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Room Treatment Plan - The Retirement Gift Update

Danaxus

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Hi all!

About a year ago, my parents decided to build a new home. As a retirement gift for my father, I decided I would design a dedicated music room for him. And thus I gingerly dipped my foot into the rabbit hole of acoustics and promptly fell into the infinite void.

A year later, the house is almost complete, the music room is constructed. I present you with (drum roll please):
Music Room Construction 1.jpg
Music Room Construction 2.jpg


So yeah, it's a work in progress. Don't worry about the drywall on the ceiling - that was a mistake by the constructor and it will get torn down.
I have however, come up with a finalised treatment plan, which I present below:
Treatment Plan Top-Down.jpg
Treatment Plan Side View.jpg


All of this is subject to the listening position and speaker position ending up more-or-less where I expect them to. I'll go in to the untreated room once it's finished, set up a speaker, and try to find the optimal listening position. If that turns out to be somewhere very different than the diagrams above, I'll come up with a new plan of attack. I decided to follow @kemmler3D 's advice, and soundproof as much as is reasonable (That's the -7cm numbers you see - 7cm of soundproofing will be put on certain walls).

The end result should look like:

Music Room E1.jpg
Music Room E6.jpg

Music Room E5.jpg
Music Room E8.jpg


Some notes: Ignore the quadratic diffusers - the design/rendering software I used doesn't have binary diffusers, which is what I'll be using. Also ignore the side-boards of the diffusers - the frame there should be open to allow absorption from a side angle, with just fabric covering it. The front, back, and side walls all have 20cm of porous absorption (rock or mineral wool with 6000-10000 Flow resistivity (Pa.s/m2)), with a 20cm air gap behind. The entire walls will be covered in fabric, leading to something that I hope will look almost as good as the renders. The front door, the wall opposite it, the window, and the wall opposite that, will be the only parts of the room that remain untreated. Even though the rear wall is entirely treated, there's room left in the back there to add some membrane traps (probably purchased from GIK), if they're necessary once final measurements are done. Finally, I've tentatively placed the subwoofer dead-centre between the two speakers, and at equal distance to the listening position. From what I've heard, you don't tell the subwoofer where it goes - it tells you where it goes. I'll try to keep it somewhere near the front wall, maintaining if possible, the same distance as the speakers, but at the end of the day, I'll put it where it wants to go (I pray it's happy there though, as I have 40cm of treatment directly behind it, begging to be used).


So now is the time where I humbly petition you all: please spare me some time, share your expertise with me (free of charge :p), and let me know what's wrong, what could be improved, alternative treatment strategies, etc. The point of no return is fast approaching. In a couple of weeks the doors and floor will be installed, at which point I will start the first set of untreated room measurements. Shortly after and with the constructor's help, I'll install the treatment right into the walls, at which point nothing can be changed without vast expense (i.e. my dad's stuck with it). I will of course, be sharing information, pictures, and measurements with you all, in the hopes that it is of value to someone.


Thank you all
 

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Curvature

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Cool.

No bass absorbers or plan for bass?

What kind of speakers and subwoofers will you be using?

What kind of BAD panel are you using for diffusion?

How did you plan for HVAC and environmental noise?

What plans do you have for the door design?
 

ppataki

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Some questions that came to my mind:

- why do you need all those diffusers around the listening position? Wouldn't absorbing the first reflection points be enough?

- what are you planning to use for the 7cm soundproofing?

- have you considered some absorbtion on the ceiling too?

- for bass absorption I would consider tuned membrane absorbers or very thick (60cm) treatment in the corners
 

muslhead

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Congrats on the retirement. Hope its all you planned for
 
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MRC01

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...
No bass absorbers or plan for bass?
...
I have the same question. IME, large (2') diameter tube traps are quite effective at reducing bass modes over a wide frequency range.
Once you take measurements you'll know what you need for bass control, likely a mix of broad and narrow band treatments.
 
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Danaxus

Danaxus

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Cool.

No bass absorbers or plan for bass?

What kind of speakers and subwoofers will you be using?

What kind of BAD panel are you using for diffusion?

How did you plan for HVAC and environmental noise?

What plans do you have for the door design?
Just the porous absorbers for the bass. They're 20cm deep with a 20cm air gap behind them - they should be effective down to 40Hz or so I'm hoping. My contingency is to load the back wall with membrane traps if I need more bass management.

Speakers are KEF LS60 Wireless. Subwoofer I'm torn between the SVS SB16 (sealed), or the SVS PB-4000 (ported). This is causing me no end of anxiety, let me tell you!

The diffusion is all binary diffusion - just a ton of slats arranged vertically according to the mathematical sequence I have...somewhere.

HVAC system is a ductless Lunos system. I have a 2-way duct in the room, near the window in the rear. It will be right where the ceiling goes up.

Door is...how to say this - it's heavy one full of chip wood? Not the regular hollow doors. It's not a professional studio door or anything, but it's heavy and solid.


Some questions that came to my mind:

- why do you need all those diffusers around the listening position? Wouldn't absorbing the first reflection points be enough?

- what are you planning to use for the 7cm soundproofing?

- have you considered some absorbtion on the ceiling too?

- for bass absorption I would consider tuned membrane absorbers or very thick (60cm) treatment in the corners
Not sure if I need the diffusers - I just heard they help expand the soundstage. From what I understand, they do no harm and potentially can help the room feel nicer to be in. I'm not an acoustics engineer, not even close - this is just the best of my understanding and could be completely wrong.

The soundproofing will consist of a 0.5cm rubber layer pressed into the wall, completely air-tight, followed by 2 layers of drywall (2.5cm thick total), followed by 5cm of heavy rockwool, followed by a final layer of drywall. May be more than 7cm now that I'm adding it all up...

Oh yeah, the ceiling is 100% absorption. 20cm air gap, 20cm porous absorption in the front of the room (the grey fabric-covered stuff). The rear of the room will have 10cm air-gap and 10cm absorption (this may be a bad idea - I'm worried it will deaden the room by absorbing too much high and and not enough low end).

I'm afraid 60cm isn't possible - I'd block the door in the front and window in the back. All I can do is leave some space for membrane traps.
 

kemmler3D

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This looks really exciting, but I'm a little concerned that there is too much absorption and you'll end up with a deficit in the treble. Just having 100% absorption on the ceiling, you've already gone pretty far down the road of absorbing highs, depending on what they're faced with. I would make sure to give yourself some wiggle room in terms of facing the absorbers so you don't end up with a boomy / muddy sound.
 

Curvature

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they should be effective down to 40Hz
They will not be.

The easiest way to modify your plan and include bass treatment without breaking the bank is to hang mass loaded vinyl in the airgap. Tuned membrane traps like you mentioned, will also work well.
SVS PB-4000
Much more powerful. Sealed vs. ported doesn't matter perceptually for good subs like these. Planning for multiple subs instead of one is a good strategy for handling bass as well.
Door is...how to say this - it's heavy one full of chip wood? Not the regular hollow doors. It's not a professional studio door or anything, but it's heavy and solid.
As long as steps have been taken to ensure a good seal around the edges when it's closed that's fine. Have you taken STC measurements, by the way?

The BAD panels are a good idea for the early reflections. I would also suggest using space couplers for the ceiling:
1692810343138.jpeg
 

kemmler3D

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From what I understand, they do no harm and potentially can help the room feel nicer to be in. I'm not an acoustics engineer, not even close - this is just the best of my understanding and could be completely wrong.
Diffusers theoretically scatter the sound evenly rather than reflecting it. This can break up flutter echoes and subjectively can have the effect of making the room bigger, but it can also potentially harm perception of the stereo image by breaking up first reflections. Whether you want a diffuse or specular (normal) first reflection is probably a matter of taste.

They also need a certain amount of distance to work. Designed properly, diffusers will evenly scatter all frequencies they're designed for in all directions. However, if you're too close, some frequencies will be scattered more than others, and you end up with a weirdly uneven frequency response. Rule of thumb is you need distance of 3x the longest wavelength to get even frequency response from a diffuser.
 

Curvature

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Diffusers theoretically scatter the sound evenly rather than reflecting it. This can break up flutter echoes and subjectively can have the effect of making the room bigger, but it can also potentially harm perception of the stereo image by breaking up first reflections. Whether you want a diffuse or specular (normal) first reflection is probably a matter of taste
BAD panels look like this:

1692811162494.png

RPG originated the design: https://www.rpgacoustic.com/product/bad-panel/

They are more like an absorptive wall than a regular diffuser.
 
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Danaxus

Danaxus

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I'm guessing BAD meanings Binary Amplitude diffusers. If I understood correctly, these come in two flavours - the ones with the holes as in the picture above, which scatter both horizontally and vertically, and the ones with the vertical lines (really easy to DIY), which scatter only horizontally. Since my ceiling in just a deep void and because horizontal diffusion is really easy to do, I opted for that.

GIK-Acoustics-Alpha-Series-scattering-options-with-corner-screws-510_600-510x600.jpg
 

ppataki

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Just the porous absorbers for the bass. They're 20cm deep with a 20cm air gap behind them - they should be effective down to 40Hz or so I'm hoping. My contingency is to load the back wall with membrane traps if I need more bass management.

Speakers are KEF LS60 Wireless. Subwoofer I'm torn between the SVS SB16 (sealed), or the SVS PB-4000 (ported). This is causing me no end of anxiety, let me tell you!

The diffusion is all binary diffusion - just a ton of slats arranged vertically according to the mathematical sequence I have...somewhere.

HVAC system is a ductless Lunos system. I have a 2-way duct in the room, near the window in the rear. It will be right where the ceiling goes up.

Door is...how to say this - it's heavy one full of chip wood? Not the regular hollow doors. It's not a professional studio door or anything, but it's heavy and solid.



Not sure if I need the diffusers - I just heard they help expand the soundstage. From what I understand, they do no harm and potentially can help the room feel nicer to be in. I'm not an acoustics engineer, not even close - this is just the best of my understanding and could be completely wrong.

The soundproofing will consist of a 0.5cm rubber layer pressed into the wall, completely air-tight, followed by 2 layers of drywall (2.5cm thick total), followed by 5cm of heavy rockwool, followed by a final layer of drywall. May be more than 7cm now that I'm adding it all up...

Oh yeah, the ceiling is 100% absorption. 20cm air gap, 20cm porous absorption in the front of the room (the grey fabric-covered stuff). The rear of the room will have 10cm air-gap and 10cm absorption (this may be a bad idea - I'm worried it will deaden the room by absorbing too much high and and not enough low end).

I'm afraid 60cm isn't possible - I'd block the door in the front and window in the back. All I can do is leave some space for membrane traps.

I know the room is going to be a present so I am not sure if the below is feasible but I would do the followings:

- determine the position for your speakers in the room using REW Room Sim
- once that is done, determine the first reflection points (on the side-walls, on the ceiling and on the back wall) - you can do that with a mirror once you have the speakers in place or you can use this calculator: https://www.acoustic.ua/forms/calculator4.en.html
- once your first reflection points are identified I would treat them with a 10cm absorber, only up to a half square meter each
- I would perform a REW measurement and check the waterfall and the T60M curves to see the decay time for each frequency
- Based on that I might increase the absorption area further (e.g. up to 1 m2 each) or not
- Also based on the measurement you will know exactly what bass frequencies you will need to target with properly tuned membrane absorbers - then you can fill your corners with those (ideally floor to ceiling)
- using multiple subs with MSO or Dirac Bass Control is also a great idea

Personally I am not a fan of diffusers for the same reasons mentioned by @kemmler3D
I would rather focus on absorption and only as much as needed otherwise your room will be acoustically dead (and believe me it is very easy to get there!)
 
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Danaxus

Danaxus

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I know the room is going to be a present so I am not sure if the below is feasible but I would do the followings:

- determine the position for your speakers in the room using REW Room Sim
- once that is done, determine the first reflection points (on the side-walls, on the ceiling and on the back wall) - you can do that with a mirror once you have the speakers in place or you can use this calculator: https://www.acoustic.ua/forms/calculator4.en.html
- once your first reflection points are identified I would treat them with a 10cm absorber, only up to a half square meter each
- I would perform a REW measurement and check the waterfall and the T60M curves to see the decay time for each frequency
- Based on that I might increase the absorption area further (e.g. up to 1 m2 each) or not
- Also based on the measurement you will know exactly what bass frequencies you will need to target with properly tuned membrane absorbers - then you can fill your corners with those (ideally floor to ceiling)
- using multiple subs with MSO or Dirac Bass Control is also a great idea

Personally I am not a fan of diffusers for the same reasons mentioned by @kemmler3D
I would rather focus on absorption and only as much as needed otherwise your room will be acoustically dead (and believe me it is very easy to get there!)
I played around with REW Sim - it looks likes my original plans work well - I couldn't actually do much better unless I placed the sub literally underneath the seat. Changing the crossover from 80Hz to 70Hz made everything much better generally - thankfully the KEF speakers should be able to handle that with ease. I see a few spikes and dips - the 50Hz one is most worrying, but if that rears its ugly head, I assume I can tame it with some membrane traps. The other issues show up at 100, 110, and 160 - I would have assumed the porous absorption would have dealt with those, so not sure why those are there.

1692877912617.png



I could buy some boards to cover the binary diffusers, and compare the diffused first reflections to the specular ones, then pick which one I prefer. I assume diffusion on the back wall is desirable regardless - Thanks for the advice! I'd like to understand the 10cm absorption recommendations however - is it desirable to absorb some of the high frequencies and let the lower ones bounce around? Is the idea that it will improve the soundstage whilst preventing the music sounding overly bright?

Thanks!
 

ppataki

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Thanks for the advice! I'd like to understand the 10cm absorption recommendations however - is it desirable to absorb some of the high frequencies and let the lower ones bounce around? Is the idea that it will improve the soundstage whilst preventing the music sounding overly bright?

When using 10cm of absorption material you would not only absorb the highs but actually going down to the low-mids (wideband absorption)
I am using Caruso Isobond btw.
Usually in an untreated room you will have a lot of reflections - you can see those in the Impulse Response of your measurement + you will see elevated decay times even for the mids and the highs on the waterfall and T60M graphs. By placing absorbers on the first reflection points you will decrease both the reflections and the decay time

For bass though you will need either at least 60cm of these absorbers (stuffed floor to ceiling in the corners) or tuned membrane absorbers or equivalent

Don't worry about the spikes in the bass region if you have room correction DSP those will be cut (Dirac, Trinnov, Audyssey XT32, etc)
 

ozzy9832001

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I played around with REW Sim - it looks likes my original plans work well - I couldn't actually do much better unless I placed the sub literally underneath the seat. Changing the crossover from 80Hz to 70Hz made everything much better generally - thankfully the KEF speakers should be able to handle that with ease. I see a few spikes and dips - the 50Hz one is most worrying, but if that rears its ugly head, I assume I can tame it with some membrane traps. The other issues show up at 100, 110, and 160 - I would have assumed the porous absorption would have dealt with those, so not sure why those are there.

View attachment 307619


I could buy some boards to cover the binary diffusers, and compare the diffused first reflections to the specular ones, then pick which one I prefer. I assume diffusion on the back wall is desirable regardless - Thanks for the advice! I'd like to understand the 10cm absorption recommendations however - is it desirable to absorb some of the high frequencies and let the lower ones bounce around? Is the idea that it will improve the soundstage whilst preventing the music sounding overly bright?

Thanks!
Until you have actual measurements, I'd be careful with what your treating and how. Room sim is a good planning tool, but it's also not very accurate because it doesn't account for any deviations in the room, e.g. windows, doors, closets, furniture, etc. You would want to absorb as much low end energy as possible. And in most spaces, its really, really hard to do. People end up over absorbing the high end because of it. That's why traps need to be either targeted or have limiters in place. Diffusion usually sounds weird on the side walls. I'd go with absorbers instead.

Getting a 250ms decay time on 60hz and lower is hard. Getting it at 1khz is much, much easier.
 
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Danaxus

Danaxus

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Until you have actual measurements, I'd be careful with what your treating and how. Room sim is a good planning tool, but it's also not very accurate because it doesn't account for any deviations in the room, e.g. windows, doors, closets, furniture, etc. You would want to absorb as much low end energy as possible. And in most spaces, its really, really hard to do. People end up over absorbing the high end because of it. That's why traps need to be either targeted or have limiters in place. Diffusion usually sounds weird on the side walls. I'd go with absorbers instead.

Getting a 250ms decay time on 60hz and lower is hard. Getting it at 1khz is much, much easier.
Thanks for the advice - I plan on doing this in several stages. I'll measure the empty room to find the best listening position (the place where I need to fight the low modes the least), then treat the front and back walls first. I'll listen again, measure, then do the ceiling. If I start to dislike the room, I'll back off.

I saw in one of the studio construction videos, that diffusion was strategically placed in locations that would scatter sound from the listening positioning, but not from the speakers. I could absorb all the first reflections, but leave diffusers everywhere else. I could even extend the diffusion to the planes above/below ear height (then maybe vertical scattering with a 2D BAD might be more useful than horizontal alone).

My understanding so far is that a dead room happens when there's uneven absorption - i.e too many thin absorbers that kill the high end, but barely touch the low end. This, unless I've really misunderstood things badly, would result in uneven reverb across the frequency range, with low frequencies not being absorbed at all, and highs being completed absorbed. This would make everything sound dull and muffled - like the tweeters have been smothered with a pillow. Ex:


My hope is that by using deep absorption, everything will be absorbed equally down to the low-ish bass, meaning at worst the room would sound boomy with bass-heavy audio, but not dead. To deal with that my plan was to aggressively tackle the low end with membrane traps and EQ, whilst trying to protect some of the highs with diffusion. Those are things I would add at the very end however. Measure, check where in the room the particular mode has high pressure buildup, buy membrane traps from GIK (I don't think I'm skilled enough to make those), treat the appropriate wall (only rear and side wall, then measure again.

Once I'm happy with the sound I'll paint the room, furnish it, and pray EQ/Dirac can deal with whatever is left and whatever damage the furniture causes.
 
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ObjectiveSubjectivist

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Nice I will be watching as Im going to "buil" my own room in the near future, and my rooms dimensions are very similar.
 
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