A couple of questions for building my first bass trap

[Lockerz]

Hey, new to this forum however found some great useful tips on here already!

I am building 2 floor to ceiling bass traps in 2 corners of my room (as well as other acoustic slabs - GIK 244 Bass slabs, 4 to cover L & R Reflection points & 1 for ceiling mix cloud), They are going to be roughly 7 & a half feet tall and have a surface face of 2.25ft (triangle shape), I am going to be purchasing knauf insulation rs45 to fill them with (been told that is good stuff?)

My room is 9ft width, 12.9ft length, 7 ft 10 height

My 2 questions are..

1. I can buy it in either 50mm, 75mm or 100mm thickness, does the thickness make a difference to the acoustic properties or is it just preference and price etc.?

2. Am i supposed to fill the triangle shaped bass traps, i know that the insulation comes in slabs, so i am going to need to do a bit of cutting to fill them, however i wasn't sure if the idea is to absolutely fill the triangle shaped traps (more insulation the better?) or whether or not i am just supposed to build them then put 1 slab in and leave the rest air? - Would like to mention on this on either outcome there will be a separate air gap between the trap and the wall to improve the acoustic property of it

Thank you if you can help me out that would be great!!

[Soundman2020]

Hi "Lockerz", and Welcome!

1. I can buy it in either 50mm, 75mm or 100mm thickness, does the thickness make a difference to the acoustic properties or is it just preference and price etc.?

Since you will be cutting those up into triangles and stacking them, it doesn't make much difference. However, if you were going to use them as full panels across the corners, or in other locations, then it would make a difference, and you'd probably want the thickest one then.

2. Am i supposed to fill the triangle shaped bass traps, i know that the insulation comes in slabs, so i am going to need to do a bit of cutting to fill them, however i wasn't sure if the idea is to absolutely fill the triangle shaped traps (more insulation the better?)

Yup! Full triangles, floor to ceiling, will give you the best results.

Would like to mention on this on either outcome there will be a separate air gap between the trap and the wall to improve the acoustic property of it

I'm not sure what you are trying to say there: You cut the triangles so the fit directly into the corner of the room, and stack them floor to ceiling. So each triangle butts up directly against the two walls of the room: How can there be more air space behind that?

- Stuart -

[Lockerz]

Thanks for the reply Stuart

What i mean on the last question is i wast thinking about building the traps as free standing, so they have a complete separate frame from the wall, then ensuring that they are placed a few inches in front of the wall, or i was also thinking of building a frame - within a frame kind of thing, for example building my frame against the wall but also ensuring that there is a 2'' gap between my insulation and the wall, i figured this could give me better results

I just have one more question if you don't mind, you know i mentioned i am going for the knauf insulation rs45, i have since read that the 'pink fluffy loft insulation stuff' can also work, given the size of my traps (7 and a half ft high with a surface of 2.25ft filled), i get just the same results as to filling my traps with this loft insulation or am i better going for the knauf insulation stuff? Just i know the loft insulation is cheaper and if its going to yield the same results may as well go for that..

Sorry about all the questions just I'm fairly new to acoustics (apart from reading a few producer books with acoustic sections in) and really want to get this right!

Thanks again

[Soundman2020]

What i mean on the last question is i wast thinking about building the traps as free standing, so they have a complete separate frame from the wall, then ensuring that they are placed a few inches in front of the wall,

As long as it is just an open frame, with no backing on it, then that would work, but I'm not sure how much of a benefit you'd get from that, or if it would be efficient use of the materials. If you keep it away from the side walls, then you are not maximizing the front face, which is important. And if you try to keep the front face covering the diagonal completely, then you'd end up cutting some weird shaped triangles to make that happen and also leave air gaps at the rear.

Air gaps behind flat panels make sense, but I don't see how that would help much for a superchunk, and I don't recall ever having seen any research done on that.

... get just the same results as to filling my traps with this loft insulation or am i better going for the knauf insulation stuff? Just i know the loft insulation is cheaper and if its going to yield the same results may as well go for that..

The factor that matters with insulation is something called "gas flow resistivity", which is about how the sound waves "see" the internal structure of the insulation, and how it affects them. Most manufacturers of ordinary insulation never bother testing for this, since it isn't very useful for the main purpose of their product: thermal insulation. Fortunately, there's a very rough correlation between gas flow resistivity and the density of the insulation, so folks like us who want to use the insulation for acoustic purposes, not thermal purposes, can get an idea of what will work best. It turns out that each type of insulation is different, so the optimum density id you use some type of fiberglass insulation is around 30 kg/m3, but if you are using a mineral wool type of insulation, then optimum density is more like 50 kg/m3. So find out what you can get in your area at the lowest price, look for something with density close to those figures, and that will be fine.

- Stuart -

[Lockerz]

Thanks so much for the replies, very helpful and i now know what i am looking for!

I just have one very last question if you don't mind, i have come accross a 'mix cloud', i was thinking about just using one panel ( as displayed below)

http://www.virtualpj.com/images/Newhometheater15.jpg

to cover my mix cloud however i came accross this..

http://futuremusic.com/news/images/prim ... tratus.jpg


The lower one is about 3x the price, however i was wondering, are mix clouds THAT important? I have watched a tonne of 'in the studio with' videos from future music and think i have only seen one person with it, could i save myself money and not get one and still have a very nice room to mix in or are they essential?

Thank you!!

[Soundman2020]

however i was wondering, are mix clouds THAT important?

Yup, they sure are!

I have watched a tonne of 'in the studio with' videos from future music and think i have only seen one person with it,

That's because professional studios are normally designed to have that type of treatment incorporated into the ceiling itself, as part of the basic design, so no extra cloud is needed. You only need one if you don't have one!

The purpose of the cloud is first and foremost to control the first reflection point on the ceiling. You need to treat ALL of your first reflection points, but the one on the ceiling is often overlooked, and it is very large. A cloud does the job well.

Another possible function for a cloud is to help break up or re-direct vertical room modes. That might or might not be necessary in your case.

A third purpose is to deal with flutter echo, if that happens to be a problem in that location in your room.

One more possibility is to act as a bass trap, to a certain extent, although a cloud isn't as effective as other methods.

And another possibility is simply to add absorption to the room, if it happens to be too bright.

So yes, you most likely do need one, for one or more of the above.

could i save myself money and not get one and still have a very nice room to mix in

Probably not!

Designing a room for mixing isn't just about putting bass traps in the corners. That's a good start, yes, but there are many, many other factors that go into it, starting with the correct geometrical position of the speakers in the room, and the correct geometrical position of the listening position in relation to the speakers and to the room. Once that is in place, then you need to treat all of your first reflection points, put in the bass traps, add enough basic absorption to get the required number of sabins for your your room, then measure the acoustic response of the room to see what still needs to be done.

But that's what we're here for! To help you do that.


- Stuart -

[Lockerz]

Thanks again that information was VERY helpful.

I am going to be ordering my Acoustic bits this week and I have decided on 2 bass traps that I originally mentioned. 4 x GIK 244 bass panels 1200 x 600 x 118mm) for my L & R reflection points.

I phoned up a local insulation dealer about my knauf insulation and he said he stocks a product for ceilings, it's foam (not auralex stuff - he said it performs better than rockwool etc.) which is 1200 x 1200 x 50mm. I basically now have the choice between that and a 1200 x 600 x 100 GIK 244 bass slab to use as my cloud. Do you know which one will best suit the job? It seems Asif the first covers a larger surface area but is half the thickness of the latter. I don't know if the thickness makes a difference in this scenario giving it is on my ceiling and not corners etc. do you know which one may perform better on my ceiling? There both similar prices also

Going to get this stuff, put it all up then see how my room sounds from there on.

Thanks again!!

[BriHar]

+1 to all Stuart said.

Before you decide what to use for a cloud, you should run some sound tests. As you notice from Stuart's post, clouds can serve various purposes, important here is that these different purposes can equate to variations in the construction, mounting, and/or materials used. So you need to check for the various problems you may be facing first to better decide what you have to address.

[Lockerz]

Yeah I understand, I'm guessing the best way to find my problems is to install my other Acoustix traps/ panels then run test frequencies to determine a problem then depending on the frequency depends what I need on the ceiling (thicker traps for lower frequencies etc)

Thanks!

[RJHollins]

Yeah I understand, I'm guessing the best way to find my problems is to install my other Acoustix traps/ panels then run test frequencies to determine a problem then depending on the frequency depends what I need on the ceiling (thicker traps for lower frequencies etc)

Thanks!

If this helps ... without seeing your actual floorplan [but based on the supplied dimensions] ...

I can see your concern regarding 'clouds' due to your ceiling height ... my new room is slightly larger [L & W], but restricted on the height [that's all I had available].

Just mentioning that you probably should plan on clouds going in. In the design I was fortunate to get from 'Gilfo' he had called for 3 hardbacked clouds that were angled [for the front of the room], and and 5 'soft' clouds past the seating position.

When my treatment was going in, the Super Chunk corners and wall absorbers transform my echo chamber .... but when those clouds went up ... the room went to a higher level. Fortunately, due to the cloud angles and low ceiling height, their location is toward to front of the room where I don't traffic much ... so really not much of an issue ... especially considering the major improvement.

What I've noticed about treating a room ... the pieces go in/up and you really hear a change ... but you ALSO hear where all the other room problems show up ! I had to temp remove 1/2 of a corner trap to run to small lines from my duckless HVAC unit. The resultant HORRIBLE sound that came just from that corner ... I could wait to put those piece back.
I see why doing only partial treatment is NOT the way. Because it seems to work as an integrated system ... maybe similar to the MSM wall isolation system. As an engineer, I am intrigued with the interaction ... and happy when it all starts to behave

Hope my rambling helps in some way !

Sincerely.

[Lockerz]

Yes you have helped me out thanks a lot !