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Dutch & Dutch 8C Quasi-Anechoic Spinorama and Measurements

napilopez

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The D&D 8C is one of those blessed few speakers with multiple sources of measurements out there, but as far as I know, none in spinorama form.

I'm having trouble with the bass summations, so I'm leaving them out for now. But in any case, there are already a variety of measurements out there, and I was mostly interested in presenting the directivity characteristics in a format we're more familiar with around here.

As usual, measurements made from 1m and gated at 6.5ms for maximum resolution within indoors measurements. Tested a few angles at 2m as well and no difference within the quasi-anechoic range that I can notice. Reference axis is between the tweeter and woofer, 26.5cm from the bottom as noted in the manual. While normally you would set the distance to the rear wall and sidewalls in the D&D app in order to take advantage of the speaker's boundary coupling effect, the speaker was set to its freestanding mode for this measurement.

Spin using 25dB per decade scale, as implied by CTA-2034A:
8c Spin.png


Remember this is a a different scale than Amir, who I believe is trying to matching the scale used by Harman in most of its spins. This slightly obscures some issues. Using Amir's/Harman's scale (based on m16 review), you get this:
8c Spin ASR.png

Recently we've discussed some confusion about how early reflections are calculated (see here). You can see the visual impact it has with this speaker in the apparent smoothness of the ERDI curve in particular.
8c Early Reflections.png


Horizontal Response 0 to 80 degrees in 10 degree intervals + Listening Window again:
8c Horizontal.png


Note how though the measurements only go down to about 200 Hz, you can see the cardioid directivity in how much lower the bass is in level

Presented differently, here's the polar map(1/6) normalized to the on axis. The lines represent 3dB drops
8c Horizontal Contour.png


You can see it matches D&D's own polar map quite nicely, though they use a different scale and color gradients:
Snag_a26f4d3.png

It's quite an audible effect too; when measuring it was pretty wild how much quieter the speaker is from behind than from in front.

One type of measurement we've been lacking on these is their vertical response, so here it is out to 15 degrees as well as the Ceiling and Floor reflections. As a recap, Ceiling reflections is an average of 40/50/60 above the reference axis, and Floor reflections is the average of 20/30/40 below the reference axis..

Note the on-axis measurement is slightly "messier" than in the horizontal charts as this required placing the speaker on its side to capture the vertical data. Still, it's useful for noting directivity characteristics.


8c Vertical.png


I'd consider this a good result. The speaker is not very sensitive to changes in vertical height within the listening window, so you don't have to worry about keeping your head in a vice even when listening nearfield. Almost every speaker with vertically aligned drivers displays some kind of lobing, and I prefer the approach seen here, where the lobing is relatively narrow, as opposed to speakers with lobing covering a wider range of frequencies.

Taking a broader approach, here is the vertical response in polar map form.
8c Vertical Contour.png


Lastly, here is SPL Compression from 80dB to 100dB in room, as well as the same measurement converted to a quasi-anechoic one. In white is the deviation from linearity from 80 dB to 100dB.
8c Compression.png


It's hard to see exactly what's going on in the bass given room modes at my measurement location, but overall you can see there is little change in energy level at 100 dB. D&D claims the speakers 'max linear spl @1m' is 102B from 35Hz upwards. Unless you listen at crazy high volumes from very far away you are unlikely to get this speaker to compress.

Subjective thoughts:
The D&D 8c do just about everything right. My favorite thing about them is easily the bass. The built in EQ features based on the speaker distance to the wall have an immediate and obvious effect on their clarity. Once I inputted distances to the walls, they had the best bass presentation I've heard in my room without spending hours messing with REW and two subs. That said, you can mess around further with REW and load PEQs into each speaker to further refine the speakers, although I did not find a huge audible improvement. @mitchco covered that really well in his review so I don't feel the need to get into it.

My only real acoustic qualm with them is a personal one rather than a real criticism: I usually prefer wider-directivity designs. But here the 8c have an advantage too. The great off-axis response, cardioid directivity, and built-in EQ features mean you have a whole lot of flexibility for changing the spatial presentation. Don't use toe in and they sound more spacious. You even can toe them in 45 degrees for 'extreme' toe in and get a much more spacious sound akin to a wider directivity design.

On a non-acoustic front, I wish they had wi-fi or bluetooth. Not for playback, but because it's a pain to have to use ethernet to change settings if you want to put these in your living room. I had to use an extra router I had lying around to make a private network for the 8cs, as I was not able to plug them into my regular network without getting a ridiculously long ethernet cord or buying new networking equipment. Also, one of my review units had a board issue and required a replacement board to be shipped in. Luckily that was a simple repair that took all of 5 minutes.

Dr Toole likes to say something to the effect that the best speakers are not necessarily the ones that impress you the most, but rather the ones that are the least flawed. That defines the 8c in many ways. If you've been listening to good speakers for a long time and already take the effort to EQ your room properly, I do not think the D&D 8Cs will be some kind of golden eared sonic revelation. Instead, they are some of the most well thought out and versatile speakers out of the box I've ever tested. They are able to sound fantastic with a few seconds of tweaks no matter where you place the speakers, and you can rapidly change their sound with in-app tone controls and distance parameters. They are designed to be placed near walls, which is quite frankly something most speaker manufacturers should be doing. And personally, I think they are some good looking speakers too, especially in the white colorways.

At $12,500 a pair, one would hope they are good, of course. I'm going to miss them.:)
 
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Soniclife

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When you put them in their sides to measure did you block the vent at all?

Have you had a chance to hear the Kii 3?
 

Soniclife

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My only real acoustic qualm with them is a personal one rather than a real criticism: I usually prefer wider-directivity designs.
How wide is wide? These don't look narrow to me, just narrow all the way down. Do you have an example of wide you like?
 

Kundroc

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The spinorama graph using Amir's/Harman's scale seems to look exactly the same as the graph using CTA-2034A scale. Am I missing something?
1584556584327.png
 

Ron Texas

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Nice set of measurements.
 
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napilopez

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The spinorama graph using Amir's/Harman's scale seems to look exactly the same as the graph using CTA-2034A scale. Am I missing something?
View attachment 54849

It looks like you vertically stretched the ASR scale graph? That would indeed make them look the same:). Anyway, the differences are subtle in this case - it's more notable for speakers that aren't so flat in the first place. But here's the difference in the ER curve for instance.

Snag_ad68846.png


Obviously Amir's measurements are higher resolution in the first place. Just sometimes I see people eyeballing measurements from different sources without looking at scaling.
 

kaka89

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Wow, so the cardioid pattern in 8C works even outside a room? (without front and side-walls)

How come no other speakers do that? The best directivity speakers we have seen so far (8341A, R3) lose their directivity below 500Hz.
 
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napilopez

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When you put them in their sides to measure did you block the vent at all?

Have you had a chance to hear the Kii 3?

It did indeed block part of one of the vents but it seemed to have a negligible impact on the frequency response. I double checked this by simply moving the microphone vertically instead of turning the speaker; the nulls were in the same spots and moving the microphone led to more variation in the frequency response.

I've not yet heard the Kii's, but that's on the list.

How wide is wide? These don't look narrow to me, just narrow all the way down. Do you have an example of wide you like?

Note I didn't say these were particularly narrow, but they aren't particularly wide either. I find myself usually preferring very wide directivity designs :).

Also note I wouldn't consider any of the wider directivity speakers I've heard 'better' but I did think they sometimes sound bigger. The D&D 8C when toed in has a very sharp and focused soundstage, but not huge. You can vary this rather dramatically with varying degrees of toe in though.

As I've said in other posts, I find it easier to get a sense of directivity from horizontal SPL charts. If found that good speakers with deep waveguide speakers tend to show very similar patterns from 1K up.

For example, in the narrowish camp, here's the 8C again:
8c Horizontal.png


60 degrees off-axis, it's down roughly 10 dB at 8K. 75 degrees its down roughly 15 dB

Similar behavior can be seen in the KEF R3 (note I use 15 degree intervals in my old measurements):
R3-Horizontal-1-796x608.png


And Buchardt S400:
S400-Horizontal-Response-796x660.png


And the Neumann KH80:
esfZtxu.png


Compare that to what I consider wider directivity speakers, which usually have minimal or no waveguides. They are usually "messier" than speakers with good waveguides, but tend to maintain more energy into the treble, at last up to 6-10K, after which there's a steeper treble drop off. There's a small bit discussion in Toole's book that some people might prefer a messier wide directivity design to a cleaner narrow directivity design. Anecdotally, I think this is sometimes the case for me, but of course not always.

Focal Chora:
Chora Horizontal.png


At 60 degrees it's only down 4-7 dB. 5-10 at 75 degrees.

iLoud Micro Monitor:
Hor off Axis.png


Q Acoustics Concept 20:
Concept 20 Horizontal.png


JBL L100 Classic:
L100 horizontal.png


Devialet Phantom Reactor:
Reactor Horizontal Response.png


Note that this is what the Salon 2 seems to do very well with its fancy shallow waveguide and tapered cabinets. It has both the off-axis evenness of a speaker with a good deep waveguide while having the width (high SPL levels off axis) of a speaker with no waveguide.

Snag_af73255.png


At 8KHz, It's only down about 4-5dB at 60 degrees off axis, 7-8dB at 75 degrees.
 
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Soniclife

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Thanks, great work.

Interestingly the 8c is barely any narrower than some of the wide ones, if you reference the 60 deg 8k to the 60 Deg 200hz, for most speakers it makes no difference as they are close to Omni at 200.

I was all set to try and hear these very soon, and their natural competition, but I'm not sure it's the right time with everything going on.
 
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napilopez

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Thanks, great work.

Interestingly the 8c is barely any narrower than some of the wide ones, if you reference the 60 deg 8k to the 60 Deg 200hz, for most speakers it makes no difference as they are close to Omni at 200.

I was all set to try and hear these very soon, and their natural competition, but I'm not sure it's the right time with everything going on.

I think you're interpreting 'narrow' vs wide a bit different than I am - you're looking at the difference between the low frequencies and the highs, it seems, while I'm primarily looking at the difference between the on-axis curve/LW and the 60 or 75 degree curves between roughly 1K to 10K. That region seems to be a big part of how we percieve a sense of space:
Snag_b20cefb.png


But yes, the 8C is more timbrally flat off axis than the others in the big waveguide camp.
 

tuga

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Dutch & Dutch 8C (wave-guided cardioid narrow baffle box with rear woofers)
719DD8Cfig3.jpg


Kef Blade 2 (wave-guided coax narrow baffle box with side woofers)
615KEF2fig05.jpg


PSB T3 (wave-guided narrow baffle box)
816PSBT3fig5.jpg


Sonus Faber Stradivari (650mm wide baffle box)
SFSfig5.jpg


Jamo R907 (open baffle)
209Jamfig5.jpg


Gradient Helsinki 1.5 (waveguided coax open baffle)
810Helfig3.jpg


MartinLogan Montis (planar dipole above 300Hz)
912Montisfig4.jpg


Avantgarde Uno Nano (horns above 350Hz)
709AGUfig5.jpg


MBL Radialstrahler 101E Mk.II (omni)
412MBLfig3.jpg


source: https://www.stereophile.com/
 
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HammerSandwich

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Wow, so the cardioid pattern in 8C works even outside a room? (without front and side-walls)
The cardioid's produced by the midrange driver & its vents, not room reflections. Dutch's recommendation to place the 8C near the front wall is to reinforce the subwoofers' output, so a different issue.

How come no other speakers do that? The best directivity speakers we have seen so far (8341A, R3) lose their directivity below 500Hz.
Those are both fairly small speakers, so that behavior's expected. To control horizontal directivity below 500Hz, you need a phased array (as in the 8C, Kii, etc.) or a much wider baffle (including in-wall mounting). Double the R3's baffle width, and its pattern will be controlled an octave lower - below 300Hz.

Why doesn't, say, KEF make speakers with wide baffles? Because they want their speakers to sell.
 
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napilopez

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By the way, just in case anyone doubts whether indoors quasi-anechoic measurements can approximate the real thing, there's quite good agreement between my measurements and the NRC's, even off-axis. Different degree intervals, but on-axis, 30, and 60 degrees track very well.

1584566308247.png


You can do a whole lot with a Umik-1 and a lazy susan if you have a bit of open space in your home.

Of course, you lose resolution at the low end and splicing the bass gets complicated, but with enough measurements at different distances you can get a pretty complete picture. I think I'll write up a guide one of these days if anyone else wants to get started taking quasi-anechoic measurements who can't send speakers to Amir - which is of course usually the preferred option.
 
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Jon AA

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You can do a whole lot with a Umik-1 and a lazy susan if you have a bit of open space in your home.
I'm in the process of building a "SpeakerSusan" myself. I've found it's tough to get the angles accurate without one.
 

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napilopez

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I'm in the process of building a "SpeakerSusan" myself. I've found it's tough to get the angles accurate without one.

Neat, I'm thinking of building a custom one myself (or rather, asking someone to help me as I am not particularly handy). My current setup is quite jerry rigged.

I use a cheap plastic turntable from amazon that I labelled with the relevant angles using a printed protractor. I then place the turntable on my kitchen island, on top of which i place my regular speaker stands. That elevates the speakers about 5.5 feet from the ground.

This works fine for horizontal measurements, but for vertical measurements I sometimes need to do some precarious balancing and use a cam strap to stop the speakers from toppling over when centering the reference axis over the turntable's the axis of rotation. It's an anxious half hour of being afraid of dropping a 60 pound, $6,000 speaker =] So I want to build something bigger and sturdier, while still minimizing reflections from the stand itself.
 
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Soniclife

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I think you're interpreting 'narrow' vs wide a bit different than I am - you're looking at the difference between the low frequencies and the highs, it seems, while I'm primarily looking at the difference between the on-axis curve/LW and the 60 or 75 degree curves between roughly 1K to 10K.
Interpreting might be a bit grand for what I was doing, I was really just observing how different they were.

If the predicted in room response was the same between 2 different speakers, but they got there in different ways, would they sound the same size?
 

Soniclife

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Dutch's recommendation to place the 8C near the front wall is to reinforce the subwoofers' output, so a different issue.
I think it's also to avoid comb filtering of the bass, where the cardioid 100 - 400 range does not filter like a normal speaker would in that position.
 
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