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Neumann KH 80 DSP Monitor Review

ctrl

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And what about 3-way? Also at tweeter axis or between tweeter or mid driver?
You can check by measuring on-axis and vertical -10deg (or +10deg if the mid woofer is above the tweeter). If the -10deg SPL is around the crossover frequency "above" the on-axis measurement (better phase summation of tweeter and mid woofer), then the loudspeaker developer used an axis between tweeter/mid driver as reference (or ignored the phase shift at all ;)).

The relative time delay (different distance to the ear) between mid woofer and woofer is, other then by tweeter/mid woofer, in most cases unproblematic, because of the low crossover frequency. For a 200-400Hz crossover the phase shift could be ignored (<15deg, for speaker with normal dimensions).

It really matters when the crossover frequency is high and the distance between mid woofer and tweeter is not narrow. For example, B&W speakers with 6-7'' mid woofer and crossover at 3-3.5kHz.

Here a simulation of a 2-Way-Speaker 25cm x 40cm (same for 3-way) with a second order Butterworth crossover at 3.5kHz. Goal is a warm sounding hifi-speaker, so we want a reduced power response around the ear channel resonance (around 2.7kHz). Developed for hearing between tweeter and mid driver:
BaW_like_2way_1.jpg

It's obvious, measuring on tweeter axis (-10deg vert) would not be the best starting point.

We use an even order crossover, so the radiation lobe at the crossover frequency isn't tilted:
BaW_like_2way_2.jpg



But as Juhazi said, reality is far more complicated:
Tall speakers often have the tweeter on top, above listener's ear level. This may help to get best phase match at listening spot height! A tilted or stepped baffle is used to set back the tweeter which helps delay matching. ...

Designers with modern methods must define optimal design axis, but there is no fixed location for that. Common practise is to set it at midline between tweeter and mid for 3-ways. Some 2-ways have it on tweeter axis, others at midpoint between woofer and tweeter like KH80.
 
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amirm

amirm

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If I were you I would like to know if the device I paid so much is performing according to Klippel's spec.
And if I were you, I would learn what the limits of such measurements are, and where usefulness stops.

On the other hand, independent measuring of any device has always been about confirming or denying manufacturer's specs, so outcome should be clear if KH80 deliverd or not.
Hardly any manufacturer publishes such specs. And even if they as in this case, it is full of vagueness.



Interpolated to you means what precisely? What needed interpolating? Where was this speaker tested? What microphone? What axis? You have a picture of that? What input level and gain was used?

And you expect me to match those results with these outstanding questions?
 

MZKM

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Let me remind you that 3/4 or 0.75dB off is not a small thing when you need to confirm that 100% of loudspeakers produced are ±0.26 dB.
0.75dB is more than 3 times larger than 0.26dB.
The largest dip is ~2kHz and where the crossover is, if the speaker was measured on the reference axis, that dip would go away, and the hot treble would be lessened, bringing the window much tighter, there is still the dip ~8kHz; it looks like it may be present in other graphs, so that may be a mic calibration issue, which Amir said he did not enter yet.
 

Krunok

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And if I were you, I would learn what the limits of such measurements are, and where usefulness stops.


Hardly any manufacturer publishes such specs. And even if they as in this case, it is full of vagueness.



Interpolated to you means precise? What needed interpolating? Where was this speaker tested? What microphone? What axis? You have a picture of that? What input level and gain was used?

And you expect me to match those results with these outstanding questions?
Heh, don't get me wrong - I am not saying that your statement toward usefullness is wrong. It is quite clear that we couldn't be able to hear the difference between flat response which oscillates within ±0.26 dB vs the one within ±1.3 dB.

It is about Neumann who specced their speakers so boldly and are charging money for that, so I think it would be good if your measurement either confirms it or not.
 

Krunok

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The largest dip is ~2kHz and where the crossover is, if the speaker was measured on the reference axis, that dip would go away, and the hot treble would be lessened, bringing the window much tighter,
I agree, that would probably happen but there is only one way to be sure, right?

there is still the dip ~8kHz; it looks like it may be present in other graphs, so that may be a mic calibration issue, which Amir said he did not enter yet.
IMHO that also should be done before measuring such extremely linear speakers as Neumanns are.
 

Krunok

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@amirm Please also keep in mind that Neumann can find the fact that your measurement didn't confirm their specs offending as that may hurt their market image. As their market is mostly in professional segment, not home use, they may ask for another independent measurement to confirm their specs. If that independent measurement confirms their ±0.26 dB spec than your image will be hurt, and that is something none of us would like to see, so I really recommend you reconsider to re-measure KH80 as in that case you did everything right, and if KH80 fails to deliver the specs either Neumann or Klippel would need to answer some questions, but your hands would be clean. You were a top corporate executive, I'm sure you understand what I'm talking about.

Let me finish this post with car analogy:

You can't measure a Lambo and publish it can't reach 300km/h, no matter how meaningless that speed is. As it was never about speed at the first place. ;)
 

aarons915

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If I were you I would like to know if the device I paid so much is performing according to Klippel's spec. On the other hand, independent measuring of any device has always been about confirming or denying manufacturer's specs, so outcome should be clear if KH80 deliverd or not.

So how did we come to bad intent? To me it seems it is about vanity..
Did the Revel C52 measurement not confirm that for you? I would think duplicating a measurement made over a decade ago in an anechoic chamber would satisfy most people. Most already acknowledge that the KH80 was driven too loud and some bass protections were possibly kicking in, other than that it measures great. The newest JBL 104 measurement shows the proper drive level so the issue has been solved and minor deviations in the reference axis won't affect the overall graph much at all, they are all averaged curves.

I say let's move on and measure more speakers.
 

Krunok

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Did the Revel C52 measurement not confirm that for you? I would think duplicating a measurement made over a decade ago in an anechoic chamber would satisfy most people. Most already acknowledge that the KH80 was driven too loud and some bass protections were possibly kicking in, other than that it measures great. The newest JBL 104 measurement shows the proper drive level so the issue has been solved and minor deviations in the reference axis won't affect the overall graph much at all, they are all averaged curves.

I say let's move on and measure more speakers.
It is not about me - you simply can't publish Neumann that a professional class speaker like KH80 didn't meet the spec and than carry on. Please read my post above.
 

edechamps

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That's nonsense. I am trying to get you guys to stop obsessing over small differences in frequency response. I have not even bother to put in the calibration for my microphone in there because 1 dB here and there is not material.
1 dB deviation is material when it's a broad, low-Q deviation (such as a tilt). I agree that we can safely ignore 1 dB "wiggles" (which are way less audible) but that's not what this is about. This is about the overall trend of the frequency response being wrong. Not wrong by much, but wrong enough to be audible.

Someone reading your review is likely to come away with the conclusion that the KH 80 is great, but it seems to lack a bit of bass and is a bit too bright. Given what we've discussed, it's very likely that this conclusion would be false.

Of course there is if you are going to argue that the manufacturer used it in their measurements and I didn't. You have a picture of their setup on how they created their graphs?
To be clear, I am not claiming with 100% certainty that the difference in treble response is due to other measurements using the manufacturer's reference axis and yours using the tweeter axis. That just seems like the most likely explanation for the discrepancy, given what we know (especially since it tends to disappear on the -10° vertical measurement). It's certainly way more likely than some kind of "measurement variance". If it was measurement variance, third party measurements would be affected too. That is not the case. I really doubt the Klippel NFS itself is so inaccurate that it will invent broad frequency response tilts where there are none.

Not going to do. I am not going to reward bad intent. The future of what we are doing is what is at stake. I can just see the same losing the high level picture and insisting in minutia in every review.
I for one will be happy as long as we fix these issues on future reviews. You already agreed to adjust the output level going forward, and that's great.

I'm not sure we reached agreement on the reference axis question, though. Are you going to use the procedure described in CTA-2034-A for the reference axis in future reviews? Or are you going to always use the tweeter as the reference axis no matter what, even if the speaker's manual says otherwise? In the latter case I will need to make a mental note to ignore any broad treble tilt in future reviews.

Interpolated to you means what precisely? What needed interpolating? Where was this speaker tested? What microphone? What axis? You have a picture of that? What input level and gain was used? And you expect me to match those results with these outstanding questions?
I suspect getting consistent measurements (with "consistent" here meaning "no broad, low-Q deviations") is not as difficult as you make it out to be. Case in point: at least 2 other people seemed to have had no trouble taking a measurement of the KH 80 that agree way more closely with Neumann's than yours. Is it just luck? Or is it simply because they used the proper level and reference axis? I guess we'll never know for sure, since you're not going to remeasure the speaker. All we can hope for is improvements in future reviews.
 

Arnandsway

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Please you are starting to repeat yourselfs. It is clear now that the differences are probably caused by a too high SPL and not measuring on the same axis (or representing that axis, if you will).
The fact is this is still a great speaker. Multiple sources proof this.

Personally I'm not interested in going deeper in this review. Let's just assume the reviews will refine over time while we see more interesting speakers, and give Amir some rest :) .
 

ctrl

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The largest dip is ~2kHz and where the crossover is, if the speaker was measured on the reference axis, that dip would go away, and the hot treble would be lessened, bringing the window much tighter, there is still the dip ~8kHz; it looks like it may be present in other graphs, so that may be a mic calibration issue, which Amir said he did not enter yet.
In the -10deg vertical measurement the 2kHz dip is still there. This could be a mic-calibration issue too.

I'm using a good measuring mic (which is nearly class 1) and still need the calibration file to get proper measurements. Otherwise I get a dip in the low-mid treble frequencies and a bump > 10kHz.
Maybe Amir could post the calibration file, then we can see if it would make a difference.

Speaker measurement with my mic - red with mic calibration, azure without:
mic_calibration.jpg
 
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Krunok

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Please you are starting to repeat yourselfs. It is clear now that the differences are probably caused by a too high SPL and not measuring on the same axis (or representing that axis, if you will).
The fact is this is still a great speaker. Multiple sources proof this.
.
Ok, so you took Lamborghini Aventador to test and measured top speed of 320 km/h (spec is 349 km/h). You published that result with explanation that it didn't reach spec probably due to headwind during measurement and conclude that it is still a great car as multiple sources proof that. When asked by your readers to remeasure the top speed at calm weather you reply that there is no need as 320km/h is more than usefull top speed.

Does that still sound good enough to you? ;)
 
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Not going to do. I am not going to reward bad intent. The future of what we are doing is what is at stake. I can just see the same losing the high level picture and insisting in minutia in every review.
I will now make one last attempt to explain my intentions. After that, I promise to stay silent.

I registered for this forum a few days ago, because I wanted to point out that you made a mistake in setting the speakers, which could have potentially distorted the result. (I know the speakers quite well because i bought them for a friend and helped setting them up). As it turned out, this error probably had no effect, but that you made some decisions that indicate that you did not take the specifics of the KH80, which are documented in the manual, into account when testing.

The results are therefore worse than expected. This leads some readers to conclude that the manufacturer's specifications cannot be trusted. At the same time, the review didn´t provide a good reference for future measurements (from the perspective of readers, i know you don´t need this kind of reference). After all, the KH80 was recommended for testing for this very reason.

Repeating the test probably makes not a big difference to the question whether the KH80 is a good loudspeaker. The interesting questions are as follows:
- Is Neumann's data correct?
- Is your methodology, with which you have only little experience yet, correct, or will it have to be adapted in the future?
- For the interested reader: How do the results of the Klippel relate to the known test results of anechoic chambers (you already know that, i get it, but it would have been interesting for us to see it here).
- And, unfortunately, the main issue is now: How do you deal with the fact that readers point out possible errors to you? (As I wrote elsewhere: Trust is hard to earn and easy to lose).

I wanted to help to eliminate possible sources of error right at the beginning of your project. Nobody is perfect. I am a scientist too, but in a different discipline. I find that doubt and criticism are very useful to improve one's own results.

I find the project extremely exciting and am curious about the next results. However, my anticipation is now somewhat dampened. I am sorry, but you have not yet earned my trust. I really hope this will change and i wish you all the best. I will remain open-minded and interested in your reviews.

Goodbye.
 

Pio2001

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I still think this is a very bizarre argument =] Aside from what @thewas_ said, it doesn't really matter if their measurements are flat because Neumann were aiming for flat.
It should be obvious that Neumann's measurement is self referent.
It looks flat because they made it flat, not necessarily because the KH-80 is flat in itself.

If their measurement microphone was broken and had a +3 dB peak at 3000 Hz, for example, they would still trust it, and make their speaker flat, creating a -3 dB dip in its frequency response. And they would publish a completely flat frequency response for it.
The frequency responses that they publish about their own products are flat by design.
 

MZKM

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In the -10deg vertical measurement the 2kHz dip is still there. This could be a mic-calibration issue too.

I'm using a good measuring mic (which is nearly class 1) and still need the calibration file to get proper measurements. Otherwise I get a dip in the low-mid treble frequencies and a bump > 10kHz.
Maybe Amir could post the calibration file, then we can see if it would make a difference.

Speaker measurement with my mic - red with mic calibration, azure without:
View attachment 47386
If you look at my normalized vertical directivity graph, -10 has slightly more energy ~2kHz; I'll restate that -10 is likely not the reference axis, -5 likely is, but we don't have a measurement of that to confirm.
 
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Not going to do. I am not going to reward bad intent. The future of what we are doing is what is at stake. I can just see the same losing the high level picture and insisting in minutia in every review.
Why such a big needless ego? Multiple members are interested in a remeasure and they have a point. KH 80 is not some throwaway speaker, it’s the first truly high end loudspeaker product measured here and it deserves better. We also don’t have distortion measurements. Seems like you have a preferential bias towards those Samsung speakers.
 

Arnandsway

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Ok, so you took Lamborghini Aventador to test and measured top speed of 320 km/h (spec is 349 km/h). You published that result with explanation that it didn't reach spec probably due to headwind during measurement and conclude that it is still a great car as multiple sources proof that. When asked by your readers to remeasure the top speed at calm weather you reply that there is no need as 320km/h is more than usefull top speed.

Does that still sound good enough to you? ;)
Well sure, for that kind of money I would complain ;). It's not a great comparison though, because we are talking of a different ballpark here.

But honoustly, I think your critisms are clear and of good intent, but to stay in a loop isn't helping anybody. Don't get me wrong, nobody (IMO) has been rude yet on this discussion.
This goes for both ends ofcourse.
 

Krunok

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Well sure, for that kind of money I would complain ;). It's not a great comparison though, because we are talking of a different ballpark here.

But honoustly, I think your critisms are clear and of good intent, but to stay in a loop isn't helping anybody. Don't get me wrong, nobody (IMO) has been rude yet on this discussion.
This goes for both ends ofcourse.
I am repeating my arguments to try to make Amir reconsider re-measuring. Measuring home grade cheap speakers is one thing but when you are publishing that professional speaker didn't meet spec you better have very solid explanation for that.

P.S. $500 is quite a lot of money for a small 2-way speaker and linearity of ±0.26dB is equally impressive as Lambos top speed. Anyway, car analogies were never meant to be perfect. ;)
 
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