In this review, we will be comparing RP-504C II and R400, two Passive Center Channel speakers from Klipsch and Polk Audio.
Let's have a brief look at the main features
of Klipsch RP-504C II and Polk R400 first before getting into our more
detailed comparison.
| Key Specs | Klipsch RP-504C II | Polk R400 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Tractrix Horn | 1" Pinnacle Ring Radiator |
|---|
| Woofer | 4 x 5.25" Cerametallic cone | 2 x 6.5" Polypropylene Turbine Cone |
|---|
| Frequency response | 50-25k Hz | 48-39K Hz |
|---|
| Sensitivity | 96 dB | 89 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | up to 150 watts | 20-200 watts |
|---|
| Weight | 16.50kg / 36.3lbs | 14.91kg / 32.8lbs |
|---|
| Dimensions (H x W x D) | 6-15/16" x 32-3/16" x 15-1/8"
177.0 x 818.0 x 385.0mm | 7-13/16" x 24-5/16" x 14-5/8"
199.0 x 618.0 x 372.0mm |
|---|
What size room are the Klipsch RP-504C II 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* |
Klipsch RP-504C II |
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.
**This post contains affiliate links, and we will be compensated if you make a purchase after clicking
through our links. As an Amazon Associate I earn from qualifying purchases.
Drivers
Both RP-504C II and R400 are 2-way speakers.
Klipsch RP-504C IIPolk 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 |
Klipsch RP-504C II |
Polk R400 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
4 x 5.25-inch
|
2 x 6.5-inch
|
RP-504C II features a 1" titanium Tractrix Horn Tweeter and 4 x 5.25" Cerametallic cone Woofer with a Crossover frequency at 1950 Hz. 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
RP-504C II has a frequency range of 50-25k Hz whereas R400 has a frequency range of 48-39K Hz. With a minimum frequency of 48Hz, the R400 can go slightly deeper then the RP-504C II's min frequency of 50Hz.
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
RP-504C II and R400 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. RP-504C II sensitivity is rated at 96 dB and the R400's is at 89 dB. This 7 dB difference makes the Klipsch RP-504C II 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.
R400 can handle a max power of 200 watts RMS, whereas RP-504C II has a max power handling value of 150 watts RMS, 50 watts less than the R400.
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
RP-504C II features Binding post type posts and R400 has a Binding post type posts. None of these speakers feature bi-amping/bi-wiring.
Klipsch RP-504C II's Binding post terminals
Polk R400's Binding post terminals
Cabinet Type and Port Position
Both RP-504C II 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 Klipsch RP-504C II's and Polk R400's external dimensions. Klipsch RP-504C II has external dimensions of 177.0 x 818.0 x 385.0mm (6-15/16 x 32-3/16 x 15-1/8inch) 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 200mm narrower and 13mm less deeper than Klipsch RP-504C II but it is also 22mm taller.
Below you can see the front view size comparison of Klipsch RP-504C II and Polk R400 in scale.
Comparison image of Klipsch RP-504C II and Polk R400 Size and External Dimensions
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 Klipsch RP-504C II is approximately 3149.3cm2 / 488.1inch2 and base area of the Polk R400 is approximately 2299.0cm2 / 356.3inch2. The RP-504C II requires 37% more surface area than the R400 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 Klipsch RP-504C II weighs 16.50kg / 36.3lbs and the Polk R400 weighs 14.91kg / 32.8lbs. This makes the RP-504C II 11% heavier than the R400.
Here is a comparison of how RP-504C II 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 Klipsch RP-504C II?
Here are the items that are included inside the box of RP-504C II:
- Center channel loudspeaker
- Grille
- User Manual
- Important Safety Instructions
- Warranty Information
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 |
96 dB
vs
89 dB
|
Play louder with same amount of amplification power |
 Number of Woofers |
4
vs
2
|
More woofers |
 Height |
177mm
vs
199mm
|
Easier to fit in smaller spaces |
 Max Input Power |
200 watts
vs
150 watts
|
Handle more power from your amplifier |
|
Woofer Size |
6.5 inches
vs
5.25 inches
|
Larger woofer |
|
Low Frequency Response |
48 Hz
vs
50 Hz
|
Generates deeper bass |
 High Frequency Response |
39k Hz
vs
25k Hz
|
Generates higher frequency |
 Base Surface Area |
2299cm2
vs
3149cm2
|
Takes less floor space |
 Price per pair* |
649USD
vs
799USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
Klipsch Reference Premiere RP-504C II |
Polk Audio Reserve R400 |
| Brand |
Klipsch |
Polk Audio |
| Speaker Type |
Center channel speaker |
Center channel speaker |
| Power Range |
up to 150 watts |
20-200 watts |
| Sensitivity |
96 dB |
89 dB |
| Impedance |
8 ohms |
8 ohms |
| Impedance |
n/a |
4.1 ohms |
| Frequency Response |
50-25k Hz |
48-39K Hz |
Drivers |
|
|
| Woofer Quantity |
4 |
2 |
| Woofer Size |
5.25" |
6.5" |
| Woofer Composition |
Cerametallic cone |
Polypropylene Turbine Cone |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Tractrix Horn |
Pinnacle Ring Radiator |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1950 Hz |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
177.0mm (7") |
199.0mm (7.8") |
| Width |
818.0mm (32.2") |
618.0mm (24.3") |
| Depth |
385.0mm (15.2") |
372.0mm (14.6") |
| Weight |
16.50kg (36.3lbs) |
14.91kg (32.8lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Wood-grain vinyl |
n/a |
| Available Colors |
Walnut, Black |
Black, Walnut |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
No single best speaker here - they are built to different priorities, and the right one depends on your room, your amplifier and what you listen to.
| Area | Better | Why |
|---|
| Bass |
evenly matched |
Much the same reach (50Hz vs 48Hz). |
| Amplifier needs |
A |
Klipsch RP-504C II is more sensitive (96dB vs 89dB), so it goes louder on the same amplifier. |
| Headroom |
B |
Polk R400 takes more power (200W vs 150W) - more in hand in a big room. |
| Size |
depends |
Similar cabinet size - neither is easier to fit. |
| Price |
B |
Polk R400 is cheaper - $649 against $799, about 19% less. |
A Klipsch RP-504C II
B Polk R400
depends neither is better in the abstract - it turns on your room, placement 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?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. If your amplifier is modest, vintage or valve-based, Klipsch RP-504C II is the safer partner - the other will want more current or more watts to sound its best.
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.