Advice on setting up Arc Ultra and Sub Gen-4?

You’ll find the set up procedure here: https://www.sonos.com/en-us/guides/arcultra and here https://support.sonos.com/en/article/set-up-your-sonos-sub

You are of course free to follow the set up guide from some YouTube channel above Sonos’ advice here: https://support.sonos.com/en-us/article/tune-your-sonos-speakers-with-trueplay

edit: link is now English

There are two aspects of Trueplay tuning for sonos home theater systems. It will have you sit in your preferred tv watching position and tune for that location. It will also have you move about the room. This aspect is tuning to the room dynamics and is also done when Trueplay tuning other sonos speakers.

When doing Trueplay tuning for your home theater setup (Arc Ultra & Sub), the app will guide you through the whole process, which will include both the sitting position and the room tuning.

Exactly as Knowling says. The Trueplay procedure just differs between Android phones and iOS devices... on Android, you sit in the listening position, whereas on an iPhone, you perform the calibration by walking around the listening room... give it a try... and you'll see.

As you’ve noticed over the ages, the music or video sounds different in each room and each listener location within each room. TruePlay’s goal is to transform your listening experience into that intended by the content creator.

The first step in TruePlay tuning determines the distance between the listener and each speaker. The second step measures the room characteristics. The room and your listening position may emphasize or de-emphasize certain frequencies. TruePlay attempts to compensate for this. Most of the time TruePlay improves the experience, but there are limits. For example, it’s not possible to transform a listener’s gymnasium-type room (lots of echo) into a library (no echo).

Sometimes, depending on how you hold the phone or walk the room, TruePlay obviously gets it wrong. In this case try again. If TruePlay does not improve your experience, simply don’t use it.

When I set up my Arc Ultra I did the Trueplay from my main seat first and then the walk-around part the app asked for, and it sounded right straight away. The one thing I changed after was the Sub level, which I turned down a touch because the bass was a bit heavy in my room at first.

TruePlay is a good ‘baseline’ settings, but then I modify it afterwards for my personal preferences. I don’t have the same ears as a Sonos engineer! And some of my rooms I’ve used TruePlay in, in others, I don’t. There is no requirement to do so, and I’ve found sometimes I don’t perceive a difference, so I just don’t bother. 

Just make sure the room is very quiet while executing TruePlay.  The only change I made after TruePlay was set the sub output to -2.  If your iPhone ( if that’s what you have ) has a cover remove it before running TruePlay.  A cover like Otter Box can have an effect on how the microphone perceives sound.

During the second walk around phase aim the microphone away from your body and as you are walking around the room move the phone up and down slowly.  No jerky movements.  I think there is access to a video showing the process.