Foreword / YouTube Video Review

This speaker was loaned to me by Emotiva. They did not see the review before it was published.

The review on this website is a brief overview and summary of the objective performance of this speaker. It is not intended to be a deep dive. Moreso, this is information for those who prefer “just the facts” and prefer to have the data without the filler. The video below has more discussion.

Information and Photos

Some specs from the manufacturer:

The Airmotiv C2+ is a three-way center channel loudspeaker that delivers a superb listening experience with surround sound music and movies. The Airmotiv C2+ combines exceptional accuracy, amazing precision and detail retrieval, and unsurpassed smoothness - all in one truly great sounding loudspeaker. The Airmotiv C2+ features a 32 mm Airmotiv folded ribbon tweeter, dual 3” woven fiber midrange drivers, dual 6-1/2” woven fiber woofers, and a rear ported cabinet.

The center channel loudspeaker is one of the most critical components in a high-performance home theater system. Because most important dialog is directed to the center channel, it is especially important that your center channel speaker be able to accurately reproduce both instruments and voice clearly and intelligibly, but without the slightest hint of distortion or harshness. And, in order to ensure proper positioning of sounds within the sound stage, the ideal center channel speaker must offer exceptionally wide flat frequency response, both on and off axis. With its full three-way design the Airmotiv C2+ avoids the limitations of many other center channel designs, to blend perfectly with your main speakers, and deliver pinpoint accurate imaging across the entire sound stage.

Price is approximately $399 USD for the single speaker.

If you are interested in purchasing this speaker, please consider using the following affiliate link which earns me a small commission at no additional cost to you: Buy from Emotiva

CTA-2034 (SPINORAMA) and Accompanying Data

All data collected using Klippel’s Near-Field Scanner. The Near-Field-Scanner 3D (NFS) offers a fully automated acoustic measurement of direct sound radiated from the source under test. The radiated sound is determined in any desired distance and angle in the 3D space outside the scanning surface. Directivity, sound power, SPL response and many more key figures are obtained for any kind of loudspeaker and audio system in near field applications (e.g. studio monitors, mobile devices) as well as far field applications (e.g. professional audio systems). Utilizing a minimum of measurement points, a comprehensive data set is generated containing the loudspeaker’s high resolution, free field sound radiation in the near and far field. For a detailed explanation of how the NFS works and the science behind it, please watch the below discussion with designer Christian Bellmann:

The reference plane in this test is at the tweeter as this yielded the most neutral response overall. Testing was performed without the grille.

Measurements are provided in a format in accordance with the Standard Method of Measurement for In-Home Loudspeakers (ANSI/CTA-2034-A R-2020). For more information, please see this link.

CTA-2034 / SPINORAMA:

The On-axis Frequency Response (0°) is the universal starting point and in many situations it is a fair representation of the first sound to arrive at a listener’s ears.

The Listening Window is a spatial average of the nine amplitude responses in the ±10º vertical and ±30º horizontal angular range. This encompasses those listeners who sit within a typical home theater audience, as well as those who disregard the normal rules when listening alone.

The Early Reflections curve is an estimate of all single-bounce, first-reflections, in a typical listening room.

Sound Power represents all of the sounds arriving at the listening position after any number of reflections from any direction. It is the weighted rms average of all 70 measurements, with individual measurements weighted according to the portion of the spherical surface that they represent.

Sound Power Directivity Index (SPDI): In this standard the SPDI is defined as the difference between the listening window curve and the sound power curve.

Early Reflections Directivity Index (EPDI): is defined as the difference between the listening window curve and the early reflections curve. In small rooms, early reflections figure prominently in what is measured and heard in the room so this curve may provide insights into potential sound quality.

Early Reflections Breakout:

Floor bounce: average of 20º, 30º, 40º down

Ceiling bounce: average of 40º, 50º, 60º up

Front wall bounce: average of 0º, ± 10º, ± 20º, ± 30º horizontal

Side wall bounces: average of ± 40º, ± 50º, ± 60º, ± 70º, ± 80º horizontal

Rear wall bounces: average of 180º, ± 90º horizontal

Estimated In-Room Response:

In theory, with complete 360-degree anechoic data on a loudspeaker and sufficient acoustical and geometrical data on the listening room and its layout it would be possible to estimate with good precision what would be measured by an omnidirectional microphone located in the listening area of that room. By making some simplifying assumptions about the listening space, the data set described above permits a usefully accurate preview of how a given loudspeaker might perform in a typical domestic listening room. Obviously, there are no guarantees, because individual rooms can be acoustically aberrant. Sometimes rooms are excessively reflective (“live”) as happens in certain hot, humid climates, with certain styles of interior décor and in under-furnished rooms. Sometimes rooms are excessively “dead” as in other styles of décor and in some custom home theaters where acoustical treatment has been used excessively. This form of post processing is offered only as an estimate of what might happen in a domestic living space with carpet on the floor and a “normal” amount of seating, drapes and cabinetry.

For these limited circumstances it has been found that a usefully accurate Predicted In-Room (PIR) amplitude response, also known as a “room curve” is obtained by a weighted average consisting of 12 % listening window, 44 % early reflections and 44 % sound power. At very high frequencies errors can creep in because of excessive absorption, microphone directivity, and room geometry. These discrepancies are not considered to be of great importance.

Horizontal Frequency Response (0° to ±90°):

Vertical Frequency Response (0° to ±40°):

Horizontal Contour Plot (not normalized):

Horizontal Contour Plot (normalized):

Vertical Contour Plot (not normalized):

Vertical Contour Plot (normalized):

“Globe” Plots

Horizontal Polar (Globe) Plot:
This represents the sound field at 2 meters - above 200Hz - per the legend in the upper left.

Vertical Polar (Globe) Plot:
This represents the sound field at 2 meters - above 200Hz - per the legend in the upper left.

Additional Measurements

On-Axis Response Linearity

Impedance Magnitude and Phase

Harmonic Distortion

Harmonic Distortion at 86dB @ 1m:

Harmonic Distortion at 96dB @ 1m:

Dynamic Range (Instantaneous Compression Test)

The below graphic indicates just how much SPL is lost (compression) or gained (enhancement; usually due to distortion) when the speaker is played at higher output volumes instantly via a 2.7 second logarithmic sine sweep referenced to 76dB at 1 meter. The signals are played consecutively without any additional stimulus applied. Then normalized against the 76dB result.

The tests are conducted in this fashion:

1. 76dB at 1 meter (baseline; black)
2. 86dB at 1 meter (red)
3. 96dB at 1 meter (blue)
4. 102dB at 1 meter (purple)

The purpose of this test is to illustrate how much (if at all) the output changes as a speaker’s components temperature increases (i.e., voice coils, crossover components) instantaneously.

Long Term Compression Tests

The below graphics indicate how much SPL is lost or gained in the long-term as a speaker plays at the same output level for 2 minutes, in intervals. Each graphic represents a different SPL: 86dB and 96dB both at 1 meter.

The purpose of this test is to illustrate how much (if at all) the output changes as a speaker’s components temperature increases (i.e., voice coils, crossover components).

The tests are conducted in this fashion:

1. “Cold” logarithmic sine sweep (no stimulus applied beforehand)
2. Multitone stimulus played at desired SPL/distance for 2 minutes; intended to represent music signal
3. Interim logarithmic sine sweep (no stimulus applied beforehand) (Red in graphic)
4. Multitone stimulus played at desired SPL/distance for 2 minutes; intended to represent music signal
5. Final logarithmic sine sweep (no stimulus applied beforehand) (Blue in graphic)

The red and blue lines represent changes in the output compared to the initial “cold” test.

Smoothing the On-Axis response

Parting / Random Thoughts

If you want to see the music I use for evaluating speakers subjectively, see my Spotify playlist.

I always listen to speakers before I measure them. This ensures I am not swayed by the measurements before I listen. Listening done on-axis but I also turned the speakers to face out into the room as well. I found on-axis to provide the best overall response. Listening volume between 80-95dB at 4m.

• Good sensitivity at 89.4dB @ 2.83v/1m.
• Punchy bass from this speaker that is quite nice. The bass doesn’t dig super deep but does have a respectable F3 of 63Hz. The data and my listening sessions indicated good bass output but you’ll still need a subwoofer. That said, I can’t imagine anyone using this speaker in a home theater that wouldn’t also be using a subwoofer.
• Linearity is reasonable and would be even quite good if it weren’t for the significant peak/dip in the 1.5kHz region. I think we have two things going on around this frequency. One is cabinet ringing. The other is lobing from the midrange speakers as the crossover is 3.2kHz which is an octave above where the center-to-center spacing between these two midrange speakers lies (which is approximately 4.5 inches). Above 1.5kHz you can see a comb filter pattern evidenced by the peak/dip/peak/dip until it smooths out at the tweeter crossover point of 3.2kHz. I can’t help but think that the C2+'s little brother, the C1+ would perform better in this regard simply because it has only a single midrange. These two issues provide the “perfect storm” resulting in non-linear response in the horizontal plane and result in a really narrow sweet spot.
• The radiation pattern of this speaker - like most center channels - is pretty rough and has a narrow sweet spot both horizontally and vertically. The horizontal radiation pattern is uniform for only about ±20°. To put this in context, this means that if you’re sitting about 8 feet from your TV or screen you (or your friends/family) will need to be within 3 feet of the center of the center channel. Sitting to the side of the main listening axis more than a few feet will result in a drastically different sound between seats. At 12 feet you can sit a bit over 4 feet to the side. Realistically, you can make an exception and sit a bit further off but the further you go to the side, the more dialogue you’re going to lose because the midrange drops out significantly past about ±30°.
• The vertical positioning isn’t much better and you’ll need to be within about 10° of the tweeter to get the best sound.
• The high frequency has a clearly audible boost above 10Khz that seems present in other Emotiva speakers which is likely just a characteristic of the ribbon tweeter they use. It’s not annoying but it isn’t something I prefer to have and when EQ’ing it out, I much preferred the more linear EQ’d response.
• The distortion and compression performance are quite good, at least until you get to very high output levels (102dB at 1m) where the tweeter compression really becomes an issue; losing as much as 1.5dB to 2.5dB above 7kHz. But 102dB at 1 meter for a single speaker is quite loud in a room so I wouldn’t fret too much (even though you do not get the added benefit of another speaker like you do with a stereo pair).

I think what you’re paying for here is output in lieu of linearity. This speaker is big and imposing. It has plenty of volume (no pun intended) to make most home theater enthusiasts content. Though, the response linearity could use work but that’s commonplace with center channel speakers, unfortunately. The price is a great intro as well. Just mind where you sit; don’t sit too far to the side or too high above the tweeter.

As stated in the Foreword, this written review is purposely a cliff’s notes version. For more details about the performance (objectively and subjectively) please watch the YouTube video.

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