This is a review and detailed measurements of the Revel C25 center home theater speaker. It is on kind loan from a member and costs US $825.
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The C25 is gorgeously finished and cabinet feels very solid. There are a set of four screws on the bottom that you can use with a mounting system to hang the speaker if desired.
Back panel shows lack of port which is typical of center speakers:
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You can see the nice gloss finish of the speaker.
NOTE: our company Madrona Digital is a dealer for Harman products (although we don't do any retail business). As such, you can feel free to read any level of bias in my subjective remarks.
Measurements that you are about to see were performed using the
Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise.
Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.
Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.
Reference axis was the center of the tweeter (aligned by eye). The grill was not used although it is a very transparent one so it should not impact the sound much. Measurement room was at 10 degrees C which may lower bass output a bit. Accuracy is better than 1% for most of the audio spectrum degrading to 2% above 4 kHz.
Revel Concerta2 C25 Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
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I was very impressed with the frequency response of the C25. Other than a gentle rise in mid region, it is almost flat on axis with excellent directivity. Many Revel speakers have low sensitivity but not the C25. It is better than 90 dB! Lack of port means the classic drop off in bass response which starts at 200 Hz.
You can see the nice early window directivity when we look at the most important reflections in a room:
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Putting both graphs together we get our in-room predicted in-room frequency response which predictably is excellent:
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Story is not perfect though. We know this type of 2-way design causes cancellation and narrowing of the response in the woofer region and that is what C25 does:
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You need to sit quite far from the speaker to have decent coverage for seating. I will report on this in my listening section.
Quite the opposite is the case in vertical dimension providing near perfection:
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Another impressive area of performance is incredibly low distortion especially given the small drivers here:
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Narrow spikes in these graphs indicate resonances by the way which we can confirm in the impedance and phase graph:
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And also visible in CSD/waterfall display:
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Finally, for those looking for more timing measurements, impulse and step responses:
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Revel C25 Listening Tests and Equalization
The first impression was delightful mid and high frequencies but lack of bass. First correction I applied was for the slight rise in on-axis response between 1 and 2 kHz:
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That still did not create an enjoyable experience. Problem was that there was enough bass there to think that there was not enough of it! In other words, if the speaker didn't play any bass you could just dismiss that aspect. Here, the bass response is quite anemic, constantly reminding you that there is not enough of it. Given the exceptionally low distortion I took a shot at boosting the upper bass frequencies with Band 1 filter and I was shocked what a great improvement it provided. Speaker tonality became much warmer and now there was good bit of tactile bass with no audible sign of distortion!
I tested for horizontal coverage and answer there is not good. I could only move half a seat before tonality changed. So if you are going to cover even a medium seating area, the response would not be optimal.
I then turn the speaker 90 degrees. The sides are flat and wide so speaker was quite stable this way. What I heard was mesmerizingly good! Spatial projection (halo around the speaker) enlarged and I was listening to truly high fidelity sounding speaker.
Conclusions
This little speaker (less than 24 inches wide), is superbly designed in many areas but can't escape the physics of dual woofers causing narrowing of the response in horizontal axis. As such, it is not a great choice for a center speaker if you want coverage for more than one seat. Use it for one seat and/or rotate it vertically and you have a compact yet fantastic speaker with just two EQ filters. I am still smiling about how good the sound was in this usage. Part of the credit goes to dual woofers providing exceedingly low distortion, enabling you to play quite loud with no sign of strain or distortion.
Without EQ and for center usage, I can't recommend the Revel C25. With EQ and narrow seating are horizontally or vertically otherwise, it is a superb sounding speaker despite its tiny size and gets my limited recommendation that way.
P.S. One note on the price. From what I have seen in the last couple of years, Revel dealers significantly discount speakers so don't go by the list price I showed in the first part of the review.
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