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NHT Pro M-00 Powered Monitor Review

amirm

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#1
This is a review and detailed measurements of my NHT Pro M-00 powered studio monitor (speaker). I purchased it probably 15 years ago upon a hugely positive review from stereophile(?). It said some famous recording engineer used to mix a ton of popular albums. I bought the package with the S-00 subwoofer. Each speaker cost $249 and the sub was $500 for a total of $1,000.

Years later, NHT hit hard times and closed shop for a while. Then went online direct. I have not kept track of what they do now. These speakers are no longer available but as part of our effort to build up some "speaker measuring muscle," I thought it would make for a good second review. Be sure to read my first review of JBL 305P Mark ii to understand this data better.

The M-00 is a small but weighs like it is filled with rocks:

NHT M-00 Powered Studio Monitor Speaker Review.jpg

The case is made of some aluminum alloy which also acts as the heatsink for the internal amplifiers which are discrete, class AB. Here is the back side:

NHT M-00 Powered Studio Monitor Back Panel Speaker Review.jpg

It has a very rough textured finish which can't be cleaned as you can see from all the scuff marks on mine.

There is nice connectivity in the form of both RCA and XLR/TRS inputs. There is also a switch for "near-field" vs "far-field." I tested it in the former mode because I have them on my desk and assumed that was the correct setting. It is supposed to lower the high frequencies some.

Speaker Spinorama Measurements
If you have read my previous review you know that the heart of our measurements are anechoic measurements of the speaker all around it. These measurements are grouped in different ways to give us insight into how the speaker can sound in our rooms:

NHT M-00 Powered Studio Monitor Speaker CEA-2034 Spinorama Audio Measurements.png


Glancing at all four curves up above we instantly see a major issue with this speaker: a sudden rise in response or put inversely, a suck out in upper bass frequencies. We want our on-axis response in black to be as flat as possible. Here it shows that wide drop which audibly is bad because more musical notes fall in it and hence are lowered in amplitude.

There is also some peaking in high frequencies but if early reflections are allowed to get to you, they balance that out (since there is usually a drop off in high frequencies as you go off-axis from front of the speaker):
NHT M-00 Powered Studio Monitor Speaker CEA-2034 Estimated In-room Response Audio Measurements.png


If on the other hand you think every studio needs to resemble an anechoic chamber with side walls fully absorptive, then the speaker may sound somewhat bright.

Guess what? We are done! We don't need 500 different graphs. The above tell the story and tell it well. But I know some of you want more data so let's provide a bit of that. As usual much more is available. For those of you who just want the top level message, I suggest jumping to listening tests.

Advanced Speaker Measurements
Folks like pretty and colorful graphs so here we are with contour plots in both horizontal and vertical axis:

NHT M-00 Powered Studio Monitor Speaker Contour Audio Measurements.png



NHT M-00 Powered Studio Monitor Speaker Contour Vertical Audio Measurements.png


The more uniformity and gradual change, the better in these graphs. Vertical axis performance tends to be worse in many speakers and such is the case here. So absorbing those if your room is not already too dead may be advised.

I took feedback to trim down these measurements some. Let me know if they are easier to read:
NHT M-00 Powered Studio Monitor Speaker Horizantal and Vertical reflections Audio Measurements.png


They tell us what the contour graphs do but without the fancy colors.

Informal Speaker Listening Tests
I setup the JBL 305P Mark ii as my left channel on my desk and the NHT Pro M-00 for the right. I matched the levels and then played one of the tracks I use for room optimization. The quality different was incredible. The 305P had a super balanced tone with lots of rich and warm detail in upper frequencies. The NTH M-00 in contrast sounded dead and bright.

Thinking I may be biased by my measurements I invited my wife to listen. As I was showing her the controls with her standing on my side she immediately pointed to the JBL 305P and said, "I like that one better!" Still, I forced her to sit down and do the test properly (in Adobe Audition by selecting one or the other channel to play the mono track). She again quickly concluded that the JBL 305 was much better.

Before leaving though, she said that if she was listening to guitar, she may like the NHT Pro better. She plays some guitar and brought it up to show me in person. Instantly I was reminded that neither speaker sounded as "real" has her guitar. :) That aside, she was tuning in to sharper tones in NHT thinking that it would allow her to distinguish the individual strings in an acoustic guitar better. I asked her if she just wanted to sit back and enjoy music, which one should would like and she said with confidence the JBL 305P Mark ii.

Research shows that quality of bass is worth almost 30% in overall preference for a speaker. Best not get that wrong as is the case with the NHT. Fortunately there is a matching sub for it that helps mitigate some of this.

Conclusions
Like a mechanic that listens to an engine and can quickly determine what may be the issue, I hope you are starting to get a feel for the power of these measurements. Even though the measurements are from "anechoic" origin (computed in this case), they are still powerful predictors of listener preference. You better not violate the edict of flat on-axis and smooth early reflection directivity easily.

Knowing what I know know, I would not remotely use the NHT M-00 relative to JBL 305P Mark ii. The difference in overall fidelity and pleasantness is immense. So don't go looking for used NHT M-00. I would have given it a cut-off-head panther award but I want us to get more experience with other speakers to know whether it ranks at the bottom or not.

------------
As always, questions, comments, recommendations, etc. are welcome.

I feel so poor I had to winterize our RV (camper) myself instead of having someone else crawl under the darn thing. I hope you feel sorry enough for me to donate generously using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Sancus

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#2
Advanced Speaker Measurements
Folks like pretty and colorful graphs so here we are with contour plots in both horizontal and vertical axis:
Folks do indeed love them so many thanks for including both :D

I took feedback to trim down these measurements some. Let me know if they are easier to read:
Edit: I do think these are easier to read now. However, I still have quite a bit of difficulty recognizing areas of cancellation, and at what specific angles they're happening. Obviously "bunched lines at a given frequency" is a sign of bad things, but for example, when there are asymmetries and loud-to-soft-to-loud transitions happening at certain angles, I honestly cannot figure that out at all from the SPL line graphs.

Maybe this is simply my lack of experience! But that's why I've been very vocal about preferring the contour plots.

The quality of data you can present using the Klippel is incredible, to say the least.
 
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jhaider

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#3
Will the software let you start the X-axis at 300 or 500Hz? Unless the speaker is a dipole or cardoid, there's not much point to looking lower than that.

If you want to be ultra conservative, Sound und Recording generally has the Y-axis at 100Hz.
 

Sancus

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#4
Will the software let you start the X-axis at 300 or 500Hz? Unless the speaker is a dipole or cardoid, there's not much point to looking lower than that.
Speakers with controlled directivity below 500hz(Genelec Ones and D&D 8c for example) will probably be measured though, and it's easier to compare if all graphs always have the same x axis.... I don't feel like the redundant bass data makes anything harder to read.
 
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amirm

amirm

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Thread Starter #7
Sorry - polar maps.
Ah, there are almost no controls on those graphs. They are created by a plug-in that has its own 3-D renderer.
 

digicidal

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#10
Thanks for another great review. I'm probably biased more than average but I'd put that bass-area-importance value at more like 50% I think. Just looking at the graphs I could tell I would not like these. It's strange because I am, subjectively, quite irritated by upper-mid and high-end peaks. However in listening to dozens of speakers with problems in those areas - even on-axis, where they are most pronounced - I'm able to overlook (listen through?) those problems on speakers with relatively linear delivery of everything below 800Hz or so. I guess I'm just a natural bass-head. ;)
 

gr-e

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#11
Let me know if they are easier to read:
While not having + and - angles for horizontal plots is an improvement, 10dB scale makes it much harder to read and leaves a lot of empty space. Also I'd prefer having less graphs, say 0-40 or 0-50 degrees. That will be enough to see the effects of diffraction and how they are dealt with (you can see a dip around 4k here to balance out the bunching up). I don't think that more extreme angles need separate measurements. Their effect shows up better on CEA2034 graphs.
 
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#12
This is probably more middle of the road. The JBL 305s have a reputation for being better than what is typical.
 

gr-e

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#13
I noticed that all three measurements so far have a bump around 150Hz. Is this an effect of close-miking?
 
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#15
HAHA!! my friend actually owns a pair similar to these. I knew something was up with the sound. It's not that they sound bad at all but now i know it was the high lows. It's almost like you say in the article, they sound like they get sucked out of the spectrum. I still like them though.
 
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amirm

amirm

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Thread Starter #17
I noticed that all three measurements so far have a bump around 150Hz. Is this an effect of close-miking?
It may be. I may have to measure from longer distance. Have to wait until I have a speaker with spin data from other sources.
 

PaulD

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#18
It may be. I may have to measure from longer distance. Have to wait until I have a speaker with spin data from other sources.
Amirm, I would expect your measurement mic to be omni - these do not have precedence effect (bass boost when in close proximity too the source). If your mic is an omni as 99% of measurement mics are, then the bass boost cannot be because of precedence effects from the micing distance. It may be because of room effects, or perhaps the source has then lump.
 

napilopez

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#19
Good to see a relatively 'meh' speaker compared to the JBL @amirm. Shows how much you can tell just by these masurements. Took all of a few seconds, before even reading your listening impressions and labelling on the graphs, I thought something like "seems bright, probably sound pretty dull due to the bass suckout and minimal bass extension in the first place. Would probably sound better well off axis." Lo and behold...

Thanks for simplifying the horizontal and vertical graphs! That said, I still think the vertical up and down should be on separate plots or at least different colors- there's no way of telling which lines correspond to which measurement, for instance, and the lobing usually isn't completely symmetrical. This is particularly notable for monitor speakers which will often have a stronger desk reflection than ceiling reflection in many setups, so telling the up and down apart is important. Likewise if you have a low ceiling, you might care more about the ceiling reflection.

For example, here are my vertical measurements measurement of the neumann kh80 I just posted in another thread.
KH80 Vertical  Full.png

Fairly different responses in both directions. I guess this is evident from the polar graph but those give me a headache =]
I also really liked how you included the ceiling and floor reflection curves in the JBL review - I'd actually take just those two curves over the vertical graphs as currently shown.

Thanks for all your hard work!
 

napilopez

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#20
Amirm, I would expect your measurement mic to be omni - these do not have precedence effect (bass boost when in close proximity too the source). If your mic is an omni as 99% of measurement mics are, then the bass boost cannot be because of precedence effects from the micing distance. It may be because of room effects, or perhaps the source has then lump.
I believe they're referring to baffle step, which will cause a bass bump in nearfield measurements if not corrected in software, though I assumed the Klippel corrected for this. The speakers may also very well just measure this way though - it's pretty common to see a bass bump right before the rolloff.
 
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