to the source (depending on the source, of course).
But when you're dealing with transmitters that have an effective range of much less than a mile, probably feet for clear, static free audio, what's the point? Even if you're the only listener, you're probably going to be listening in when there's static and other artifacts introduced to the sound just by virtue of the micro power used in these transmitters.
Broadcasting in mono FM will give these flea powered transmitters a bit more range, and more importantly, a bit more range for that static/artifact free listening zone. There's more power for the content carrying signal (as opposed to the pilot and the stereo differences).
I would also bet that most people on most listening devices would not be able to tell the difference between 64kbps mono streaming and a much higher bitrate. Even with headphones.
What you will be able to tell, even at 64kbps mono, is the differences in quality of the source material. If the source material comes from noise-ridden 78s, and is in mono anyway (never mind maybe coming from acoustic recordings), then a higher bitrate will make no difference at all for anyone. And stereo is just distortion, in my opinion - it's not the original intent.
I've encoded high quality modern stereo recordings at 64kbps mp3 mono, and then higher bitrates, again at mono. It's very very difficult to discern the differences. I'm sure you could come up with some material where it does make a difference, perhaps classical pieces with lots of instruments and background activity, but for common, popular music? I doubt it.
i mentioned in another thread that Radio World had a run of articles about exactly this in 2022:
April 17, 2022
Let’s Talk About Mono
https://www.radioworld.com/columns-and-views/guest-commentaries/lets-talk-about-mono
"... Many FM broadcasters are sending the programming out on both the left and the right channel, plus lighting the FM pilot. Why? They can send the audio out as mono and not have the penalties of L – R. Reception in the Grade B contour would be improved. Nothing would change RF wise, but you would have a stronger signal. You have half the audio chain to deal with! No phase issues!..."
September 7, 2022:
Mono on FM? Hang on a Moment
https://www.radioworld.com/news-and-business/programming-and-sales/mono-on-fm-hang-on-a-moment
"... I don’t wish to enter into a disagreement with my good friend David Bialik, but there is an argument that modern car radio algorithms essentially eliminate the disadvantages of stereo FM transmissions. ...."
October 25, 2022:
Feedback on FM Stereo vs. FM Mono
https://www.radioworld.com/columns-and-views/readers-forum/your-feedback-on-fm-stereo-vs-fm-mono
".... The “stereo penalty” is a known engineering issue; it is real when it comes to coverage. It is a fact: FM monaural uses only 15 kHz of bandwidth while stereo uses 53 kHz. The greater the bandwidth, the more noise gets in and degrades the audio, a definite tune-out for most listeners. ..."
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I use mono for FM as the Decade basic model is mono only(the Procaster FM is both) because radios are more sensitive in mono and the signal is more dense and will be better at the fringe areas, especially for our micro powered stations.
@mark That's the primary point of those articles linked above, FM in mono not only provides a cleaner signal, but also more range at the same power level.