In this review, we will be comparing Motion 30i and Q650c, two Passive Center Channel speakers from MartinLogan and KEF. Let's have a brief look at the main features
of MartinLogan 30i and KEF Q650c first before getting into our more
detailed comparison.
What size room are the MartinLogan 30i and KEF Q650c 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 MartinLogan 30i and KEF Q650c 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 Motion 30i and Q650c are 2-way speakers.
Driver |
MartinLogan 30i |
KEF Q650c |
Driver Setup
|
2-way
|
2-way
|
Tweeter
|
1.0 x 1.4-inch
|
1-inch
|
Midrange
|
- |
- |
Woofer
|
1 x 5.25-inch
|
2 x 6.5-inch
|
Motion 30i features a 1.0 x 1.4" Folded Motion Tweeter and 1 x 5.25" Aluminum Woofer with a Crossover frequency at 400Hz and 2600Hz. On the other hand, the Q650c features a 1" vented aluminum Dome Tweeter and 2 x 6.5" aluminum Woofer with a Crossover frequency at 2500Hz.
Frequency Response
Motion 30i has a frequency range of 65-25k Hz whereas Q650c has a frequency range of 64-28k Hz. With a minimum frequency of 64Hz, the Q650c can go slightly deeper then the Motion 30i's min frequency of 65Hz.
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
Motion 30i is a 4 ohms speaker compared to the Q650c which has a nominal impedance of 8 ohms. Lower impedance speakers, especially the ones that are rated at 4 ohms may put more pressure on the amplifier unit especially when played at high volume levels, so make sure the amp you pair with the Motion 30i can provide this impedance level.
These two speakers also have different sensitivity levels. Motion 30i sensitivity is rated at 91 dB and the Q650c's is rated at 87 dB. This 4 dB difference makes the MartinLogan 30i 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.
Motion 30i 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 Motion 30i.
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
Motion 30i features Binding post type posts and Q650c has a Binding post type posts. None of these speakers feature bi-amping/bi-wiring.
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 MartinLogan 30i's and KEF Q650c's external dimensions. MartinLogan 30i has external dimensions of 177.0 x 423.0 x 281.0mm ( 6-15/16 x 16-5/8 x 11-1/16inch) whereas 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) .
KEF Q650c is clearly the larger of the two speakers. Its body is 208mm wider, 35mm taller and 23mm deeper than MartinLogan 30i.
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 MartinLogan 30i is approximately 1188.6cm2 / 184.2inch2 and base area of the KEF Q650c is approximately 1918.2cm2 / 297.3inch2. The Motion 30i requires 38% less surface area than the Q650c 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 MartinLogan 30i weighs 8.18kg / 18lbs and the KEF Q650c weighs 13.64kg / 30lbs. This makes the Q650c 67% heavier than the Motion 30i.
Here is a comparison of how Motion 30i and Q650c'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 MartinLogan 30i?
Here are the items that are included inside the box of Motion 30i:
Center-channel loudspeaker Grille 4 Rubber feet Users Manual Warranty/Registration Information
What's in the Box of KEF Q650c?
Here are the items that come with the Q650c:
Center-channel loudspeaker 4 Self-adhesive rubber feet Owners Manual Warranty Information
Max Input Power |
200 watts
vs
150 watts
|
Handle more power from your amplifier |
Sensitivity |
91 dB
vs
87 dB
|
Play louder with same amount of amplification power |
Height |
177mm
vs
212mm
|
Easier to fit in smaller spaces |
Base Surface Area |
1188cm2 (423x281mm)
vs
1918cm2 (631x304mm)
|
Takes less floor space |
Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
Woofer Size |
6.5 inches
vs
5.25 inches
|
Larger woofer |
Number of Woofers |
2
vs
1
|
More woofers |
Low Frequency Response |
64 Hz
vs
65 Hz
|
Generates deeper bass |
High Frequency Response |
28k Hz
vs
25k Hz
|
Generates higher frequency |
Passive Radiator |
one 6.5-inch
vs
None
|
Increases the bass performance |
Price per pair* |
750USD
vs
900USD
|
costs less (*prices may change depending on the seller, location and time) |
General |
MartinLogan Motion 30i |
KEF Q650c |
Brand |
MartinLogan |
KEF |
Speaker Type |
Center channel speaker |
Center channel speaker |
Power Range |
20-200 watts |
15-150 watts |
Sensitivity |
91 dB |
87 dB |
Impedance |
4 ohms |
8 ohms |
Impedance |
n/a |
4.2 ohms |
Frequency Response |
65-25k Hz |
64-28k Hz |
Drivers |
|
|
Woofer Quantity |
1 |
2 |
Woofer Size |
5.25" |
6.5" |
Woofer Composition |
Aluminum |
aluminum |
Woofer Surround Material |
Rubber |
Rubber |
Tweeter Size |
1.0 x 1.4" |
1" |
Tweeter Type |
Folded Motion |
Dome |
Aimable Tweeter |
No |
No |
Midrange Driver |
No |
No |
Crossover Frequency |
400Hz and 2600Hz |
2500Hz |
Firing Direction |
rear |
n/a |
Suggested Break-in Period |
Allow 72 hours of break-in at 90 dB |
n/a |
Physical Specs |
|
|
Height |
177.0mm (7") |
212.0mm (8.3") |
Width |
423.0mm (16.7") |
631.0mm (24.8") |
Depth |
281.0mm (11.1") |
304.0mm (12") |
Weight |
8.18kg (18lbs) |
13.64kg (30lbs) |
Enclosure |
Bass Reflex |
Passive Radiator |
Finish |
MDF/Lacquer |
n/a |
Available Colors |
White |
Satin White, Satin Black, Walnut |
Grille |
Yes |
optional |
Moisture Resistancy |
No |
No |
Connections |
|
|
Biamp Inputs |
No |
n/a |
Other |
|
|
Parts Warranty |
5 Years |
5 Years |
Labor Warranty |
5 Years |
5 Years |