In this review, we will be comparing Special Forty and LS50, two Passive Bookshelf speakers from Dynaudio and KEF.
Let's have a brief look at the main features
of Dynaudio Special Forty and KEF LS50 first before getting into our more
detailed comparison.
| Key Specs | Dynaudio Special Forty | KEF LS50 |
|---|
| Brand | Dynaudio
Denmark · founded 1977 | KEF
United Kingdom · founded 1961 |
|---|
| Design | 2-way | 2-way |
|---|
| Uni-Q driver | — | 11th Generation Uni-Q |
|---|
| Tweeter | 1.1" Soft-Dome | 1" Vented dome |
|---|
| Woofer | 6.5" MSP | 5.25" Magnesium/aluminum alloy |
|---|
| Frequency response | 41-23k Hz | 79-28k Hz |
|---|
| Sensitivity | 86 dB | 85 dB |
|---|
| Impedance | 6 ohms | 8 ohms |
|---|
| Power range | — | 25-100 watts |
|---|
| Weight | 8.10kg / 17.8lbs | 7.20kg / 15.8lbs |
|---|
| Dimensions (H x W x D) | 14-3/16" x 7-13/16" x 12-1/16"
360.0 x 198.0 x 307.0mm | 11.8" x 7.8" x 10.9"
302.0 x 200.0 x 278.0mm |
|---|
What size room are the Dynaudio Special Forty and KEF LS50 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* |
Dynaudio Special Forty |
KEF LS50 |
| Near-field |
Good |
Average |
| Small Room |
Good |
Good |
| Mid-size Room |
Average |
Average |
| Large Room |
Poor |
Poor |
| Very Large Room |
No way |
Bad |
(* 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.
Drivers
Both Special Forty and LS50 are 2-way speakers.
Dynaudio Special FortyKEF LS50
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Dynaudio Special Forty |
KEF LS50 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1.1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 6.5-inch
|
1 x 5.25-inch
|
Special Forty features a 1.1" Esotar Forty Soft-Dome Tweeter and 1 x 6.5" MSP Woofer with a Crossover frequency at 2000 Hz. On the other hand, the LS50 features a 1" Aluminum Vented dome Tweeter and 1 x 5.25" Magnesium/aluminum alloy Woofer with a Crossover frequency at 2200Hz.
Frequency Response
Special Forty has a frequency range of 41-23k Hz whereas LS50 has a frequency range of 79-28k Hz. With a minimum frequency of 41Hz, the Special Forty can go significantly deeper on the low side and provide stronger bass compared to the LS50's min frequency of 79Hz.
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
Special Forty is a 6 ohms speaker compared to the LS50 which has a nominal impedance of 8 ohms.
These two speakers also have different sensitivity levels. Special Forty sensitivity is rated at 86 dB and the LS50's is rated at 85 dB. This 1 dB difference makes the Dynaudio Special Forty a more sensitive speaker compared to KEF LS50, hence will play louder with the same amount of watts.
Sensitivity
Bookshelf Speakers
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
Special Forty features Post type posts and LS50 has a Post type posts. None of these speakers feature bi-amping/bi-wiring.
KEF LS50's Post terminals
Cabinet Type and Port Position
Both Special Forty and LS50 have rear firing ports. Rear ported speakers generally need more room between the backside of the speaker and the wall compared to sealed and front/bottom ported speakers. Placing the speakers too close to the walls may cause the bass to sound boomy.
If you are limited in space and can't get the speakers away from the backwall, check our Speakers with Front Firing Ports page.
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 Dynaudio Special Forty's and KEF LS50's external dimensions. Dynaudio Special Forty has external dimensions of 360.0 x 198.0 x 307.0mm (14-3/16 x 7-13/16 x 12-1/16inch) whereas KEF LS50 has external dimensions of 302.0 x 200.0 x 278.0mm (11.8 x 7.8 x 10.9inch).
KEF LS50 is 58mm shorter and 29mm less deeper than Dynaudio Special Forty but it is also 2mm wider.
Size, drawn to scale
Both speakers and both views share one scale, so everything here is directly comparable. Hover a box for its dimensions.
One scale for both, standing on the same surface and pushed back to the same wall, so the deeper one visibly sticks out further.
Dynaudio Special Forty needs about 9% more floor or shelf area. Dynaudio Special Forty is 29mm deeper, so it stands that much further out from the wall. Dynaudio Special Forty is 58mm taller.
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 Dynaudio Special Forty is approximately 607.9cm2 / 94.2inch2 and base area of the KEF LS50 is approximately 556.0cm2 / 86.2inch2. The Special Forty requires 9% more surface area than the LS50 which gives it a small disadvantage 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 Dynaudio Special Forty weighs 8.10kg / 17.8lbs and the KEF LS50 weighs 7.20kg / 15.8lbs. This makes the Special Forty 13% heavier than the LS50.
Here is a comparison of how Special Forty and LS50'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 LS50?
Here are the items that come with the LS50:
- 2 Bookshelf loudspeakers
- 2 Foam port plugs
- 8 Self-adhesive rubber feet
- Owner's Manual
- Warranty Registration Card
 Max Input Power |
200 watts
vs
100 watts
|
Handle more power from your amplifier |
 Sensitivity |
86 dB
vs
85 dB
|
Play louder with same amount of amplification power |
 Woofer Size |
6.5 inches
vs
5.25 inches
|
Larger woofer |
|
Low Frequency Response |
41 Hz
vs
79 Hz
|
Generates deeper bass |
 Nominal Impedance |
8 ohms
vs
6 ohms
|
Less selective with amplifiers |
 High Frequency Response |
28k Hz
vs
23k Hz
|
Generates higher frequency |
 Height |
302mm
vs
360mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
556cm2
vs
607cm2
|
Takes less floor space |
 Price per pair* |
1300USD
vs
2999USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
Dynaudio Special Forty |
KEF LS50 |
| Brand |
Dynaudio |
KEF |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Sensitivity |
86 dB |
85 dB |
| Impedance |
6 ohms |
8 ohms |
| Impedance |
n/a |
3.2 ohms |
| Frequency Response |
41-23k Hz |
79-28k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6.5" |
5.25" |
| Woofer Composition |
MSP |
Magnesium/aluminum alloy |
| Woofer Surround Material |
n/a |
Rubber |
| Tweeter Size |
1.1" |
1" |
| Tweeter Type |
Soft-Dome |
Vented dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
2000 Hz |
2200Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
360.0mm (14.2") |
302.0mm (11.9") |
| Width |
198.0mm (7.8") |
200.0mm (7.9") |
| Depth |
307.0mm (12.1") |
278.0mm (10.9") |
| Weight |
8.10kg (17.8lbs) |
7.20kg (15.8lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
n/a |
Polymer/Lacquer |
| Available Colors |
n/a |
Black, High Gloss Piano Black, High Gloss Piano White |
| Mounting Bracket |
|
No |
| Recommended Stand Height |
n/a |
18-28" |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
No |
Other |
|
|
| Parts Warranty |
|
5 Years |
| Labor Warranty |
|
5 Years |
These sit in different price classes - Dynaudio Special Forty costs roughly 2.3x what KEF LS50 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 | A | Dynaudio Special Forty digs deeper - 41Hz against 79Hz. |
| Amplifier needs | evenly matched | Similar sensitivity (86dB vs 85dB) - both want much the same power. |
| Amplifier match | B | KEF LS50 is the easier load at 8 ohms. |
| Headroom | A | Dynaudio Special Forty takes more power (200W vs 100W) - more in hand in a big room. |
| Size | depends | KEF LS50 is easier to place; Dynaudio Special Forty is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | Neither adds bi-amping, a sub output or height drivers. KEF LS50 sits in a wider range (10 models), so a matched surround system is easier later. |
| Price | B | KEF LS50 is cheaper - $1,300 against $2,999, about 57% less; arguably a different class. |
A Dynaudio Special Forty B KEF LS50
depends neither is better in the abstract - it turns on your room, your system 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?
Dynaudio Special Forty is ahead, but only on 1 of the measured areas, and it costs about 131% more. That is a lot of money for a narrow margin on paper - KEF LS50 looks like the sensible buy unless something else about the Dynaudio Special Forty appeals to you. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 79Hz anyway, which makes the cheaper KEF LS50 much easier to justify. Match it to your room: we rate Dynaudio Special Forty the better fit for near-field listening; elsewhere the two are rated the same.
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.