In this review, we will be comparing SX-70 and ES30, two Center Channel speakers from Cambridge Audio and Polk Audio.
Let's have a brief look at the main features
of Cambridge Audio SX-70 and Polk ES30 first before getting into our more
detailed comparison.
Cambridge Audio SX-70 Key Specs
- 2-way Design
- 1" dome Tweeter
- 2 x 4" treated-paper Woofer
- 65-22k Hz Frequency Response
- 85 dB Sensitivity
- Impedance: 8ohms
- Power Range:10-100watts
- Weight:4.00kg
- Dimensions (H x W x D): 139.0" x 14-1/4" x 9-3/4"( 139.0 x 362.0 x 248.0mm )
Polk ES30 Key Specs
- 2-way Design
- 1" High-res dome Tweeter
- 2 x 5.5" mica-reinforced polypropylene Dynamic Balance Woofer
- 55-40k Hz Frequency Response
- 89 dB Sensitivity
- Impedance: 8ohms
- Power Range:20-125watts
- Weight:8.64kg
- Dimensions (H x W x D): 191.0" x 20-1/16" x 10-5/8"( 191.0 x 510.0 x 270.0mm )
In the following sections, we will get into more detail in order to better understand how the Cambridge Audio SX-70 and Polk ES30 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 SX-70 and ES30 are 2-way speakers.
| Driver |
Cambridge Audio SX-70 |
Polk ES30 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
2 x 4-inch
|
2 x 5.5-inch
|
SX-70 features a 1" Silk dome Tweeter and 2 x 4" treated-paper Woofer . On the other hand, the ES30 features a 1" Terylene High-res dome Tweeter and 2 x 5.5" mica-reinforced polypropylene Dynamic Balance Woofer .
Frequency Response
SX-70 has a frequency range of 65-22k Hz whereas ES30 has a frequency range of 55-40k Hz. With a minimum frequency of 55Hz, the ES30 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
SX-70 and ES30 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. SX-70 sensitivity is rated at 85 dB and the ES30's is at 89 dB. This 4 dB difference makes the Polk ES30 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.
SX-70 can handle a max power of 125 watts RMS from the amp the whereas SX-70 has a max power handling value of 100 watts RMS , 25 watts less than the ES30.
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
SX-70 features 5-Way post type posts and ES30 has a 5-Way post type posts. None of these speakers feature bi-amping/bi-wiring.
Polk ES30's 5-Way post terminals
Polk ES30 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 Cambridge Audio SX-70's and Polk ES30's external dimensions. 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) whereas Polk ES30 has external dimensions of 191.0 x 510.0 x 270.0mm ( 7-1/2 x 20-1/16 x 10-5/8inch) .
Polk ES30 is clearly the larger of the two speakers. Its body is 148mm wider, 52mm taller and 22mm deeper than Cambridge Audio SX-70.
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 Cambridge Audio SX-70 is approximately 897.8cm2 / 139.2inch2 and base area of the Polk ES30 is approximately 1377.0cm2 / 213.4inch2. The SX-70 requires 35% less surface area than the ES30 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 Cambridge Audio SX-70 weighs 4.00kg / 8.8lbs and the Polk ES30 weighs 8.64kg / 19lbs. This makes the ES30 116% heavier than the SX-70.
Here is a comparison of how SX-70 and ES30'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 Cambridge Audio SX-70?
Here are the items that are included inside the box of SX-70:
Center-channel loudspeakerGrille4 Self-adhesive rubber feetInstallation Guide
What's in the Box of Polk ES30?
Here are the items that come with the ES30:
Center-channel loudspeakerGrille (attached)4 Self-adhesive rubber feetOwners ManualOnline Product Registration
 Height |
139mm
vs
191mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
897cm2
vs
1377cm2
|
Takes less floor space |
 Price per pair* |
189USD
vs
299USD
|
costs less (*prices may change depending on the seller, location and time) |
 Max Input Power |
125 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 |
5.5 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 |
| General |
Cambridge Audio SX-70 |
Polk Audio Signature Elite ES30 |
| Brand |
Cambridge Audio |
Polk Audio |
| Speaker Type |
Center channel speaker (Matte Black) |
Center channel speaker |
| Power Range |
10-100 watts |
20-125 watts |
| Sensitivity |
85 dB |
89 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
65-22k Hz |
55-40k Hz |
Drivers |
|
|
| Woofer Quantity |
2 |
2 |
| Woofer Size |
4" |
5.5" |
| Woofer Composition |
treated-paper |
mica-reinforced polypropylene Dynamic Balance |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
dome |
High-res dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
N/A" |
N/A" |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
139.0mm (5.5") |
191.0mm (7.5") |
| Width |
362.0mm (14.3") |
510.0mm (20.1") |
| Depth |
248.0mm (9.8") |
270.0mm (10.6") |
| Weight |
4.00kg (8.8lbs) |
8.64kg (19lbs) |
| Enclosure |
Acoustic Suspension |
Bass Reflex |
| Finish |
n/a |
MDF, Wood-grain vinyl |
| Available Colors |
Black |
Black, Walnut, White |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |