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KEF Reference 4C Review (Center Speaker)

Rate this speaker:

  • 1. Poor (headless panther)

    Votes: 5 1.5%
  • 2. Not terrible (postman panther)

    Votes: 6 1.8%
  • 3. Fine (happy panther)

    Votes: 73 22.4%
  • 4. Great (golfing panther)

    Votes: 242 74.2%

  • Total voters
    326

Beershaun

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There it is! A coaxial center channel solves the horizontal dispersion problem. Fantastic. I wonder if a center channel equivalent of the LS50 would give the rest of us an affordable option that performs well enough. Give up a little low range for better dispersion
 

stevenswall

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Now, that’s an end-game center channel we’ve been waiting for.
Thanks for the review.

This or a Genelec or a Devialet Phantom... Or I imagine a Kali to some extent. So long as a speaker has coaxial drivers it shouldn't be busted like nearly all other center channel's I've seen.
 

id.ray

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This is a review and detailed measurements of the KEF Reference 4C Center home theater speaker. It was kindly purchased new by a member and drop shipped to me. 4C costs US $7,500.

View attachment 179847

Apology for using stock picture. Speaker weighs 100 pounds and I got interrupted mid-review with our home flooding so still in measurement room. I had finished the measurements though and hence this write up. You can't tell from above picture but this speaker is deep, very deep. The finish is gorgeous but I found a tiny blemish which was disappointing. Back bindings are custom tool metal ones and the best I have seen and felt. No question KEF has targeted high level of execution with this speaker.

A coaxial driver handles midrange and tweeter responsibility. Woofers then bring the bass along (3-way total).

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.

Reference axis was the center of the tweeter (aligned by eye). Measurement room was at 10 degrees C which may lower bass output a bit. I used a higher resolution scan than normal which turned out to not be necessary as the speaker is very well behaved in higher frequencies. Accuracy is better than 1% as a result in most of the frequency spectrum.

KEF 4C Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

View attachment 179848

While not ruler flan, on-axis response is very good. Even better is directivity index (dashed blue at the bottom) showing that important early reflections are similar to on-axis response which you can see better here:

View attachment 179849

Bass response is stepped down due to port tuning being low. We can see this in the near-field response:

View attachment 179850

Cabinet/port resonances are kept at bay so don't cause coloration in upper midrange as they usually do in ported speakers.

Predicted in-room response is excellent:
View attachment 179851

BTW, sensitivity is also excellent at 90 dB although you better have an amplifier that doesn't mind the very low impedance dip of just 2.9 ohm:

View attachment 179852

The quad bass drivers and capable mid-range translate into incredibly low distortion and power capability:

View attachment 179853
View attachment 179854

The biggest issue with the design of most center speakers is that the doubled up woofer/mid-woofer causes horizontal dispersion to narrow due to timing differential between them. Is that solved here with the coaxial mid-range/mid-woofer? Let's see:


View attachment 179855

View attachment 179856

Speaker is so wide that there is still good bit of distance between the woofers causing some cancellation. But generally, this is way better than most center speakers we have tested.

The vertical response though shows how good this could be if all the drivers were aligned horizontally:

View attachment 179857

For fan of timing analysis, here are the rest of the measurements of that type:
View attachment 179860
View attachment 179861


View attachment 179862

Listening Tests
I was in the process of wiring up the speaker to listen to it in the measurement lab when my worried wife ran into the room and said: "downstairs bathroom is flooding!" I rushed out to deal with that and have not had a chance to listen to the 4C yet. I hope to still get a chance to do so and report back.

Conclusions
The fit and finish, design and capabilities of the 4C clearly show that this is a very serious engineering effort by KEF to produce a highly capable center speaker. Physics of sound wavelengths still attack it a bit causing slight narrowing of directivity but otherwise, it is very hard to find fault with this speaker.

I am going to recommend the KEF 4C based on objective data and subjective look and feel of the unit. I expect it to be a super capable center speaker and a great one for 2-channel listening if you use it vertically.

-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Yeah, if you have an acoustically transparent projector screen this is the center channel turned up vertically. Maybe even three of them across the front. Alas that is a $22.5 k problem.

This is a review and detailed measurements of the KEF Reference 4C Center home theater speaker. It was kindly purchased new by a member and drop shipped to me. 4C costs US $7,500.

View attachment 179847

Apology for using stock picture. Speaker weighs 100 pounds and I got interrupted mid-review with our home flooding so still in measurement room. I had finished the measurements though and hence this write up. You can't tell from above picture but this speaker is deep, very deep. The finish is gorgeous but I found a tiny blemish which was disappointing. Back bindings are custom tool metal ones and the best I have seen and felt. No question KEF has targeted high level of execution with this speaker.

A coaxial driver handles midrange and tweeter responsibility. Woofers then bring the bass along (3-way total).

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.

Reference axis was the center of the tweeter (aligned by eye). Measurement room was at 10 degrees C which may lower bass output a bit. I used a higher resolution scan than normal which turned out to not be necessary as the speaker is very well behaved in higher frequencies. Accuracy is better than 1% as a result in most of the frequency spectrum.

KEF 4C Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

View attachment 179848

While not ruler flan, on-axis response is very good. Even better is directivity index (dashed blue at the bottom) showing that important early reflections are similar to on-axis response which you can see better here:

View attachment 179849

Bass response is stepped down due to port tuning being low. We can see this in the near-field response:

View attachment 179850

Cabinet/port resonances are kept at bay so don't cause coloration in upper midrange as they usually do in ported speakers.

Predicted in-room response is excellent:
View attachment 179851

BTW, sensitivity is also excellent at 90 dB although you better have an amplifier that doesn't mind the very low impedance dip of just 2.9 ohm:

View attachment 179852

The quad bass drivers and capable mid-range translate into incredibly low distortion and power capability:

View attachment 179853
View attachment 179854

The biggest issue with the design of most center speakers is that the doubled up woofer/mid-woofer causes horizontal dispersion to narrow due to timing differential between them. Is that solved here with the coaxial mid-range/mid-woofer? Let's see:


View attachment 179855

View attachment 179856

Speaker is so wide that there is still good bit of distance between the woofers causing some cancellation. But generally, this is way better than most center speakers we have tested.

The vertical response though shows how good this could be if all the drivers were aligned horizontally:

View attachment 179857

For fan of timing analysis, here are the rest of the measurements of that type:
View attachment 179860
View attachment 179861


View attachment 179862

Listening Tests
I was in the process of wiring up the speaker to listen to it in the measurement lab when my worried wife ran into the room and said: "downstairs bathroom is flooding!" I rushed out to deal with that and have not had a chance to listen to the 4C yet. I hope to still get a chance to do so and report back.

Conclusions
The fit and finish, design and capabilities of the 4C clearly show that this is a very serious engineering effort by KEF to produce a highly capable center speaker. Physics of sound wavelengths still attack it a bit causing slight narrowing of directivity but otherwise, it is very hard to find fault with this speaker.

I am going to recommend the KEF 4C based on objective data and subjective look and feel of the unit. I expect it to be a super capable center speaker and a great one for 2-channel listening if you use it vertically.

-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are

This is a review and detailed measurements of the KEF Reference 4C Center home theater speaker. It was kindly purchased new by a member and drop shipped to me. 4C costs US $7,500.

View attachment 179847

Apology for using stock picture. Speaker weighs 100 pounds and I got interrupted mid-review with our home flooding so still in measurement room. I had finished the measurements though and hence this write up. You can't tell from above picture but this speaker is deep, very deep. The finish is gorgeous but I found a tiny blemish which was disappointing. Back bindings are custom tool metal ones and the best I have seen and felt. No question KEF has targeted high level of execution with this speaker.

A coaxial driver handles midrange and tweeter responsibility. Woofers then bring the bass along (3-way total).

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.

Reference axis was the center of the tweeter (aligned by eye). Measurement room was at 10 degrees C which may lower bass output a bit. I used a higher resolution scan than normal which turned out to not be necessary as the speaker is very well behaved in higher frequencies. Accuracy is better than 1% as a result in most of the frequency spectrum.

KEF 4C Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

View attachment 179848

While not ruler flan, on-axis response is very good. Even better is directivity index (dashed blue at the bottom) showing that important early reflections are similar to on-axis response which you can see better here:

View attachment 179849

Bass response is stepped down due to port tuning being low. We can see this in the near-field response:

View attachment 179850

Cabinet/port resonances are kept at bay so don't cause coloration in upper midrange as they usually do in ported speakers.

Predicted in-room response is excellent:
View attachment 179851

BTW, sensitivity is also excellent at 90 dB although you better have an amplifier that doesn't mind the very low impedance dip of just 2.9 ohm:

View attachment 179852

The quad bass drivers and capable mid-range translate into incredibly low distortion and power capability:

View attachment 179853
View attachment 179854

The biggest issue with the design of most center speakers is that the doubled up woofer/mid-woofer causes horizontal dispersion to narrow due to timing differential between them. Is that solved here with the coaxial mid-range/mid-woofer? Let's see:


View attachment 179855

View attachment 179856

Speaker is so wide that there is still good bit of distance between the woofers causing some cancellation. But generally, this is way better than most center speakers we have tested.

The vertical response though shows how good this could be if all the drivers were aligned horizontally:

View attachment 179857

For fan of timing analysis, here are the rest of the measurements of that type:
View attachment 179860
View attachment 179861


View attachment 179862

Listening Tests
I was in the process of wiring up the speaker to listen to it in the measurement lab when my worried wife ran into the room and said: "downstairs bathroom is flooding!" I rushed out to deal with that and have not had a chance to listen to the 4C yet. I hope to still get a chance to do so and report back.

Conclusions
The fit and finish, design and capabilities of the 4C clearly show that this is a very serious engineering effort by KEF to produce a highly capable center speaker. Physics of sound wavelengths still attack it a bit causing slight narrowing of directivity but otherwise, it is very hard to find fault with this speaker.

I am going to recommend the KEF 4C based on objective data and subjective look and feel of the unit. I expect it to be a super capable center speaker and a great one for 2-channel listening if you use it vertically.

-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
They have a deal right now for 2 of them in an LR config

 

DHT 845

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7 of these and a good sub and we have nice HT speaker setup for ab. $55.000.
 

Robbo99999

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I gave this speaker a "Great" vote in the poll, it's the best measuring centre speaker I remember seeing, have we measured a better one? Either way it's miles better than most in terms of directivity (& also distortion) and also frequency response. The price is huge though. (I might change my vote to "Fine" if Amir's updated listening test doesn't come back positive, but I expect it will.)
 

RndmLstner

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A comparison to the Revel Voice2 (center for the Salon2 series) would be interesting given they are each the top model of 2 well-respected brands (Revel v KEF) yet have very different (& unique) designs.

I'm particularly interested because I have Salon2s as my L/R and a Voice2 as a center. The Salon2s are great. In sharp contrast, I've always been underwhelmed with the Voice2. I'm about to replace the processor (integra 80.2 w/ audyssey xt32 original) w/ an onkyo tx-rz50 (using its pre outs - uses Dirac) so this will test my current working theory (that audyssey xt32 BBC dip is causing it - cant turn that dip off w 80.2 version of audyssey; honestly don't know if this theory makes sense but it's the only thing I've come up with to explain my underwhelmed response since it's generally considered a great center speaker. My only other theory is my speaker is defective somewhere. I have a umik but never got around to running rew to see if there is an obvious abnormailty).

The Voice2 has not been tested here. Does anyone have a link to Klippel results by someone else (maybe even Revel)? In any event, it'd be an interesting review by Amir, particularly now that this center speaker has been tested.
 
Last edited:

sifi36

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Makes me want to see what the Reference 1's, 3's, and 5's are capable of.

Don't think anyone mentioned how visually stunning it is.

Understand they also wall mount the Reference Series. Quite a look

ci5160-header.jpg
I believe that’s the in-wall models, Ci5160RL and Ci3160RL. At £5300 MSRP for the pictured trio somewhat more affordable! Certainly more so than the in-wall Reference Ci5160REF!

 

pierre

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I get similar results as @Maiky76. I limited the PEQ to Q=2 and I get:

Code:
         SPK auEQ
-----------------
NBD  ON 0.55 0.49
NBD  LW 0.38 0.30
NBD PIR 0.32 0.25
SM  PIR 0.84 0.94
SM   SP 0.97 0.97
LFX       29   29
LFQ     1.43 1.43
-----------------
Score    6.0  6.6
w/sub    7.3  7.9
-----------------
+5.99 +6.60 KEF Reference 4C

which yields the following:

filters_eq.png

The eq is :
Code:
EQ for KEF Reference 4C computed from ASR data
Preference Score 6.0 with EQ 6.6
Generated from http://github.com/pierreaubert/spinorama/generate_peqs.py v0.14
Dated: 2022-01-18-08:44:52

Preamp: -2.5 dB

Filter  1: ON PK Fc  1045 Hz Gain +1.00 dB Q 1.96
Filter  2: ON PK Fc  1761 Hz Gain -1.11 dB Q 0.46
Filter  3: ON PK Fc  1093 Hz Gain +1.04 dB Q 1.91
Filter  4: ON PK Fc 13699 Hz Gain +2.36 dB Q 1.71
Filter  5: ON PK Fc   344 Hz Gain +0.95 dB Q 2.00
Filter  6: ON PK Fc   151 Hz Gain -0.58 dB Q 0.19
Filter  7: ON PK Fc  5217 Hz Gain -0.93 dB Q 1.96
Filter  8: ON PK Fc  8556 Hz Gain +0.50 dB Q 1.99
Filter  9: ON PK Fc   340 Hz Gain +0.71 dB Q 1.99

For this speaker, the PIR is really good out of the box and I think I would not use an EQ above Schroeder, a listening would rules that out.
 

FeddyLost

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it shouldn't be busted like nearly all other center channel's I've seen.
I think 3-way with custom waveguide (for both tweeter and mid) like modern version of ATC C6C may somehow compete with coax.
Obvoiusly, no line array without WG can have decent DI.
 

Rja4000

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The biggest issue with the design of most center speakers is that the doubled up woofer/mid-woofer causes horizontal dispersion to narrow due to timing differential between them. Is that solved here with the coaxial mid-range/mid-woofer? Let's see:


KEF REFERENCE 4C Measurement Horizontal Beam width Response Centre Channel Speaker.png


KEF REFERENCE 4C Measurement Horizontal Directivity Response Centre Channel Speaker.png


Speaker is so wide that there is still good bit of distance between the woofers causing some cancellation. But generally, this is way better than

This result seems strange to me.

Why is it narrowing at 500Hz, while, at that frequency, it mostly uses the (unique) Coax driver ?
The multiple bass drivers' contribution should be low at 500Hz.

Is that a consequence of the box itself ?

Would we get better results with, say, only 2 bass drivers ?
 
Last edited:

3125b

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I’d never spend that much, but this does bode well for the R2c that, with less but still respectable bass extension, only costs 800€.
3-way centers are definitely the way to go.
 

Badou

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I'm very interested to see how his little brother, the q650c perform.
 

Beave

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The impedance is low, as Amir mentions, but that is somewhat ameliorated by the high sensitivity and by the fact that the phase angles of the impedance are quite mild (ranging from about -25 deg to +25 deg).

The distortion measurements appear to be excellent.

As for the R2C, Erin measured it last summer:

Erin's Review of KEF R2C center
 

MZKM

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This result seems strange to me.

Why is it narrowing at 500Hz, while, at that frequency, it mostly uses the (unique) Coax driver ?
The multiple bass drivers' contribution should be low at 500Hz.

Is that a consequence of the box itself ?

Would we get better results with, say, only 2 bass drivers ?
The crossover is stated at 350Hz, so if it’s a low order slope then it still has some contribution. I wonder is the R2C does better at the loss of the higher sensitivity.
 

TheTalbotHound

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Makes me want to see what the Reference 1's, 3's, and 5's are capable of.

Don't think anyone mentioned how visually stunning it is.

Understand they also wall mount the Reference Series. Quite a look

ci5160-header.jpg
Pierre Aubert has some very limited vendor data for the KEF Reference 5, but what is there is truly top level. Perfect directivity, very good bass extension, and very close to perfect FR.

If you have that amount of money to spend on speakers, KEF seems like the best choice. The Genelec coaxial monitors are great too but idk how they fare in compression tests comparatively since they are intended for nearer field use, as opposed to the KEF towers that are made more for home hi-fi or home theater.
 
Last edited:

Matias

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