In this review, we will be comparing CSi A6 and R400, two Passive Center Channel speakers by Polk Audio.
Let's have a brief look at the main features
of Polk CSi A6 and Polk R400 first before getting into our more
detailed comparison.
| Key Specs | Polk CSi A6 | Polk R400 |
|---|
| Brand | Polk Audio
United States · founded 1972 | Polk Audio
United States · founded 1972 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Dynamic Balance | 1" Pinnacle Ring Radiator |
|---|
| Woofer | 2 x 6.5" Dynamic Balance polymer composite | 2 x 6.5" Polypropylene Turbine Cone |
|---|
| Frequency response | 55-26k Hz | 48-39K Hz |
|---|
| Sensitivity | 90 dB | 89 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | 20-200 watts | 20-200 watts |
|---|
| Weight | 13.18kg / 29lbs | 14.91kg / 32.8lbs |
|---|
| Dimensions (H x W x D) | 7-13/16" x 24-1/16" x 14-1/4"
199.0 x 612.0 x 362.0mm | 7-13/16" x 24-5/16" x 14-5/8"
199.0 x 618.0 x 372.0mm |
|---|
What size room are the Polk CSi A6 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:
| Listening Environment* |
Polk CSi A6 |
Polk R400 |
| Near-field |
Poor |
Poor |
| Small Room |
Average |
Average |
| Mid-size Room |
Good |
Good |
| Large Room |
Average |
Average |
| Very Large Room |
Poor |
Poor |
(* 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 CSi A6 and R400 are 2-way speakers.
Polk CSi A6Polk R400
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Polk CSi A6 |
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
|
CSi A6 features a 1" silk/polymer Dynamic Balance Tweeter and 2 x 6.5" Dynamic Balance polymer composite Woofer. 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
CSi A6 has a frequency range of 55-26k 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 CSi A6's min frequency of 55Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Center Channel class in our database.
Low Frequency
Center Channel 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
CSi A6 and R400 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. CSi A6 sensitivity is rated at 90 dB and the R400's is at 89 dB. This 1 dB difference makes the Polk CSi A6 a more sensitive speaker compared to Polk R400, 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. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
CSi A6 and R400 have the same power range of 20-200 watts.
Note that higher power handling does not make a speaker louder: that depends mainly on
sensitivity and impedance. The calculator below shows how loud each of these actually plays
on a real amplifier.
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
CSi A6 features Binding post type posts and R400 has a Binding post type posts. None of these speakers feature bi-amping/bi-wiring.
Polk CSi A6's 5-Way post terminals
Polk R400's Binding post terminals
Cabinet Type and Port Position
Both CSi A6 and R400 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.
Polk R400 dual Port
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 Polk CSi A6's and Polk R400's external dimensions. Polk CSi A6 has external dimensions of 199.0 x 612.0 x 362.0mm (7-13/16 x 24-1/16 x 14-1/4inch) 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 CSi A6 is 6mm narrower and 10mm less deeper than Polk CSi A6 but they have the same height of 199.0mm.
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 CSi A6 is approximately 2215.4cm2 / 343.4inch2 and base area of the Polk R400 is approximately 2299.0cm2 / 356.3inch2. The CSi A6 requires 4% 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 Polk CSi A6 weighs 13.18kg / 29lbs and the Polk R400 weighs 14.91kg / 32.8lbs. This makes the R400 13% heavier than the CSi A6.
Here is a comparison of how CSi A6 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 Polk CSi A6?
Here are the items that are included inside the box of CSi A6:
- One cherry center channel speaker
- One 9.5-inch kickstand
- One 5.5-inch kickstand (installed)
- 4 Self-adhesive rubber feet
- Owners Manual
- Online registration sheet
- Polk Audio product brochure
What's in the Box of Polk R400?
Here are the items that come with the R400:
- Center-channel loudspeaker
- Grille
- Owners Manual
- Online Registration
 Sensitivity |
90 dB
vs
89 dB
|
Play louder with same amount of amplification power |
 Base Surface Area |
2215cm2
vs
2299cm2
|
Takes less floor space |
 Price per pair* |
399USD
vs
649USD
|
costs less (*prices may change depending on the seller, location and time) |
 Low Frequency Response |
48 Hz
vs
55 Hz
|
Generates deeper bass |
 High Frequency Response |
39k Hz
vs
26k Hz
|
Generates higher frequency |
| General |
Polk Audio CSi A6 |
Polk Audio Reserve R400 |
| Brand |
Polk Audio |
Polk Audio |
| Speaker Type |
Center channel speaker (Cherry) |
Center channel speaker |
| Power Range |
20-200 watts |
20-200 watts |
| Sensitivity |
90 dB |
89 dB |
| Impedance |
8 ohms |
8 ohms |
| Impedance |
n/a |
4.1 ohms |
| Frequency Response |
55-26k Hz |
48-39K Hz |
Drivers |
|
|
| Woofer Quantity |
2 |
2 |
| Woofer Size |
6.5" |
6.5" |
| Woofer Composition |
Dynamic Balance polymer composite |
Polypropylene Turbine Cone |
| Woofer Surround Material |
n/a |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Dynamic Balance |
Pinnacle Ring Radiator |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
199.0mm (7.8") |
199.0mm (7.8") |
| Width |
612.0mm (24.1") |
618.0mm (24.3") |
| Depth |
362.0mm (14.3") |
372.0mm (14.6") |
| Weight |
13.18kg (29lbs) |
14.91kg (32.8lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Available Colors |
Black, Cherry |
Black, Walnut |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
n/a |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
These sit in different price classes - Polk R400 costs roughly 1.6x what Polk CSi A6 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 | B | Polk R400 digs deeper - 48Hz against 55Hz. A subwoofer would even that out. |
| Amplifier needs | evenly matched | Similar sensitivity (90dB vs 89dB) - both want much the same power. |
| Headroom | evenly matched | Similar power handling (200W vs 200W). |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Price | A | Polk CSi A6 is cheaper - $399 against $649, about 39% less; arguably a different class. |
A Polk CSi A6 B Polk R400
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?
Polk R400 is ahead, but only on 1 of the measured areas, and it costs about 63% more. That is a lot of money for a narrow margin on paper - Polk CSi A6 looks like the sensible buy unless something else about the Polk R400 appeals to you. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 55Hz anyway, which makes the cheaper Polk CSi A6 much easier to justify. Think about the whole system, not just the speakers: the roughly $250 saved by taking the cheaper pair would buy a subwoofer or a better amplifier, and either usually does more for the sound than the difference between these two.
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.