I couldn't agree more. Like a computer sub, especially while playing music. Just terrible. 

Have you subsequently submitted a diagnostic, and contacted Sonos?

Yes I have

I noticed the volume needed to be turned up slightly higher as others have mentioned, but the audio clarity all around is better for me. I did do the tuning again with Trueplay and it does sound better than it did before. Having the Beam Gen 2 before the Arc, the Arc’s dialogue clarity didn’t seem as good, but now post-update, after watching a few episodes of a show with Dolby Digital 5.1 format. I noticed a difference all around and definitely the voices compared to pre-update with the same show. My setup is Arc + Sub Gen 3. 

Update 

I have redone truplay and no change I have to watch  at volume level 30 when before I would use 15 

For movie night level it's now 50-55 before was 35 I have never had the volume over 50 before as it was to loud

Again I have had to increase the bass and sub level and when I use the movie night level I have to turn treble down as it is to harsh 

Before the update the front soundstage sounded wider as well if that makes sense 

As for clarity it was fine before I never had to use speech enhancement for dialogue and for the level I use for movie night if I do not reduce the treble it sounds like the way my dad has his TV set up and he was deaf!

In short it sounds awful now 

I also rang sonos and submitted diagnostics 1479794144

They are looking into it apparently

Thanks for letting us know they're looking into it. It can't stay like this. Sounds terrible. Needs to be rolled back for sure. The Arc would not win any awards sounding like this. Absolutely got it wrong with 14.12

I posted in another post but I am also experiencing the same thing. Did TruePlay all over again since the update dropped it. Did not help. Seems like center channel volume has decreased which affected the overall volume. I submitted a diagnostic report as well. Did not call though.

I understand your frustration, but be careful not to assume that every user is experiencing the same problems as you. With my setup, I have noticed no difference with the volume level and can tell that dialog clarity has been improved. I just tested Blade Runner 2049 on Blu-ray (which is known for its impressive bass) and I still experienced the same room-shaking bass that I had before the update.

More than likely, Sonos will not roll back the update but just make some adjustments to address the issues that some users, like you, are experiencing.

@GuitarSuperstar i hope they do fix it I am not looking for a rollback but a fix

Just as 10.06 didn't affect everyone I know this hasn't but it has me

Another thing that I noticed that when I watch a surround heavy movie with helicopters flying round the room the quality of sound appears better from my ones than the arc

Then it's quite hard to understand and you're very lucky when most of the users are having the same problem...

I happen to be in the same ‘boat’ as @GuitarSuperstar, I’ve not noticed any significant change on either of my two Arc setups. 

However, if you are indeed concerned, providing Sonos with hard data about your system, via a diagnostic submission followed by a phone call, so they can look at the diagnostic, is probably the best way to proceed, as some have already done. Just responding with a ‘me too’ in the community forum doesn’t give them much in the way of hard data to investigate whether or not there could be an issue. 

@Airgetlam
i already have called support and provided all information and diagnostic data I was asked for and all my observations 

Which is appreciated, I suspect, and why I put “as some have done” , but there are others who don’t have appeared to have done so. 

The engineers I work with appreciate more hard data, from multiple sources, and react poorly to “someone said something on a forum”. Makes it hard for them to track down an issue. 

@Airgetlam agreed and during the call I was told they were aware of the issues affecting some users and were actively looking at the problem 

Same here. It sucks.

Couldn’t agree more with this. My set up has the same issues. I redid the trueplay and it did nothing. I guess we can hope for a patch soon.

Update 

Dts 5.1 is better than dolby sources possibly because dts has been recorded with higher gain

So it appears dolby atmos and 5.1 appear affected more by the update 

Tested with a couple of blurays so far

Though output is higher still quality not as  good need to turn treble down to-2 to stop wincing at certain high action scenes 

Hi, from Spain (europe)

Buy Sonos Arc and 2 Sonos Five, after a short time very low audio fail after firmware installation :(

Thanks for taking the time to reply. I get that, not all users will experience the same issues, that's mainly down to different individuals and their equipment and ears or tonal tastes. For me, concurring with the majority on here, the dialogue on the Arc has been over 'improved' and now that's all I can hear, when turned up 10 more levels. I've never done true play tuning and I've always kept the EQ on a default out of the box, which immensely satisfied me and the sole reason for purchasing. After all, that's how the Arc won awards, for how it originally sounded and performed. All that has changed now since 14.12 and I urge the likes of What HIFI to have a listen now and see where their head is at, because I'm almost certain it wouldn't win any awards sounding like this. I've spent a lot of money on Arc, Sub and Surrounds and for a team to come along and tweak something which was never wrong in the first place and somewhat ruin it (for me at least) I think is quite frankly disappointing and upsetting. I'm left begging for either a roll back (which is unlikely as you say) or a quick fix to get it back to how it used to sound. I'm sorry that I feel so passionate about it but I'm sure I speak for others in their utter disappointment that such a 3 minute software update has brought them.

IMHO this is an excellent update. I have an Arc, Ones and Sub and have always found this quite poor with music - way too in your face and bass heavy. The tweaking of the arc in this newest update gives a WAY better overall sound. Instead of having bass at -3, treble at +3, loudness off, sub at -5...and still having the music thudding off my concrete walls, I now have well-balanced sound with bass at -1, treble at +1, loudness on and sub at 0. The arc has always been good for classical and jazz, but I found too intrusive for pop and rock. This update gets a big thumbs up from me.

My home theater setup: Arc, Sub Gen 3, (2) One SLs. I loved my system before the 14.12 update. After the update, my Sub output was drastically reduced. I would liken it to someone turning the gain 70% down on a car audio subwoofer amplifier. Or potentially, hooking a sub up to an amp with a high-pass crossover turned on preventing the sub from being able to perform in the sound frequency range it was designed to.

Here is what I did to attempt to rectify the issue: 

Removed sub from home theater group, disconnected sub and reset it, ran trueplay multiple times, adjusted manual sub audio and bass equalizer settings (all the way up), also tested with and without trueplay tuning. For reference, pre update my home theater group equalizer settings were: Bass +3 and Sub Audio +3.

In the end, my sub output is still a fraction of what it was before this update (even with bass and sub audio levels all the way up. Bass +10 & Sub Audio +15).

Someone mentions this might be a gen 3 sub issue. Been noticing that affected users seem to be on Gen 3 rather than 2? Might be worth confirming. 

This 14.12 update ruined my system! I’ve spent a lot of money because I love sonos products but everything is significantly lowered now during music and movies since this update. It turned my bass down to almost nothing, the bass isn’t what it used to be. Please Sonos fix these issues!

You do know you can manually tune the Sub and surround levels, right?