ATC SCM20PSL vs KEF R3 Comparison

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ATC SCM20PSL

Passive Bookshelf | 55-25k Hz

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KEF R3

Passive Bookshelf | 52-28k Hz

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ATC SCM20PSL

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KEF R3

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ATC SCM20PSL

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KEF R3

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ATC SCM20PSL vs KEF R3 Speaker Comparison

In this review, we will be comparing SCM20PSL and R3, two Passive Bookshelf speakers from ATC and KEF.

Let's have a brief look at the main features of ATC SCM20PSL and KEF R3 first before getting into our more detailed comparison.

Key Specs	ATC SCM20PSL	KEF R3
Design	2-way	3-way
Uni-Q driver	—	12th Generation Uni-Q
Tweeter	—	1" Dome
Midrange	—	5"
Woofer	—	6.5" Hybrid aluminum
Frequency response	55-25k Hz	52-28k Hz
Sensitivity	85 dB	87 dB
Impedance	—	8 ohms
Power range	75W-300W watts	15-180 watts
Weight	—	13.55kg / 29.8lbs
Dimensions (H x W x D)	—	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 SCM20PSL 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 SCM20PSL	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.

**This post contains affiliate links, and we will be compensated if you make a purchase after clicking through our links. As an Amazon Associate I earn from qualifying purchases.

Drivers

One of the fundamental differences between these two speakers is that SCM20PSL 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.

Driver	ATC SCM20PSL	KEF R3
Driver Setup	2-way	3-way
Tweeter	-inch	1-inch
Midrange	-	1 x 5-inch
Woofer	1 x -inch	1 x 6.5-inch

SCM20PSL features a " Tweeter and 1 x " 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

SCM20PSL has a frequency range of 55-25k 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 SCM20PSL's min frequency of 55Hz.

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

SCM20PSL

Min

Average

Median

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

SCM20PSL is a ohms speaker compared to the R3 which has a nominal impedance of 8 ohms.

These two speakers also have different sensitivity levels. SCM20PSL sensitivity is rated at 85 dB and the R3's is rated at 87 dB. This 2 dB difference makes the KEF R3 a more sensitive speaker compared to ATC SCM20PSL, hence will play louder with the same amount of watts.

Sensitivity

Bookshelf Speakers

SCM20PSL

Min

Average

Median

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 SCM20PSL 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.

Input Type and Bi-Amping / Bi-Wiring

R3 features Binding post posts which make bi-amping or bi-wiring possible. SCM20PSL has a 1 x Rear Panel Mounted Female XLR, pin 2 hot 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 SCM20PSL's and KEF R3's external dimensions. ATC SCM20PSL has external dimensions of () 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).

KEF R3 is clearly the larger of the two speakers. Its body is 199mm wider, 423mm taller and 337mm deeper than ATC SCM20PSL.

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

Reasons to choose ATC SCM20PSL over KEF R3

Height	0mm vs 423mm	Easier to fit in smaller spaces
Base Surface Area	0cm² vs 670cm²	Takes less floor space

Reasons to choose KEF R3 over ATC SCM20PSL

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 inches	Larger woofer
Low Frequency Response	52 Hz vs 55 Hz	Generates deeper bass
High Frequency Response	28k Hz vs 25k Hz	Generates higher frequency
Price per pair*	2200USD vs 6499USD	costs less (*prices may change depending on the seller, location and time)

ATC SCM20PSL vs KEF R3 Specs Table

Detailed comparison of specifications

General	ATC SCM20PSL	KEF R3
Brand	ATC	KEF
Speaker Type	Bookshelf speakers	Bookshelf speakers
Power Range	75W-300W watts	15-180 watts
Sensitivity	85 dB	87 dB
Impedance	n/a	8 ohms
Impedance	n/a	3.2 ohms
Frequency Response	55-25k Hz	52-28k Hz
Drivers
Woofer Quantity	1	1
Woofer Size	"	6.5"
Woofer Composition		Hybrid aluminum
Woofer Surround Material	n/a	Rubber
Tweeter Size	-	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	mm (0")	423.0mm (16.7")
Width	mm (0")	199.0mm (7.8")
Depth	mm (0")	337.0mm (13.3")
Weight	n/a	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

Verdict

These sit in different price classes - ATC SCM20PSL costs roughly 3x what KEF R3 does. Expect it to lead on paper; the question is whether the gap is audible enough in your room to be worth it.

Area	Better	Why
Bass	B	KEF R3 digs deeper - 52Hz against 55Hz. 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.
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 $6,499, about 66% less; arguably a different class.

A ATC SCM20PSL 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 SCM20PSL if its size, looks or fit in your room suit you better. Match it to your room: we rate ATC SCM20PSL 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.