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NHT Pro M-00 Powered Monitor Review

thefsb

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I took feedback to trim down these measurements some. Let me know if they are easier to read:
I find these very hard to read. I cannot tell which line corresponds to which angle. And the lines are complex and overlay each other so I cannot follow them left to right. I find the colored contour plots are easy to understand.

A couple of other things to try: radial contour plot; interactive line graph in which JavaScript allows the user to enable/disable each line.
 

StevenEleven

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It is very easy to show misleading CSD graphs. Setting the minimum level easily changes the look of it. The software generates them but whatever I post I like to be able to defend. Here is a snapshot of it for the NHT:

View attachment 45710

I should note that the NHT also buzzes at certain frequency during the sweep at pretty high levels. It is not loud as the JBL but it is clearly there in the back.

To me a buzz in a powered loudspeaker is much worse than a hiss. I would want to be on notice of any hiss or buzz, but a buzz is much more likely to result in a DO NOT BUY based on my own preferences. With the 350Ps, upon casual listening at Guitar Center it seemed evident I could totally forget about this hiss at practical volume levels from more than maybe two feet away, and would stop being able to hear it in a normal environment at three to five feet away. I would not be so sure about that if it were a buzz.
 

Krunok

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Practical experiments have shown limited success however even in this case.

Indeed. And this is what I believe to be the explanation: unlike shallow dip in the region 200-900Hz dip at 4Khz looks quite problematic as Early reflections and Sound power curves don't follow it. But if you imagine pushing that dip up with the carefully choosen Q for 2-2.5dB dip would look much better. Early reflection and Sound power curves would also be pushed up but they still wouldn't look (nor sound) nasty and you may end up with the better sound than if not touching that dip.

NHT M-00.png
 
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amirm

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I find these very hard to read. I cannot tell which line corresponds to which angle. And the lines are complex and overlay each other so I cannot follow them left to right. I find the colored contour plots are easy to understand.

A couple of other things to try: radial contour plot; interactive line graph in which JavaScript allows the user to enable/disable each line.
The graphing capabilities in Klippel are very limited. It can export data but then it is a lot of work to plot them externally. If such data was useful, I would put in the work. But they are not really.

I can provide some exports for people to play with however. Would you like that?
 
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amirm

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To me a buzz in a powered loudspeaker is much worse than a hiss. I would want to be on notice of any hiss or buzz, but a buzz is much more likely to result in a DO NOT BUY based on my own preferences. With the 350Ps, upon casual listening at Guitar Center it seemed evident I could totally forget about this hiss at practical volume levels from more than maybe two feet away, and would stop being able to hear it in a normal environment at three to five feet away. I would not be so sure about that if it were a buzz.
Well, both of them buzz the same with the sweeps. If you are not hearing it with 305p, you won't hear it with NHT either. :)
 

q3cpma

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It is very easy to show misleading CSD graphs. Setting the minimum level easily changes the look of it. The software generates them but whatever I post I like to be able to defend. Here is a snapshot of it for the NHT:

View attachment 45710

I should note that the NHT also buzzes at certain frequency during the sweep at pretty high levels. It is not loud as the JBL but it is clearly there in the back. I have not had time to play with it and find the frequency and correlation with CSD graph.

A somewhat related concern is if it makes the measurement fixture resonate. So far I have been able to verify that is not the case by lifting the speaker and seeing if the problem persists. But that is not a solution of course.

I may just have to measure the cabinet resonances differently using MEMS sensor that stereophile uses or similar.
Yes, but as you said, obvious resonances like JBL's 705p show should stand up and should be good to separate the wheat from the chaff. While not a fan of the 3D diagrams, it is at least here, thanks.

On distortion, it plays a minor role between two different speakers sine linear differences in frequency response is often so large. That large difference sets preference scores. Now, if you have two identical speakers with same linear responses, the distortion may matter.
While I agree about THD, IMD might be another matter.

Resonances and/or uneven decay are either incorporated into magnitude graphs or they are not relevant.
Proof?
 
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amirm

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Here is the text export of one of the directivity plots if someone wants to take a shot at plotting it differently.
 

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amirm

amirm

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While not a fan of the 3D diagrams, it is at least here, thanks.
Keep in mind that the CSD I post is in-room measurement, not anechoic. So it includes room modes.
 

Blumlein 88

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Here is the text export of one of the directivity plots if someone wants to take a shot at plotting it differently.
It imports right into Gnumeric nicely laid out in frequency, SPL DB, and degrees. Easy to work with from there I think.
 
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bogart

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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.
View attachment 45665

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!

I *love* the frequency range buckets on the chart you posted. Super helpful. What software is that?
Edit: Looks like someone said gnumeric? I gotta crawl through more of the thread :)
 

Krunok

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Higher SPL at Time 0 would mean the decay would have higher SPL, thus looking like ringing.

My question was why would you be interested in decay/resonances as they are either already showing in magnitude charts, or if not than they are anyhow irelevant?
 

Blumlein 88

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I *love* the frequency range buckets on the chart you posted. Super helpful. What software is that?
Edit: Looks like someone said gnumeric? I gotta crawl through more of the thread :)
I don't think he used Gnumeric for that. Gnumeric is an open source spreadsheet. The text file also opens neatly in LibreOffice Calc, I'm just more used to Gnumeric. I did do some colored charts with colors for each angle. But nothing too fancy.
 

Krunok

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Common logic. Once you measured consequences you don't really need to investigate the cause that might or might not caused them. Unless of course you are speaker designer so you want to rectify the consequences. ;)

Toole also made a similar comment on that on John Atkinson cabinet resonance measurements.
 

MZKM

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My question was why would you be interested in decay/resonances as they are either already showing in magnitude charts, or if not than they are anyhow irelevant?
Uneven decay will effect tonal balance.

If Time 0 is not normalized, it becomes difficult to tell if unevenness or ringing is a result of uneven frequency response or if the actual decay is uneven/peaking.
 

Thomas_A

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Well, both of them buzz the same with the sweeps. If you are not hearing it with 305p, you won't hear it with NHT either. :)

Is the resonance/buzz in the same frequency range in both speakers? If they occur >1 kHz then I cannot understand how that could be cabinet resonances (even if these speakers appear quite small, which can push the frequencies up a bit). What is the cabinet material in these speakers?

Can you pinpoint at what frequencies the buzzing occurs more precisely? I have two small monitors built with and without constrained damping layers/MDF and the one without have "buzz regions" in the range of 300-400 Hz. The damped cabinet is silent.
 

617

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I think it's hard for some to appreciate that a frequency response chart shows the exact same information as a CSD chart or impulse or step response or whatever.

They are derived from the exact same measurement. They just highlight different aspects of the same data. Krunok is right; CSD is (sometimes) useful in design, but everything you need to know about what is audible in terms of resonances, phase wrinkes, energy storage and frequency response deviations are contained the in the FR plot - because they are all the same thing.
 

napilopez

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I think it's hard for some to appreciate that a frequency response chart shows the exact same information as a CSD chart or impulse or step response or whatever.

They are derived from the exact same measurement. They just highlight different aspects of the same data. Krunok is right; CSD is (sometimes) useful in design, but everything you need to know about what is audible in terms of resonances, phase wrinkes, energy storage and frequency response deviations are contained the in the FR plot - because they are all the same thing.

At this point you might as well just consider me a Toole Book Auto-Reply Bot, but to further elaborate on this point (Section 4.6/p78):

"Simple resonances are found in electronic, acoustical or mechanical devices and constitute “lumped elements” in a resonating system: a mass component (inductance), a compliance (capacitance) component and a damping (resistance) component. The mass and compliance determine the frequency of the resonance. The damping determines the amount of energy loss in the system, which defines the quality factor, or Q. This determines the bandwidth of the resonance in the frequency domain and the duration of the buildup and decay of energy in the time domain. High-Q resonances have a small footprint in the frequency domain (a narrow, sharpish spike in a frequency response) and a long buildup and decay in the time domain. As Q falls, the resonance gets wider in the frequency domain and occupies less space in the time domain. Eventually, the frequency response gets to be “flat,” there is no evidence of a resonance, and the time-domain misbehavior disappears. So it is inevitable that all systems designed to minimize resonances have flattish, smooth frequency responses."

I *love* the frequency range buckets on the chart you posted. Super helpful. What software is that?
Edit: Looks like someone said gnumeric? I gotta crawl through more of the thread :)

Wait are you talking to me or Amir? I don't use gnumeric. I use REW for all my measurements (plus a couple other tools to help process the data).

To activate the frequency range labels in REW simply go to the all SPL graph, click controls, and then "show frequency bands." These labels will remain when you use the capture function too. Note that I'm pretty much always using the most recent REW beta and I'm not sure if this feature is available in the stable version, I don't think it was before.

Snag_f37705c.png


I actually wish I could change the labels a bit since it's weird for me to see FR labels without a 'treble' section, but it works well enough =]
 
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