Weak nav beep

Update: I contacted Garmin support and they offered no other solution than sending it in for replacement with a refurbed unit at the usual fee...around $120 as I recall.

Hi.
I too have the same problem. Noticed this other thread with the same issue.
https://forums.garmin.com/forum/into-sports/cycling/edge-820-aa/1457329-different-worse-tone-for-navigation-prompts

Ha! I knew I saw it somewhere, but I couldn't find it with my feeble search attempts. The description of the problem in that thread seems different than my problem...a shorter higher pitched alert rather than the decreased volume that I have. I'll have to pay closer attention next time and see if my problem is more like their's. Per that thread, a reset cures it, but I've already done a reset. Just for the heck of it, I'll try it again. I've been saving my settings.fit file and putting it back in after the reset to prevent having to set everything up again. It might be possible that the problem is related to the settings.fit file and reinstalling it reinstalls the problem. IDK. I could try it after a reset but before reinstalling my save settings.fit file. If/when I try that, I'll report back.

Yes mine is a quiet blip, have almost missed a few turnings

I'm guessing it's a new feature introduced in 11.0 or possibly earlier.
In my case, this very short beep appears at exactly 200 meters before the turn, and then normal beep at 50 meters before. Not quite sure about the numbers, but it's something like that.
In any case, there are short and normal beeps durig course navigation.

I've not been able to hear my alert bleeps for a while. 800 was fine, with a louder and lower tone. Keeps things interesting, having to keep looking down at the screen whilst riding on pot-holed roads..

I went for another ride navigating and the only time I could hear the beeps was when I was deliberately going very slowly and paying specific attention. Even then I could barely hear them. There have always been preparatory beeps a hundred yards or so ahead of an upcoming turn and a different chirping beep just before the turn. I still get those but they're basically inaudible while riding.

I'd like to know if it's a software or hardware issue and the experiences others are having might provide a clue. One hardware issue I theorize is the speaker becoming detached or loose inside the case. That's something I could fix, but would require some delicate disassembly that I'd rather not do without more certainty that it's not a software issue.

I still think it's a feature, and no disrespect to anyone, but I really wonder how some of you cannot hear it.
Although it really is a rather quiet, preparatory beep, I can hear it every time, even in windy conditions (although winds do not exceed some 25 kph).

^^^ perhaps yours is not exhibiting the problem. I few months ago I was able to hear it easily and usefully while riding. I no longer hear it at all except in very quiet circumstances. It might as well not be beeping at all. How would be making it inaudible be a feature?

This is my third 820. I currently also have an 520 and 500, and have had other Edge units as well. The 820 is, as of recently, the only one I can't hear.