Change the ‘default’? No, but when you set up an alarm, you also set up the stream it plays. You may want to read the Alarm FAQ. It does, however, play that ‘default’ if for some reason, the speaker is unable to connect to the stream at the moment of the alarm, so even if there’s a failure, you’re still pinged by the alarm. 

Bruce, 

Thanks for the feedback regarding the alarms and the notification. I'm actually trying to change the default notification for timers and I don't know if there's some way of setting that with when a timer is set or changing the default that it uses.  I don't currently use alarms with the Sonos for anything, but again I thought there might be some sort of a default that could be set at the system would use for both?

Thx,

Chris

As I said, no, there is no ‘setting’ to change the defaults in the Sonos software. 

Bruce,

Thx for your feedback.  I think my confusion lies in the fact that you referenced the “alarm” set up and I was talking more specifically about the timer function.  Maybe they are one in the same and use the same default audio file for notifications.

Regards,

Apologies. In my mind, they’re the same thing, just two different ‘interfaces’. In neither usage am I aware of any modification offered to the default sounds. 
 

Edit: beyond allowing you to set up your own music stream. But that doesn’t alter the default ‘chime’, should the Sonos device be unable to reach the specified stream. 
 

Sorry, but I don't understand the question. There's no such timer on Sonos, but the sleep timer which stops the playing music without any chime.

Well, I can tell Sonos...”Hey Sonos, set 10 minute timer” and it does so.  When the timer expires the music stops if it’s playing and there is a series of chimes until I give it the command, “Hey Sonos, cancel timer”.  

Ah, on SVC. Sorry, I don't use SVC and I was not aware that it had a timer.