In this review, we will be comparing Q650c and R400, two Passive Center Channel speakers from KEF and Polk Audio. Let's have a brief look at the main features
of KEF Q650c and Polk R400 first before getting into our more
detailed comparison.
What size room are the KEF Q650c and Polk R400 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:
In the following sections, we will get into more detail in order to better understand how the KEF Q650c and Polk R400 compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
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Drivers
Both Q650c and R400 are 2-way speakers.
| Driver |
KEF Q650c |
Polk R400 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
2 x 6.5-inch
|
2 x 6.5-inch
|
Q650c features a 1" vented aluminum Dome Tweeter and 2 x 6.5" aluminum Woofer with a Crossover frequency at 2500Hz. On the other hand, the R400 features a 1" Pinnacle Ring Radiator Tweeter and 2 x 6.5" Polypropylene Turbine Cone Woofer with a Crossover frequency at 2500Hz.
Frequency Response
Q650c has a frequency range of 64-28k Hz whereas R400 has a frequency range of 48-39K Hz. With a minimum frequency of 48Hz, the R400 can go significantly deeper on the low side and provide stronger bass compared to the Q650c's min frequency of 64Hz.
Below graphs depict how these two speakers compare with the max, min and average values of the Min and Max Frequencies of other speakers in the Center Channel class in our database.
Low Frequency
Center Channel Speakers
High Frequency
Center Channel Speakers
None of these speakers achieves full range experience which is commonly agreed as 20Hz-20kHz. In order to achieve lower lows / deeper bass, we recommend you pair these with a subwoofer. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
Q650c and R400 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. Q650c sensitivity is rated at 87 dB and the R400's is at 89 dB. This 2 dB difference makes the Polk R400 a more sensitive speaker compared to KEF Q650c, hence will play louder with the same amount of watts.
Sensitivity
Center Channel Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. While using an amplifier within this range ensures the nominal performance , inputting a power that is higher than the max wattage can result in a damaged speaker.
Q650c can handle a max power of 200 watts RMS from the amp the whereas Q650c has a max power handling value of 150 watts RMS , 50 watts less than the R400.
Keep in mind that a higher max power handling value doesn't necessarily make that a louder speaker
compared to a lower max handling speaker. Loudness or the sound level is also impacted by parameters
such as Impedance, sensitivity and system efficiencies.
Input Type and Bi-Amping / Bi-Wiring
Q650c features Binding post type posts and R400 has a Binding post type posts. None of these speakers feature bi-amping/bi-wiring.
KEF Q650c's Binding post terminals
Polk R400's Binding post terminals
Polk R400 dual Port
Physical Specs
Size of a speaker can sometimes become an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare KEF Q650c's and Polk R400's external dimensions. KEF Q650c has external dimensions of 212.0 x 631.0 x 304.0mm ( 8-5/16 x 24-13/16 x 11-15/16inch) whereas Polk R400 has external dimensions of 199.0 x 618.0 x 372.0mm ( 7-13/16 x 24-5/16 x 14-5/8inch) .
Polk R400 is 13mm narrower and 13mm shorter than KEF Q650c but it is also 68mm deeper.
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 KEF Q650c is approximately 1918.2cm2 / 297.3inch2 and base area of the Polk R400 is approximately 2299.0cm2 / 356.3inch2. The Q650c requires 17% less surface area than the R400 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 KEF Q650c weighs 13.64kg / 30lbs and the Polk R400 weighs 14.91kg / 32.8lbs. This makes the R400 9% heavier than the Q650c.
Here is a comparison of how Q650c and R400's weights compare with the average, max and min weights in Passive Center Channel class.
Weight
All Center Channel Speakers
What's in the Box of KEF Q650c?
Here are the items that are included inside the box of Q650c:
Center-channel loudspeaker 4 Self-adhesive rubber feet Owners Manual Warranty Information
What's in the Box of Polk R400?
Here are the items that come with the R400:
Center-channel loudspeakerGrilleOwners ManualOnline Registration
 Minimum Impedance |
4.2 ohms
vs
4.1 ohms
|
Very low impedance levels puts more pressure on amplifier |
| Passive Radiator |
one 6.5-inch
vs
None
|
Increases the bass performance |
 Base Surface Area |
1918cm2 (631x304mm)
vs
2299cm2 (618x372mm)
|
Takes less floor space |
 Max Input Power |
200 watts
vs
150 watts
|
Handle more power from your amplifier |
 Sensitivity |
89 dB
vs
87 dB
|
Play louder with same amount of amplification power |
 Low Frequency Response |
48 Hz
vs
64 Hz
|
Generates deeper bass |
 High Frequency Response |
39k Hz
vs
28k Hz
|
Generates higher frequency |
 Height |
199mm
vs
212mm
|
Easier to fit in smaller spaces |
 Price per pair* |
649USD
vs
750USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
KEF Q650c |
Polk Audio Reserve R400 |
| Brand |
KEF |
Polk Audio |
| Speaker Type |
Center channel speaker |
Center channel speaker |
| Power Range |
15-150 watts |
20-200 watts |
| Sensitivity |
87 dB |
89 dB |
| Impedance |
8 ohms |
8 ohms |
| Impedance |
4.2 ohms |
4.1 ohms |
| Frequency Response |
64-28k Hz |
48-39K Hz |
Drivers |
|
|
| Woofer Quantity |
2 |
2 |
| Woofer Size |
6.5" |
6.5" |
| Woofer Composition |
aluminum |
Polypropylene Turbine Cone |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Dome |
Pinnacle Ring Radiator |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
N/A" |
| Crossover Frequency |
2500Hz |
2500Hz |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
212.0mm (8.3") |
199.0mm (7.8") |
| Width |
631.0mm (24.8") |
618.0mm (24.3") |
| Depth |
304.0mm (12") |
372.0mm (14.6") |
| Weight |
13.64kg (30lbs) |
14.91kg (32.8lbs) |
| Enclosure |
Passive Radiator |
Bass Reflex |
| Available Colors |
Satin White, Satin Black, Walnut |
Black, Walnut |
| Grille |
optional |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
n/a |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |