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Dutch & Dutch 8c Review

Scholl

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Playing devil's advocat: Why not put speakers in or on a wall or even corners? Much simpler engineering, better efficiency and the speaker is out of the way (WAF).
Well, that is funny because I actually have in wall mounted speakers in my home studio room. But it is not easy at all to build such an installation correctly (it took me months), and once it is built you cannot move things around anymore. You really have to plan things precisely and in advance (I modelled my room in a 3D renderer before building it). I also use EQ to compensate for the bass increase, and to correct the last few FR problematic areas. Furthermore, you need speakers that work in such an installation and they are not that common.

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Long story short, not a feasible solution for 99.9% of domestic, non professional rooms.

As far as "on wall" speakers are concerned, if they are not cardioid designs, they are going to suffer from SBIR with the front wall (destructive reflection interference). To keep things simple, you will have cancellations starting at F=c/(4*d) with c=speed of sound and d=woofer to wall distance. Even if the speaker is right against the wall, the effect will still be there. For instance a 30cm deep speaker will have a 286Hz first cancellation. Too low of a frequency, baffle step does not make sound directional to the front yet (cardioid speakers excepted). Unless you use really shallow speakers, which are probably going to be compromised in a lot of other ways, you won't get good results. I have tried and measured that kind of configuration multiple times.

Corner speakers are also complicated in practice, because you have to work with the room's dimensions (+SBIR as always). And most of the time it won't be ideal with regard to listening position, furniture placement etc.
 
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markus

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Well, that is funny because I actually have in wall mounted speakers in my home studio room. But it is not easy at all to build such an installation correctly (it took me months), and once it is build you cannot move things around anymore. You really have to plan things precisely and in advance (I modelled my room in a 3D renderer before building it). Furthermore, you need speaker that work in such an installation and they are not that common.

View attachment 169162View attachment 169160View attachment 169161View attachment 169159

Long story short, not a feasible solution for 99.9% of domestic, non professional rooms.

As far as "on wall" speakers are concerned, if they are not cardioid designs, they are going to suffer from SBIR with the front wall (destructive reflection interference). To keep things simple, you will have cancellations starting at F=c/4*d with c=speed of sound and d=woofer to wall distance. Even if the speaker is right against the wall, the effect will still be there. For instance a 30cm deep speaker will have a 286Hz first cancellation. Too low of frequency before baffle step make sound directional to the front. Unless you use really shallow speakers, which are probably going to be compromised in a lot of other ways, you won't get good results. I have tried and measured that kind of configuration multiple times.

Corner speakers are also complicated in practice, because you have to work with the room's dimensions (+SBIR as always). And most of the time it won't be ideal with regard to listening position, furniture placement etc.
Well, you get SBIR even with cardioid's or speakers in-wall as there's a floor, ceiling and back wall. So always compromises involved.
On-wall could look something like this:

on-wall.jpg
 

abdo123

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@markus

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From these tests Dr. Toole concluded that anything other than IN-wall and free standing in the middle of the room is not a good idea.

In In-wall installation the sound power becomes the on-axis response in these figures, which means the speaker must be tuned accordingly (no more baffle-step)

the Dutch and Dutch 8C makes it so you don't have the nulls we see in On-wall installation.
 

markus

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@markus

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From these tests Dr. Toole concluded that anything other than IN-wall and free standing in the middle of the room is not a good idea.

In In-wall installation the sound power becomes the on-axis response in these figures, which means the speaker must be tuned accordingly (no more baffle-step)

the Dutch and Dutch 8C makes it so you don't have the nulls we see in On-wall installation.
Thanks abdo123. Rest assured that I'm not saying what I've said above because I'm ignorant of all the issues involved. I'm well aware what those issues are but I'm also aware that those issues can be resolved to some degree. I've built multiple prototypes over the years. The industry isn't interested in such solutions because they can't create a viable business case. The IKEA speaker is an absolute exception but it's also not the level of performance that could be achieved (although Amir liked it a lot).

P.S. The Dutch & Dutch's or Kii's are certainly great engineering examples but please make no mistake that when you put them in a room you will see SBIR. Simple to test. Get a pair, put them in your room and measure.
 

abdo123

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P.S. The Dutch & Dutch's or Kii's are certainly great engineering examples but please make no mistake that when you put them in a room you will see SBIR. Simple to test. Get a pair, put them in your room and measure.

Not from the front wall. and that's the most problematic wall because it's the closest the source (in this case). There is simply no sound coming from the back of these speakers. this phenomenon is physically impossible.
 

markus

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Not from the front wall. and that's the most problematic wall because it's the closest the source (in this case). There is simply no sound coming from the back of these speakers. this phenomenon is physically impossible.
Yep, and I didn't deny that, did I? And, I was comparing on/in-wall with cardioid.

P.S. There IS actually "sound coming from the back of these speakers", that's what makes them work ;)
 

abdo123

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Yep, and I didn't deny that, did I? And, I was comparing on/in-wall with cardioid.

P.S. There IS actually "sound coming from the back of these speakers", that's what makes them work ;)
Anyway i really don't think anything except in-wall and free space is anything remotely Hi-Fi. Just stick the speakers in the center of the room and make them a statement piece. make speaker stands out of solid marble .etc whatever it takes because even a Dutch & Dutch 8C would suffer from an on-wall placement, just less so than traditional speakers.
 

markus

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Anyway i really don't think anything except in-wall and free space is anything remotely Hi-Fi. Just stick the speakers in the center of the room and make them a statement piece. make speaker stands out of solid marble .etc whatever it takes because even a Dutch & Dutch 8C would suffer from an on-wall placement, just less so than traditional speakers.
What you'll perceive in-wall vs. free space (=anechoic) is VERY different.
 

abdo123

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What you'll perceive in-wall vs. free space (=anechoic) is VERY different.
yeah ofcourse, that's why many people like big speakers with big baffles because they're forward firing for a decent chunk of the spectrum (audible benefit). In-wall speakers are forward firing for the entire spectrum, it's just incredibly expensive and irreversible to install them like that which pushes people away.

marble stands imported from Italy sounds much more economical and convenient at this point than hiring a contractor to have a hole in your wall and exposing the entire room adjacent to the listening room to exactly whatever you're listening to.
 

markus

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yeah ofcourse, that's why many people like big speakers with big baffles because they're forward firing for a decent chunk of the spectrum (audible benefit). In-wall speakers are forward firing for the entire spectrum, it's just incredibly expensive and irreversible to install them like that which pushes people away.

marble stands imported from Italy sounds much more economical and convenient at this point than hiring a contractor to have a hole in your wall and exposing the entire room adjacent to the listening room to exactly whatever you're listening to.
Sorry, you've lost me at "marble stands" :) On-wall IS an option when done right.
 

pozz

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Pretty sure that what's happening in the several hundred Hz region is due to the rear radiation. Pretty decently behaved, though.
in-room%20vs%20PIR.png

On-wall IS an option when done right.
Can you give an example when it's done right? With measurements, I mean.

I would guess most people don't have too much space and place the speakers within 1m of the rear wall and some varied distance from the side walls. And try to make it work with EQ, etc.
 

fluid

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Can you give an example when it's done right? With measurements, I mean.
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...
 

bigjacko

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Is it possible to use absorption or diffusion to tame those dips? Or is 200 Hz too hard to absorp and diffuse? I am thinking how about making normal hard reflective material or absorping material surround the speaker and form an extention of wall that protrude out?
 

Frgirard

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Is it possible to use absorption or diffusion to tame those dips? Or is 200 Hz too hard to absorp and diffuse? I am thinking how about making normal hard reflective material or absorping material surround the speaker and form an extention of wall that protrude out?
Diffusion at 200Hz: no. 75 cm for the deepest 1D and 82 cm for the 2D.


Absorbsion at 200Hz: easy.
You can use Acousticmodelling web site to make your simulation.
 

fluid

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Pretty sure that what's happening in the several hundred Hz region is due to the rear radiation. Pretty decently behaved, though.
Both basic distance and Boundary Element simulations show that the rear radiation is not causing that by itself, there is a small contribution but the bulk comes from the further boundaries.
Is it possible to use absorption or diffusion to tame those dips? Or is 200 Hz too hard to absorp and diffuse? I am thinking how about making normal hard reflective material or absorping material surround the speaker and form an extention of wall that protrude out?
As the biggest contributor to the dips do not come from the wall behind then yes they can be absorbed, 200Hz with 6 to 8 inch absorbers and a big enough air gap is doable. The wall behind is better to be reflective with these (at least for some it) to allow the most bass boost from the near wall placement.
 

markus

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Pretty sure that what's happening in the several hundred Hz region is due to the rear radiation. Pretty decently behaved, though.
in-room%20vs%20PIR.png

Would have been great if Erin had shown the in-room data comparing cardioid and monopole. Usually you get a MORE ragged steady-state response once you start eliminating certain room interactions. This doesn't mean it sounds worse though ;)

Can you give an example when it's done right? With measurements, I mean.


I would guess most people don't have too much space and place the speakers within 1m of the rear wall and some varied distance from the side walls. And try to make it work with EQ, etc.

I do have a ton of measurements but as I can't drag anything outside for measuring it's nearly impossible to generate plots that are easily digestible without writing several pages of explanatory text.
The back wall (behind the speaker) reflection is just one of the many hurdles for a good on-wall design. There's for example also diffraction effects that need to be minimized. This calls for very shallow and therefore very large enclosures that are impossible to sell through regular channels. Here's an example:

image_18996.jpg
 
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