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ijansch 12-01-2019 09:41 AM

The Dutch Confusion Build (diy)
 
After lurking for a number of years, then building a house and preparing for a home cinema for nearly two years, I’ve finally started my build.

Many things are inspired by what I’ve seen here and I’ve had lots of great answers to my questions already from many of you (and special thanks to @BIGmouthinDC : not just for his direct answers but his historic posts are like an Encyclopedia of Cinema Builds).

I’ve named my build ‘Dutch Confusion’ after discovering halfway through my baffle wall build that 2x4 size lumber does not actually mean 2 by 4 inches, so after converting to metric sizes I ended up with, let’s call it, a very solid baffle construction.

Many of the hardware that will be in my build was chosen because it was crafted with love and has many fans. Where I can avoid the corporate big brands I will try. Here’s the current list:

- Arendal 1723 speakers from Norway.
- Two Arendal 5.1 subs
- Apollon amps from Austria
- a Silver Ticket screen imported from the US
- a Marantz 8805 prepro
- Epson TW9400 projector
- a boss riser based on jbl stage1210 and a behringer amp (to be built, only have the parts now)




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ijansch 12-01-2019 09:42 AM

Reserved for completion photos near the end.


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ijansch 12-01-2019 10:04 AM

The Dutch Confusion Build
 
This was the empty space during construction of the house. A concrete prefab basement. On the right is the wall that isolates the room from the staircase. It’s been a challenge to cope with this construct as it makes the room asymmetric but so far I’ve planned solutions around it.

https://uploads.tapatalk-cdn.com/201...07babc7c5b.jpg

The room is 13’4” wide and 19’8” tall.

After construction finished, during some preliminary tests with absorption and diffusion, this is the back of the room. The red chair is a temporary placeholder for the main seat (in a row of 4). https://uploads.tapatalk-cdn.com/201...41ff0a269.file





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ijansch 12-01-2019 11:10 AM

This is the planned layout , not entirely to scale. You can see how that corner for the stairs impacts the room layout.

https://uploads.tapatalk-cdn.com/201...c19157b995.jpg

This plan doesn’t reflect the baffle wall yet that I later added. Also I’m still doubting that overflow bar.


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ijansch 12-01-2019 11:17 AM

The Dutch Confusion Build
 
The first project is the baffle wall. It’s inspired by @Nyal Mellor ’s work on the acoustic frontiers blog, and the baffle wing design from The Beast Unleashed.

Constructing the frame out of slightly too sturdy lumber:
https://uploads.tapatalk-cdn.com/201...8129887393.jpg

My 4 year old daughter was in charge of decorating the lumber:
https://uploads.tapatalk-cdn.com/201...663d62bae5.jpg

Got the frame up. When I mounted it I toed it in a little more than in this picture (23.5 degrees). This is for the left speaker. It will line up behind an AT screen. The position is partly based on the Dolby and thx recommendations and opinions on this forum. It’s between the 16:9 and 21:9 edges and vertically centered to ear height.
https://uploads.tapatalk-cdn.com/201...ae04e785fd.jpg

I lined the speaker cabinets with mdf and rubber:
https://uploads.tapatalk-cdn.com/201...5e39529af8.jpg

I separated the frame from the floor with 0.5” padding and I mounted the frame to the concrete ceiling with isolating clips:
https://uploads.tapatalk-cdn.com/201...d84aa2add6.jpg


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ijansch 12-01-2019 11:48 AM

The Dutch Confusion Build
 
For the acoustic treatments I’m getting some valuable input through a Dutch HT forum from knowledgeable people such as @bert stoltenborg . I noticed both the approaches and materials on this forum are too different from what is available over here so I’m trying to get that knowledge from local people.
This is currently in the planning and idea phases. It will take a few weeks before I get to the actual treatment.


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ijansch 12-01-2019 12:13 PM

The Dutch Confusion Build
 
Because tinkering with lumber is fun, but playing with gear is more fun, meanwhile I’m also installing the 19” rack which nicely fits under the stairs behind that wall (so it’s good for something after all).

I’m getting some advise and local good deals from a local HT installer, All4Control (https://www.all4control.nl/).

One key thing in my home theater is that I want this to serve both as a hobby and an educational experience. If I have to learn how to install carpet if I need carpet, then that’s what I’ll learn. The process is:

1. deciding what I want.
2. Researching how I get there and what the best practices are
3. Doing it
4. Wondering if I should reconsider bullet 1 :)

https://uploads.tapatalk-cdn.com/201...d443c2f7c8.jpg

Back side:

https://uploads.tapatalk-cdn.com/201...64ebd71482.jpg


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ijansch 12-08-2019 01:33 PM

The Dutch Confusion Build
 
I’ve got all three baffle wings up:

https://uploads.tapatalk-cdn.com/201...9a54dc9341.jpg

With the laser level I tried to focus on the speakers (the framing is allowed to be off as long as the speakers are level). For an amateur it went pretty well. (I can’t get that ‘...laser aligned surround speakers...’ from the imax countdown trailer out of my head.)

I also ran some smurf tube for the speaker wires.

https://uploads.tapatalk-cdn.com/201...90b1ab79b5.jpg

I do have a question: due to the lumber not being perfectly straight the mdf speaker frame doesn’t 100% line up with the lumber. It’s about a 0.08” (2mm) gap on the front (near the back they meet up 100%):

https://uploads.tapatalk-cdn.com/201...f95ac0d203.jpg

Will I get away with that? Should I stuff it with something? I did screw the mdf to the lumber with a few screws so it’s not going anywhere easily, so maybe it doesn’t matter?

BIGmouthinDC 12-08-2019 02:44 PM

I doubt that will cause any problem. Pound it with your fist to make sure it doesn't rattle. If you want you could squirt it full of caulk but I don't think it is necessary.

ijansch 12-09-2019 05:32 AM

Quote:

Originally Posted by BIGmouthinDC (Post 58931922)
I doubt that will cause any problem. Pound it with your fist to make sure it doesn't rattle. If you want you could squirt it full of caulk but I don't think it is necessary.


it doesn’t rattle when I pound it. That did reveal a few rattles though from smurf tube against the frame, so that was a good test. Will need to check how I can avoid that. More tube fasteners I guess.


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ijansch 12-09-2019 01:27 PM

Started layering the fiberglass insulation panels (it’s like fluffy pink but yellow (isover brand).

I’m going to have to use multiple layers to fill up the wings. There’s this thin paper that holds the sheets together. Does it matter whether that paper faces inwards or outwards? Since it’s layered there will be multiple paper sheets in between. For warmth insulation the product recommends paper facing the room, mostly to keep the fibers behind it.

Or should I find a paperless fluffy stuff when layering? I’ve got about 12” to fill at the outer baffle edges. That’s about 6 layers of the stuff.

https://uploads.tapatalk-cdn.com/201...f542d985d8.jpg


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ijansch 12-09-2019 01:59 PM

The Dutch Confusion Build
 
Meanwhile learned that it’s called faced if it has the paper and unfaced if it doesn’t have it. Also it seems that avsforum posts < 2010 seem to favor unfaced whereas later posts seem to say it doesn’t really matter.

Not sure if layering makes a difference in that conclusion.


Edit: the manufacturer states that it’s not actually paper but a thin layer of glass fiber to ease working with it. Not sure if that changes the situation. It ís indeed easy to work with as they stay in place with no fastening.

bert stoltenborg 12-10-2019 12:18 PM

Quote:

Originally Posted by ijansch (Post 58931724)
I’ve got all three baffle wings up:

https://uploads.tapatalk-cdn.com/201...9a54dc9341.jpg

With the laser level I tried to focus on the speakers (the framing is allowed to be off as long as the speakers are level). For an amateur it went pretty well. (I can’t get that ‘...laser aligned surround speakers...’ from the imax countdown trailer out of my head.)

I also ran some smurf tube for the speaker wires.

https://uploads.tapatalk-cdn.com/201...90b1ab79b5.jpg

I do have a question: due to the lumber not being perfectly straight the mdf speaker frame doesn’t 100% line up with the lumber. It’s about a 0.08” (2mm) gap on the front (near the back they meet up 100%):

https://uploads.tapatalk-cdn.com/201...f95ac0d203.jpg

Will I get away with that? Should I stuff it with something? I did screw the mdf to the lumber with a few screws so it’s not going anywhere easily, so maybe it doesn’t matter?


I guess you're going to finish this one way or another, so don't worry.to much.

ijansch 12-12-2019 02:49 PM

I ended up swapping the fluffy around so the thin fiberglass paper layer is on the outside. Also got some thicker panels for the other layers so there’s less of the paper in the wall.

Some of the center wing cavities are now filled up, need to do some more on the rest of the wings. https://uploads.tapatalk-cdn.com/201...4447d27081.jpg

To not spend all the time cutting and stacking fiberglass panels, I started pulling the speaker wire through the smurf tube. It’s 3/4” tube so I could easily suck a wire through the tube. (Tried with the vacuum cleaner first but just using my mouth worked just as well. The tubes aren’t that long anyway.)

Finished the cables with a few nakamichi banana plugs.

https://uploads.tapatalk-cdn.com/201...8f80c31236.jpg

bert stoltenborg 12-13-2019 06:48 AM

Why is the middle part of the construction sticking out?

ijansch 12-13-2019 09:47 AM

The mdf plate you mean? I wanted to provide support for the back of the speaker. It’s slightly longer than the lumber frame.

Or do you mean the center bottom part which is deeper? That’s a place for one or two subs.


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bert stoltenborg 12-13-2019 10:08 AM

Quote:

Originally Posted by ijansch (Post 58952916)
The mdf plate you mean? I wanted to provide support for the back of the speaker. It’s slightly longer than the lumber frame.

Or do you mean the center bottom part which is deeper? That’s a place for one or two subs.


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No, I mean it looks like the side wings reach to almost the back of the middle wing.
The middle wing seems to stick out.
I wonder about that because wouldn't that generate trouble like diffraction from the middle wing speaker and reflections from the side wing speakers on the sides of the middle wing that sticks out?


(dat middenstuk waar de center speaker in komt lijkt uit te steken ten opzichte van die wings. Daardoor kan er weer geluid om dat middenstuk heenbuigen en geluid uit die zijspeakers reflecteert tegen die zijkanten van dat middenstuk. Of zie ik dat verkeerd?).

ijansch 12-13-2019 03:19 PM

The Dutch Confusion Build
 
@bert stoltenborg yes that was a point of doubt. Here’s how I drew that:

https://uploads.tapatalk-cdn.com/201...320e731c74.jpg

I had a discussion about it where this seemed to be the best trade-off to save space for the front wall. The discussion can be found here:
https://r.tapatalk.com/shareLink/top...ink_source=app

I do have doubts since in that thread the example doesn’t have these connected sections. But I don’t have enough width in the room to space them further apart. Would it be better to ‘open’ the back so sound from the left and right wing can enter the insulation of the center section? I do think I need that wood to support the speaker.


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BIGmouthinDC 12-13-2019 04:41 PM

just cover any problematic edges with absorption.

bert stoltenborg 12-14-2019 06:54 AM

I have to

bert stoltenborg 12-14-2019 06:55 AM

have 5 posts before

bert stoltenborg 12-14-2019 06:55 AM

I can post a drawing.

bert stoltenborg 12-14-2019 06:56 AM

1 Attachment(s)
Quote:

Originally Posted by BIGmouthinDC (Post 58955042)
just cover any problematic edges with absorption.


Yes, or something like this?

ijansch 12-14-2019 07:46 AM

Interesting solution. How do sound waves behave in this corner (green arrow), isn’t the baffle supposed to be 180 degrees to be effective?

https://uploads.tapatalk-cdn.com/201...64f515a693.jpg

Also in reality the two purple dots line up horizontally. So the place where this ‘filler’ would end is almost at the speakers edge. So you’d get a 157 degree baffle there. Would that work?


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bert stoltenborg 12-14-2019 10:58 AM

Quote:

Originally Posted by ijansch (Post 58956646)
Interesting solution. How do sound waves behave in this corner (green arrow), isn’t the baffle supposed to be 180 degrees to be effective?

https://uploads.tapatalk-cdn.com/201...64f515a693.jpg

Also in reality the two purple dots line up horizontally. So the place where this ‘filler’ would end is almost at the speakers edge. So you’d get a 157 degree baffle there. Would that work?


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The fold in the baffle will work a bit as a waveguide-horn.
How bad that is you should probably measure.
Your original situation also has a fold, you cannot prevent that.
I would be more worried about that piece of wood sticking out and generating reflections and diffraction.

ijansch 12-15-2019 01:12 AM

The Dutch Confusion Build
 
@bert stoltenborg maybe it’s a good moment for a first measurement. What would be a good way to measure any effects of the current situation? Maybe a frequency sweep, using just that one speaker? Or wouldn’t that be measurable without the rest of the room treatments.

bert stoltenborg 12-15-2019 04:33 AM

Quote:

Originally Posted by ijansch (Post 58959866)
@bert stoltenborg maybe it’s a good moment for a first measurement. What would be a good way to measure any effects of the current situation? Maybe a frequency sweep, using just that one speaker? Or wouldn’t that be measurable without the rest of the room treatments.


Yes, a sweep is sweet.
You can in the time domain of REW use a window function to zoom in on the impulse response, I guess.
(Edit: REW presents the impulse response on a square root dB-scale making it difficult for me to recognize reflections. I'm used to a MLSSA/ARTA-approach).

That way you can exactly see where reflections are, keeping in mind that sound moves at about 340 m per second.
So the distance between the speaker and the obstacle causing a reflection can be calculated, you can use a window to include and exclude the reflection and so you can see in the frequency domain what the effect of the reflection is.
And you could try to use absorption and see what that does to tame the reflection.

ijansch 12-24-2019 12:55 PM

The Dutch Confusion Build
 
Dad was around for Christmas so got some help this afternoon. The center baffle insulation is now done and the first layer of mdf is up:

https://uploads.tapatalk-cdn.com/201...8bd5ae62ac.jpg

There’s some mixed info about whether mdf should be the first, middle or last layer (see my separate post on this subject), so I did mdf first. Will do the drywall once I’m at the same point for the left and right baffle but I ran out of fluffy pink so will have to get some more after Christmas.

Merry Christmas everyone!

ijansch 12-29-2019 10:26 AM

The Dutch Confusion Build
 
Added the last layers of insulation. Stuffed one of them with leftovers, but there’s enough layers beneath the left overs so there should be sufficient stuff. Also added some more framing to be able to attach the mdf.

https://uploads.tapatalk-cdn.com/201...c66ee6ce3f.jpg

To ensure that I don’t drill a screw in another screw or in a void, I marked where all the lumber starts and ends and where the screws roughly are:

https://uploads.tapatalk-cdn.com/201...5810bbd802.jpg

ijansch 12-29-2019 01:56 PM

One thing I’m not sure of: should I do green glue only between the two gypsum layers or also between mdf and gypsum? Or use regular glue there? Or only screws?


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