This is a review and detailed measurements of the HTD Level 3 bookshelf speaker. I got talked into buying it by members due to its popularity in home theater forum. For you all's sake, it better perform! 
I don't remember what it cost me but the current price in black is US $429 from the company direct.
I must say, I am very pleased with the way they look:
I guess I have a soft spot for white woofers. I also like the rather serious look of that tweeter.
Back panel shows a couple of screws which should make it much easier to hang this from walls for your side and rear channels:
Screw binding posts are too close together making it a pain to tighten or loosen them.
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. Using computational acoustics, far-field response is computed and that is what I present. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber.
I performed over 1000 measurement which resulted in error rate of about 1%. Clean high frequency response is responsible for ease of measurement in this regard.
Reference axis is approximately the center of the tweeter. Grill was not used.
HTD Level Three 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:
The only word that comes to my mind is "wow" as is "wow, that is bad!" There are so many problems here. First and foremost is the peaking tweeter response as frequencies climb. The overall response is so jagged and we have some sudden anomalies. Sensitivity is also quite low as evidenced by me having to turn up the gain to measure the speaker by some 4 to 5 dB above average speaker. For some clues as to why the response is so bad, I disconnected the rear binding posts from upper and lower halves and measured the tweeter and woofer independently:
We clearly see some of the issues behind our frequency response errors. The port is letting out some nasty resonances and the tweeter response is anything but smooth and flat.
Even the impedance measurement shows us something seriously is wrong:
One can say that getting proper frequency response is difficult for smaller companies but impedance measurements are dead simple. Whatever is going on around 260 Hz should have been found and dealt with. While on this graph, unlike many speakers, the minimum impedance is ht around 2 khz to the tune of 3.6 ohm. For bass frequencies it is above 6 ohm which is good.
Back to our "spin" information, let's look at the early and strongest reflections in a typical room:
We see many of the same problems here. As noted, if you put an absorber behind your seating position (your back wall, speaker's "front wall"), it may help with the extra brightness.
Predicted in-room response smooths out some of the problems but leaves a lot:
There is some good news in the form of very good directivity control of the tweeter in the horizontal dimension:
Vertically is a mess but so are many 2-way speakers:
Getting proper distortion measurements is hard because the frequency response is so wild. I adjusted it for mid-range levels and got these:
These are some of the worst distortion measurements on record but note that many of the issues are narrow peaks so audibility will not be as bad it may look.
HTD Level 3 Listening Tests
The immediate reaction was the extreme shrillness of the highs. It is over the top unless you have lost all of your high frequency hearing in which case, it sounds fine. This "showroom sound" can sound appealing -- for a bit at least -- so please don't write that you don't think it sounds bright. Measurements say so as do my ears. But the overall feeling of clarity that such overboosted highs present is hard to deny.
There is some cleverness in the bass response in that this speaker can play very loud without bottoming out. It simply filters out deep bass that it can't play so fits its intended usage of home theater sound with subs and such.
At times, I enjoyed listening to them despite all the flaws there. This may be due to controlled horizontal directivity.
I did not bother to develop an EQ. There are just too many issues here to deal with. Best to get a better speaker that doesn't require so many fixes.
Conclusions
Objectively the HTD Level 3 is a disaster. Clearly no measurements were performed to verify efficacy of the design. That said, while some aspects like high frequency boost are clearly audible and annoying, the rest of the response hurt the eye more than the ear. Bass tuning is clever to keep the speaker from distorting and hence allowing it to play quite loud. And there is something to that wide and controlled horizontal directivity that I can't quantify but I think contributed to sound that is not nearly as bad as measurements show.
We could look at this speaker as a puzzle given the huge number of flaws in its design but yet, not so horrible sound and try to figure out what is going on. Me? I just rather get a good speaker that doesn't make me spend this kind of effort on it. The designer should do more than is delivered here so my work is touch up and no more.
I can't recommend the HTD Level Three and curse all of you who made me buy it.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
I don't remember what it cost me but the current price in black is US $429 from the company direct.I must say, I am very pleased with the way they look:
I guess I have a soft spot for white woofers. I also like the rather serious look of that tweeter.
Back panel shows a couple of screws which should make it much easier to hang this from walls for your side and rear channels:
Screw binding posts are too close together making it a pain to tighten or loosen them.
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. Using computational acoustics, far-field response is computed and that is what I present. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber.
I performed over 1000 measurement which resulted in error rate of about 1%. Clean high frequency response is responsible for ease of measurement in this regard.
Reference axis is approximately the center of the tweeter. Grill was not used.
HTD Level Three 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:
The only word that comes to my mind is "wow" as is "wow, that is bad!" There are so many problems here. First and foremost is the peaking tweeter response as frequencies climb. The overall response is so jagged and we have some sudden anomalies. Sensitivity is also quite low as evidenced by me having to turn up the gain to measure the speaker by some 4 to 5 dB above average speaker. For some clues as to why the response is so bad, I disconnected the rear binding posts from upper and lower halves and measured the tweeter and woofer independently:
We clearly see some of the issues behind our frequency response errors. The port is letting out some nasty resonances and the tweeter response is anything but smooth and flat.
Even the impedance measurement shows us something seriously is wrong:
One can say that getting proper frequency response is difficult for smaller companies but impedance measurements are dead simple. Whatever is going on around 260 Hz should have been found and dealt with. While on this graph, unlike many speakers, the minimum impedance is ht around 2 khz to the tune of 3.6 ohm. For bass frequencies it is above 6 ohm which is good.
Back to our "spin" information, let's look at the early and strongest reflections in a typical room:
We see many of the same problems here. As noted, if you put an absorber behind your seating position (your back wall, speaker's "front wall"), it may help with the extra brightness.
Predicted in-room response smooths out some of the problems but leaves a lot:
There is some good news in the form of very good directivity control of the tweeter in the horizontal dimension:
Vertically is a mess but so are many 2-way speakers:
Getting proper distortion measurements is hard because the frequency response is so wild. I adjusted it for mid-range levels and got these:
These are some of the worst distortion measurements on record but note that many of the issues are narrow peaks so audibility will not be as bad it may look.
HTD Level 3 Listening Tests
The immediate reaction was the extreme shrillness of the highs. It is over the top unless you have lost all of your high frequency hearing in which case, it sounds fine.
This "showroom sound" can sound appealing -- for a bit at least -- so please don't write that you don't think it sounds bright. Measurements say so as do my ears. But the overall feeling of clarity that such overboosted highs present is hard to deny.There is some cleverness in the bass response in that this speaker can play very loud without bottoming out. It simply filters out deep bass that it can't play so fits its intended usage of home theater sound with subs and such.
At times, I enjoyed listening to them despite all the flaws there. This may be due to controlled horizontal directivity.
I did not bother to develop an EQ. There are just too many issues here to deal with. Best to get a better speaker that doesn't require so many fixes.
Conclusions
Objectively the HTD Level 3 is a disaster. Clearly no measurements were performed to verify efficacy of the design. That said, while some aspects like high frequency boost are clearly audible and annoying, the rest of the response hurt the eye more than the ear. Bass tuning is clever to keep the speaker from distorting and hence allowing it to play quite loud. And there is something to that wide and controlled horizontal directivity that I can't quantify but I think contributed to sound that is not nearly as bad as measurements show.
We could look at this speaker as a puzzle given the huge number of flaws in its design but yet, not so horrible sound and try to figure out what is going on. Me? I just rather get a good speaker that doesn't make me spend this kind of effort on it.
The designer should do more than is delivered here so my work is touch up and no more.I can't recommend the HTD Level Three and curse all of you who made me buy it.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
