Ceiling cloud placement, over speakers or listening position?

[aleatoric]

I am building a ceiling cloud next week (703, 4 inches thick, 4 feet by 4 feet). I am wondering what is the ideal placement for the cloud, over my listening position, over my speakers or somewhere in between. Thanks.

[jdg]

same place as any first reflection point.
nice graphic from realtrap site: (just apply to the ceiling)

[jayfrigo]

The angle of incidence equals the angle of reflection. Treat first where it will stop the first reflection. Last post is a good illustration of this. A ceiling reflects the same way as a wall.

[Scoobz]

Of course Jay is right I would also add though that this is the way I would do it



This way you're covering the reflection point but also cutting down on SBIR by having the insulation between the wall and the speakers too.

So in answer to your original question, all the way from above the speakers to the refection point is the best option.

[Ethan Winer]

Originally Posted by aleatoric

I am wondering what is the ideal placement for the cloud, over my listening position, over my speakers or somewhere in between.

The answers above show my drawing for finding the reflection point (area) on the side walls. But you asked about the ceiling. For the ceiling reflections it's even easier, because the tweeters should be at ear height. In that case the center point of the area is exactly halfway between your ears and the front of the speaker cabinet. So the center of the cloud is not above the speakers, or above your head, but halfway between.

--Ethan

[Jax]

BTW, I don't think you can "over-cover" the ceiling, within reason. Even covering a foot or so wider than you need to won't hurt anything.

[Ethan Winer]

^^^ Agreed fully.

[Glenn Kuras]

Originally Posted by Jax

BTW, I don't think you can "over-cover" the ceiling, within reason. Even covering a foot or so wider than you need to won't hurt anything.

Yea I like to cover the whole area if possible. It gives you a wider area to not be out of the zone (kind of).

[ironmine]

Originally Posted by Ethan Winer

In that case the center point of the area is exactly halfway between your ears and the front of the speaker cabinet. --Ethan

Hello!

I am trying to improve the acoustics of my listening room. My speakers have three drivers and are quite tall (91 cm).

My ceiling clouds are kind of small - 1 m x 0,5 m, so I need to position them accurately. I have a question about how to position the cloud better. Does each cloud have to be centered (1) around the mirror reflection of the speaker's tweeter on the ceiling (as seen from my sweet spot), or (2) around the mirror reflection of the mid driver?

In other words - is it important for the ceiling cloud to cover the reflection of the tweeter mainly or it is equally important to cover the reflections of ALL drivers? Or, maybe, the LF driver is most important of all (because it is most omni-directional?)

I would appreciate any advice.

Regards,
Eugene K.

[nixoblivion]

well it depends on what frequencies your drivers reproduce. But i would say that the LF will be least important. Try to get both the Mid and the HF, for a good result!

[Dange]

Originally Posted by ironmine

My ceiling clouds are kind of small - 1 m x 0,5 m, so I need to position them accurately. I have a question about how to position the cloud better. Does each cloud have to be centered (1) around the mirror reflection of the speaker's tweeter on the ceiling (as seen from my sweet spot), or (2) around the mirror reflection of the mid driver?

You can do this accurately using ETC (Energy Time Curve) measurments. This will show you if you're hitting the reflection points

The LF driver will most probably be emitting frequencies below the Schroeder Frequency for you room, i.e. the sound waves from it will be behaving mode like, rather than relfection/ray like. Therefore it's probably the least important driver to consider, try picking a mid point between your mids and tweeters.

[Ethan Winer]

Originally Posted by Dange

You can do this accurately using ETC (Energy Time Curve) measurments. This will show you if you're hitting the reflection points

Great answer. Eugene should also make the cloud area larger if possible.

--Ethan

________________
The Acoustic Treatment Experts

[macc]

One tip from recent experience;

I had a reflection at 2.54ms (as seen in ETC) that was driving me NUTS. I spent almost a week's worth of man-hours hunting it down, thought I had it but I didn't, thought it was coming from the upper left/upper right ceiling corners, maybe the floor, etc etc etc. It drove me absolutely NUTS.

After giving up, while working on a different reflection, I nudged my cloud (2x 6" 703, suspended on two cables) forward a bit for cosmetic effect. That didn't so much move the cloud as angle it differently, due to the 'sag' in the cable. That bastard reflection completely disappeared. It had been coming from the cloud itself!

Angling the cloud to a slightly more normal incidence, from the speaker's POV, meant either/both that the reflection was absorbed better, or that it was reflected to a point in front of the listening position.

The moral of the story (for me anyway) is that either too much rockwool or too wide an incident angle can lead to the reflection 'skimming' off the surface, rather than being absorbed. Don't assume that because there is rockwool there, it will absorb. Dense rockwool at a wide angle will just deflect/reflect the sound. Others have found this too. So: Angle your cloud accordingly.

IMO, IME, FWIW, YMMV and all that

[SAC]

Many folks forget that "absorbers" also have a reflective component, increasing with angle of incidence and increasing frequency (and also effected by the facing material choice!)

After installing, it is always wise to measure in order to verify that the result is as desired without any 'interesting' artifacts that may require a bit of touch up!

Well done!!!!!!

[macc]

The obvious analogy is skipping stones on a lake. Throw them directly at the water and they disappear without trace. Throw them low, with a shallow angle, and they bounce right off the surface

[AnthonyRochester]

or if you look directly down onto water you see the bottom but if you look across it you see the reflection of the sky.

also mirages in the desert..

[nixoblivion]

Originally Posted by macc

That bastard reflection completely disappeared. It had been coming from the cloud itself!

Angling the cloud to a slightly more normal incidence, from the speaker's POV, meant either/both that the reflection was absorbed better, or that it was reflected to a point in front of the listening position.

T

And you are sure its not the material, that covers the absorbers??
In what way would the angle make the most sense?
Im thinking maybe pointing the absorbers, sothat they would reflect sideways would be the best, but i often see it reflecting infront (back to the speakers)

[ironmine]

Originally Posted by macc

I had a reflection at 2.54ms (as seen in ETC) that was driving me NUTS.

Could you please tell me which software programs can measure ETC? Can Room EQ Wizard do it?

Thanks

[AnthonyRochester]

I am new to the whole acoustic area and I did a kind of ETC thing just to look at how my absorption panels affect the first reflections just by using ProTools. Played a short dry clap sample and recorded it with a mic at my mix position. Also recorded it through electronic loopback, to compensate for latency in my converters, using that one as my time reference. I was able to see a clear reflection point on the waveform, and by measuring the time delay and working out the distance travelled by the sound, I worked out that it is definitely from my ceiling, so I'm going to make a little cloud there..

[AnthonyRochester]

My point above is to say that you don't really need special ETC software if you just want to look at where your first reflections are.

[ironmine]

Originally Posted by beebay007

My point above is to say that you don't really need special ETC software if you just want to look at where your first reflections are.

Hello Beebay!

So, basically, I just clap my hands and record this sound and then I analyze this recording in SoundForge?

[AnthonyRochester]

Originally Posted by ironmine

Hello Beebay!

So, basically, I just clap my hands and record this sound and then I analyze this recording in SoundForge?

Not quite. You need to play back a very short percussion sample and record it with a mic at your listening position, making sure you account for any delay through your converters when you are working out how much time delay there is..

[nixoblivion]

Well it would be better to play white or pink noise since hand claps dont have all frequencies. But i guess a hand clap would work for the main reflections!

I did quite a few ETC's yesterday and the ceiling was by far the worst of all reflections (after the table, which i wont be able to compensate for).
So i think ceiling is the most important thing in a room.

[AnthonyRochester]

yes, I found from my dodgy examination that the ceiling reflection is bigger than the sidewall ones..

[ironmine]

Originally Posted by beebay007

Not quite. You need to play back a very short percussion sample and record it with a mic at your listening position, making sure you account for any delay through your converters when you are working out how much time delay there is..

Thanks everyone for responses!

Is there any software program which can help me to check reflection arrival delays automatically?

[AnthonyRochester]

yes, use a calculator. All you need to know is speed = distance / time. Or distance = speed x time. And the speed of sound is 343 m/s. You should be able to measure the time between the initial signal and a reflection that you see in your DAW.