Pros and Cons of Sealed Listening Rooms

[BlueFox]

I like my ceiling at 12’ high on the speaker side then sloping down to 8’ on the other side. Plus, there is a wooden ceiling beam going across the room at the first reflection point. As I mentioned earlier, my speakers in this room sound just like the speakers at Magico’s custom listening room.

 

[kach22i]

If i would use the louden ratio for optimal room dimensions it would be : Louden ratio of 1 1.4 1.9 .
3 meter high ceiling gives 4,2 m wide 5,7 meters long.

Plus i would use off sett walls min 5 - 10 ° degrees or something like that for side walls and then 5 ° + for the ceiling .
The front and the back preferably divided / split and angled construction wise , or else with a big diffusor.
That would then be the raw construction for example in which one can can add bass traps do all kind of things .
,diffusors and some absorption can be done later .
Just a bit of thinking

I did find a diagram showing a trapezoidal room.

The Louden ratio seems to favor higher ceilings than other ratios I've looked at including the one on the Cardas site.

https://realtraps.com/art_studio.htm

 

[kach22i]

Another trapezoidal room.

Best Home Theater Room Sizes and Dimensions
https://hometheateracademy.com/best-home-theater-room-sizes-dimensions/

 

[kach22i]

I've been reading up on Bolt Area and the Bonello graph and found an online calculator the likes I've never seen before.

Amroc
https://amcoustics.com/tools/amroc?l=15&w=11&h=7&ft=true&r60=0.6

FYI: first posted in another forum here:
https://www.audiosciencereview.com/...room-node-calculators-what-does-it-mean.8062/

The 2nd video (Ideal Room Size Ratios & How To Apply The Bonello Graph) by Dennis Foley of Acoustic Fields is also good to watch (as usual).
https://audiophilereview.com/room-a...ions-and-ratios-for-audiophile-listening.html

Video link below on how to use the far above Amroc tool.

Subwoofer helper and room modes vid 20

 

[sbnx]

The amroc tool is really great. I have used it for years. The developer is just a hobbyist like the rest of us. I have emailed him a few times and he is fairly responsive for just a web app that he supports for free.

For ceiling height - taller is better. As an example, if we assume that the tweeter height is 3' and your seated ear height is 3' and that you sit 10' from your speakers. Then the first reflections from a 7' ceiling is at 1.8ms; an 8' ceiling is at 3.3ms; a 9' ceiling is at 4.2ms; a 10' ceiling is at 6ms. So just to get out of the 5 ms window we need a 10' ceiling. Anything less than this definitely needs to absorb the first reflection from the ceiling.

I know some argue that reflections from the vertical plane don't matter but that is simply not my observation. These reflections don't affect the stereo imaging but they definitely affect the clarity, dynamics and "harshness" of the sound.

~Todd

 

[Duke LeJeune]

For ceiling height - taller is better. As an example, if we assume that the tweeter height is 3' and your seated ear height is 3' and that you sit 10' from your speakers. Then the first reflections from a 7' ceiling is at 1.8ms; an 8' ceiling is at 3.3ms; a 9' ceiling is at 4.2ms; a 10' ceiling is at 6ms. So just to get out of the 5 ms window we need a 10' ceiling. Anything less than this definitely needs to absorb the first reflection from the ceiling.

Thank you for doing the math! Very enlightening. A little bit of additional ceiling height goes a long ways!

Reduced vertical dispersion can arguably help by putting less energy into the floor and ceiling reflections.

I know some argue that reflections from the vertical plane don't matter but that is simply not my observation. These reflections don't affect the stereo imaging but they definitely affect the clarity, dynamics and "harshness" of the sound.

Yesss!!

"The earlier and the greater in level the first room reflections are, the worse they are." - Earl Geddes

“The earlier a reflection arrives the more it contributes to masking the direct sound.” - David Griesinger

"When presence is lacking the earliest reflections are the most responsible." - David Griesinger

"Transients are not corrupted by reflections if the room is large enough - and 10ms of reflections free time is enough." - David Griesinger. The implication is that we would do well to avoid reflections arriving within 10 ms of the direct sound, which is difficult to accomplish in the vertical plane.

 

[spiritofmusic]

Guys, can I ask if one unique aspect of my room is inadvertently adding to how good things are sounding?

It's an attic space w descending eaves at 30° from midline apex of 9' high.

Because we needed a massive amount of steelwork for structural stability, there are chunky steels at 2m centres, 8 in total, incl btwn spkrs and front wall, 0.5m in front of spkrs, either side of my listening position, and behind me.

The steels are 30 cm deep and 1cm thick.

Are these acting as diffusers or otherwise breaking up standing waves/nodes?

Because for the life of me I can't work out how a ceiling varying from 9' high at midline to 4' high at side walls, can be a positive.

 

[Duke LeJeune]

Because we needed a massive amount of steelwork for structural stability, there are chunky steels at 2m centres, 8 in total, incl btwn spkrs and front wall, 0.5m in front of spkrs, either side of my listening position, and behind me.

The steels are 30 cm deep and 1cm thick.

Are these acting as diffusers or otherwise breaking up standing waves/nodes?

Imo these are acting as diffusors, but are not large enough to have any effect on the longer wavelengths we normally associate with standing waves.

...for the life of me I can't work out how a ceiling varying from 9' high at midline to 4' high at side walls, can be a positive.

For one thing I don't think you'll have strong floor-to-ceiling standing wave modes because the height of your room is too "fuzzy". Also, shorter wavelengths striking the ceiling will tend to be deflected in the horizontal plane more than normal, which may also be beneficial, I'm not sure.

 

[spiritofmusic]

Thanks Duke. Let's put it this way, one wouldn't actively choose this layout, but having been landed w it and no choice in the matter, I would now absolutely not switch to my 4x larger volume main living space 35x30x20. And would rather give up the hobby then go back to my previous room.

If I'd had my way, this 4x larger room is the one I'd have chosen. With maybe drastically challenging results (for a start 35x30x20 is not far off a cube).

 

[Zero000]

As of next Thursday, I shall be controlling my room acoustics via 3 remote control roof mounted velux windows

Well maybe not it's a tad cold and wet here at the moment. But soonish. Post corona peak probably

 

[kach22i]

For ceiling height - taller is better. As an example, if we assume that the tweeter height is 3' and your seated ear height is 3' and that you sit 10' from your speakers. Then the first reflections from a 7' ceiling is at 1.8ms; an 8' ceiling is at 3.3ms; a 9' ceiling is at 4.2ms; a 10' ceiling is at 6ms. So just to get out of the 5 ms window we need a 10' ceiling. Anything less than this definitely needs to absorb the first reflection from the ceiling.....................

~Todd

Todd, how does using a planar speaker affect this?

I have a Martin Logan hybrid speaker.

Similar radiation pattern to the below I assume.

https://alsyvox.com/our-technology/

 

[sbnx]

Kach,
planer speakers is something i have limited experience with so I can’t answer with certainty. But first order reflections are almost never good. Acoustic treatment is pretty cheap and east to experiment with. I always suggest get a couple panels, put them on the ceiling and let your ears be the judge —especially if you have a ceiling less than 10’.

Todd

 

[Duke LeJeune]

Todd, how does using a planar speaker affect this?

I have a Martin Logan hybrid speaker.

Well I'm no Todd, but I've spent many years with line-source-approximating dipole speakers (SoundLabs).

A line-source-approximating speaker has very little interaction with the floor and ceiling, as shown in the diagram you posted. If you take that kind of speaker and toe it in enough that it effectively misses the side walls, now you have virtually eliminated the early sidewall reflections as well. If you can also pull your dipole speakers about five feet or so out in front of the wall, then the backwave is arriving after a long enough time delay that it doesn't degrade the clarity or tonality or imaging, but instead is overall beneficial.

Not that these are the only things that matter, of course.

 

[sbnx]

Duke,
im not claiming to be an absolute authority. Just experimented with a lot of acoustics stuff. If you saw my room you would laugh at all the different acoustic implements i have not to mention what has been moved to the garage. I find the research from toole, welti, geddes and others seems to strongly correlates to what i hear. For example, i have tried all the subwoofer setup methods and strongly prefer a modified Geddes approach. (Not trying to turn this into a subwoofer thread)

todd

 

[Duke LeJeune]

Duke,
im not claiming to be an absolute authority. Just experimented with a lot of acoustics stuff. If you saw my room you would laugh at all the different acoustic implements i have not to mention what has been moved to the garage. I find the research from toole, welti, geddes and others seems to strongly correlates to what i hear. For example, i have tried all the subwoofer setup methods and strongly prefer a modified Geddes approach. (Not trying to turn this into a subwoofer thread)

todd

Of the names you mention Geddes has influenced me the most, and in the area of subs (while hopefully not going too far down that rabbit hole) Earl's ideas inform my own efforts. Earl turned me on to David Griesinger, whose focus is mainly on concert hall acoustics and psychoacoustics, but I think many of the principles he teaches are applicable to home audio. Imo Griesinger is another brilliant outside-the-box thinker.

Griesinger on YouTube:

 

[KeithR]

+1

And a high ceiling.

how tall do you consider "high?"

 

[Exlibris]

I don't mean to go off-topic but the complexity of this thread seems to beg the question of near-field listening. I have a bad room and I'm thinking I might try going back to near-field listening to try and take the room out of the equation.

 

[sbnx]

Exlibris,
Why do you say you have a bad room? Is it a cube? Or glass windows everywhere? Or lack of positioning flexibility due to domestic considerations?

 

[Ron Resnick]

how tall do you consider "high?"

If a standard ceiling is 8' or 9' I guess maybe 10' or higher is "high"?

 

[Exlibris]

Exlibris,
Why do you say you have a bad room? Is it a cube? Or glass windows everywhere? Or lack of positioning flexibility due to domestic considerations?

Yes, a wall of glass windows and lots of concrete.