New Hi Fi system is bright :(

[Pawnshop123]

Well, you have a bingo here, sir:
- that geometry
- glass wall (windows)
- bare painted concrete walls
- almost no furniture
- tile floor
+++
R3 Meta predicted in-room:
View attachment 320985
Not ear-piercing by itself but in your room and set at long wall - well, you're hearing it.
Also note it's somewhat over(or under?)designed as bass deficient, only KEF knows what a room tuning it meant to do.
Anyway, baking it into hardware seem to cause issues and not to be liked much by listeners.

Another amplifier will not solve this issue, but EQ will.
I'd just try a quick fix - negative gain HF shelving by 2-3 dB above 5 kHz, and +3 dB bass shelving below 100 Hz.
Yes, you will require a laptop, a Y-cable (3.5 to 2 RCA) if you don't have one, and an hour to install and get yourself familiar with Equalizer APO + Peace (freeware).
Way cheaper to try than buying some Arcams, isn't it?

I experimented with Apple Music EQ on Mac yesterday and I found negative gain HF shelving by 2 dB between 1-5 kHz, and +3 dB bass shelving below 100 Hz to sounds pretty good to me in my room.

Regarding acoustic treatment - will these be any good?

https://he.aliexpress.com/item/1005005978461213.html?spm=a2g0o.productlist.main.21.a3a572eddXBe5t&algo_pvid=3a136e0d-e916-4e51-a3f8-36ad556ae88c&algo_exp_id=3a136e0d-e916-4e51-a3f8-36ad556ae88c-10&pdp_npi=4%40dis%21ILS%2196.46%2121.6%21%21%21169.38%21%21%40211b88f016984071951801454ef67b%2112000035145147677%21sea%21IL%210%21AB&curPageLogUid=v80MiKaMNxrD

 

[benanders]

…

Regarding acoustic treatment - will these be any good?

https://he.aliexpress.com/item/1005005978461213.html?spm=a2g0o.productlist.main.21.a3a572eddXBe5t&algo_pvid=3a136e0d-e916-4e51-a3f8-36ad556ae88c&algo_exp_id=3a136e0d-e916-4e51-a3f8-36ad556ae88c-10&pdp_npi=4%40dis%21ILS%2196.46%2121.6%21%21%21169.38%21%21%40211b88f016984071951801454ef67b%2112000035145147677%21sea%21IL%210%21AB&curPageLogUid=v80MiKaMNxrD

Similar to fabric, IME. Unless it’s different from some other Shenzhen factory foams, but takes up a lot more room space and looks “awesome”. The canvas artwork someone suggested earlier could be similar at disrupting the HF’s troubling you.
Think more in terms of floor mats that agree with your sense of wall pattern/design, given it’s HF you want to tame with passive measures. I’ll try to dig up a crude e.g. pic later.

 

[radix]

Similar to fabric, IME. Unless it’s different from some other Shenzhen factory foams, but takes up a lot more room space and looks “awesome”. The canvas artwork someone suggested earlier could be similar at disrupting the HF’s troubling you.
Think more in terms of floor mats that agree with your sense of wall pattern/design, given it’s HF you want to tame with passive measures. I’ll try to dig up a crude e.g. pic later.

If you get canvas artwork, or even prints of some pictures, it usually has 1" or more of space behind it. You can leave it like that if the canvas is thick (e.g. a oil painting) or fill it will a foam. You can google "how to make absorbers from canvas."

 

[nygafre]

My initial response upon setting up the Metas earlier this year was a 'gut reaction' to reduce treble by -1db. I'm still running -1db treble most of the time, and commonly +2 to 2.5db for bass (in my room, setup etc). I really feel this was necessary to dial them in to my liking.

I have to say I'm impressed by coaxial speakers, these are my first.

 

[nygafre]

In my experience very often when some well measuring loudspeakers are sounding bright the problem does not lie in the higher frequencies but the lower ones, usually due to some wide bass dips, with a couple of measurements at the listening position we would know much more.

Yes! This is probably the biggest 'struggle' I had with them. Experienced some wide dips/cancellations in bass, very dependent on the positioning. I think you responded in my R3 Meta thread earlier this year.

 

[benanders]

I experimented with Apple Music EQ on Mac yesterday and I found negative gain HF shelving by 2 dB between 1-5 kHz, and +3 dB bass shelving below 100 Hz to sounds pretty good to me in my room.

Regarding acoustic treatment - will these be any good?

https://he.aliexpress.com/item/1005005978461213.html?spm=a2g0o.productlist.main.21.a3a572eddXBe5t&algo_pvid=3a136e0d-e916-4e51-a3f8-36ad556ae88c&algo_exp_id=3a136e0d-e916-4e51-a3f8-36ad556ae88c-10&pdp_npi=4%40dis%21ILS%2196.46%2121.6%21%21%21169.38%21%21%40211b88f016984071951801454ef67b%2112000035145147677%21sea%21IL%210%21AB&curPageLogUid=v80MiKaMNxrD

Given you’re already familiar with AliExpress I suggest the material below. These can quickly stack together under a bed or roll up in a closet when not in use. They’re lightweight relative to dimensions (filled with a cheap memory foam), so can be suspended with plastic stick-on wall hooks (good for renters to avoid holes).

The type with anti-slip rubber beads on the bottom work well. Not as floor mats though - the outer fabric is too delicate to be walked on daily.

It’s what I used to mitigate HF reflections from close concrete sidewalls in my previous residence (3-4 years). My speaker’s tweeters (kick in ~ 6 kHz) are designed for ~180° horizontal dispersion - yeeowch!

 

[nygafre]

Well, you have a bingo here, sir:
- that geometry
- glass wall (windows)
- bare painted concrete walls
- almost no furniture
- tile floor
+++
R3 Meta predicted in-room:
View attachment 320985
Not ear-piercing by itself but in your room and set at long wall - well, you're hearing it.
Also note it's somewhat over(or under?)designed as bass deficient, only KEF knows what a room tuning it meant to do.
Anyway, baking it into hardware seem to cause issues and not to be liked much by listeners.

Another amplifier will not solve this issue, but EQ will.
I'd just try a quick fix - negative gain HF shelving by 2-3 dB above 5 kHz, and +3 dB bass shelving below 100 Hz.
Yes, you will require a laptop, a Y-cable (3.5 to 2 RCA) if you don't have one, and an hour to install and get yourself familiar with Equalizer APO + Peace (freeware).
Way cheaper to try than buying some Arcams, isn't it?

Similarly to OP, I just did this via the iTunes equalizer. Wow, marked improvement. Calmed the speakers down in a nice way (suddenly forget that I'm listening to speakers). Now I just need to figure out how to do the same for HT applications (some day), preferably without changing any gear. Either way, good to get a feel for how customizable the R-series really is.

Edit:
Yeah, why does KEF design them like that. Purely due to expected room gain?.. or perhaps to get a 'good' roll-off if/when using subs?

 

[CapMan]

Another white room full of hard surfaces sounds too bright. I sense a theme here. I'd put a nice thick 3" or maybe more absorber behind the listening position. You can get white polyester acoustic panels or sheets, should be able to find some in a large 2-3m X 1.2m perhaps, or use multiples of smaller, neater ones.

Could also try hanging one on reflection point at the window. Personally I'd be putting some at other places too but that may be too much for some people's aesthetics

These absorbers from Thomann are not too awful . Not as thick as I’d like @ 2” but better than nothing

 

[Willem]

Will these get dirty and can you paint them?

 

[CapMan]

Will these get dirty and can you paint them?

They need to be permeable to work effectively as absorbers, so I imagine paint might have a negative impact by sealing them.

Hopefully they won’t get too grubby!

 

[radix]

There's also ATS panels that are in 2" and 4". You can buy them direct through Amazon (and others). They also sell them as kits and custom sizes. They have many colors.

Acoustic Panels by ATS Acoustics

acoustic panels

www.atsacoustics.com

 

[steve59]

A local dealer i frequent got the Dali Epikore 11 in. A $60k a pr speaker and he was getting a +10 db gain in the treble due to the high back sofa similar to what you're using! He put a micro fiber towel down at head rest height and fixed the issue. I wouldn't have thought a leather/suede type finish could reflect so much energy, but he showed me the measurements.

 

[CapMan]

$60k a pr speaker and he was getting a +10 db gain in the treble due to the high back sofa similar to what you're using! He put a micro fiber towel down at head rest height and fixed the issue.

That’s seems like a huge amount of extra treble and I’m a little surprised a thin towel did anything to attenuate that !

Did he measure using REW - did he say which particular frequencies this lift was at?

 

[steve59]

I didn't ask what software or mic he used and also question my memory on what he put over the top of the sofa to get so much attenuation at the high fq's, but I want to offer the info to our op as a possible solution to try.

 

[jonfitch]

Most bookshelf speakers with limited bass extension will sound "bright" in a larger room. Either add a sub or if your listening levels aren't high, boost the bass slightly.