In this review, we will be comparing Monitor XT30 and SX-70, two Center Channel speakers from Polk Audio and Cambridge Audio. Let's have a brief look at the main features
of Polk XT30 and Cambridge Audio SX-70 first before getting into our more
detailed comparison.
In the following sections, we will get into more detail in order to better understand how the Polk XT30 and Cambridge Audio SX-70 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 Monitor XT30 and SX-70 are 2-way speakers.
| Driver |
Polk XT30 |
Cambridge Audio SX-70 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
2 x 5.25-inch
|
2 x 4-inch
|
Monitor XT30 features a 1" Terylene High-res dome Tweeter and 2 x 5.25" bi-laminate paper cone Woofer . On the other hand, the SX-70 features a 1" Silk dome Tweeter and 2 x 4" treated-paper Woofer .
Frequency Response
Monitor XT30 has a frequency range of 55-40k Hz whereas SX-70 has a frequency range of 65-22k Hz. With a minimum frequency of 55Hz, the Monitor XT30 can go significantly deeper on the low side and provide stronger bass compared to the SX-70'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
Monitor XT30 and SX-70 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. Monitor XT30 sensitivity is rated at 89 dB and the SX-70's is at 85 dB. This 4 dB difference makes the Polk XT30 a more sensitive speaker compared to Cambridge Audio SX-70, 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.
Monitor XT30 can handle a max power of 200 watts RMS from the amp the whereas SX-70 has a max power handling value of 100 watts RMS, 100 watts less than the Monitor XT30.
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
Monitor XT30 features 5-Way post type posts and SX-70 has a 5-Way post type posts. None of these speakers feature bi-amping/bi-wiring.
Polk XT30's 5-Way post terminals
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 Polk XT30's and Cambridge Audio SX-70's external dimensions. Polk XT30 has external dimensions of 166.0 x 485.0 x 208.0mm ( 6-1/2 x 19-1/16 x 8-3/16inch) whereas Cambridge Audio SX-70 has external dimensions of 139.0 x 362.0 x 248.0mm ( 5-7/16 x 14-1/4 x 9-3/4inch) .
Cambridge Audio SX-70 is 123mm narrower and 27mm shorter than Polk XT30 but it is also 40mm 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 Polk XT30 is approximately 1008.8cm2 / 156.4inch2 and base area of the Cambridge Audio SX-70 is approximately 897.8cm2 / 139.2inch2. The Monitor XT30 requires 12% more surface area than the SX-70 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 Polk XT30 weighs 5.91kg / 13lbs and the Cambridge Audio SX-70 weighs 4.00kg / 8.8lbs. This makes the Monitor XT30 48% heavier than the SX-70.
Here is a comparison of how Monitor XT30 and SX-70'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 Polk XT30?
Here are the items that are included inside the box of Monitor XT30:
Center-channel loudspeakerGrille (attached)4 Self-adhesive rubber feetOwners ManualOnline Product RegistrationWall-Mount Template
What's in the Box of Cambridge Audio SX-70?
Here are the items that come with the SX-70:
Center-channel loudspeakerGrille4 Self-adhesive rubber feetInstallation Guide
 Max Input Power |
200 watts
vs
100 watts
|
Handle more power from your amplifier |
 Sensitivity |
89 dB
vs
85 dB
|
Play louder with same amount of amplification power |
 Woofer Size |
5.25 inches
vs
4 inches
|
Larger woofer |
| Low Frequency Response |
55 Hz
vs
65 Hz
|
Generates deeper bass |
 High Frequency Response |
40k Hz
vs
22k Hz
|
Generates higher frequency |
 Height |
139mm
vs
166mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
897cm2 (362x248mm)
vs
1008cm2 (485x208mm)
|
Takes less floor space |
 Price per pair* |
189USD
vs
199USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
Polk Audio Monitor XT30 |
Cambridge Audio SX-70 |
| Brand |
Polk Audio |
Cambridge Audio |
| Speaker Type |
Center channel speaker |
Center channel speaker (Matte Black) |
| Power Range |
30-200 watts |
10-100 watts |
| Sensitivity |
89 dB |
85 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
55-40k Hz |
65-22k Hz |
Drivers |
|
|
| Woofer Quantity |
2 |
2 |
| Woofer Size |
5.25" |
4" |
| Woofer Composition |
bi-laminate paper cone |
treated-paper |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
High-res dome |
dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
N/A" |
N/A" |
| Firing Direction |
rear |
n/a |
Physical Specs |
|
|
| Height |
166.0mm (6.5") |
139.0mm (5.5") |
| Width |
485.0mm (19.1") |
362.0mm (14.3") |
| Depth |
208.0mm (8.2") |
248.0mm (9.8") |
| Weight |
5.91kg (13lbs) |
4.00kg (8.8lbs) |
| Enclosure |
Bass Reflex |
Acoustic Suspension |
| Available Colors |
Black |
Black |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |