Dutch & Dutch 8c Review

[markus]

Here are two examples of speakers designed to be on wall. The depth needed to avoid the issues shown in the Toole extracts limits the design options. There are measurements and simulations in there somewhere.

https://www.diyaudio.com/forums/multi-way/342693-decade-planning-thanks-forum.html

https://www.diyaudio.com/forums/mul...l-speakers-startup-questions-post6163781.html

The relevance of this to the 8c review is fading quickly...

I agree. In order to get back on track here's some history regarding the D&D: https://www.diyaudio.com/forums/multi-way/192737-2-waveguide-cardioid.html

 

[hardisj]

Would have been great if Erin had shown the in-room data comparing cardioid and monopole.

I have in-room response measurements for a fair amount of other speakers I have reviewed. Feel free to peruse those at your leisure.

 

[markus]

I have in-room response measurements for a fair amount of other speakers I have reviewed. Feel free to peruse those at your leisure.

Do you have the in-room response for all speakers you've measured so far? Is speaker and mic location always the same?

 

[hardisj]

Do you measure the in-room response at the exact same location for all speakers so far?

From Jan 2021 and on, mostly. Some are a smidge closer. Look at my Kef R3. I measured them around the same time.

Keep in mind, though, the DD8c and Kii THREE were positioned close to the front wall as they were designed to be. Other speakers are out from the front wall.

 

[markus]

From Jan 2021 and on, mostly. Some are a smidge closer. Look at my Kef R3. I measured them around the same time.

Keep in mind, though, the DD8c and Kii THREE were positioned close to the front wall as they were designed to be. Other speakers are out from the front wall.

Thanks. Hard to compare. Maybe spectrograms would be more useful for that kind of comparison?

 

[fineMen]

Cardioid directivity speakers work specifically better than normal speakers when we consider the wall behind them.

Yo, I wrote my Excell script again. It is meant to show the influence of a wall behind a cardioid from first priciples. That means no baffle, just point sources with distance and delay.

Same as I told You before. A nearby wall alters the pattern. It depends on wall distance and frequency. So, three parameters, namely distance, frequency, direction. I cannot discuss it here. I cannot find a presentation, that would reveal the effects to people, who are not used to read unfamiliar diagrams.

Take-home message: despite the saying, that cardioid doesn't radiate to the back, the wall behind a 'cardiod' labeled speaker is of relevance. That much, that it possibly renders the cardiod properties defunct.

To understand this claim needs an understanding of physics and mathematics way beyond all-day knowledge. From experience I would expect a heated debate, when it comes to critisizing the next big thing. More demanding arguments would be torn to pieces and cluttered by misunderstandings.

 

[fluid]

Same as I told You before. A nearby wall alters the pattern. It depends on wall distance and frequency. So, three parameters, namely distance, frequency, direction. I cannot discuss it here. I cannot find a presentation, that would reveal the effects to people, who are not used to read unfamiliar diagrams.

Of course it does any close boundary will have a significant effect on the response. It is unfortunate that you cannot produce anything to demonstrate your position. I put a reasonable amount of effort to simulate the effect in a Boundary element model and display the results graphically.

Take-home message: despite the saying, that cardioid doesn't radiate to the back, the wall behind a 'cardiod' labeled speaker is of relevance. That much, that it possibly renders the cardiod properties defunct.

A cardioid radiates less to the rear and rear sides, no one should be saying that it does not radiate behind. A 20dB reduction directly behind (like the 8c has at some frequencies) is quite a significant reduction. It is this reduction in output behind that reduces the impact of the close wall on the overall response.

As you haven't shown anything to illustrate what you say it is hard to even know if your position is that different from anyone else's.

 

[markus]

Yo, I wrote my Excell script again. It is meant to show the influence of a wall behind a cardioid from first priciples. That means no baffle, just point sources with distance and delay.

Same as I told You before. A nearby wall alters the pattern. It depends on wall distance and frequency. So, three parameters, namely distance, frequency, direction. I cannot discuss it here. I cannot find a presentation, that would reveal the effects to people, who are not used to read unfamiliar diagrams.

Take-home message: despite the saying, that cardioid doesn't radiate to the back, the wall behind a 'cardiod' labeled speaker is of relevance. That much, that it possibly renders the cardiod properties defunct.

To understand this claim needs an understanding of physics and mathematics way beyond all-day knowledge. From experience I would expect a heated debate, when it comes to critisizing the next big thing. More demanding arguments would be torn to pieces and cluttered by misunderstandings.

The speaker doesn't behave like a cardioid throughout its full frequency range. At its lower end it behaves like a monopole anyway. So where do you think is the transition frequency where back wall distance and cardioid behavior stop fighting each other?

 

[abdo123]

A cardioid radiates less to the rear and rear sides, no one should be saying that it does not radiate behind.

The definition of a cardioid implies that there is complete cancelation at -/+ 180 degress at least at exactly one frequency.

For example that frequency is somewhere between 100Hz and 120Hz for the Kali Three, I'm not sure at which frequency the D&D exhibit this.

 

[fineMen]

As you haven't shown anything to illustrate what you say it is hard to even know if your position is that different from anyone else's.

@fluid, as said, I really feel sorry not being able to present my findings in a digestible format. You took some effort, I know. The more I felt obliged to respond with a qualified, data driven argument. Not to challenge You, but to clarify the topic. Alas, for the time being I ask to take my appologies.

Anyway, if someone fell in doubt regarding the 'cardioid' thing, the easiest thing should be to take measurements. If these look o/k, the better. If measurements are out of reach, the discussion would be fruitless anyway.

Br

ps: since it is easy to set up a cardiod with two drivers and digital delay, I'm willing to do the measurements. But I have to wait for summer, in order to have a ground plane available. The ground plane acts like the wall behind the speaker.

 

[fluid]

The definition of a cardioid implies that there is complete cancelation at -/+ 180 degress at least at exactly one frequency.

That implies perfect cardioid radiation which neither the 8c or the Kii have at any frequency. The 8c has 20dB 180 degree maximum rejection which is still very good. Cardioid to describe these speakers is a shorthand as you can see the Kii is also Hyper cardioid at some frequencies where the maximum rejection moves away from 180 degrees.

When I say rear radiation I mean the rear hemisphere not 180 degrees behind.

 

[markus]

ps: since it is easy to set up a cardiod with two drivers and digital delay, I'm willing to do the measurements. But I have to wait for summer, in order to have a ground plane available. The ground plane acts like the wall behind the speaker.

Great idea! Looking forward to that data as we can't ask Erin to do additional measurements.

 

[abdo123]

That implies perfect cardioid radiation which neither the 8c or the Kii have at any frequency.

Can you substantiate that claim?

When I say rear radiation I mean the rear hemisphere not 180 degrees behind.

Then lets use rear hemisphere moving forward .

 

[fluid]

Can you substantiate that claim?

Sure as this is an 8c thread, look at the normalized directivity contours, I have highlighted the areas or greatest rejection. You can see that it is 150 degrees or so where the highest rejection is and that at 180 degrees it is something like 20 to 25 dB down from the on axis level. Certainly it does not get to a perfect heart shaped 0 at 180 as that would require total cancellation.

A cardioid like speaker with 20 dB rear rejection across a wide frequency range looks like this, excuse the inversion of 0 and 180 degrees in the simulation.

Some words from the designer here
https://www.diyaudio.com/forums/multi-way/281789-leaky-supercardioid-mids-post4501094.html

In the Kii three graph above 100Hz has the most 180 degree rejection at about -20dB from the on axis level. When it goes hypercardioid there is more rejection almost perfect cancellation at 200Hz but again it is more like 150 degrees with a rear lobe forming from the nulls.

 

[fluid]

Anyway, if someone fell in doubt regarding the 'cardioid' thing, the easiest thing should be to take measurements. If these look o/k, the better. If measurements are out of reach, the discussion would be fruitless anyway.

Erin did test it somewhat like that so maybe he does have some data that might help

 

[purebordem]

Not sure if this has come up yet, but to throw some weight behind the idea of "cardioid-like responses help audible perception" you might find this paper interesting.

The precedence effect with increased lag level

Gist of it is, the precedence effect is still noticeable even with +8dB on delayed signals less than 5ms from direct signal; which would imply maybe cardioid isn't that big of deal. However, the clarity of perception appears to be reduced and became more variable. Some listeners who are sensitive even began experience oscillations in perception at the higher end of the scale. Important bit from the summary

As lag level was increased, both within- and between-subjects variability increased, suggesting that the task of lateralizing became more challenging. Binaural analysis further showed that increasing lag level resulted in a more complex binaural display, with ITDs and ILDs varying wildly across frequency and conflicting with each other. It is unclear how these binaural cues might be integrated across frequency and with each other to yield a perceived intracranial position. This is reflected in the high intra- and inter-subject variability and represents a second factor that likely influenced perceived lateralization.

Taken together, these results suggest that listeners who primarily valued binaural cues at the onset of the stimulus may have been likely to exhibit lateralization that is relatively constant across ISIs. On the other hand, listeners who included salient binaural information from the ongoing portion of the stimulus in their decision variable may have been likely to produce strongly oscillatory performance patterns. A possible confounding factor is the way in which individual listeners integrated these ongoing binaural cues across frequency; this may also have been a determining factor in the form and extent of the oscillations in perceived lateralization.

What I take away from this is that reducing reflection level does indeed help sound localization and transient response. It also appears to be "easier" on the ears/brain. How far down those reflections need to be is another matter entirely. I can imagine even a 10dB reduction would be beneficial given that is general perceived doubling/halving of volume to most ears.

While I would assume most folks would find the concept of "reduced reflections = better" to be intuitive, it is nice to see some related research. That said, if you are more into "enveloping/3d sounding" speakers, maybe cardioid-like is less of a concern at that point.

 

[JanRSmit]

I will search again through my achive remains. But a study done soms 60 years ago demonstrated that delay and intensity did work, but in a limited frequent band, most pronounced in the band between 1000 and 2000 hertz. It allowed a clear separation/position in the lateral dimension regardless of listerner position. It worked very well when i was building speakers in the 70-thies.
Below ~200 hertz and above ~ 7000 hertz lateral discrimination in out hearing is negiglebel . (High freq source localisation only whith strong intensity difference, typically in combinatie with small movements of the head.)

 

[fineMen]

Not sure if this has come up yet, but to throw some weight behind the idea of "cardioid-like responses help audible perception" you might find this paper interesting.

The precedence effect with increased lag level

You only quote the summary. The artical seems to live or die behind a paywall, just like Schrodingers cat? Did You read, please explain?

An anecdote: deodorants containing a specific aluminium salt are practically banned here. Reason is, people fear aluminium. Why? There was a scientific (sic!) article like "Alzheimer Desease, Aluminium Kill Brain Cells" Someone read the title, maybe the sumary and concluded that Al was potentionally harmfull. Clue is, the scientists invention actually was to injected vast amounts of an aluminium salt solution directly into rats brains to partly kill it as to simulate Alzheimer. That sa(i)d individual (not) reader went crazy on internet, and many rats followed ... Now we stink.

Better read the article fully ;-)

Another fun fact: Here a specifc sort of "Healing Earth" is very popular with the same folks who banned Al in deodorants. Only that this "Healing Earth" is just Aluminiumoxide.

Fun fact there: the stimulus has length of 200ms, while delay is up to 5ms. First and delayed sound overlap. Hmm, gives the sensation of "modulation", namely oszillation. What that might mean to stereo?! Lets set up public funding for further investigations, urgently!

 

[purebordem]

You only quote the summary. The artical seems to live or die behind a paywall, just like Schrodingers cat? Did You read, please explain?

My apologies, I didn't realize I was auto-logged based on Geo-IP. I was on campus while reading that article. Try the Sci-Hub link. I'll update the original post accordingly.

An anecdote: deodorants containing a specific aluminium salt are practically banned here. Reason is, people fear aluminium. Why? There was a scientific (sic!) article like "Alzheimer Desease, Aluminium Kill Brain Cells" Someone read the title, maybe the sumary and concluded that Al was potentionally harmfull. Clue is, the scientists invention actually was to injected vast amounts of an aluminium salt solution directly into rats brains to partly kill it as to simulate Alzheimer. That sa(i)d individual (not) reader went crazy on internet, and many rats followed ... Now we stink.

Better read the article fully ;-)

Another fun fact: Here a specifc sort of "Healing Earth" is very popular with the same folks who banned Al in deodorants. Only that this "Healing Earth" is just Aluminiumoxide.

Really not sure if this addressed at me or what point you are trying to make.

Fun fact there: the stimulus has length of 200ms, while delay is up to 5ms. First and delayed sound overlap. Hmm, gives the sensation of "modulation", namely oszillation. What that might mean to stereo?! Lets set up public funding for further investigations, urgently!

Again, not sure what you are addressing here but evidently you found the article on your own since you know the stimuli was 200ms.

 

[fineMen]

Gist of it is, the precedence effect is still noticeable even with +8dB on delayed signals less than 5ms from direct signal; which would imply maybe cardioid isn't that big of deal. However, the clarity of perception appears to be reduced and became more variable. Some listeners who are sensitive even began experience oscillations in perception at the higher end of the scale.
...

Nope, it was an oszillation in the perceived direction with ever increasing level of delayed signals. Rather than a gradual shift into the direction of delayed ;-)

What I take away from this is that reducing reflection level does indeed help sound localization and transient response. It also appears to be "easier" on the ears/brain. ... imagine even a 10dB reduction would be beneficial ...

..., if you are more into "enveloping/3d sounding" speakers, maybe cardioid-like is less of a concern at that point.

There is no transient response mentioned, is there? Easyness? As it comes to the amplitude of reflections, in this experiemnt they were up to 8dB greater than the first sound, maintaining roughly localization from the first. With speakers reflections are necessarily quiter than the direct sound. Reflection loss, directivity and attenuation by distance! Mind You, this experiement was centered at 750Hz, where even sloppily designed speakers exhibit quite a deal of directivity, if not unvoluntarily.

Not the least, the research quoted is focussed on human hearing, decidedly not on stereo.

(Yes, I'm reading and understanding a bit fast, don't worry. 5min it took, and You read it?)