When you Trueplay (TP) tune the Arc/Sub setup to your room, that will provide you with a flat/level EQ across the general frequency range in the room - if you want more Bass you can do two things, increase the Bass in the Arc room EQ settings between value 0 and +10 and/or increase the Sub volume between value 0 and +15 and see if you can find a level that suits how you like to hear your chosen audio. You can also try the setup with, or without, TP enabled.

If still no joy, then try the Sub-Mini in a different location in the room. In my own particular case, I prefer a Sub positioned out in front of my chosen listening position, in a corner of a room, rather than behind me, but that’s really a matter for what may best suit you and your listening environment. 

If you still can’t get along with the Sub Mini, then you might want to consider the larger Sonos Sub instead (or two of them). I have both type of Sonos Subs here at home and personally I find the Sub-Mini does an excellent job for its size in the rooms here. I use one in the bedroom with the Beam/Ones and have another in the Kitchen/Diner with a Ray/One SL’s and both setups sound great.. I really notice the difference that the Sub has made to both rooms and my room settings are pretty much at default settings.

Anyhow perhaps try the things mentioned and see how you get along with changing the levels mentioned or even repositioning the Sub in the room.

Perhaps see this link too: https://blog.sonos.com/en-gb/beginners-guide-to-bass

Thanks, first I try to change trueplay on/off, but in both cases I need to put the Sub volume to +10 to feel the BASS.

The Bass in the ARC room EQ settings, is the BASS of the ARC or the BASS of the ARC+Sub Mini?

Apparently there is an overlap. The Bass control affects frequencies from just below the midrange and lower. The Sub Mini level affects only frequencies handled by SUB. These tend to be below 80-100Hz

Everyone’s idea of the ‘proper’ amount of bass is different, it’s up-to you what sounds ‘best’, but perhaps also try the Sub Mini in different locations in the room. The purpose of the controls in the App is to customise the settings to suit your own listening needs in your chosen environment.

But its normal that I have to put the Sub mini +10 to feel something? What do you use to test it? A movie, music, video youtube?

I can’t answer that, as each listening environment is different and I can’t hear what you’re hearing, but can you touch the Sub-Mini speakers to make sure they are moving - 

Maybe try this movie…

Car chase at start of ‘6 Underground’ (movie) Netflix 

Music track…

Wow - by Post Malone

Thanks, I will try change the place of the sub mini

Subs are not directional speakers.  You do not have to have them pointing directly at you to produce a proper sound environment.  What they need is something solid to contain or reverberate the pressure waves they produce.  
 

For instance, putting a sub next to or behind a sofa and there is open area behind that area you will lose a lot of that lower frequency.  
 

If you move that sub to a corner wall in the front or back of the room you will notice a big difference.  
 

My suggestion, get an extension cord that can cover the whole room.  Start a song or scene with a lot of bass or action and then put the sub in different spots of the room then sit in your normal listening location.  No matter how ridiculous the spot may be try everywhere but utilize the walls if possible.  
 

Make note of the spot that sounds acceptable then dial it in from there.  Then tune it and see if it's more noticable without being overbearing. It should add deeper feels to movies and a drive to music not rattle the walls. Good luck and you should be able to find the sweet spot for your room. 

I have the same setup as you and my room is about the same size and i definitely notice the sub doing its thing. For music i set it at level 0 and when watching TV i usually set it to +4.  Depending on the source material this is boomy enough me, i can sometimes feel the bass when sitting on the couch.

A sub gen 3 would be likely be overkill. I also don't need to have the bass shaking the room constantly, for me the sub is for just that extra oomph and depth. 

 The tv and Arc are against the back-wall, the bass on the Arc is set to -1. The sub is placed neer a side wall about 1.5 meters into the room as seen from that same back-wall. 

Tossed it up for weeks and bought a sub mini to team with my Arc. Medium sized loungeroom. Turned it to +10 and it works fine. Really enhances the sound generally and produces good bass.

It doesn’t shake the room but I don’t want it to.

THANKS for the tips. Really useful.