Hi ​@DerekMc171, 

I’m sorry to hear that your Sub isn’t performing as you’re expecting.

At +10 sub level, then it should be more than barely noticeable. If you’re running the latest version then I’d suggest un-bonding and re-bonding the Sub to your Arc.

A lot of our users recommend a ‘sub crawl’ to find the best location for your Sub. While you didn’t have to do it for the Arc, it would be worth doing for the Arc Ultra if you’ve never tried this before. The following threads have some useful information: 

If this doesn’t help or you’ve already tried the above, then I’d recommend contacting our support team for further troubleshooting support.

I hope this helps!

We are stuck with the laws of physics. Subwoofer and listener placement are very important -- in three dimensions.

In my college apartment I discovered a spot where the bass seemed to explode from within one’s body and I placed a chair on that “peak”. That was the favorite location for males. If I moved the chair a few inches the effect was gone. About midway between two peaks is a “null” where bass will be minimized.

If you want to explore the physics, search for “room modes”.

I will try to unpair and re pair the sub, but I don’t think moving locations is my solution. This sub has been in this location for years and the response only dropped off with this newest upgrade. The sub is the oldest part of the system and has always been in this location. It was paired with a playbar and 2 ones, then an upgrade to an Arc. Next was an upgrade to 300s. Now the next upgrade to Arc Ultra. The sub has always had great response in its current location. I really feel it is the processing of what frequencies are being sent (or not being sent) to the sub channel now that it is paired to the Arc Ultra.

I’m not ruling out that SONOS has made some changes in system equalization

You can experiment with changing the “phase” of SUB. The ARC ULTRA emits stronger bass than ARC. There could be some interference between the ULTRA’s bass and SUB. Phase and location will have some effect.

Have you fixed this? I have exactly the same issue! Please Sonos support help!!!

Have not found a fix yet. I am also noticing other issues where channels from the Ultra get loud and soft as if the wrong channels go to the wrong locations. I don’t know if it’s the how the Ultra manages the channels, the pairing with 300s and what they expect to receive, or a combination of both. I know I didn’t have any of these issues with the original Arc paired with the 300s and sub. Hoping for a fix soon, but would be nice just to see an acknowledgment of these problems. That would make me feel like they are documented and working on them. 

This is a community forum. If you want to speak with Sonos Support directly, you need to call them to discuss it.

I contacted Sonos support and they were fantastic

My sub gen2 does not communicate with arc-ultra because the sub was bought in Europe and the Ultra was bought in US - the two regions use different wireless channels to communicate

Sonos customer support diagnosed the problem and then sent me a new US sub at no cost (i had to return my EU sub)

Now everything works perfectly - THANK YOU SONOS! Amazing customer support!!! 

I am updating this. I have seen many other complaints about this issue but no real resolution. I have moved my sub to another room leaving it paired to the arc ultra just to hear the level it is outputting. With my sub at +10 it is still outputting so low with content playing at a comfortably loud level it is not functioning like it was. I then removed the sub from my arc ultra system and paired with my arc and 2x5s system. After the true play it had a healthy output but once again under performed. Because the sub can output but isn’t I have to think something happened on one of the firmware updates. Something is clearly off with the low frequency channel. 

Have you submitted a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it?

The last time I called support for my Roam it took over an hour. That was a few years ago. I don’t have that kind of time in the evenings when I get home from work anymore. What I do have is 2 minutes to fire off a post in the hopes a solution has been found. I have done enough searching to see that this is an issue others are experiencing. That would leave me to think someone should be looking into this.

Seems to only affect a few users, but is still a big problem.

When I bought the Ultra and Era300 I still had my Sub2, I have since switched to Sub4.

The first time I connected everything and set it up with my Sub2 I also had some challenges with my Sub2. It was not as powerful as before when it was connected to the Playbar and Play1 as a surround.

Removed the Sub2 from the system, reset it and connected it again. That helped a lot, however it never had quite the same deep sound but close. In my opinion this is because the Ultra has a built-in mini sub and thereby tones down the external Sub a bit, probably something the software does.

Have since switched to a Sub4 and have not experienced any challenges with it, currently it is set to 0 as I have neighbors and even at 0 they can complain about the house shaking when I watch movies :)

​@Peter_254 

Thank you for sharing your experience. That is really unfortunate. I know when I was replacing my rears with the new and exciting Era300s and swapping my Arc with the new Arc Ultra there was no discussion about compatibility issues. Like when we went from the S1 to S2 app, we knew which product would be supported. Sonos does not have that extensive of a product line that bench testing new product with existing product should be fully vetted before release. I replaced my rears to 300s before I upgraded my Arc and I remember my sub still preforming great. It was around the time I updated the arc to the arc ultra that I noticed a big difference. Sad to say that is also around the time we had app and firmware updates almost weekly to fix the horrible new app deployment. It is hard to say which was the problem in my system, change in hardware or firmware. 90% of the time my kids are watching something or listening to their kiddy stations and low frequency isn’t something I notice on that content. I can’t say exactly when the change happened. When I really noticed they were watching Pixar shorts LAVA and in the middle of the song the volcano erupts. This would normally hit real hard, but the lack of bass sent me down this rabbit hole.