This is a review and detailed measurements of the NHT C3 3-way, sealed speaker. It was purchased new by a member and kindly drop shipped to me. It costs US $391 on Amazon for a single unit.
I must say, I was impressed by the fit and finish of the C3:
The enclosure is sold and dense with a beautiful piano black finish.
I love that the back panel has threaded screw holes to mount the speaker to the wall/ceiling for surround/Atmos applications:
Speaker is manufactured in China.
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.
I performed over 1000 measurement which resulted in error rate of around 1%.
It is down to freezing outside so the best I could do was raise the temperature to 56 degrees. Speaker however was kept warm indoors prior to measurements.
Reference axis was that of the tweeter. Grills were not used.
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.
NHT C3 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:
EDIT: looks like the mid-range is damaged in this unit. It has a dimple on the bottom of it. This could explain the mid-frequency dip. Unfortunately I only have one unit to test so can't verify.
On-axis response is kind of wavy. This was unexpected as measurements performed elsewhere are much flatter. My in-room measurements showed the same so I don't think it is an issue with NFS measurements. Likely a design change was made to tilt up the highs more to keep up with the competition in the showroom. We can see the uneven response in individual driver response:
Seems like one could push up the tweeter level a bit or else, bring the tweeter down. The tweeter by itself has uneven response.
As noted in the first graph directivity is good so for good or bad, early window reflections follow on-axis irregularities:
Predicted in-room response shows very little tilt so speaker is going to sound bright:
As I noted, directivity is good due to use of mid-range driver:
If you are going to use this up high for surround applications, be sure to tilt it down some:
Distortion was two completely different stories depending on level:
At 86 dB, this is professional monitor level of distortion, not a budget passive speaker! Push it though and things get bad especially with that tweeter. I have not seen one fall apart this badly. Fortunately that is where we have elevated response so we would want to EQ that down anyway and that should help keep that distortion in check.
Needless to say, at 94 dBSPL it exceeds our threshold:
Impedance is typical of these speakers, down to 4 ohm or so:
I forgot to mention earlier that sensitivity is rather low, dropping to 82 to 83 dB in mid-range area. Company advertises 87 dB which would only be true of the peaking tweeter.
NHT C3 Listening Tests and Equalization
The high frequency peaking was not obnoxious but clearly overdone (as appealing as that could be for a few seconds). So had to EQ that anyway and while there, might as well tweak the rest:
Filling that little but wide dip in upper bass was important in providing balance relative to highs (which I did not fully cure on purpose). I then filled in the 1 to 4 kHz region and job was done. Once there, the benefits of a sealed enclosure was there with its ability to play sub-bass without getting distorted. Alas, without the boosted upper bass that we get from ported speakers, the bass was a bit light but I was fine with that.
Dynamics was very good and speaker could handle a lot of power. And a lot of power is what I had to feed it so don't get a 50 watt amp. You need more than that.
Conclusions
It is a shame we didn't measure the C3 as well as others had. That would have made it a lot closer to ideal. As is, without EQ it is bright and hence "detailed." To my ears, that gets old fast so EQ is mandatory in my book. And so is filling in the other two dips. Speaker takes EQ well since we are not trying to push it where distortion is highest.
Overall, I was happy with the NHT C3 and would recommend it with EQ. No without.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
I must say, I was impressed by the fit and finish of the C3:
The enclosure is sold and dense with a beautiful piano black finish.
I love that the back panel has threaded screw holes to mount the speaker to the wall/ceiling for surround/Atmos applications:
Speaker is manufactured in China.
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.
I performed over 1000 measurement which resulted in error rate of around 1%.
It is down to freezing outside so the best I could do was raise the temperature to 56 degrees. Speaker however was kept warm indoors prior to measurements.
Reference axis was that of the tweeter. Grills were not used.
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.
NHT C3 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:
EDIT: looks like the mid-range is damaged in this unit. It has a dimple on the bottom of it. This could explain the mid-frequency dip. Unfortunately I only have one unit to test so can't verify.
On-axis response is kind of wavy. This was unexpected as measurements performed elsewhere are much flatter. My in-room measurements showed the same so I don't think it is an issue with NFS measurements. Likely a design change was made to tilt up the highs more to keep up with the competition in the showroom. We can see the uneven response in individual driver response:
Seems like one could push up the tweeter level a bit or else, bring the tweeter down. The tweeter by itself has uneven response.
As noted in the first graph directivity is good so for good or bad, early window reflections follow on-axis irregularities:
Predicted in-room response shows very little tilt so speaker is going to sound bright:
As I noted, directivity is good due to use of mid-range driver:
If you are going to use this up high for surround applications, be sure to tilt it down some:
Distortion was two completely different stories depending on level:
At 86 dB, this is professional monitor level of distortion, not a budget passive speaker! Push it though and things get bad especially with that tweeter. I have not seen one fall apart this badly. Fortunately that is where we have elevated response so we would want to EQ that down anyway and that should help keep that distortion in check.
Needless to say, at 94 dBSPL it exceeds our threshold:
Impedance is typical of these speakers, down to 4 ohm or so:
I forgot to mention earlier that sensitivity is rather low, dropping to 82 to 83 dB in mid-range area. Company advertises 87 dB which would only be true of the peaking tweeter.
NHT C3 Listening Tests and Equalization
The high frequency peaking was not obnoxious but clearly overdone (as appealing as that could be for a few seconds). So had to EQ that anyway and while there, might as well tweak the rest:
Filling that little but wide dip in upper bass was important in providing balance relative to highs (which I did not fully cure on purpose). I then filled in the 1 to 4 kHz region and job was done. Once there, the benefits of a sealed enclosure was there with its ability to play sub-bass without getting distorted. Alas, without the boosted upper bass that we get from ported speakers, the bass was a bit light but I was fine with that.
Dynamics was very good and speaker could handle a lot of power. And a lot of power is what I had to feed it so don't get a 50 watt amp. You need more than that.
Conclusions
It is a shame we didn't measure the C3 as well as others had. That would have made it a lot closer to ideal. As is, without EQ it is bright and hence "detailed." To my ears, that gets old fast so EQ is mandatory in my book. And so is filling in the other two dips. Speaker takes EQ well since we are not trying to push it where distortion is highest.
Overall, I was happy with the NHT C3 and would recommend it with EQ. No without.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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