Sub Gen 2 cross over keeps default to zero

I submitted a diagnostics had a chat with a technical member of their team. And after all of a sudden and done, they asked me to just reset the app.
 

They told me that the amp or the arc ultra would look after controlling the crossover and the I guess if you wanna call the intensity of the sub.

I told them that’s not the case. I’ve had this now for four years and I could adjust the sub by the plus or minus and also the crossover and it would hold it and you could hear the difference in the output. And they are insistent that that is not the case. I love spending $10-$12,000 on subs architectural speakers all over the place arc ultra amps all over record players. Everything Sonos to be told essentially I mistaken. 
 

So I’m left with it as it is and I’m convinced there’s something wrong like something to do with Your the app requiring a fix that they probably didn’t realize I don’t know. I always like to have it set for +3 And I like to have the crossover I would have it set for that. I believe it was a -85 and it worked well for my room, but according to the Sonos technical help, I don’t know anything disappointed.

Have you tried removing the Sub from the Amp in the app then adding it back?

Clearly, the information you were told was not accurate, so if this suggestion results in the same behaviour, contact support again and ask to escalate if necessary.

Same exact issue for me for both Sub Gen 3 and Sub mini. Tried pretty much everything at this point with customer support, and nothing has worked. Factory resets, wifi changes, latest updates to apps, ceremonial rain dance etc. Sonos support isn’t able to see the issue in the technical report. Likely, it’s the app that’s the issue. 

Frustrating as my TV room setup is optimized for Sonos (Sonos Arc, Sonos Sub Gen 3, two sonos architectural speakers, sonos amp, and hardwired via ethernet..except the sub). 

Same issue in my den for a sonos sub mini connected wireless to a sonos amp. 

Both sub controls work fine, except for crossover frequency reverts to 0, effectively making the subs worthless. Strange considering when the app is working correctly, I believe “0” isn’t even an option for crossover frequency. 

Anyone have the same issue, and figured out a fix? 

Going back and getting escalated to a higher level at support is likely your best bet. Keep things simple, just discuss the Amp and associated Sub, don't let them wander off to other combinations where there is no Sub crossover setting, only level and phase.

Any support staff confusing Sub settings between an Amp and other Sonos speakers has been poorly trained.

Sometimes the forum moderators can look into things and assist with incorrect support staff provided information. 

As I recall the sub crossover setting is only applicable when bonded to an amp with 3rd party speakers. Otherwise say when bonded to a soundbar or other Sonos speakers the crossover is set according to the lead Sonos product. When I get home I’ll research further.

AjTtrek1 is correct. When using a SONOS SUB with a SONOS speaker or soundbar SONOS has already established the best crossover frequency, however, you can adjust the SUB level. When using a 3rd party subwoofer with AMP, you can adjust the crossover frequency.

No, that hasn’t been my experience. Family Room setup is all sonos. Den setup is sonos Amp, sub mini, and B&W CCM664 in ceiling speakers. Same issue there—crossover frequency keeps resetting to zero.

Again, this is only since the last sonos update. Otherwise, the system was fine and stable since installed in 2023. 

My neighbor has similar setup, but able to alter the crossover frequency for the sonos sub. 

So, no, i don’t believe that my system is behaving as it should. Further, Sonos’ UI is such that if a setting isn’t available due to system parameters, it’s grayed out (for example “enable / disable wifi”), again hinting that this app behavior is a bug. 

EDIT

For that setup you shouldn’t have the option to adjust the crossover for the sub as the Arc is the control speaker that sets the crossover point. 

You need to explain more about this setup. What 3rd party speakers are being driven by the Amp. I assume there is no Sonos soundbar involved.