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An attempt to build K-402-MEH clone in wood


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3 minutes ago, Marvel said:

It's a diffuser, and doesn't need to be acoustic foam. They make them out of polystyrene, too. They can be smooth and painted, or whatever. The wood always looks cool, but weighs too much. I looked at aircraft balsa, but it was going to be too expensive.

 

Did you use QRDude to calculate the design for the frequencies you wanted to diffuse?

 

From what i know, it should be made out of material dense enough not to be absorptive or worth 'transparent' in the needed frequency range, rather it should be reflective which is achieved by it being dense.

 

Don't have any calculations on hand. Was going to use some tried and proven designs which are not terribly complicated. Just need to choose the right technology to build them. If i am to cover 50% of the space between listening position and front wall, i'll have to fabricate 12-15 pieces.

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10 minutes ago, Marvel said:

Did you use QRDude to calculate the design for the frequencies you wanted to diffuse?

 

 

2 minutes ago, StabMe said:

Don't have any calculations on hand.

 

FYI only:  it's been my experience that the frequency band 600-2500 Hz is where I see a rise in T30 values when measured at 1 m in front of the loudspeaker in a predominantly untreated room with loudspeakers having fairly good full-range directivity control, like the following:

 

1771397518_AMT-1ShinallKKSBassBin(UntreatedRoom).jpg.2811dacd4ae35f38c06c98961e4c6813.jpg

 

If you plug in 600-2500 Hz frequencies into the "QRDude" application, it might be interesting to see what results.

 

Chris

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Chris,

 

I was going to use Leanfuser for my side walls and back wall as shown on the picture a few posts above. It is not very deep (only 7.5cm) and starts working at about 1KHz. Here is a simulation of 7 diffusers put together in an array:

 

image.thumb.png.1dac39dc747a8f0e25df727ae9ea422b.png

Will need to explore QRDude and educate myself on how to design 2D diffusers in this application.

image.png

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Babies are home:

 

image.thumb.png.12459e2b2302b2017eb5aa6e4b41155a.png

 

Quality of this image is awful, but here are a few more photos of the process and the MEHs. 

 

All the walls (vertical and horizontal) have a spongy material that gets squeezed to about 0.2-0.5mm which is used to prevent air leaking. Now, In retrospect i understand that i should have designed the MEH so that i would have a prebuilt box with all the walls tightly glued to each other into which i would submerge the horn with drivers already attached. This would better prevent air leakage.

 

Each speaker weighs about 60 kilos. We had to bring them into my apartment on the 4th floor - it was hell :) 

 

I haven't tested the system yet. Have to bring amplifiers, a soundcard and a PC which would serve as a DSP and the source.

 

So, how do you like the looks? :)

 

Really excited about the fact that the main part of the project is now finished. 

 

How do i tune it? :)

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Don't be disappointed if when you first hook them up if fhey do not sound good. The dial in process will take a while. Chris had mine sounding pretty good after a few times and then after a few more they just popped in to where they soonded. Magical. 

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On 9/15/2021 at 3:38 PM, StabMe said:

I was going to use Leanfuser for my side walls and back wall as shown on the picture a few posts above. It is not very deep (only 7.5cm) and starts working at about 1KHz.

The arqen.com site has a lot of great material.

 

I assume you will be putting some other furniture in the room and raising up the horns. Four floors up, without an elevator?

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6 hours ago, NBPK402 said:

Don't be disappointed if when you first hook them up if fhey do not sound good. The dial in process will take a while. Chris had mine sounding pretty good after a few times and then after a few more they just popped in to where they soonded. Magical. 

 

Yeah, i suppose tuning it will take some time. Hopefully Chris may find some time to give me a few pieces of advice based on measurements.

2 hours ago, Marvel said:

The arqen.com site has a lot of great material.

 

I assume you will be putting some other furniture in the room and raising up the horns. Four floors up, without an elevator?

 

Yes, i am waiting for the TV stand which i ordered in a local wood workshop. They take forever to finish it. It is 3 meters wide and 60cm tall. Speaker stands are made of metal. Will post a pic of the whole setup with stands and furniture in future posts.

 

As for the other furniture - there will be a book shelf on a side wall near the back wall. Currently deciding on putting Leanfusers on the backwall as well. I have 8 of them made out of plywood that i don't use currently, so maybe i'll paint them to better fit the room design and hang on the back wall.

 

Ordered XPS insulation panels of 35kg/m3 density. Will be making 2D diffusers for the ceiling between couch and front wall and Leanfusers for the side wall and front walls near the horns (between each horn flange and TV). Hopefully i'll be able to paint them so they fit the room.

 

Maybe i'll put thick fiberglass panels behind the horns to handle the mid bass reflections.

 

And yes - no elevator in this 4 floor building :(

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