KEF ci250RRM-THX In-ceiling Speaker Review

[kyuu]

I have to wonder if it would be possible to drop the mid-tweeter unit from those into an LS 50 cabinet and get a much more performant speaker. Maybe for sale as a spare part? I think the mid-tweet is the same size as the LS 50 Meta unit.

I think the infinite baffle, 10" woofer, and 3-way crossover is doing most of the magic so I'm not sure about that.

 

[kyuu]

Yeah I've got pretty cheap ceiling speakers in my setup as well and they seem fine.

These seem like they should be used for in-wall mains more than Atmos. Maybe Atmos for a serious theater setup.

 

[jhaider]

If only the Uni-Q were angled instead of firing straight down. This and their 8” model would be so much compelling for immersive if they were configured properly.

 

[SuicideSquid]

If only the Uni-Q were angled instead of firing straight down. This and their 8” model would be so much compelling for immersive if they were configured properly.

Why? The whole point of this design is that it provides balanced sound when you're not sitting directly under the speaker - which is the ideal configuration for overhead and surround use.

 

[Alice of Old Vincennes]

I use what may be called the baby brother to these - the Kef Ci200R-THX (also reviewed by Amir - Amir's Review of Ci200R-THX).

Quite a bit less expensive and a fantastic ceiling speaker to go with the rest of my Kef setup. The ci250RRM-THX takes it to a whole new level by comparison. As others have mentioned, it's actually priced very competitively considering what it is and the likely relatively low sales volume. Yet another great speaker by Kef!

Priced competitavely to what? Might as well bolt tower speakers to ceiling. Put some foam in 200 speakers instead. Price is ridiculous.

 

[jhaider]

Why? The whole point of this design is that it provides balanced sound when you're not sitting directly under the speaker - which is the ideal configuration for overhead and surround use.

That’s not my interpretation of the data. There’s a small window where it works, with dullness on the outside and hot-spotting on the inside. And the overall sound power is of course tipped up compared to a speaker designed to be listened to on axis.

Properly aimed drive units just work so much better.

 

[restorer-john]

So you end up building a cabinet for each of these speakers in a normal roof (trusses)?

The say the ideal rear volume is 150L and the minimum rear volume is 80L. @amirm what rear volume did you use?

 

[JSmith]

what rear volume did you use?

Klippel NFS Baffle system

NFS – Near Field Scanner Baffle - Assembly — Klippel Manual 2.0 documentation

www.klippel.de

which creates anechoic measurements from a speaker mounted in a square panel. It automatically excludes edge diffractions and back energy in addition to its standard reflection elimination. The result is a "2 pi" response of the speaker as if it is mounted in a very large panel.

JSmith

 

[Old_School_Brad]

NFS – Near Field Scanner Baffle - Assembly — Klippel Manual 2.0 documentation

www.klippel.de

JSmith

Yeah, but this would be more like the driver's response in an infinite baffle. It’s useful for capturing frequency response and distortion profile but doesn’t reflect the low-frequency behavior you'd get in an actual enclosure. I think Amir should've included a note about this in the review, as most people likely don’t know what “2 Pi” really means.
Or does the Klippel NFS simulate an enclosure? – Probably not, since it’s described as a 2 Pi measurement. I’m not too familiar with the specifics of the NFS software, though.

 

[JSmith]

It’s useful for capturing frequency response and distortion profile but doesn’t reflect the low-frequency behaviour you'd get in an actual enclosure.

Sure, but then this is how Amir tests all in wall and ceiling speakers, providing a dataset that can be compared across measurements for different speakers.

I suppose someone could build and donate a 100 cm x 50 cm x 30 cm (150L) enclosure.


JSmith

 

[SuicideSquid]

That’s not my interpretation of the data. There’s a small window where it works, with dullness on the outside and hot-spotting on the inside. And the overall sound power is of course tipped up compared to a speaker designed to be listened to on axis.

Properly aimed drive units just work so much better.

I think you're misinterpreting the data. I'd say frequency response for these speakers is very good from around 20-70 degrees off axis, and fantastic from 30-50 degrees. If your ears are around 5-6 feet from the ceiling while seated, then you start being in that sweet spot when you're only two feet off centre, and that sweet spot extends to about 16' off centre. If I installed these in my living room that would make the sweet spot my entire living room excluding a 2' radius directly under the speaker. That's going to give a much better experience for every listening position in my room than an aimed driver would.

 

[amirm]

The say the ideal rear volume is 150L and the minimum rear volume is 80L. @amirm what rear volume did you use?

From the white paper:

"All KEF architectural loudspeakers are designed as infinite baffle, with all the required stiffness built into the driver. This means that no stiffness reinforcement is required from the finite and fixed air volume provided by a backbox. Instead, the installer can focus on ensuring that the enclosure is of a large enough size to take advantage of the low frequency output capabilities of a KEF architectural loudspeaker."

As I noted in the review, my measurements simulate infinite baffle. Same model as KEF assumes. As to what is in the spec, the white paper explains:

"To provide maximum flexibility, KEF publishes a ‘Ci Cabinet Volume’ table modelled. This table lists all current KEF architectural models and provides a minimum enclosure volume for ‘Reasonable’ and ‘Ideal' bass response. The volumes are calculated so that the final bass response meets a certain level of flatness when the enclosure is empty: 1dB overshoot for ‘Reasonable’ and 0.5dB overshoot for ‘Ideal.’ The use of wadding material, such as polyester fibre in the enclosure can help smooth the overshoot. Ci250RRMTHX is specified as requiring an 80L enclosure for ‘Reasonable’ bass and 150L for ‘Ideal.’"

My measurements reflect the red line. An enclosure of any size, would slightly change the response per above. But since no one knows what the air volume really is in any installation, I go by infinite baffle.

 

[amirm]

I should add that the above is for any backbox you build. Standard buildings have leaking construction so are very close to the infinite baffle.

 

[thewas]

I have to wonder if it would be possible to drop the mid-tweeter unit from those into an LS 50 cabinet and get a much more performant speaker. Maybe for sale as a spare part? I think the mid-tweet is the same size as the LS 50 Meta unit.

No, it is a mid-tweeter Uni-Q like on all KEF 3-way models that has smaller surround and X-max which are needed for a 2-way design.

 

[vkvedam]

I admire KEF, they are engineers foremost, who are enthusiastic about speakers and audio

 

[pavuol]

don't shoot me but it really looks like the HEPA filter for your industrial vacuum cleaner

 

[ThELiZ]

I see people complaining about the price, and I get that, especially if using these for Atmos channels... But aren't these better suited as in ceiling LCR? That's how I'd use them, especially if I were using a TV over a projector. If I'm using a projector, then I'll have the speakers behind the screen.

I think these are incredible and would definitely be using them for my next theatre.

 

[beagleman]

Wow, what a great job by KEF. Impressive. The price tag is justified when you know that they will not be sold in large numbers, so R&D costs must be spread over a smaller number.

Hmm, I have to wonder though if potential buyers make a decision based on a high price being "justified", or simply want something decent at a reasonable price?

I mean we are talking about a relatively simple "Speaker" not luxury watches, Cars or Purses or clothing.
As I said earlier, yes I could easily "Afford" these, but the poor to mediocre value, makes me cringe.

 

[kawauso]

I see people complaining about the price, and I get that, especially if using these for Atmos channels... But aren't these better suited as in ceiling LCR? That's how I'd use them, especially if I were using a TV over a projector. If I'm using a projector, then I'll have the speakers behind the screen.

I think these are incredible and would definitely be using them for my next theatre.

I think hearing the LCR sound coming from above your head would feel unnatural. It would primarily serve as a high-end Atmos speaker.

 

[5150]

Hmm, I have to wonder though if potential buyers make a decision based on a high price being "justified", or simply want something decent at a reasonable price?

I mean we are talking about a relatively simple "Speaker" not luxury watches, Cars or Purses or clothing.
As I said earlier, yes I could easily "Afford" these, but the poor to mediocre value, makes me cringe.

Funny you mention luxury goods in the same sentence you argue it's just a speaker... Speakers are luxury goods. Speakers for Atmos or in wall installation even moreso. It doesn't have to be priced in any way like it's simple, because it's not.

Many people using these will be doing ground up home theater builds. The speakers will only be a small portion the total cost.

These are so overkill for ceiling though. Much better as an in wall bed channel