Neumann KH150 Review

[staticV3]

Hi everyone!

I must admit that I am not able to make head or tails for the "Multi-tone response" graph. Can someone help me by giving a quick breakdown of it?

Blue is the original stimulus played back through the speakers, red all intermodulation distortion created by the speaker.
Black the noise floor.


This is the same as red above, with two differences:

1.Multitone distortion plotted as a single line connecting the peaks of every frequency bin, to aid readability
2. Plotted not as absolute SPL values, but relative to the amplitude of the stimulus at any given frequency.
E.g: At 1300Hz, Multitone IMD reached 30dB below the fundamental.


Same as above, but shows what happens when you high-pass the test signal and relieve the woofer.


Both Multitone fundamental and Multitone distortion plotted as lines, showing behavior at different SPLs


Multitone distortion plotted as lines and relative to the fundamental (same as graph #2), but this time at various SPLs to show (non)linearities as you increase volume.

Since the MT distortion produced by the woofer increases more with increasing SPL than that of the tweeter, it shows that the woofer is the factor that's limiting high SPL playback. The tweeter has more to give.

And indeed, if we see how loud the KH150 can play each frequency before exceeding 3% THD, this is confirmed:

Source

One might say that the tweeter is over-engineered, considering that the peak amplitudes of natural sound/music typically decrease with increasing frequency.

So it's difficult to make use of all that tweeter headroom if the woofer calls it quits much sooner.

 

[lowerfe]

Wow, absolutely stunning performance, especially the woofer Klippel measurements. This is how a woofer should be designed when used in an active speaker, and this is how an active speaker should be designed. Do you have the Le(x) measurements of the woofer?

 

[Curvature]

One might say that the tweeter is over-engineered, considering that the peak amplitudes of natural sound/music typically decrease with increasing frequency.

So it's difficult to make use of all that tweeter headroom if the woofer calls it quits much sooner.

Neumann uses the same tweeter and a similar waveguide for all speakers. Makes sense for a lot of reasons.

 

[Nuyes]

Wow, absolutely stunning performance, especially the woofer Klippel measurements. This is how a woofer should be designed when used in an active speaker, and this is how an active speaker should be designed. Do you have the Le(x) measurements of the woofer?

Yes — the LSI module also measures Le(x), so I do have that data.
I just “held back” on including it because when too many parameters get involved, the scope of the review can quickly become overwhelming.


As for why the KH150’s woofer shows such low levels of almost every IMD (Intermodulation Distortion) component — except for Doppler distortion — I’d say it ultimately comes down to one thing: it’s simply built around an exceptionally well-engineered driver.

 

[lowerfe]

View attachment 469772

Yes — the LSI module also measures Le(x), so I do have that data.
I just “held back” on including it because when too many parameters get involved, the scope of the review can quickly become overwhelming.


As for why the KH150’s woofer shows such low levels of almost every IMD (Intermodulation Distortion) component — except for Doppler distortion — I’d say it ultimately comes down to one thing: it’s simply built around an exceptionally well-engineered driver.

Holy crap that's incredible inductance control. This is very close to Purifi level performance. My hat's off to Neumann. Is the woofer using a neo motor?

 

[beagleman]

By the standards of the 1970's, the response could be deemed to be quite good, as it more or less falls within a ±3dB range.

I mean even today that is quite good.

I know WHY we strive for really flat response, but not so sure its truly the goal overall. I mean the room, our ears and hearing and program material all factor in, and just HAVING flat on axis response, its not a Guarantee of hearing that in your head at your final listening position

 

[Jazigo]

View attachment 469738
Blue is the original stimulus played back through the speakers, red all intermodulation distortion created by the speaker.
Black the noise floor.

View attachment 469737
This is the same as red above, with two differences:

1.Multitone distortion plotted as a single line connecting the peaks of every frequency bin, to aid readability
2. Plotted not as absolute SPL values, but relative to the amplitude of the stimulus at any given frequency.
E.g: At 1300Hz, Multitone IMD reached 30dB below the fundamental.

View attachment 469736
Same as above, but shows what happens when you high-pass the test signal and relieve the woofer.

View attachment 469735
Both Multitone fundamental and Multitone distortion plotted as lines, showing behavior at different SPLs

View attachment 469734
Multitone distortion plotted as lines and relative to the fundamental (same as graph #2), but this time at various SPLs to show (non)linearities as you increase volume.

Since the MT distortion produced by the woofer increases more with increasing SPL than that of the tweeter, it shows that the woofer is the factor that's limiting high SPL playback. The tweeter has more to give.

And indeed, if we see how loud the KH150 can play each frequency before exceeding 3% THD, this is confirmed:
View attachment 469751
Source

One might say that the tweeter is over-engineered, considering that the peak amplitudes of natural sound/music typically decrease with increasing frequency.

So it's difficult to make use of all that tweeter headroom if the woofer calls it quits much sooner.

Thank you so much for taking time to break this down!

Follow-up question 1: In graph #4 and #5 (in your post), I see that the MDs are different from previous posts. Is it correct to assume that in graph #4, a different test is performed that in the previous graphs? (Perhaps the fundamental is pink-noise or something).

Follow-up question 2: Given graph #4, say I listen to these speakers at 76db at home and I also have the exact same noise-floor, would the distortion be below the noise floor and (in-turn) be inaudible?

 

[staticV3]

Follow-up question 1: In graph #4 and #5 (in your post), I see that the MDs are different from previous posts. Is it correct to assume that in graph #4, a different test is performed that in the previous graphs? (Perhaps the fundamental is pink-noise or something).

#5 is consistent with #1,2,3 from what I can tell. Smoothing is slightly different, but the underlying data seems to match.

#4 is the odd one out though.
I'm sure @Nuyes can tell you why

Follow-up question 2: Given graph #4, say I listen to these speakers at 76db at home and I also have the exact same noise-floor, would the distortion be below the noise floor and (in-turn) be inaudible?

I'd say so, yes.

 

[Curvature]

By the standards of the 1970's, the response could be deemed to be quite good, as it more or less falls within a ±3dB range.

I mean even today that is quite good.

On axis response has to be taken into the context of the total response of the speaker. Alone it doesn't say much.

This is a better way to think about speaker FR: https://www.audiosciencereview.com/...-fancy-accessories.59214/page-14#post-2358410

That spin result is terrible. No other word for it.

 

[RogerSmith]

Nice review, thanks, I know it is in the review from Amir, but why did you not include the estimated in-room response?

 

[Curvature]

Nice review, thanks, I know it is in the review from Amir, but why did you not include the estimated in-room response?

While that curve is missing, you can infer it from the listening window.

Here it is from Amir's measurments: https://www.spinorama.org/speakers/Neumann KH 150/ASR/asr/Estimated In-Room Response.html

 

[Curvature]

Nice review, thanks, I know it is in the review from Amir, but why did you not include the estimated in-room response?

View attachment 469890
While that curve is missing, you can infer it from the listening window.

Here it is from Amir's measurments: https://www.spinorama.org/speakers/Neumann KH 150/ASR/asr/Estimated In-Room Response.html

Here's a demonstration of how closely they match within the limits of Nuyes' gated measurements.

 

[Nuyes]

Thank you so much for taking time to break this down!

Follow-up question 1: In graph #4 and #5 (in your post), I see that the MDs are different from previous posts. Is it correct to assume that in graph #4, a different test is performed that in the previous graphs? (Perhaps the fundamental is pink-noise or something).

Follow-up question 2: Given graph #4, say I listen to these speakers at 76db at home and I also have the exact same noise-floor, would the distortion be below the noise floor and (in-turn) be inaudible?

#5 is consistent with #1,2,3 from what I can tell. Smoothing is slightly different, but the underlying data seems to match.

#4 is the odd one out though.
I'm sure @Nuyes can tell you why


I'd say so, yes.

I perform two types of Multitone Tests:

1. Fixed Level
2. Increased Level

Both use the default templates provided in the Klippel measurement module.
The first type follows a white spectrum, meaning all test frequencies are played at the same output level.
The second type follows the IEC 60268 curve, so the stimulus signal is slightly attenuated in the low and high frequency ranges, as shown in the example graph.

 

[witwald]

On axis response has to be taken into the context of the total response of the speaker.

Well, I suppose that goes without saying...

Alone it doesn't say much.

That seems a tad harsh. Alternatively, it says quite a lot and provides an entirely reasonable and substantial, if incomplete, window into the loudspeaker's performance envelope.

 

[stoneeh]

Props for including IMD & compression charts

 

[witwald]

I know WHY we strive for really flat response, but not so sure its truly the goal overall. I mean the room, our ears and hearing and program material all factor in, and just HAVING flat on axis response, its not a Guarantee of hearing that in your head at your final listening position

Well, amongst the litany of vagaries affecting our subjective interpretation of program material, why would it be desirable to have anything other than a flat on-axis response when this is a very important contributor to our overall perception of a loudspeaker in the room? For example, all other things being equal, will not a rising top end in the on-axis response come across as a rising top end in a majority of listening environments, and thus be heard as a defect in the loudspeaker's fidelity? If one has a loudspeaker with a preponderance towards a non-flat on-axis response, as room effects are reduced, what is left? Nothing but the erroneous, distorted, subjectively objectionable, non-flat on-axis response. Prima facie, if a loudspeaker cannot achieve a flat (anechoic) on-axis response, what hope does it have of working well across a range of listening environments, let alone sonic variations in program material?

 

[Tovarich007]

Is the 8341 worth the extra $$$ over KH150?

Two different excellent designs, so it's impossible to answer your question.
What are the main points :
- the Neumann is ruler flat (FR wise) and has a stunning bass response and SPL for its size.
- the Genelec is slightly less ruler flat (but very good for overall neutrality anyway), she descends a little bit less in the low bass, but its coax does marvels in coherency and imaging in small/medium rooms.

If it's for you mainly a budget question, go for the Neumann. If you can push up the expense, try to arrange a direct comparison between these two speakers with equalized level and choose the one you prefer, because as theoricaly good are they both on tests, they won't sound exactly the same by themselves.
Measurements tell a lot, for sure, but the sound in real conditions is never the same and always a question of taste, we are subjective animals after all.
And in the end, don't forget that EQ and calibration well done may reduce the perceived differences.

 

[Music1969]

Compression Test

Is this the short term burst test like Erin does? Or longer term steady state test like Erin does?

Can you clarify

 

[peniku8]

Directivity
View attachment 469187
Even with no smoothing applied, the response is smooth across nearly all angles — it almost looks smoothed.
Classic Neumann performance.

Thanks for the data and nice to see how your measurements compare to the NFS data!

Do you have a write-up on your measurement setup somewhere? Gated in-room spliced with near field measurements? GP? Big stick? I couldn't find any info in your signature (might be a good place to put it).

A small (non cardioid) speaker like this will exhibit nowhere near 10dB of rearward rejection at 200Hz (as backed up by the NFS measurement that shows more like 1-2dB), so I'd suspect the measurement distance being too close (looks like maybe even closer than 1m?). Your graph likely looks smoothed, as you describe it, because of short gating times (looks like slightly too short variable gate timings to me, which lowers frequency resolution and results in pretty much the same thing as regular smoothing).
I'd suggest to shade the directivity plots below 500Hz or so, if that's possible, to show that it's not entirely reliable data.

Also let me take this opportunity to express my personal grief with the Klippel colors:
-3dB: Dark red
-6dB and -9dB: almost the same kind of.. also red... in a rainbow map... cmon!
Btw, since you're using the Klippel software maybe you know: is it possible to change the color gradient of the contour plots?
There is a plethora of perceptually uniform color maps (examples here: https://colorcet.com/gallery.html) and VACS for example has quite a nice selection. I personally really like the "heatmap" color gradients, such as CET-L17, which comes close to the "Otto" and "Friedrich" settings in VACS.

Here are some examples:

"Friedrich" applied to one of my horn designs:

I would love to see NFS data presented with a better color gradient (spinorama.org is quite a lot better already). Amir's contour plots are especially challenging to read, since (to me at least, with a good color calibrated display) everything from 0dB to -10dB looks like a big red mess. If it was somehow possible, my personal preference would be CET-L17 as non-stepped color gradient plus (3dB) contour lines. Kinda what Vituix generates, just with CET-L17 instead of the rainbow gradient. Maybe an idea for @kimmosto *wink wink*

 

[Tom C]

View attachment 469179
After quite some time, Neumann finally released a new model in late 2022.
What makes this one especially exciting is that it neatly fills the gap between the KH80 (4") / KH120 (5") and the KH310 (8") — at a very versatile 6.5" size.




View attachment 469180
The back panel follows Neumann’s traditional style.
With the XLR connector mounted from the bottom up, you can place the speaker flush against a wall or bracket without interference — a thoughtful touch.




Frequency Response
View attachment 469181
As expected from a professional monitor, performance is excellent.
The overall balance is flat and smooth, with the -6 dB low-end extension measured at 39.4 Hz.


For reference, my graphs use 1/24-oct smoothing. (The CEA-2034 standard specifies a minimum of 1/12-oct; a larger denominator means higher resolution in the data.)




Cross check with ASR Data
View attachment 469182
I overlaid my results with the official measurements from Audio Science Review.
The two sets of data match extremely well, except for the low-end extension.
The Klippel NFS system used by @amirm is especially reliable in the low-frequency range.




Nearfield Measurements
View attachment 469184

As you’d expect from Neumann, all responses are clean and well-controlled.
The woofer shows no signs of breakup modes at higher frequencies, and the port is free from pipe resonance noise.


Let’s take a closer look at that last point.




View attachment 469183
In the rear-panel teardown photo, note the white section I’ve outlined.

This is an effort to control the inherent pipe resonance that can occur in any port design.
For a more detailed explanation of this topic, please see my article here:


https://audiore.kr/스피커-성능-측정-보고서/


Interestingly, there’s an opening at roughly one-quarter of the port’s length, backed with acoustic damping material to absorb resonances.
On closer inspection, there’s also a layer of black foam sandwiched between the white foam and the port opening — with each layer having noticeably different density.




This appears to be a multi-stage acoustic impedance transition.
By gradually increasing the acoustic impedance between the port air column and the damping material, the design likely improves absorption efficiency and reduces internal reflections.



In simple terms:
When sound travels through different media, the more similar their acoustic impedance, the more easily it passes through.
A sudden mismatch in impedance causes reflections instead of transmission.
Neumann’s layered approach likely minimizes these reflections and boosts damping efficiency.




CEA-2034
View attachment 469185
The on-axis response is smooth, but the Listening Window curve is even smoother and flatter.
This suggests Neumann may have designed and tuned the KH150 with the Listening Window in mind, rather than focusing solely on the exact 0° axis.




Directivity
View attachment 469186
View attachment 469187
Even with no smoothing applied, the response is smooth across nearly all angles — it almost looks smoothed.
Classic Neumann performance.




View attachment 469188
View attachment 469189
Vertical directivity is also excellent: narrow, consistent, and stable well into the top end.
(The apparent widening above ~17 kHz is due to a slight dip in the 0° response at that frequency.)




Beamwidth
View attachment 469190
The beamwidth narrows gradually and evenly, making it difficult to pinpoint the woofer–tweeter crossover just from the curve — a sign of a finely tuned waveguide and excellent driver matching.




View attachment 469191




Polar Plots
View attachment 469192
Among enthusiasts, there’s ongoing debate over whether narrowing or constant beamwidth is preferable.
Here, Neumann has gone for a gently narrowing pattern, achieving remarkably uniform attenuation at almost every radiation angle — even to the sides and rear — except for a small section in the extreme treble.




View attachment 469193
Vertical polar results are also tightly clustered within the intended radiation angles, with only a slight narrowing around 2 kHz due to the non-coaxial layout.





THD
View attachment 469194
As a reviewer, I try to avoid bias — but with brands like KEF, Neumann, and Genelec, it’s hard not to expect excellence even before measuring.
Fortunately, my microphone and test rig are free of such bias, so you can trust the objectivity of the data.


Performance is impressive across the board, especially the low distortion even below 100 Hz — notable for a speaker capable of solid output in the 30 Hz range.




View attachment 469195
View attachment 469196
3rd harmonic distortion is practically at the noise floor.




View attachment 469197
When increasing the measurement output, I noticed something odd in the 150–400 Hz range — not only visible on the graph, but also audible as a noise during playback.
First, the sharp spikes in the THD curve at those points are not part of the speaker’s intrinsic response; rather, they are the result of an interaction between my measurement stand and the speaker itself.

As with the KH120’s upgrade to the “II” version, the KH150’s enclosure has also been switched to plastic.
Because of this, the speaker’s total weight is relatively low compared to the strength of its woofer, meaning that if it’s placed directly on a perfectly smooth, flat surface, a certain resonance can cause the cabinet to “walk” at specific frequencies.

This is not unique to the KH150 — I’ve occasionally encountered other models with similar issues.
These days, when such problems arise, I apply additional damping measures during testing.
However, when I measured this unit back in 2023, my view at the time was that “the interaction between the product and the test environment is inevitable, and maintaining consistency is more important.”
So I decided to record the data as-is.

That said, the issue can be mitigated by placing a heavy book on top of the speaker (to add mass) or by putting a layer of felt or EVA foam sheet under the base.




View attachment 469198
View attachment 469199
Aside from this artifact, performance is excellent.




Woofer Measurement
View attachment 469200
With the owner’s permission, I opened the unit to examine the woofer in more detail.




View attachment 469201
Close-mic measurements of 3rd harmonic distortion showed similar trends to the far-field results (blue trace).





LSI(Large Signal Identification)
View attachment 469202
This might be the first time I’ve shown this type of graph in my speaker review series.
The Klippel measurement system includes a module called LSI (Large Signal Identification), which is a useful tool for observing the driver’s state in real time, by displacement, when the driver is operating at large excursions.
For this review, I’ve brought in only two parameters: Bl(x), which represents the force from the voice coil and permanent magnet, and Kms(x), which represents the restoring force of the suspension.

Since these graphs may look unfamiliar, let me explain briefly:
The x-axis indicates the distance the speaker cone moves forward or backward from the center position of 0 mm (measured in millimeters).
The y-axis shows the magnitude of each force (Bl and Kms) when the speaker is displaced by that amount.




View attachment 469212

If a speaker could maintain its best performance whether stationary or in motion, that would be ideal — but reality is different.
Because the voice coil moves and the permanent magnet remains fixed, Bl(x) will vary in real time depending on the coil’s position.




View attachment 469213
The same is true for the restoring force of the suspension.
In a loudspeaker, this role is handled by the surround and the spider.
The further these parts move away from rest, the greater their restoring force becomes by nature.
(Think of pulling on a piece of fabric or a rubber band!)




View attachment 469203

For this reason, even in well-made speaker drivers, the Bl(x) curve typically takes on a smooth inverted-U shape, and the Kms(x) curve takes on a smooth U shape.
(The example above shows the LSI measurement results for a KEF R-series 6.5-inch driver.)


The narrower and sharper these curves become, the more the 3rd harmonic distortion component will increase relative to displacement.
The more asymmetric the curves become, the more the 2nd harmonic distortion component will increase relative to displacement.

It’s a slightly difficult topic, but thank you for following along.
Now, let’s look at the KH150’s case.




View attachment 469202
Even over a very large displacement range, the KH150 shows almost no change in the values of Bl(x) and Kms(x), maintaining a consistent shape.
In the small displacement range, the symmetry is also excellent.

This, I believe, is the secret to how this speaker can reproduce frequencies in the 30 Hz range while maintaining clean quality.







Multitone Test
View attachment 469204
View attachment 469205
Multitone distortion performance is generally very strong.
It is especially impressive below 500 Hz.
Above that, the gradual rise up to around 1.7 kHz is likely dominated by Doppler-related IMD (Intermodulation Distortion), caused by the woofer handling upper midrange content in a 2-way design.




80Hz~
View attachment 469206




View attachment 469207
View attachment 469208

That’s pure strength, through and through.
In the mid-to-low frequencies in particular, I don’t think there’s anything in its class that can match it.




Compression Test
View attachment 469209
No words needed — it’s a beast, delivering well beyond what its size might suggest.




Deviation between 2 samples
View attachment 469210
“Neumann being Neumann.”
From the KH80 through the KH120 II, the integration of DSP has pushed their QC standards to an exceptional level.




Final Thoughts
In closing, here are my personal thoughts.
Once again, Neumann has lived up to expectations, delivering top-tier engineering.
That said, with all this added muscle paired to a lighter body, it might need just a little helping hand from the user.

That’s all.


----

Thank you for this excellent review. I especially enjoyed the extra discussion on speaker suspension.