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Neumann KH 80 DSP Monitor Review

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DivineCurrent

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I don't know anything about speaker measurements, but I recall hearing about something called the "BBC Dip". Basically, an intentional dip in the upper midrange (1-3kHz). It looks like these speakers do exactly that with that dip at 2 kHz. I wonder if it is intentional?

I don't know how this works with speaker measurements, but I have a lot of listening time with headphones, specifically comparing the Sennheiser HD 600 and HD 58X. The 58X also has a dip in this region at 2-3kHz, and it does subjectively sound more "immersive" to me, less in your face and upfront as if the sound is deeper and coming from further away. So I wonder if Neumann put this dip in there on purpose, because the rest of the speaker seems to measure very flat.
 

napilopez

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But what does mean a reference axis for near field holographic measurement ? All axis are measured.
It means that the software is going to choose a given curve among others to display. I'm not sure that this curve is chosen by Amir. He would have to tell the x, y, z coordinates of the tweeter to the software. Is it the case ? If not, the Klippel is probably detecting the axis where the treble response is the strongest.
It is rather a good thing that all speakers are mesured equally. In doubt, we have to read the listening window curve instead of the on-axis curve.
The fact that the speaker was designed to have a best response in a different direction must be taken into account when we interpret the measurements.

I can't imagine the software would simply choose the position where the treble is strongest; that's often not the best listening position. I do think amir has to give it a reference point, and some of the klippel documents mention the ability to choose an expansion point. But you're right that since it's doing spherical calculations, it seems like adjusting the reference point shouldn't be a particularly big deal. It might just affect the accuracy bit if, say, we're measuring at 10 degree intervals, but the optimal angle is somewhere in between. My concern wasn't just with the bass, but the rising treble as well.

Thats said, I forgot the CTA2034.zip file contained the individual 10 degree angles as well. We see at 10 degrees below the tweeter axis, which would probably be the closest available curve to a measurement starting from the reference axis, the response is closer to what's expected. So that makes me feel a bit better:)

KH80.jpg


Thanks for the comparison.
Neumann's measurement should be discarded, as it is self-referent : the speaker was designed to sound flat according Neumann's measurements, therefore Neumann's curve is obviously flat..

Surely this doesn't make sense? Otherwise we should discard every anechoic manufacturer curve, including Harman's, because they all target something roughly flat. It should simply be a matter of whether we find the manufacturer's measurement trustworthy. In theory, flat is flat everywhere, which is why we have microphone accuracy standards and the like.

But there is Indeed a difference between near-field direct measurements, as yours, and Klippel's holographic measurement. One explanation, given above, is that holographic measurement gives an accurate result, while direct near-field captation is an approximation. To confirm this, we need to understand the limitations of direct measurement, if they exist.
We might, if we get the chance, compare with other measurement methods. Half space might not settle the argument, as it is a bit inaccurate in this frequency range, where there is a transition between direct radiation and half-space radiation.
Ground plane (microphone against a concrete plane) might be interesting.
True free-field would be ideal, but it requires a lot of Equipment (a crane to lift the speaker far above the ground).

The bass difference is still a puzzler to me, since as previously mentioned, the Neumann measurements in anechoic chambers should be anechoic down to 100Hz before calibration kicks in. The treble is also more uneven, which makes me wonder a bit, since as far as I recall the Klippel is using gated measurements as opposed to holographic expansion for the highs. But that probably does not have a meaningful perceptual effect.

I just want to get to the bottom of this mystery if possible, because it makes me think that if the Klippel is truly the most accurate way of capturing bass - which is what I thought myself up to this point and have defended in other threads - then there are a lot of innaccurate anechoic measurements out there, and a lot of speakers that are supposed to be flat that are not, in fact, flat. This may well be possible, but I want to be sure rather than dismissing years of measurements right away.

On a related note I have access to two rooftops in my building directly across from one another with a big gap in between. I wonder how close to free field conditions I could get this way....
 

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Juhazi

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Just some remarks,
- The reference axle (0¤) location not being exactly the same stated by the manufacturer left/righ and/or up/down makes only small deviations from factory measurements. That can be seen in overlaid responses and spectrograms, but it takes and experienced watcher! A compromise is to set on-axis in midpoint of line between mid and tweeter.
- Listening test should include standing up from the chair and moving around the room. Directivity problems and bass behaviour are easier to detect that way. The problem is variance between rooms and positioning...
- Speaker configuration, bass output and directivity vary a lot, and are important to how a speaker sounds in a room.

Recommended vs. realistic positioning and listener preferences vary a lot, this is why everyone who is buying a speakers, should perform private listening tests, preferably at home, with friends and at least over a weekend. Comprehensive and masterfully conducted measurements can only give guidelines and hints for purchase! (Us diy-guys will naturally break this rule!)

About the difference in bass between NFS and Neumann, I don't know which is more "true". I think that this question is mission impossible. Every measurement technique has it's problems and inaccuracies. We can compare only similar measurements directly to each other.
 
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napilopez

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Just two remarks,
- The reference axle (0¤) location not being exactly the same stated by the manufacturer left/righ and/or up/down makes only small deviations from factory measurements. That can be seen in overlaid responses and spectrograms, but it takes and experienced watcher! A compromise is to set on-axis in midpoint of line between mid and tweeter.
- Listening test should include standing up from the chair and moving around the room. Directivity problems and bass behaviour are easier to detect that way. The problem is variance between rooms and positioning...
- Speaker configuration, bass output and directivity vary a lot.

Good stuff, but I disagree with your first point. Sometimes the variations are massive just a few degrees up or down. Not the case with the neumanns, but certainly on a variety of speakers I've measured.

Focal Chora 806 at 0/5/10/15/30 above and below the tweeter axis:
Chora Vertical (1).png


Buchardt S400 0/5/10/15/30 above and below the reference axis (where waveguide and tweeter meet):

S400 Vertical 0 to 30.png


Note the 0-degree curve isn't fully accurate as these measurements were with the speakers on their sides, but the trends should be representative of real performance. Also note both speakers flatten out significantly at steeper vertical angles so these issues don't affect the in-room sound as bad as it might seem here.

Would be concerned about being even slightly off the vertical reference axis in or measurements for these speakers. These are also not speakers you want to use in the nearfield and want to position carefully in the vertical domain =]
 
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Absolute

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If i understand correctly, Amir´s measurement can´t be trusted in this matter because he used a wrong reference point for the acoustical axis. Is that right? If it is true, think it would be helpful if @amirm adds a comment about this to the initial post or measure again.
The measurements can be trusted, but perhaps the 10 degree angle (or 5 degree or any degree) should be considered on-axis for any given speaker. This will be different for every speaker, so let's stay with a simple reference point for every speaker for ease of mind.

For me it doesn't matter if the on-axis angle is correct relative to the acoustical centre because the listening window will average out the main differences regardless.

Personally I look at the smoothness (lack of resonances and peaks/dips) of listening window and at the detailed off-axis graphs. All info needed is there and if everything is smooth and good, you can tune the overall tonality to taste.

In any case the listening window can blatantly lie about expected sound quality if you aim to have a weird on-axis angle when designing speakers. If you say that a certain speaker is designed to listen at 30 degrees off-axis because that's where the listening window is most flat, then you're basically saying that certain off-axis angle response doesn't really matter much. I think that sounds silly.
 

Frank Dernie

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The Wankel engine in a Mazda is tiny when compared to a typical V6 3 liter that it competes against in terms of power. But it has a fuel consumption thats very similar to a V6 3 liter.
Quite a bit worse in fact, The Wankel is mechanically smooth but both the combustion and gas flow are poor compared to a poppet valve piston engine. Above about 3000 rpm the rotor tip speed exceeds the flame path speed so all mixture upstream of the spark plug at the time of ignition ends up going out of the exhaust and burning there. That is why the racing versions were so abominably loud.
I have put a power monitor on the power supply of the Phantom and it takes very little power above idle power unless there is a high level of deep bass. It is several years ago and I don't remember the exact figures now.
Edit, my curiosity was piqued so I got my monitor out again.
The Phantom idles at 20 watts.
When playing music at my normal (my family say too loud) level it goes up to 24 to 25 watts. If I play a film sound track with bass sound effects it goes up to 50 watts. So about 5 watts for music and 30 for bass effects. The meter is smoothed but I have no idea of the time constant.
 
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napilopez

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If i understand correctly, Amir´s measurement can´t be trusted in this matter because he used a wrong reference point for the acoustical axis. Is that right? If it is true, think it would be helpful if @amirm adds a comment about this to the initial post or measure again.

The measurements can be trusted, but perhaps the 10 degree angle (or 5 degree or any degree) should be considered on-axis for any given speaker. This will be different for every speaker, so let's stay with a simple reference point for every speaker for ease of mind.

For me it doesn't matter if the on-axis angle is correct relative to the acoustical centre because the listening window will average out the main differences regardless.

Personally I look at the smoothness (lack of resonances and peaks/dips) of listening window and at the detailed off-axis graphs. All info needed is there and if everything is smooth and good, you can tune the overall tonality to taste.

In any case the listening window can blatantly lie about expected sound quality if you aim to have a weird on-axis angle when designing speakers. If you say that a certain speaker is designed to listen at 30 degrees off-axis because that's where the listening window is most flat, then you're basically saying that certain off-axis angle response doesn't really matter much. I think that sounds silly.

To be clear, I think the measurements are still relevant - it's just the on-axis graph that's off in the treble (plus the bass mystery, but that's another matter), with too much energy in the highs. The listening window might be a tiny bit off too, but everything else should be very similar.

While I do almost always prioritize the listening window and practically ignore the on-axis I do think it is a bit different for studio monitors used on a desk or otherwise very close I don't know about you, but when I'm at my computer, I move far less horizontally than I do vertically. In a living room, vertical listening window isn't as important because of reflections and the great distance meaning small angular changes. At a desk, leaning in or back will significantly affect your vertical position, while I'd guess horizontal changes are fewer.
 

DJBonoBobo

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To be clear, I think the measurements are still relevant - it's just the on-axis graph that's off in the treble (plus the bass mystery, but that's another matter), with too much energy in the highs. The listening window might be a tiny bit off too, but everything else should be very similar.

Given all the effort that went into doing excellent measurements with reference quality and even questioning other reference measurements by well-known experts, wouldn´t it be best to just re-measure and clarify this? Just asking as a curious reader without expert knowledge.
 

MZKM

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Well, that is why the test is marked as informal. For me, I need to conduct them to build as good as a calibration I can between what I am measuring and hearing. I am sharing it with you all just in case it is of value. The rigor will increase in these tests including fully blind ones in the future once there is appropriate fixture.

If I don't listen, there will be even louder cries. :)
Also, as stated, the scoring is for a listening room, not near-field. The main differences would be the soundstage width and perhaps the tonal balance. See post #81, where I show how the smoothness is similar but scoring is very different.

The JBL is about as smooth as the Neumann, but the JBL's PIR has a flat slope, which R2 does not like, thus giving a low score despite near equal "smoothness".

I am trying to work on a way around this, but I am not having luck. Anyone have a suggestion to find r2 with a near 0 slope?
 
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neutralguy

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The tests are informal so I don't want to spec them too much to make them otherwise. That said, it was about 75 dB. I do turn the master volume up and down during the test.

So speakers are measured at 75db while amplifiers are tested and ranked at 5W which for most speakers is 90+ db.
 

HammerSandwich

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You must measure your room and speakers in situ below transition frequencies and properly EQ the system. No way do you want to follow such "dumb" rules. It is one thing for Genelec to want to find a filter they can embed their speakers to sell as a feature. It is entirely another matter to follow them there as a consumer and listener.
Surely Genelec, Neumann, et al. do measure when designing boundary compensation features.

The KH80 has a switch that makes the speaker behave as Neumann intended when it sits on a desk. Putting the speaker on a desk without using the switch seems contrary, even if aimed at fair comparisons. How would you react if a reviewer placed a Klipschorn 5' from any wall, because "That's where I place all review speakers."?
 

bobbooo

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I think it did. I was not watching it since it took so long. :)

And how about the JBL, could you post recomputed 1/20-octave data for that? As it's currently also only at 1/10-octave resolution.
 
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maxxevv

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Quite a bit worse in fact, The Wankel is mechanically smooth but both the combustion and gas flow are poor compared to a poppet valve piston engine. Above about 3000 rpm the rotor tip speed exceeds the flame path speed so all mixture upstream of the spark plug at the time of ignition ends up going out of the exhaust and burning there. That is why the racing versions wwere so abominably loud.

OOT but I have to ask which generation of the Wankel / Mazda are you referring to here ? Or for that matter, which year ?

A good friend had the RX8 for some 6-7 years. Whenever he could he would push it past 5000 rpm comfortably as I've been in his car at least 10 times over the years. And no, the car was hardly noisy at all, definitely not louder than your typical boy-racer sports coupe. I've never heard him complain about it and he sold it off only because he upgrade to something more extravagant.

I have worked on Wankel applications that operate them at over 6000 rpm too.
 
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amirm

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So speakers are measured at 75db while amplifiers are tested and ranked at 5W which for most speakers is 90+ db.
No. Read again what you quoted. And keep in mind near field vs far.
 
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amirm

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If I understand correctly, 75 dB is not the level of the measurement, but the level of the listening session.
It is not that either. I used that level to calibrate speaker levels not to listen at.
 

Frank Dernie

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OOT but I have to ask which generation of the Wankel / Mazda are you referring to here ? Or for that matter, which year ?

A good friend had the RX8 for some 6-7 years. Whenever he could he would push it past 5000 rpm comfortably as I've been in his car at least 10 times over the years. And no, the car was hardly noisy at all, definitely not louder than your typical boy-racer sports coupe. I've never heard him complain about it and he sold it off only because he upgrade to something more extravagant.

I have worked on Wankel applications that operate them at over 6000 rpm too.
They run happily at very high rpm, it is just the combustion and port flow which is poor.
It is inherent so it doesn't matter which one. The Mazda made big steps forward in the other problem area, gas sealing and the twin plug engines, which have one plug firing just after the tip goes by and another near the middle of the awful banana peel shaped combustion volume.
The fuel consumption of all of them is inevitably poor because the concept is flawed. It is the racing ones with no silencers or catalytic converters which are so hideously noisy - The Le Mans Mazdas for example, louder than any others.
They are just too flawed IMO, and that of every engine designer I know (though most of those are only designing racing engines).
 

DDF

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plus the bass mystery, but that's another matter

The best theory was mentioned earlier in the thread: it's possibly the DSP compressor/limiter controlling bass distortion by limiting the bass response at high SPLs. A good illustration of this effect is shown in the response vs level of a bluetooth speaker, for example:
http://www.oluvsgadgets.net/2015/09/review-jbl-flip-3-ue-boom-killer.html
entirevolumerange.png


FWIW I authored a patent on this: https://patents.google.com/patent/US6201873
and this response accurately represents what a compressor with that function does.
 
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amirm

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Surely Genelec, Neumann, et al. do measure when designing boundary compensation features.
They measure based on certain assumptions (distance from listener, height, surface height, etc.). In this day and age when we have easy and free tools for measuring, and much more flexible EQ than just a few dumb switches, I see no need to use them at all. Indeed the owner of this unit used REW and external EQ which is the proper way to tailor the sound/fix room modes.

The KH80 has a switch that makes the speaker behave as Neumann intended when it sits on a desk. Putting the speaker on a desk without using the switch seems contrary, even if aimed at fair comparisons. How would you react if a reviewer placed a Klipschorn 5' from any wall, because "That's where I place all review speakers."?
I would be fine with it if the test was labeled "informal" as mine are. I put zero value on dumb compensation switches. If the target market was audiophiles which detest EQ, digital, etc., then I could understand. But not the target market here which should know better than to just rely on these switches.

And how would this be fair if each compensation feature corrects for a different frequency and amount?

Anyway, this getting frustrating on both listening side and measurements. Listening tests are informal and just shared for what it is. And measurements have to be taking in larger context, and not focusing on half a dB difference here, and there. It is the big picture that matters.
 
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Generally I agree, but a wide average based filter there is still better than nothing and to show that an example of my own listening position measurement of a Genelec monitor placed behind and a bit higher (as this is better than placing directly) from the desk, no smoothing:
Why would anyone interested in good sound be using the "nothing" option? Nothing I am doing here can rescue from bad bass if you don't invest in proper analysis and fixes for that region. That aside, I hope you also listened to the correction to make sure it sounded better than no EQ rather than just following what Genelec said years ago.

All EQ should be confirmed with listening tests to confirm efficacy. Otherwise it is trivial to screw things up based on wrong notions of what is right or wrong to correct. Single microphone measurements can be quite faulty so care needs to be taken to verify the results. This is not like electronics gear where the notion of goodness can be confirmed strictly by measurements.
 
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