There is no way that an app update can make improvements in the way a speaker sounds, I tested a while now and the Arc still do not sound good! Period

Try doing a new trueplay. It surely fixes the muddy bass from a tuning point. Would make sense as they can manipulatie the way audio sounds using trueplay. Make sure that there is actually no other sound happen when doing the trueplay. Als make sure that you walk in front of the arc at least once. 
 

Really did the trick for me.  So fingers crossed it will solve your muddy bass as well. :)

What's surprising, is that noone else really has commented on the latest update. So many people complained about the sound in the previous months, including myself, and now (past 12.0.6) there is noone else to confirm there is an improvement or not aside from one person. Weird... 

In my case, after the update I still have the treble sounds at -6, I think people do not write because many have already returned it and those who have not are already discouraged

The 12.0.6 update did not fix the issue for me.

If Trueplay was the way to fix it, that wouldn’t really be a good thing since there are lots of people out there who can’t Trueplay because they don’t have an iOS device.  

Trueplay shouldn’t fix problems in my opinion, it should only enhance the sound to make it sound even better for the room it’s in.  The soundbar should sound good without Trueplay being done.

However, after trueplaying again for me… the muddy bass still exists.

I’ve just kind of given up until I see firmware hit my soundbar before I really put it through it’s paces.  I did try again this time because of 2 people reporting it here in the thread but didn’t really have high hopes, for good reason.

Got fed up and could never see an improvement happening so returned mine.. No complaints now 

12.0.6 didn't help. I did second truetone calibration. Same story - using this device near 50% of volume makes some bass frequencies unlistenable. It is even hard to say how bad it is. It sounds like some cheap speaker put at 100% of volume.

I'm disappointed...

Can anyone guide me with RMA procedure?

Log in to Sonos account and hit returns in menu.. Its all quite simple and done well. 

Well, my overall experience improved but I had my RMAed. Will keep watching this thread. 

I did the upgrade, rebooted the Arc and redid Trueplay. So far it sounds much better. At regular listening levels it seems like that wierd bass sound is gone. It no longer sounds like someone banging on a plastic tub. If I have trueplay on I hear it slightly, if I turn trueplay off it seems to be gone. We’ll see how it goes over time

Updated the App to 12.0.6, and redid Trueplay on my Arc + 2 One’s. No difference whatsoever… I always check bollywood movie Drive on Netflix at 35 min, wobbling bass all over te place… You hear it already clearly at 30% volume or so.

@Sonos , I created some diagnostics, number is 2024072718

This needs to be dealt with, once and for all, I am not expecting the moon here, just expect the bass not to sound like a 20€ speaker...

I sent my back today. Waiting for replacement. Will let you guys if it helped.

Got my replacement (2008 build date) in and tested with the drive movie on Netflix and still same wobbly bass sound at 35min in… however, this 12.0.6 update did seem to improve the bass sound which to me seems like there is a small subwoofer. Tested on the original arc and the new replacement arc.

Overally the new arc sounds the same as the original arc. But 12.0.6 sound better than the previous sw (yes, I truetuned)

I was unable to compare it side by side but YES, it does sound better. I never said the issue has been resolved fully or it sounds amazing. I just said it sounds better! Before, it (previous versions and firmware updated) had all been failed attempts IMO.

Here are my observations after configuring replacement ARC:

1. There are some minor differences in hardware, but these are not the main source of the bass issues. The second ARC speaker is performing better, the issue is almost not present before truetone configuration (default “out of the box” configuration).
2. There is huge difference after truetone calibration in terms of quality, bass deepness and overall feeling. It sounds nice. The spell is broken near 50% of volume, in some songs near 30%, in some near 60%. But definitely after truetone calibration you have better sound on low volumes, but “cheap speaker” is present while louder listenings. If you turn truetone off the problem mostly disappears but the sound is “meh”…

I can’t imagine that Sonos accepts the solution, in which louder listenings demands setting truetone to "off"…

I hope that this is strictly software issue, and the team is working on it. It would be great if we could at least have the confirmation that the problem is processed in SONOS team.

I sent diagnostic date while problem was present, the id is: 1775975870.

I brought this new update and how some people here noticed improvement, along with myself to with Peter’s attention last week. He has tested it with the newest firmware and software. I suggest watching his video.

https://youtu.be/ppe5S6X1too

I still find there to be a lack of bass, comparing to my stereo pair of Symfonisk lamps, it really does sound like there is more bass in the symfonisk’s than the Arc. Anyways, picked up a sub which will come to me on monday so I won’t be affected much longer.

I did also view Peter Pee’s video and he does amazing Sonos related videos, however, I still find there to be no difference in audio quality. Testing with some bass heavy songs I still find there to be a lack of bass, especially at the 30-40 hz mark. I will retune a few more times and see if I can manage to get a different result.

From watching Peter Pee’s video, he has Arc Hardware version: 1.27.1.8-2.2
Mine is 1.27.1.8-2.1

What exactly does the hardware version go on? Is it the color of the Arc? Could a white Arc have a different hardware version than the black one?

What outcome can this have on the result? @Scott - Sonos  

Let’s hope it is fixed for all, I don’t experience problems atm

This thread has got to be one of the longest in Sonos history but for good reason. I’m just glad the Arc keeps getting better that’s all I asked since day one though I’ve been upset and didn’t have faith at times it seems like the muddy issue has been resolved though I need to do my own testing. Lack of bass should be in a different thread.

Color.  Do you have the white one? 

The update fixed the issue 100% on both of my Arcs.  Like a totally new speaker.  Great work!!

I have tested a few songs on my Arc with the surrounds and sub off. The Arc bass is night and day for me, and in a good way.

I have the white Arc. Version ends in 8-1.1.  interesting some end in 8-2.x. I knows the last number has been the color variety iirc. Or maybe also where it was assembled as they have 2 factories building these bars. I would like people to post their October and November Arc deliveries, maybe in a separate thread just out of my curiosity. 

Let me start by saying that I dont usually noticed any wobbliness to the bass. But someone had pointed to a Trinkets episode on netflix where a band is playing. After the update I played this once again and initially with Trueplay on I could hear the weirdness on the bass. When i turned it off this weirdness was gone. After retuning it is now fixed I dont hear any weirdness even at +2 bass with 60 percent volume. This is with my sub and rears turned off as I always tested it.

So I believe the tuning has been improved and together with the firmware update tackled this issue.

White Arc, ordered at the end of June.

Definitely sounds 10x better after the latest update. 

The Arc might not get as punchy bass as a sonos one or symfonisk this is because of smaller drivers. But that wasnt quite the issue the issue was uncontrolled wobbly weird sounding bass at higher volumes some users even reported at lower volume. That has been addressed on the update

Perceived bass also depends on tuning, on location, is your symfonisk next to the wall or  a corner etc? Is your arc mounted? Maybe the magnetic sensors are reducing bass to prevent vibrations etc. Theres a lot at play including your room dimensions and furniture carpeting etc. But the issue was different and it has been fixed. Reported by many users. Make sure to retruplay