In this review, we will be comparing RP-504C II and Airmotiv C2+, two Passive Center Channel speakers from Klipsch and Emotiva.
Let's have a brief look at the main features
of Klipsch RP-504C II and Emotiva Airmotiv C2+ first before getting into our more
detailed comparison.
| Key Specs | Klipsch RP-504C II | Emotiva Airmotiv C2+ |
|---|
| Brand | Klipsch
United States · founded 1946 | Emotiva
United States · founded 2003 |
|---|
| Design | 2-way | 3-way |
|---|
| Tweeter | 1" Tractrix Horn | 25×32 mm" folded ribbon |
|---|
| Midrange | — | 2 x 3" |
|---|
| Woofer | 4 x 5.25" Cerametallic cone | 2 x 6.5" woven fiber cone |
|---|
| Frequency response | 50-25k Hz | 45 Hz – 28 kHz |
|---|
| Sensitivity | 96 dB | 92 dB |
|---|
| Impedance | 8 ohms | 4 ohms |
|---|
| Power range | up to 150 watts | Up to 150 watts |
|---|
| Weight | 16.50kg / 36.3lbs | 16.40kg / 36.1lbs |
|---|
| 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 | 8-5/8" x 31-15/16" x 10-1/2"
220.0 x 812.0 x 267.0mm |
|---|
What size room are the Klipsch RP-504C II and Emotiva Airmotiv C2+ 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 |
Emotiva Airmotiv C2+ |
| 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
One of the fundamental differences between these two speakers is that RP-504C II is a 2-way design whereas the Airmotiv C2+ is a 3-way speaker. 3-way designs utilize a midrange driver in addition to the tweeter and woofer on 2-way designs. Designing a crossover for a 3-way speaker is a complicated process and generally increases the overall cost of the speaker.
Klipsch RP-504C IIEmotiva Airmotiv C2+
TweeterMidrangeWoofer
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 |
Emotiva Airmotiv C2+ |
|
Driver Setup
|
2-way
|
3-way
|
|
Tweeter
|
1-inch
|
25×32 mm-inch
|
|
Midrange
|
- |
2 x 3-inch |
|
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 Airmotiv C2+ features a 25×32 mm" folded ribbon Tweeter, a 3" Midrange and 2 x 6.5" woven fiber cone Woofer with a Crossover frequency at 350 Hz and 3200Hz.
Frequency Response
RP-504C II has a frequency range of 50-25k Hz whereas Airmotiv C2+ has a frequency range of 45 Hz – 28 kHz. With a minimum frequency of 45Hz, the Airmotiv C2+ can go significantly deeper on the low side and provide stronger bass compared to 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 is a 8 ohms speaker compared to the Airmotiv C2+ which has a nominal impedance of 4 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 Airmotiv C2+ can provide this impedance level.
These two speakers also have different sensitivity levels. RP-504C II sensitivity is rated at 96 dB and the Airmotiv C2+'s is rated at 92 dB. This 4 dB difference makes the Klipsch RP-504C II a more sensitive speaker compared to Emotiva Airmotiv C2+, 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.
Both handle the same maximum of 150 watts RMS, though RP-504C II is rated up to 150 watts and Airmotiv C2+ Up to 150 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
Airmotiv C2+ features Binding post posts which make bi-amping or bi-wiring possible. RP-504C II has a Binding post which doesn't feature bi-amping/bi-wiring.
Klipsch RP-504C II's Binding post terminals
Emotiva Airmotiv C2+'s Binding post terminals allows Bi-amping or bi-wiring
Cabinet Type and Port Position
Both RP-504C II and Airmotiv C2+ 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.
Emotiva Airmotiv C2+ 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 Emotiva Airmotiv C2+'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 Emotiva Airmotiv C2+ has external dimensions of 220.0 x 812.0 x 267.0mm (8-5/8 x 31-15/16 x 10-1/2inch).
Emotiva Airmotiv C2+ is 6mm narrower and 118mm less deeper than Klipsch RP-504C II but it is also 43mm taller.
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 Emotiva Airmotiv C2+ is approximately 2168.0cm2 / 336.0inch2. The RP-504C II requires 45% more surface area than the Airmotiv C2+ 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 Emotiva Airmotiv C2+ weighs 16.40kg / 36.1lbs. This makes the RP-504C II 1% heavier than the Airmotiv C2+.
Here is a comparison of how RP-504C II and Airmotiv C2+'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
 Sensitivity |
96 dB
vs
92 dB
|
Play louder with same amount of amplification power |
 Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
 Number of Woofers |
4
vs
2
|
More woofers |
 Height |
177mm
vs
220mm
|
Easier to fit in smaller spaces |
 Driver Setup |
3-way
vs
2-way
|
Have a dedicated mid-range driver |
|
Woofer Size |
6.5 inches
vs
5.25 inches
|
Larger woofer |
|
Low Frequency Response |
45 Hz
vs
50 Hz
|
Generates deeper bass |
 High Frequency Response |
28k Hz
vs
25k Hz
|
Generates higher frequency |
 Bi-Amping and Bi-Wiring |
Yes
vs
No
|
Allows bi-amping and bi-wiring connections |
 Base Surface Area |
2168cm2
vs
3149cm2
|
Takes less floor space |
 Price per pair* |
499USD
vs
799USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
Klipsch Reference Premiere RP-504C II |
Emotiva Airmotiv C2+ |
| Brand |
Klipsch |
Emotiva |
| Speaker Type |
Center channel speaker |
Center channel speaker |
| Power Range |
up to 150 watts |
Up to 150 watts |
| Sensitivity |
96 dB |
92 dB |
| Impedance |
8 ohms |
4 ohms |
| Frequency Response |
50-25k Hz |
45 Hz – 28 kHz |
Drivers |
|
|
| Woofer Quantity |
4 |
2 |
| Woofer Size |
5.25" |
6.5" |
| Woofer Composition |
Cerametallic cone |
woven fiber cone |
| Woofer Surround Material |
Rubber |
n/a |
| Tweeter Size |
1" |
25×32 mm" |
| Tweeter Type |
Tractrix Horn |
folded ribbon |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
3" |
| Crossover Frequency |
1950 Hz |
350 Hz and 3200Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
177.0mm (7") |
220.0mm (8.7") |
| Width |
818.0mm (32.2") |
812.0mm (32") |
| Depth |
385.0mm (15.2") |
267.0mm (10.5") |
| Weight |
16.50kg (36.3lbs) |
16.40kg (36.1lbs) |
| Enclosure |
Bass Reflex |
Bass reflex |
| Finish |
MDF/Wood-grain vinyl |
HDF |
| Available Colors |
Walnut, Black |
Black |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
Yes |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
These sit in different price classes - Klipsch RP-504C II costs roughly 1.6x what Emotiva Airmotiv C2+ 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 | Emotiva Airmotiv C2+ digs deeper - 45Hz against 50Hz. A subwoofer would even that out. |
| Amplifier needs | A | Klipsch RP-504C II is more sensitive (96dB vs 92dB), so it goes louder on the same amplifier. |
| Amplifier match | A | Klipsch RP-504C II is the easier load at 8 ohms; the other is 4 ohms and wants an amplifier rated for it. |
| Headroom | evenly matched | Similar power handling (150W vs 150W). |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Expandability | B | Emotiva Airmotiv C2+: bi-amping. |
| Price | B | Emotiva Airmotiv C2+ is cheaper - $499 against $799, about 38% less; arguably a different class. |
A Klipsch RP-504C II B Emotiva Airmotiv C2+
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?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 50Hz anyway, so judge these on the other rows instead. 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.