Building my home-studio

[nifaun]

I'd like to build my own studio and my mic, interface and monitors are bought. Now I have to think about the acoustics and im doubting what is the best way to do it. I saw video's about a vocal booth with sound blankets, but im afraid the sound will be too dry.. And also it not the total solution because the monitors have to stand outside the booth where the song will be listened back. I think about leaving the idea of the vocal booth and put my materials just on the wall, which might be more expensive.

Can anyone advice me on this?

[Mike Stranks]

Welcome!

What are the dimensions of your room? Where are the windows and doors..? A plan would be useful... Use Imgur to host images as the SoS Forum can't host them directly...

As you've surmised, building a vocal booth rarely gives you the sound you want... they often sound like you've built yourself a cupboard in which to record...

Acoustic treatment need not be too expensive - especially if you can DIY. But it is important and will ensure that you get the best from your room and, particularly, your monitors...

[Hugh Robjohns]

I saw video's about a vocal booth with sound blankets, but im afraid the sound will be too dry.

Dry is a good thing for vocal recording... but a common problem with home-made booths is that they sound boxy as well as dry because the construction absorbs all the mid and HF reflections, but leaves the low end uncontrolled.

So I'm not a fan of home-made 'booths' at all, and I find it's easier to get much better results with some simple DIY treatment -- temporary and removable if necessary -- in the main room... which also benefits loudspeaker monitoring when mixing, of course!

There are lots of suggestions and idea in the series of Studio SOS articles that should set you on the right direction.

[RichardT]

I agree with Hugh and Mike. It’s best to treat the room as a whole. You need some broadband traps! There’s a video from Sam Inglis on the SOS website that will show you a quick method of building some.

Embedded link - HR

[nifaun]

I have seen the Sam Inglis video, interesting. I was just wondering how to attach those acoustic panels to the wall?

This technique is definitely not a solution for bass traps because it leaves an air gap between the panel and the wall. How did you guys manage that...

[James Perrett]

This technique is definitely not a solution for bass traps because it leaves an air gap between the panel and the wall. How did you guys manage that...

I don't think that there's anything wrong with a gap as the extra distance improves the effectiveness of the panel at lower frequencies.

[RichardT]

I have seen the Sam Inglis video, interesting. I was just wondering how to attach those acoustic panels to the wall?

This technique is definitely not a solution for bass traps because it leaves an air gap between the panel and the wall. How did you guys manage that...

A gap between the trap and the wall is a good thing. It will make the trap much more effective than having it next to the wall. Leave a gap of at least 4 inches if you can. Although the sound pressure is highest at the wall, the velocity of the air molecules is zero, and it’s the velocity of the molecules that is important for transferring energy to the material of the trap.

[nifaun]

Thanks all, And also thanks Jerret,

What do you guys recommend me to do?

1. What density do the panels at least need to be
2. How thick do the absorbers and bass trap need to be
3. How do I attach them to the wall?

Kind regards,
Nifaun

[Drew Stephenson]

1. What density do the panels at least need to be
2. How thick do the absorbers and bass trap need to be
3. How do I attach them to the wall?

1) 60kg/m3 is generally the best compromise for absorption and ease or working with.

2) The thicker the better is the basic principle. A thicker absorber or trap will be effective to lower frequencies. If you think of sound as a pressure wave, at the boundary (i.e. the wall) you'll have the maximum sound pressure, but you also have the minimum air movement (because it can't push the wall around). As you move away from the wall the pressure decreases but the air movement increases. It's damping this air movement that absorbs the energy and, hence, the sound.
If you change your mental model for a moment and imagine your soundwave as a vibrating string, with opposing walls being the fixed points at the end of the string, then the point of most movement is clearly 1/4 of a wavelength.
So this means that for an absorber to have its greatest effect at a given frequency it needs to be at least 1/4 of a wavelength thick.
Unfortunately the wavelength of sound at 20Hz is about 17m, so unless you've got a room big enough to have bass traps over 4m deep then you're starting from a compromised position.
So basically the thicker the better and the deeper the better but in practice, if you can get your bass traps in corners you can get some depth without sacrificing too much room and you're also targeting the area of highest bass pressure. If you can make your broadband absorbers 4" thick they will be pretty effective across a good range of frequencies, especially if you can also space them off the wall. Which brings us to...

3) Absorbers work better if they're spaced off the wall a bit, generally it's recommended to have them their own depth off the wall. So a 2" absorber will be much more effective if it's 2" off the wall rather than butting right up to it. If you go back to your mental model above you can see how spacing the absorber off the wall gives you a greater virtual depth and therefore more efficacy at lower frequencies.
So bolting a couple of 2" beams onto the wall and then hanging your panels off that will be effective, and if you've got space for 4" panels then spacing them another couple of inches off the wall will also improve things.

[nifaun]

1. What density do the panels at least need to be
2. How thick do the absorbers and bass trap need to be
3. How do I attach them to the wall?

1) 60kg/m3 is generally the best compromise for absorption and ease or working with.

2) The thicker the better is the basic principle. A thicker absorber or trap will be effective to lower frequencies. If you think of sound as a pressure wave, at the boundary (i.e. the wall) you'll have the maximum sound pressure, but you also have the minimum air movement (because it can't push the wall around). As you move away from the wall the pressure decreases but the air movement increases. It's damping this air movement that absorbs the energy and, hence, the sound.
If you change your mental model for a moment and imagine your soundwave as a vibrating string, with opposing walls being the fixed points at the end of the string, then the point of most movement is clearly 1/4 of a wavelength.
So this means that for an absorber to have its greatest effect at a given frequency it needs to be at least 1/4 of a wavelength thick.
Unfortunately the wavelength of sound at 20Hz is about 17m, so unless you've got a room big enough to have bass traps over 4m deep then you're starting from a compromised position.
So basically the thicker the better and the deeper the better but in practice, if you can get your bass traps in corners you can get some depth without sacrificing too much room and you're also targeting the area of highest bass pressure. If you can make your broadband absorbers 4" thick they will be pretty effective across a good range of frequencies, especially if you can also space them off the wall. Which brings us to...

3) Absorbers work better if they're spaced off the wall a bit, generally it's recommended to have them their own depth off the wall. So a 2" absorber will be much more effective if it's 2" off the wall rather than butting right up to it. If you go back to your mental model above you can see how spacing the absorber off the wall gives you a greater virtual depth and therefore more efficacy at lower frequencies.
So bolting a couple of 2" beams onto the wall and then hanging your panels off that will be effective, and if you've got space for 4" panels then spacing them another couple of inches off the wall will also improve things.

Thanks Blinddrew, Thats completly clear... But I have one other question. Can I just leave a huge gap open between the wall and the bass trap, as it would be financial impossible to fill this huge space up?

[RichardT]

If you mean ‘will a bass trap work a long way from a wall?’ then the answer, in my experience, is yes - maybe not quite so well, but it will still work. If the trap is closer to the speakers because of this, then that will enhance its effect too.

[Drew Stephenson]

Yes-ish.
It's better if the gap is filled (doesn't have to be with the same heavy duty RockWool as the front of the trap, but it will still work if you have, for example, a flat panel across a corner with a gap behind it.

I can't remember reading this explicitly in the text books I've read, but if you have a flat panel too far from a parallel wall then I expect it will act as a nodal point for any dominant room modes.
To take a theoretical example: say you have a flat panel 50cm from one wall, that will be at the nodal point for a wavelength of 1m (347Hz). So it's going to do next to nothing for that frequency. If your room was, say, 4m wide, it would also be a dominant room mode so could lead to problems.
This is why it's generally recommended to space your panels off the wall by a distance equal to their own thickness. In this case the thickness of the panel is large compared to the wavelength of the space behind it, so it will still have a significant effect. In the example above we can see that a 5cm deep panel, 50cm from the wall is really pretty small compared to the wavelength of the standing wave that can arise either side of it, so therefore won't have much affect.

Putting a flat panel across a corner obviously gives you a variable distance between the wall and the panel so mitigates this effect.

[nifaun]

Yes-ish.
It's better if the gap is filled (doesn't have to be with the same heavy duty RockWool as the front of the trap, but it will still work if you have, for example, a flat panel across a corner with a gap behind it.

I can't remember reading this explicitly in the text books I've read, but if you have a flat panel too far from a parallel wall then I expect it will act as a nodal point for any dominant room modes.
To take a theoretical example: say you have a flat panel 50cm from one wall, that will be at the nodal point for a wavelength of 1m (347Hz). So it's going to do next to nothing for that frequency. If your room was, say, 4m wide, it would also be a dominant room mode so could lead to problems.
This is why it's generally recommended to space your panels off the wall by a distance equal to their own thickness. In this case the thickness of the panel is large compared to the wavelength of the space behind it, so it will still have a significant effect. In the example above we can see that a 5cm deep panel, 50cm from the wall is really pretty small compared to the wavelength of the standing wave that can arise either side of it, so therefore won't have much affect.

Putting a flat panel across a corner obviously gives you a variable distance between the wall and the panel so mitigates this effect.

Thanks Blinddrew,

I asked several isolationshops about the right rockwool plates for my studio. Most of them said they had only rockwool plates to a density of 55. When I searched online I found Rockfound Duo what has a density of 60 on the front and a density of 35 in the rear... Im kinda doubt wheter this is the panel I need, can you provide me more clarity about this? If not, can you tell me which panel is best for my studio?

[Sam Spoons]

Another advantage of a corner placement is that the reflected wave travels around the corner, reflected twice before emerging so the effective depth of the trap is greater than the actual physical depth.

[Drew Stephenson]

I asked several isolationshops about the right rockwool plates for my studio. Most of them said they had only rockwool plates to a density of 55. When I searched online I found Rockfound Duo what has a density of 60 on the front and a density of 35 in the rear... Im kinda doubt wheter this is the panel I need, can you provide me more clarity about this? If not, can you tell me which panel is best for my studio?

I suspect the difference between 60 and 55 density is negligible from both a audio and workability perspective, but if you let us know whereabouts in the world you are we can probably make some sensible recommendations.

[nifaun]

Yes-ish.
It's better if the gap is filled (doesn't have to be with the same heavy duty RockWool as the front of the trap, but it will still work if you have, for example, a flat panel across a corner with a gap behind it.

I can't remember reading this explicitly in the text books I've read, but if you have a flat panel too far from a parallel wall then I expect it will act as a nodal point for any dominant room modes.
To take a theoretical example: say you have a flat panel 50cm from one wall, that will be at the nodal point for a wavelength of 1m (347Hz). So it's going to do next to nothing for that frequency. If your room was, say, 4m wide, it would also be a dominant room mode so could lead to problems.
This is why it's generally recommended to space your panels off the wall by a distance equal to their own thickness. In this case the thickness of the panel is large compared to the wavelength of the space behind it, so it will still have a significant effect. In the example above we can see that a 5cm deep panel, 50cm from the wall is really pretty small compared to the wavelength of the standing wave that can arise either side of it, so therefore won't have much affect.

Putting a flat panel across a corner obviously gives you a variable distance between the wall and the panel so mitigates this effect.

Thanks Blinddrew,

I asked several isolationshops about the right rockwool plates for my studio. Most of them said they had only rockwool plates to a density of 55. When I searched online I found Rockfound Duo what has a density of 60 on the front and a density of 35 in the rear... Im kinda doubt wheter this is the panel I need, can you provide me more clarity about this? If not, can you tell me which panel is best for my studio?

1. I havent understood it yet... Does the distance between the panel have to be equal to the thickness of the panel?

I asked several isolationshops about the right rockwool plates for my studio. Most of them said they had only rockwool plates to a density of 55. When I searched online I found Rockfound Duo what has a density of 60 on the front and a density of 35 in the rear... Im kinda doubt wheter this is the panel I need, can you provide me more clarity about this? If not, can you tell me which panel is best for my studio?

I suspect the difference between 60 and 55 density is negligible from both a audio and workability perspective, but if you let us know whereabouts in the world you are we can probably make some sensible recommendations.

2. Okay so what about the tho measurements. Should I focus on the front one... Or does the back one matters as well.

Im based in the Netherlands, ordering from German stores is possible as well.

[Drew Stephenson]

Sorry, meant to reply earlier but forgot.

I'll see if I can draw a diagram for 1) - leave that with me. But in short, yes, the distance from the wall should be roughly the same as the thickness.

A rockwool plate of density 55 will be fine. If you went with a dual density I would guess, and it would be a guess, that you'd be better with the low density side facing the room. This would make it easier for the sound to penetrate the slab and therefore be absorbed.
If you use too high a density (100kg/m3 for example) it will still function to an extent but will actually reflect higher frequencies rather than absorb them.
Knauf Earthwool is a comparable product to Rockwool.
I have no idea if this is a good supplier, but they have 60kg/m3 rockwool and earthwool: https://www.ikoustic.co.uk/products/aco ... g8QAvD_BwE

[Drew Stephenson]

Ok, here's an attempt to answer your question 1) with some badly drawn diagrams (I couldn't easily find a sinewave so you've got ovals instead)...

Let's look at sound interacting with a wall:

The highest sound pressure is right up against the wall (because the air can't go anywhere) but the most air movement is 1/4 wavelength away from the wall.

This can be easier to visualise if you think of it like a guitar string:

N.B. we're obviously only looking at half a wavelength at this point, the rest of the wavelength continues off the screen to the right.

Right, now let's add an absorber against the wall and bring the wavelength down a bit for illustration:

As we can see, with the absorber right against the wall, it's most effective on its outside edge, where the air movement is greatest, but against the wall, where there's no air movement, it's doing almost nothing.

Let's move the absorber away from the wall a distance of its own thickness:

Now we can see that all the absorber material is in an effective zone for this wavelength.

Now, to get to your question of distance from the wall vs thickness of absorber.
Let's take the same situation and look at a higher frequency:

Even where half a wavelength matches the distance behind the absorber, we can see that it's still going to be effective because the peak air movement is still easily covered by the absorber at the next anti-node.

Ok, now take the same absorber but bring it further away from the wall:

You can see now that at longer wavelengths, where the node coincides with the position of the absorber, it will be doing very little at all.

And if we go back to the shorter wavelength:

You can see that the absorber here will be less effective because it again sits at a node.

I'm sure Hugh or Max could have explained that better (and they may still be along to correct me!) but hopefully that makes sense?

[Wonks]

Looks OK to me.

It should be noted that this really applies to standing waves/resonant wavelengths which are fractions of the rooms dimensions. Other soundwaves will hit the absorbers at all different amplitude along their wavelengths and will be attenuated to greater or lesser extents. They certainly won't all hit the wall at node points.

But it is the standing waves that cause the most problems, which is what we (hopefully) design and position the traps to reduce.

[Hugh Robjohns]

All well explained Drew, although in respect of the last two diagrams:

Ok, now take the same absorber but bring it further away from the wall:

You can see now that at longer wavelengths, where the node coincides with the position of the absorber, it will be doing very little at all.

At very low frequencies the wavelength is so long that to emulate your diagram the absorber would have to be placed several feet from the wall, which is obviously impractical, so it's never going to find itself sat in a node half a wavelength out in reality. Instead, at very low frequencies the absorber will tend towards being in the node pressure zone against the wall. Either way it loses efficiency, of course.

And if we go back to the shorter wavelength:

You can see that the absorber here will be less effective because it again sits at a node.

Except that in this situation a practical absorber will be thick enough probably to span several full (short) wavelengths, so it will actually be very efficient.