Decoupling a mixing room or treatment.

[JeromyReno]

My progress over the last few weeks

The back corners have a thick paper membrane over them to try and keep the mids and highs moving around and capture the lows. The front wings have perf board up high and down low for the same reason. I left it open where the direct reflections are.

[Soundman2020]

You seem to be starting new threads all over the place! It's really hard to keep track of what you are doing, where you came from, or where you are going like this. It is MUCH better to keep all of your posts about your room in one single thread. If you scatter them all over the place, neither you nor anyone else will be able to keep track of your build...


- Stuart -

[JeromyReno]

You seem to be starting new threads all over the place! It's really hard to keep track of what you are doing, where you came from, or where you are going like this. It is MUCH better to keep all of your posts about your room in one single thread. If you scatter them all over the place, neither you nor anyone else will be able to keep track of your build...


- Stuart -

Sorry Stuart, I’ll keep it all in this one. I thought maybe someone else had ask the same cloud questions, I hate bugging you directly cause you seem like you got a lot of people asking you a lot of questions.

[Soundman2020]

I hate bugging you directly cause you seem like you got a lot of people asking you a lot of questions.

True!


- Stuart -

[JeromyReno]

i'll respond in this thread instead of the other i shouldn't have started ha.

Why do you think you'd need broadband absorption on a cloud? Do your speakers have an unusually wide vertical dispersion angle?

i guess when i say broadband i really mean low lows. i know the upper mids and highs will be directional and I'm using the hard surfaces on the wings to circulate them around the room. but the low end is more omni directional so with the cloud i would be trying to get the lowest lows i could, and that's why i was thinking a lot of surface area and thick. the wings on my right and left are so close to me in this small room that i could not angle them to completely redirect the first reflections so i removed the reflective surface(peg board) from where the first reflections would be. i wanted the holes in the wings to absorb some of the sound instead of reflecting all of it. i figure i can always bring some back with slats.

Ummmm.... you seem to be confused about what an RFZ design is, and how to achieve it. A ceiling cloud is not something that you add to an existing and complete RFZ design because it might be a good place to have broadband absorption. Rather, a ceiling cloud is PART OF the RFZ design. In a rectangular room, if you don't have a cloud then you don't have an RFZ! Sound propagates in all three dimensions, not just two. It goes vertically, as well as horizontally. The cloud is part of the concept of an RFZ room. Either you splay the ceiling and treat it accordingly, or you have a cloud. Without one or the other, you don't have an RFZ room.

my width is not very wide so with the angles that the sound is leaving the monitors it will have to bounce a few times to get to the cloud area.
i had already planned on angling the front of it to keep the same flow as the wings i built on the sides to redirect the reflections back from the back wall. but the rest of the area behind the angle could capture the omni directional lows, and up down reflections from the omni sounds.

In your other-other-other thread, there's no signs of any membrane! There's perf panel, but no membrane. Are you confusing the two? Perf panel is not a membrane: it's a tuned treatment device. What frequency did you tune that for? And why did you chose that specific frequency? What problem where you expecting at that location in the room, and at that frequency?

i didn't take any pictures of the back wings, I'm not sure what the true meaning of membrane in this situation. i read in other threads that people where using butcher paper or plastics films to reflect highs and still let the lows pass threw. i used a very thick paper, probably just under a 1/16 inch thick, its like a card stock. it's called ram board. pretty ridged for it's thickness, no holes or anything, just flat(little bit of an arch from attaching it) and sealed all the way around the front where it's attached. i was afraid with the rear wings taking up so much of then rear foot print they might soak up all the highs and wanted this to keep them going around the room but catch some lows.

I'm also curious as to why you are posting the projected real acoustic impedance graphs for different types of treatment: What's the purpose of that? Not many people even know how to read a real impedance graph... and those that do would ask for the graph of the imaginary plot, along with the real plot... they go together!

in one of my other threads you had actually given me that picture of the graphs showing me that you could absorb low frequencies with enough roxul. i thought previously anything over 18 inches wasn't effective cause i read that on gear slutz. my understanding of impedance is that it's like the flow of water or electricity. it needs to have somewhere for the pressure to flow too, and as it absorbs the pressure wave the pressure keeps trying to take the path of least resistance so it pushes out to the sides while it's normalized, the pressure is also converted to movement in the fibers, and friction. much like a stream of tap water poring on a sponge, the bigger the sponge the less directional the water coming out the back of the sponge will be, and the time it takes to flow threw will increase. this just shows that it still has increasing resistance at 24 inches and it's not leveling off like it would if it had an infinite resistance at some point stopping the flow of pressure . that was what i thought at least i could and probably am wrong.

Now I'm curious! Where on earth did you manage to buy a chair that is ten inches shorter than the normal size for chairs? And ditto for the desk: Where did you manage to find a desk that is ten inches lower than a normal desk?

the tweeter is 43 inches from the floor so that's where my ears will be. it's the same height as my last desk and the chair i already have, i got the height by sitting in my regular mixing position and measuring how high my ears where. i have built many many desks and plan on building all the furniture from scratch. this height puts the woofer at exactly 38% of the room height. the rest of the placement of the monitors is based around them being at an equilateral triangle ending behind my head based on my listening position at 38% back from the front wall. i did have to increase the angle 5 degrees left and right to move the monitors away from the ¼ wave spacing.


my question on the cloud that i wanted to stop the up and down reflections was just how thick really, most clouds i see are 6~8 inches. but i figure if i need a lot of low end treatment in a small room then this would be a good place to put it since its not in direct line of the dispersion angle of the monitors so the omni lows will be what is hitting it the most.

[Soundman2020]

the tweeter is 43 inches from the floor so that's where my ears will be. it's the same height as my last desk and the chair i already have, i got the height by sitting in my regular mixing position and measuring how high my ears where. i have built many many desks and plan on building all the furniture from scratch. this height puts the woofer at exactly 38% of the room height.

The height of the tweeter is irrelevant. So is the height of the woofer. What matters is the height of the acoustic axis of the speaker. And the height of that should be 47.25" above the floor, which is the standard listening height for any studio, regardless of your own seating position. That's the height that you want your speakers set for. 43" at the tweeter is way too low. You will need to fix that. This is important! If your speaker is set too low, your woofer will be blocked by the desk. You won't have "line of sight" from your ears to the speaker. It has to be fixed. Move your speakers up to the correct height.

the rest of the placement of the monitors is based around them being at an equilateral triangle

The need for an equilateral triangle is a myth. It's nice if you can get it, but not necessary, and not possible in many, many home studios, simply due to the dimensions of the room.

my question on the cloud that i wanted to stop the up and down reflections was just how thick really, most clouds i see are 6~8 inches. but i figure if i need a lot of low end treatment in a small room then this would be a good place to put it since its not in direct line of the dispersion angle of the monitors so the omni lows will be what is hitting it the most.

You are still missing the point: That's not what clouds are meant for. Unless you have very unusual speakers with a very tight Q, then the ceiling above you WILL be getting some very hefty levels of mid-range from the speaker, still very much with "ray-like" behavior. Constitutionality only starts way down lower than that.

I'm getting the feeling that you did not ray-trace anything for your room design, and certainly not in the vertical direction! Red flags.... This is not looking good right now...

i know the upper mids and highs will be directional and I'm using the hard surfaces on the wings to circulate them around the room.

But I don't see any "hard surfaces on the wings" at speaker height! You have GAPS in your hard surfaces at the height of the speakers so how will that work? Red flags.... Your arrangement of hard and soft surfaces is totally backwards from what it should be. You CANNOT create an RFZ (Reflection Free Zone) with absorption! Have you looked closely at the theory of how an RFZ room works? How did you arrive at the angle for those wings? What angle are they at?

but the low end is more omni directional so with the cloud i would be trying to get the lowest lows i could,

The cloud will see plenty of mids. Do the math. Do the ray tracing. Do the geometric layout, in 3D.

and that's why i was thinking a lot of surface area and thick.

You are not reasoning correctly. That's not the purpose of a cloud in an RFZ room. It can serve several purposes, including general broad-band absorption, but that is NOT it's primary purpose.

the wings on my right and left are so close to me in this small room that i could not angle them to completely redirect the first reflections

That makes no sense at all! In a small room, it is generally pretty easy to angle the soffits and wings to do exactly that... And since you say that you did not angle them correctly, then you do not have an RFZ room. I'm not sure what principle it will be designed on, but it certainly isn't RFZ.

More red flags...

so i removed the reflective surface(peg board) from where the first reflections would be.

And thereby destroyed the concept of RFZ. It is physically impossible to to create an RFZ using absorption. Do the math, and you'll see why.

There are so many red flags, here, it's starting to look like a political rally in Russia....

i wanted the holes in the wings to absorb some of the sound instead of reflecting all of it.

Do some research on the acoustic properties of perforated panel, to understand why that wont' work, and to get an idea of what you REALLY accomplished with that.

Red flags...

i figure i can always bring some back with slats.

Do some research on slot resonators and the Helmholtz principle to find out why that won't work the way you are hoping it will.

Red flags....

my width is not very wide so with the angles that the sound is leaving the monitors it will have to bounce a few times to get to the cloud area

Ummm... not it wont. Your cloud will receive direct sound from the speakers, with zero bounces. Just plain old straight line sound, straight out of the speakers, arriving directly at your cloud. High energy, mostly mid range....

Red flags...

i had already planned on angling the front of it to keep the same flow as the wings i built on the sides to redirect the reflections back from the back wall. but the rest of the area behind the angle could capture the omni directional lows, and up down reflections from the omni sounds.

I'm not sure I even understood what you said there, but if I did then that's certainly not how a cloud works, or what it is for.

Red flags....

I'm not sure what the true meaning of membrane in this situation.

A membrane is any reasonably massive surface stretched over a sealed frame, and it is tuned by the equation d = 28900 / (M * f^2), where:
d = depth of airspace in inches
M = surface density of panel, in lb / ft^2
f = peak absorbing frequency

You have built a tuned trap there.

i read in other threads that people where using butcher paper or plastics films to reflect highs and still let the lows pass threw.

Those are foils, not membranes. Different acoustic properties. Foils are partly reflective, partly transparent, and based on an an entirely different equation: F = 90 / m, where F = frequency where the foil is 80% transparent (in other words, the mid point of the log curve), and m = Surface Mass of the foil in kg/sqm. The curve rises to about 99% reflection above that, at about 6 dB/octave, and falls off to practically 0% transparency below that, at the same rate.

Membranes are not foils. Foils are not membranes. Different principles of operation, different equations.

Red flags....

i used a very thick paper, probably just under a 1/16 inch thick, its like a card stock. it's called ram board. pretty ridged for it's thickness, no holes or anything

Why so thick? Why do you want to reflect back lows as well as highs? What's the center frequency here? Why did you chose that frequency?

and sealed all the way around the front where it's attached.

It's a membrane trap then. It is tuned to a specific frequency, and since you didn't do the math, you actually have no idea what that frequency is, or even if you need any tuned absorption at that frequency. You might very well be absorbing a frequency that does NOT need it, while ignoring others that DO need it!

Red flags....

i was afraid with the rear wings taking up so much of then rear foot print they might soak up all the highs and wanted this to keep them going around the room but catch some lows.

That might have been your intention, but since you are just guessing, not calculating anything, not researching, that's not what is going to happen. Instead, of building high-frequency reflectors, you built low frequency tuned membrane traps, that are tuned to a random and unknown frequency, or range of frequencies....

Red flags....

my understanding of impedance is that it's like the flow of water or electricity. it needs to have somewhere for the pressure to flow too, and as it absorbs the pressure wave the pressure keeps trying to take the path of least resistance so it pushes out to the sides while it's normalized, the pressure is also converted to movement in the fibers, and friction. much like a stream of tap water poring on a sponge, the bigger the sponge the less directional the water coming out the back of the sponge will be, and the time it takes to flow threw will increase. this just shows that it still has increasing resistance at 24 inches and it's not leveling off like it would if it had an infinite resistance at some point stopping the flow of pressure . that was what i thought at least i could and probably am wrong.

You sort of vaguely described how porous absorption works, but not what impedance is, except that absorption works on the velocity component of a sound wave, not the pressure component. Membrane traps work on the pressure component. Helmholtz resonators (such as perf panel and slot walls) work on the pressure component. But porous absorption does not.

Acoustic impedance is the ratio of acoustic pressure p to acoustic volume flow, and assumes oscillating pressure, not static pressure. It is therefore always related to frequency, not simple air flow. The acoustic impedance of any porous material for a specific frequency basically tells you how much sound pressure would be caused by a given acoustic flow at that frequency. In fact, acoustic impedance can be broken down into two separate components, which are called "acoustic resistance" and "acoustic reactance". Also know as the "real" and "imaginary" acoustic impedance. It is not "imaginary" in the sense that it doesn't exist: it is "imaginary" in the sense that it is calculated using math that involves imaginary numbers, or "complex" numbers. "Imaginary" acoustic impedance is still very real, and very important. You can think of it sort of like an electrical capacitor in an electronic circuit: The net power flow is zero, but there is still current flow. The net power flow with imaginary acoustic impedance is also zero, but there is still air moving and pressure changing. Still a rather important function going on.

in one of my other threads you had actually given me that picture of the graphs showing me that you could absorb low frequencies with enough roxul.

Yes you can, and yes I did show the graphs, but showing just the real impedance without also showing the coefficient of abortion and/or the imaginary impedance, is only telling part of the story, and not even the most important part.

my question on the cloud that i wanted to stop the up and down reflections was just how thick really, most clouds i see are 6~8 inches. but i figure if i need a lot of low end treatment in a small room then this would be a good place to put it since its not in direct line of the dispersion angle of the monitors so the omni lows will be what is hitting it the most.

In your posts, I see a lot of "I figure" and "I thought", and "I saw", and suchlike, indicating that you don't really know for sure at all, and are just guessing. That's a really bad way to design a studio. "guessing" is not going to work. There's probably hundreds or wrong guesses for every single aspect of studio design, and only one right guess. Your changes of hitting the right guess are very, very poor. So your chances of having a studio that works, just by guessing at everything, are about zero. Nothing. Nada. Zip.

I would really, strongly, encourage you to stop guessing, stop building, go back, take it all apart again, fix all the problems that you have created for yourself, learn how to design it right, then design it right, post your design here for comment, and only once you have a workable design in hand then start building again.


- Stuart -