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


StabMe

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15 hours ago, DirtyErnie said:

Square room?  That's going to be rough.
Best luck I had there was with taking down the corner tiles in a suspended ceiling. I guess the space above the ceiling acted as a 'resonator' to bleed off the nodes below the ceiling.  The difference was NOT subtle.

 

No, it is ~40X20 Ft.

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No, it is ~40X20 Ft.
Better than square...best would be not divisible by the same number though. Not sure what you can do about that though. My room is worse...we have to each deal with what we have as a room unless we custom build it. I am sure you will get it tuned to be the best that it can be.

Sent from my SM-G985F using Tapatalk

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11 minutes ago, NBPK402 said:

Better than square...best would be not divisible by the same number though. Not sure what you can do about that though. My room is worse...we have to each deal with what we have as a room unless we custom build it. I am sure you will get it tuned to be the best that it can be.
 

 

Actually, i already can hear HUGE improvement. Speech in movies is much easier to comprehend. Imaging is much better and i can hear a lot more detail.

 

Currently I have those diffusers on the ceiling and Leanfusers on the backwal simply standing on the floor. Can't wait to have my absorbers installed - this will improve the sound even further. 

 

I am afraid that I won't be able to tame resonance on very low frequencies - below 100Hz. Maybe some active absorption on the back wall with subwoofers a-la double bass array...

 

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22 minutes ago, StabMe said:

 

No, it is ~40X20 Ft.


That's a little 'less bad'. Easiest approach might be building some sort of divider at a ratio-friendly distance.  I've also heard of placing heavy absorption/diffusion behind that distance; leave the listening part of the room lively, and heavily killing anything that goes past the 'golden ratio' point.

This is a big project, I applaud your efforts!

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9 minutes ago, DirtyErnie said:


That's a little 'less bad'. Easiest approach might be building some sort of divider at a ratio-friendly distance.  I've also heard of placing heavy absorption/diffusion behind that distance; leave the listening part of the room lively, and heavily killing anything that goes past the 'golden ratio' point.

This is a big project, I applaud your efforts!

 

Yeah, a bit less bad :) Unfortunately, I am locked into these dimensions. At the end of the room we have a big window and there is a door just in the beginning of the room. So, dividing the space is out of question. 

 

Maybe when I move to another house... 

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This weekend I will be installing absorbers - 10 huge 2x0,6 meters and 4 smaller 1x0,6 meters. Thickness of the material is 10cm and there is an additional air gap of 5cm. I will be also placing 6 Leanfusers on the back wall and one leanfuser on each side near the listening position. 

 

Here is how the whole setup will look like:

 

image.thumb.png.9ba097ad87a53c95736013196ba57449.png

 

Ceiling diffuser is not shown.

 

Listening position is 4.7 meters from the front wall. Horn mouth is about 1 meter from the corner now, because i am going to place bass trap across the corner to tame some resonances. Angled sides of the speaker are now about 20cm from the walls because of that too (they were right at the walls before.

 

Looking at the picture and on those traps, I have a few worries:

- I moved the speaker a bit away from corners - will it reduce the loading significantly?

- absorbers are 15cm deep (6") - can it negatively affect the sound by creating surfaces for unwanted reflections?

- As can be seen on the front wall, it is almost fully treated, but is there enough treatment near the edges of the horn that is closer to the side walls?

- Does it look like I am overtreating the room? I would only be glad to keep everything as it was, but i still have 1000-1200ms reverberation so this seems like the only way to tame it.

 

Thanks!

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Ok, here is how it currently looks:

 

IMG_20211128_090703.thumb.jpg.f75ec87d860ba9d4877b2de3733f09f5.jpg

 

I was afraid that putting absorption will decrease the subjective width of the soundstage and decrease the liveliness. But the soundstage now feels even more wider, highs are even more pronounced which will have to be dealt with the housecurve (speakers are EQed flat 1m on axis currently) and the amount of detail that has emerged after those treatments is kind of spooky - can't think of any other word. I moved the speakers into the room away from corners about 30cm in AND installed traps across the corner - maybe this is the reason low end is kind of lacking. 

 

I do not have a lot of experience listening to high quality setups. This is probably the closest I have ever approached to a "quality setup", but I haven't heard a system that is so crisp, detailed, so loud and images as great as this.

 

Will get back with the measurements later today.

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Ok, some measurements at the LP to assess the effect of room treatments:

 

Reverberation (Topt):

image.png.82bba751ae9246b574dd05a299f01e6f.png

 

Clarity (C80):

image.png.86b0bda54f59204453be6dcee1cd00b1.png

 

ETC Curve (%FS):

image.png.ef0090dffe246f38869b2ddee6a7c518.png

 

So reverberation time is almost where it should be from about 200hz and onwards and a tab better in the lower frequencies as well.

 

Clarity has improved indeed: the dialogue is much easier to understand in movies. The amount of detail in music is also much greater.

 

As for the ETC - this is the first time I am trying to work with this kind of graph. I can see that spikes between 1.5ms and later are seriously reduced. Those between 0 and 1.5ms are not as reduced as the others. But the 'before' measurement also had some treatments near the edge of the horn (1" thick instead of 2" plus a gap that is used now). Is there 'an acceptable level' of ratio between the spike at 0ms and early reflections? Am i near that ideal ratio?

 

To my ears, the difference is huge. Bass is much easier to comprehend but still a bit boomy. What should i do now? Currently all the traps are placed in the first part of the room. I still have place to add a pair or 200x60cm traps in the second part. Then, a bit later I will buy a huge rack for books and stuff which will also be placed in the end of the room. Will that suffice? 

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  • 3 weeks later...
  • 1 month later...

The best acoustics for concerts are the outdoor venues

no reflections, the audience provides damping to the front

 

Soft surfaces good

Hard surfaces bad

This includes the floor

 

The back wall opposite side of the room from the speakers must be sound absorbing

Book shelves, heavy curtains, or hanging rugs work or decorated absorption panels if you like art. The entire wall.

 

An area rug on the floor between the speakers and chairs works well

 

Everything hanging from the ceiling creates reflections, to measure would require removal and measurement, before and after.......

 

Windows with heavy curtains, open is better

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  • 3 weeks later...

StabMe, a very impressive project you have going on. MEH CAD generated STEP files for CNC, that is beautiful👍 

I made my Synergy horns the old "analog" way, it was fun, but time consuming, not doing that again. 

After seeing some measurements and pictures of your listening room, I do feel I have some valid suggestions, take it for what it's worth🙂.

 

You have a very nice and big listening room, but as you know, it can be a double edge sword. With a lot of hard surfaces and relatively long distance between them, suppressing echo and flutter can be hard. 

 

With the things you have already done, you have substantial improvement over the untreated room. 

 

One very easy thing to try, is to move your listening position closer to the speakers. 3 to 4 meters from the speakers will give a much higher ratio of direct vs reflected sound at LP. By the same token, the direct sound will increase in SPL and the decay of late reflected sound will be lower in SPL. 

 

Also I would replace the diffuser on the ceiling with absorption. In that way all early reflections will be dampened. Behind the LP you could play around with different combinations of    absorbers and diffusers. In your large listening room I would look for spikes under the tab Filtered IR in REW, up to 50 ms. I have shown an  example below. All the circles in the first plot  represent unwanted reflection. Playing around with absorbers, behind LP, you should aim to remove as many spikes you can, see the "after" plot. There is still a reflection right after the initial 1. spike, in the after plot, which is from a small table. Ideally after the 1. IR spike to zero, the energy should drop as low as possible, in the first 10 ms and suppress strong peaks in the first 50 ms. These early reflections are largely responsible for messing with the stereo image and timbre of what we are hearing. Suppressing them hugely improves the clarity and detail of the stereo sound stage and the body of the instruments.

 

image.thumb.png.7e009489ee9c0ca98f547ad626adf0b0.png

 

 

 

For a more even bass response you could try to implement 1 or 2 subwoofers to smooth out the response. The key word for a tuneful even bass response is correct implementation, which there are different methods for. REW will be useful for that. Hope it helps.

 

Best Sebastian

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