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Dutch & Dutch 8c Review

abdo123

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It would be somewhat surprising if dominated by third harmonic given the advantage of a sealed box where no air is pushed out of slots, but if it's from the loss of spl due to cardioide interference and necessary EQ to up the level in the 100-300 hz area it could very well show much the same.
I'm painfully aware that far-field in-room measurements can't be trusted for distortion accuracy, but at least here's a measurement I found of Kii in the listening position after Audiolense adjusted frequency response to compensate for SBIR dip in the 200-300 range. Probably about 10 dB boost in that area, 3,5 meter distance and one speaker playing.


View attachment 167876

It'll be interesting indeed to see complete set of measurements :)

SBIR dip?? Are the speakers mounted to the ceiling or something? :oops:
 

Absolute

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SBIR dip?? Are the speakers mounted to the ceiling or something? :oops:
Contrary to popular belief, cardioide won't help against floor and ceiling reflections. Nor will it cancel sidewall and frontwall completely either.
At some point the question is whether or not the price you pay for better directivity is a price worth paying.
 

abdo123

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Contrary to popular belief, cardioide won't help against floor and ceiling reflections. Nor will it cancel sidewall and frontwall completely either.
At some point the question whether or not the price you pay for better directivity is a price worth paying.

it's still strange because a dip in the 200Hz-300Hz means the speaker has to be less than half a meter away from the ceiling.
 

Kvalsvoll

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Contrary to popular belief, cardioide won't help against floor and ceiling reflections. Nor will it cancel sidewall and frontwall completely either.
That depends on the specific design. Generally, there will also be an improvement in the vertical plane.
 

richard12511

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Contrary to popular belief, cardioide won't help against floor and ceiling reflections. Nor will it cancel sidewall and frontwall completely either.
The Genelec W371 actually has modes to deal with those reflections too :)
At some point the question is whether or not the price you pay for better directivity is a price worth paying.
I agree. I'm paying super close attention to both the 8C and Kii Three. Right now, I'm liking the 8C a bit more, due to larger drivers, larger box, and cardioid down to 100Hz. I'm also a bit suspicious that the Kii's waveguide will be as good as the D&D's, but we shall see very soon. The thing I really like about the Kii is the upgrade path available with the BXT module, though that raises the price considerably.
 

Absolute

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it's still strange because a dip in the 200Hz-300Hz means the speaker has to be less than half a meter away from the ceiling.
Depends on several factors, that. This was years ago so it's possible that it was a cancellation from the back wall as well, though I doubt it as the problem vanished with the subwoofer placed on the floor crossed at 200-250 hz.

That depends on the specific design. Generally, there will also be an improvement in the vertical plane.
Even if you don't have distributed drivers in the vertical plane? Ah, you can have acoustic vents in the vertical plane of course. :D

The Genelec W371 actually has modes to deal with those reflections too :)

I agree. I'm paying super close attention to both the 8C and Kii Three. Right now, I'm liking the 8C a bit more, due to larger drivers, larger box, and cardioid down to 100Hz. I'm also a bit suspicious that the Kii's waveguide will be as good as the D&D's, but we shall see very soon. The thing I really like about the Kii is the upgrade path available with the BXT module, though that raises the price considerably.
The W371 with different heights of the woofers is a brilliant solution. Shame that it costs more than a house. Imagine the DIY system (and probably build out your house with a huge dedicated listening room as well) you can make for the prize of a pair of these sumbitches :D

The Kii and Dutch are game changers in my opinion. They're really putting active speakers and directivity control on the map even for small speakers. I thought this back in 2017 when I got my Kiis- and now we're seeing all kinds of fancy stuff following in the wake of those little cute boxes. W371 is an example, GGNTKT M3 another, @Kvalsvoll's F205, @sigbergaudio 's new prototype, Buchardt A-series etc.

This is brilliant for us customers and I very much salute all these manufacturers that are willing to shy away from simple and high-profit solutions in order to push the boundaries with advanced and difficult acoustic designs.
First, last, late etc doesn't matter - the only thing that matters is that we consumers win.
 

fineMen

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The Kii and Dutch are game changers in my opinion.

Affirmed, if some particular problem with room integration was solved. Please see image below. A cardiod is composed of two distinct speakers (monopoles) "X" and "Y". These are separated by a certain distance "C", reversed in phase, while "Y" gets its input delayed by "distance C devided by the speed of sound". Basically, that is a cardiod. Usually this is placed at some distance "B" to a backwall.

a) a cardiod pattern is achieved only in an infinite distance, not close to the speaker-assembly (to be discussed how far 'infinite' practically is)
b) a reflective surface behind the "cardiod" disturbes the desired pattern a lot

Regarding (b) let me explain briefly. The reflections can be described as "mirror sources"--I have seen publications having this term in the title. So effectively the speaker-assembly, once standing close to a backwall, has to be described as made up from four sources. Two real sources, and two virtual sources. My Excell calculations showed not only a degradation in the cariod pattern, even a reversal was possible: more to the sides than on axis.

If this problem is solved with the game changers, the better! Patent worthy I would say.

It should be easy to test my hypothesis, and the possible patent in a half field environment outside. Position the cardiod some 10..40 inches above the ground. Let it radiate on axis to the skies. Measure the radiation to the sides.



1637843283674.png
 

fineMen

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Surely ...
Not so sure ;-) Many fell for it. Please consider argument (a). As long as the backwall, the "mirror" is less than infinitely far away the cardiod pattern is not there. So there is relevant sound output to the back.

The trick of nature (physics) here is, that the sound from speaker "Y" is less attenuated than that of speaker "X", which is more distant. The levels don't match. So the full cancellation doesn't happen. Only at infinite distance the different pathlengths become irrelevant, level wise.

I see, to think of the cardiod as a self contained "building block" is quite attractive. But one cannot argue with physics. I would really like to see the patent on how to solve this inherent problem. Nevertheless, scientifically, I offered some measures to prove my statement ;-)
 

Emlin

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Not so sure ;-) Many fell for it. Please consider argument (a). As long as the backwall, the "mirror" is less than infinitely far away the cardiod pattern is not there. So there is relevant sound output to the back.

The trick of nature (physics) here is, that the sound from speaker "Y" is less attenuated than that of speaker "X", which is more distant. The levels don't match. So the full cancellation doesn't happen. Only at infinite distance the different pathlengths become irrelevant, level wise.

I see, to think of the cardiod as a self contained "building block" is quite attractive. But one cannot argue with physics. I would really like to see the patent on how to solve this inherent problem. Nevertheless, scientifically, I offered some measures to prove my statement ;-)
But if you make the levels match (DSP, padding) you will get full cancellation and therefore cardioid, surely.
 

fineMen

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..., surely.
Still not sure ;-) In case You accept the problem statement, one might conclude, that a "cardioid" is even more sensitive to backwall distance than a monopole is? Measurement will tell. Not nearfield, but half space. Maybe @hardisj could help out next summer.

Anyway, even with a calculated, distance dependent attenuation of "Y" versus "X" the whole concept cannot work properly. And additionally it has contradicting design parameters. The lower the frequency, at which "cardiod" starts to work, the greater wall distance is required.

For instance GGNTKT uses a wide front baffle. With that alone the disperion narrows at as low as 200..300Hz. For most European living rooms the Schroeder frequency (modal regime => diffuse) sits somewhere around 150..200Hz. So what is the benefit of cardiod then?
 

FrantzM

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Affirmed, if some particular problem with room integration was solved. Please see image below. A cardiod is composed of two distinct speakers (monopoles) "X" and "Y". These are separated by a certain distance "C", reversed in phase, while "Y" gets its input delayed by "distance C devided by the speed of sound". Basically, that is a cardiod. Usually this is placed at some distance "B" to a backwall.

a) a cardiod pattern is achieved only in an infinite distance, not close to the speaker-assembly (to be discussed how far 'infinite' practically is)
b) a reflective surface behind the "cardiod" disturbes the desired pattern a lot

Regarding (b) let me explain briefly. The reflections can be described as "mirror sources"--I have seen publications having this term in the title. So effectively the speaker-assembly, once standing close to a backwall, has to be described as made up from four sources. Two real sources, and two virtual sources. My Excell calculations showed not only a degradation in the cariod pattern, even a reversal was possible: more to the sides than on axis.

If this problem is solved with the game changers, the better! Patent worthy I would say.

It should be easy to test my hypothesis, and the possible patent in a half field environment outside. Position the cardiod some 10..40 inches above the ground. Let it radiate on axis to the skies. Measure the radiation to the sides.



View attachment 168015
That is perhaps where DSP comes to the rescue. In the case of the 8C, you need to enter the distance from the back wall. The 8C also allows the use of REW to optimize the response at the listening position, parameters can be directly entered in the app.

At this point in time, it could be the answer to many audiophiles dreams:
Linearity
Truly Full Range: 20~20,000 Hz plus or minus 2.5 dB is extraordinary, ludicrous even, and yet ... such was achieved and documented by @mitchco
Good SPL capabilities, 105 dB at 35 Hz @ 3 meter in a room is no joke... That's stupendously loud in my book
Controlled, well-behaved overall directivity
Complete Audio System
Small (Relatively)
Pretty (IMO)
I wonder how the 8C works in a HT? Latency could be a serious issue...

I am by nature a first adopter. I don't see any issue with the (relative) newness of the company, Genelec or any of the favorites where at such stage only a few years back..

Interesting times for music lovers with audiophile tendencies :)

Peace
 
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fineMen

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That is perhaps where DSP comes to the rescue. In the case of the 8C, ..
Not so much. In my drawing above the X and the Y speakers are two distinct active speakers, and my description reiterates that. Since the DD8 has a mechanical, 'passive' cardiod, the relative amplitude of X versus Y is fixed by the mechanical design. The woofers on the back might not contribute too much to the cardiod. Otherwise the mechanical, always quite compromised implementation with the single 8-inch in front and the slots would have been superfluous.

D&D won't tell anyway. So it must remain a mystery.
 

Kvalsvoll

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Even if you don't have distributed drivers in the vertical plane? Ah, you can have acoustic vents in the vertical plane of course.
There is already a port for the vertical plane - the same that works for horizontal. Basically, if you make a simple box with driver on the front panel and acoustic ports on the sides, those ports will affect the pattern in all directions.

But you will not see the floor reflection go away, in the freq response. The radiation angle will (usually..) be far too wide, compared to the angle from the speaker to the floor. Say we choose a listening window around +-45 deg horizontal, as it is not desired to have too narrow, so at 45 deg the level has not sropped significantly. Then you need to go to at least 60 deg, or much more to get huge attenuation, and where are you then, on the floor - you are very close to the speaker.
 

pozz

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fineMen

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.... huge attenuation, and where are you then, on the floor - you are very close to the speaker.

I still don't understand, why the reflections are considered that bad. At least the wall behind the listener reflects. Is it really better to invest into huge effort to get rid of side wall reflections, ceiling and floor reflections, leaving the single one listener with that singled out reflections from behind? I argue that would feel a bit less natural to every day people. The total enthusiast could opt for a headphone instead.

A reflection free presentations isn't achieved easily, so many would chose an easy speaker installation and be good. Then people start to listen to music, to ease their minds.
 

abdo123

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I still don't understand, why the reflections are considered that bad. At least the wall behind the listener reflects. Is it really better to invest into huge effort to get rid of side wall reflections, ceiling and floor reflections, leaving the single one listener with that singled out reflections from behind? I argue that would feel a bit less natural to every day people. The total enthusiast could opt for a headphone instead.

A reflection free presentations isn't achieved easily, so many would chose an easy speaker installation and be good. Then people start to listen to music, to ease their minds.
These designs are not removing all reflections, they’re removing reflections at the 5ms to 30ms window of the precedence effect. Which do nothing but muddy the sound and color it.

The decay time of good rooms is usually in the 0.25s to 0.5s range. So you still have PLENTY of reflections.
 

fluid

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The woofers on the back might not contribute too much to the cardiod. Otherwise the mechanical, always quite compromised implementation with the single 8-inch in front and the slots would have been superfluous.

D&D won't tell anyway. So it must remain a mystery.
The woofers on the back are crossed at 100Hz where the pattern has become omni so they are not intended to lower the pattern control frequency.

What won't they tell and is a mystery?
 

fineMen

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These designs are not removing all reflections, they’re removing reflections at the 5ms to 30ms window of the precedence effect. ...
The decay time of good rooms is usually in the 0.25s to 0.5s range. So you still have PLENTY of reflections.

I don't get it. If the early reflections are muted in a particular direction, due to directivity, then later reflections are also muted in that direction, right? All "other", the plenty of reflections, as You put it, would originate from one direction. Namely from the sound that was emitted directly towards the listener, passing his position, as to eventually bounce off the backwall behind the listener.
I expect that human hearing is capable to perceive this situation as something quite special. If some folks appreciates such a stereo effect, well.

The woofers on the back are crossed at 100Hz where the pattern has become omni so they are not intended to lower the pattern control frequency.
What won't they tell and is a mystery?

Mystery is by which method the distance to the wall behind the speakers is considered in the design. We discussed earlier, that cardiods don't work that well close to a wall behind them. The caveat follows an argument directly derived from physics. I'm more trained in QM, but by education I should trust my findings enough to propose a verification by measurement. The how-to was also stated.

Add.: please consider to look-up the proximity-effect with cardiod microphones. Same thing, well known, and in parts appreciated, especially by male radio guys: it warms up the voice a whole lot. Same physical reason ... so?
 
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Purité Audio

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You can ’tell’ the speaker how far away it is from the front and side walls via its app.
Keith
 
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