In this review, we will be comparing SCM11 and R3, two Passive Bookshelf speakers from ATC and KEF.
Let's have a brief look at the main features
of ATC SCM11 and KEF R3 first before getting into our more
detailed comparison.
| Key Specs | ATC SCM11 | KEF R3 |
|---|
| Design | 2-way | 3-way |
|---|
| Uni-Q driver | — | 12th Generation Uni-Q |
|---|
| Tweeter | 0.98" | 1" Dome |
|---|
| Midrange | — | 5" |
|---|
| Woofer | 5.91" | 6.5" Hybrid aluminum |
|---|
| Frequency response | 56-22k Hz | 52-28k Hz |
|---|
| Sensitivity | 85 dB | 87 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | 75 to 300 Watts watts | 15-180 watts |
|---|
| Weight | 10.90kg / 24lbs | 13.55kg / 29.8lbs |
|---|
| Dimensions (H x W x D) | 15" x 9.13" x 9.29"
381.0 x 232.0 x 236.0mm | 16-5/8" x 7-13/16" x 13-1/4"
423.0 x 199.0 x 337.0mm |
|---|
What size room are the ATC SCM11 and KEF R3 speakers good for?
The size of the room in which you are planning to use these loudspeakers is an important decision
factor. Here we have compared their suitability to various sizes of environments considering their size
and max power parameters:
| Listening Environment* |
ATC SCM11 |
KEF R3 |
| Near-field |
Good |
Poor |
| Small Room |
Good |
Average |
| Mid-size Room |
Average |
Good |
| Large Room |
Poor |
Average |
| Very Large Room |
No way |
Poor |
(* Approximate Room sizes: Small < 100sq. ft / 9 m2,
Mid-size: 100-220 sq. ft / 9-20 m2, Large 220-400 sq. ft / 20-36 m2, Very Large: >
400 sq. ft / 36 m2.
Average Floor Height: 9" / 2.7m. Typical room sizes differ from country to country, and the actual
listening experience changes depending on floor height, room shape, surface materials, listening
position, speaker locations, etc.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
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Drivers
One of the fundamental differences between these two speakers is that SCM11 is a 2-way design whereas the R3 is a 3-way speaker. 3-way designs utilize a midrange driver in addition to the tweeter and woofer on 2-way designs. Designing a crossover for a 3-way speaker is a complicated process and generally increases the overall cost of the speaker.
ATC SCM11KEF R3
TweeterMidrangeWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
ATC SCM11 |
KEF R3 |
|
Driver Setup
|
2-way
|
3-way
|
|
Tweeter
|
0.98-inch
|
1-inch
|
|
Midrange
|
- |
1 x 5-inch |
|
Woofer
|
1 x 5.91-inch
|
1 x 6.5-inch
|
SCM11 features a 0.98" Tweeter and 1 x 5.91" Woofer with a Crossover frequency at 2.2kHz. On the other hand, the R3 features a 1" aluminum Dome Tweeter, a 5" Midrange and 1 x 6.5" Hybrid aluminum Woofer with a Crossover frequency at 400Hz and 2900Hz.
Frequency Response
SCM11 has a frequency range of 56-22k Hz whereas R3 has a frequency range of 52-28k Hz. With a minimum frequency of 52Hz, the R3 can go slightly deeper then the SCM11's min frequency of 56Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
SCM11 and R3 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. SCM11 sensitivity is rated at 85 dB and the R3's is at 87 dB. This 2 dB difference makes the KEF R3 a more sensitive speaker compared to ATC SCM11, hence will play louder with the same amount of watts.
Sensitivity
Bookshelf Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
R3 can handle a max power of 180 watts RMS, whereas SCM11 has a max power handling value of watts RMS, 180 watts less than the R3.
Note that higher power handling does not make a speaker louder: that depends mainly on
sensitivity and impedance. The calculator below shows how loud each of these actually plays
on a real amplifier.
Which plays louder on your amplifier?
Starting with a popular amplifier — change it to the one you own, or any you are
considering, and watch both numbers move.
Input Type and Bi-Amping / Bi-Wiring
R3 features Binding post posts which make bi-amping or bi-wiring possible. SCM11 has a Binding Posts/4mm Plugs, bi-wire which doesn't feature bi-amping/bi-wiring.
KEF R3 Port
Physical Specs
The size of a speaker can sometimes be an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare ATC SCM11's and KEF R3's external dimensions. ATC SCM11 has external dimensions of 381.0 x 232.0 x 236.0mm (15 x 9.13 x 9.29inch) whereas KEF R3 has external dimensions of 423.0 x 199.0 x 337.0mm (16-5/8 x 7-13/16 x 13-1/4inch).
ATC SCM11 is 42mm shorter and 101mm less deeper than KEF R3 but it is also 33mm wider.
Base Surface Area Comparison
Base surface area of a loudspeaker may become a determining factor when the space in your room or desk is limited.
The base surface area of the ATC SCM11 is approximately 547.5cm2 / 84.9inch2 and base area of the KEF R3 is approximately 670.6cm2 / 103.9inch2. The SCM11 requires 18% less surface area than the R3 which gives it a small advantage on placement in tight spaces.
Weight Comparison The weight of a loudspeaker can become an important factor if you need to move and reposition the unit often. Weight of a speaker can also "sometimes" be an indicator of the rigidity of the enclosure and the quality of the internal components used. The ATC SCM11 weighs 10.90kg / 24lbs and the KEF R3 weighs 13.55kg / 29.8lbs. This makes the R3 24% heavier than the SCM11.
Here is a comparison of how SCM11 and R3's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of KEF R3?
Here are the items that come with the R3:
- 2 Bookshelf loudspeakers
- 2 Grilles
- 2 Foam port plugs
- 8 Self-adhesive rubber feet
- User Manual
- Warranty Information
 Height |
381mm
vs
423mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
547cm2
vs
670cm2
|
Takes less floor space |
 Driver Setup |
3-way
vs
2-way
|
Have a dedicated mid-range driver |
 Sensitivity |
87 dB
vs
85 dB
|
Play louder with same amount of amplification power |
 Woofer Size |
6.5 inches
vs
5.91 inches
|
Larger woofer |
|
Low Frequency Response |
52 Hz
vs
56 Hz
|
Generates deeper bass |
 High Frequency Response |
28k Hz
vs
22k Hz
|
Generates higher frequency |
 Price per pair* |
2200USD
vs
2699USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
ATC SCM11 |
KEF R3 |
| Brand |
ATC |
KEF |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
75 to 300 Watts watts |
15-180 watts |
| Sensitivity |
85 dB |
87 dB |
| Impedance |
8 ohms |
8 ohms |
| Impedance |
n/a |
3.2 ohms |
| Frequency Response |
56-22k Hz |
52-28k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.91" |
6.5" |
| Woofer Composition |
|
Hybrid aluminum |
| Woofer Surround Material |
n/a |
Rubber |
| Tweeter Size |
0.98" |
1" |
| Tweeter Type |
n/a |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
5" |
| Crossover Frequency |
2.2kHz |
400Hz and 2900Hz |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
381.0mm (15") |
423.0mm (16.7") |
| Width |
232.0mm (9.1") |
199.0mm (7.8") |
| Depth |
236.0mm (9.3") |
337.0mm (13.3") |
| Weight |
10.90kg (24lbs) |
13.55kg (29.8lbs) |
| Enclosure |
Sealed |
Bass Reflex |
| Finish |
n/a |
MDF/Lacquer |
| Available Colors |
n/a |
Black Gloss, White Gloss, Walnut |
| Mounting Bracket |
|
No |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
n/a |
Yes |
Other |
|
|
| Parts Warranty |
|
5 Years |
| Labor Warranty |
|
5 Years |
A generation apart: ATC SCM11 is the newer design, against a 2018 model. Newer is not automatically better, but the older one is more likely to be discounted or near run-out.
| Area | Better | Why |
|---|
| Bass |
B |
KEF R3 digs deeper - 52Hz against 56Hz. A subwoofer would even that out. |
| Amplifier needs |
B |
KEF R3 is more sensitive (87dB vs 85dB), so it goes louder on the same amplifier. |
| Size |
depends |
ATC SCM11 is easier to place; KEF R3 is bigger, which usually goes with fuller bass. Your room decides. |
| Cabinet |
depends |
Sealed vs Ported. Sealed is tighter and happier near a wall; ported digs lower but wants space behind it. |
| Expandability |
B |
KEF R3: bi-amping. |
| Price |
B |
KEF R3 is cheaper - $2,200 against $2,699, about 18% less. |
A ATC SCM11
B KEF R3
depends neither is better in the abstract - it turns on your room, placement or how you will use them.
Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
KEF R3 is the easier recommendation: it leads on most of the measured areas and costs less. Take ATC SCM11 if its size, looks or fit in your room suit you better. Match it to your room: we rate ATC SCM11 the better fit for near-field listening and a small room, and KEF R3 for a mid-size room and a large room. If your amplifier is modest, vintage or valve-based, KEF R3 is the safer partner - the other will want more current or more watts to sound its best.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.