Choosing between two rooms for acoustic

MLV, or Mass Loaded Vinyl, is a product supposed to "isolatie". Not that it beats gypsum or anything. Not saying it's a bad product but, in my opinion and prolly lots of others too, a waste of money. Using MLV for acoustic reasons? I dunno. That has to be tested to be sure but I don't see the point. It has no absorbing qualities really. My advise is to take the known routes. There's plenty of great examples here, even on how to build it (step by step). http://www.johnlsayers.com/phpBB2/viewtopic.php?t=10304

Thanks you guys ! okay, I already have read the meta topic about bass trap somem minutes ago :D I see that people mostly used very simple design, only panel in a wood frame and clothe all around.. so, let's go for this design for bass trap that will be located in front of wall. For the corner bass trap with the carpet used as a membrane, I didn't mentionned that the carpet has to be as heavy as possible ... and if you look to the original design (look at the previous page) there are 2 carpet used as membrane ! But anyway, as you said, it makes a more expensive system without to be shure it will be really more effective..

okay Phazinhead, the pix in Johns wall units page (http://www.johnlsayers.com/HR/index1.htm) can be confusing. The first unit is a slot-resonator: It's just like a panel resonater; closed box with wool (not touching the panel) The pic shows 2 panes of wool seperated, but that doesn't matter. It's just 2 pieces of wool which should be in the box. Could as well be one giant piece. Note the last trap; the rear wall absorber. Thats' just wool and works as an absorber. The cloth is just to "hide" the wool.

Phazinhead wrote:

Thanks you guys !

you're more than welcome :)

okay, I already have read the meta topic about bass trap somem minutes ago :D

Isn't that compilation of DIY panels just great ;) !

I see that people mostly used very simple design, only panel in a wood frame and clothe all around.. so, let's go for this design for bass trap that will be located in front of wall.

Yes, it's REALLY that simple! You don't even need the woodpanel, just wrap the wool directly with cloth if you want! go cheap, wheeeehoooow!

But anyway, as you said, it makes a more expensive system without to be shure it will be really more effective..

Sure, Shure make great mics! (kiddin' ... not about the "great" part... damned, nevermind)

Thanks Ro ! it's okay now, it is clearer :) So, if we sum up the solutions for corner bass trap : - superchunk - single insulation flat panel at 45° in the corner - double insulation flat panel (maybe more efficient than single panel) at 45° in the corner. just to have an answer about my idea of the 2 panels in the same wood frame, with air between them so as to act as 2 spring-mass systems. Would it be really more efficient than just a single panel in the wood frame, or it would be just a waste of insulation ? John wall unit pix show what would be the best solution I think... and I think you agree with it ( no ? lol), but I can't stay without asking stupid things :lol: ... On the John wall unit pix in the red circles, would it makes any comb filtering with all those concave volumes made by the sides of the broadband absorbers ?

Phazinhead wrote:

- double insulation flat panel (maybe more efficient than single panel) at 45° in the corner.

No, it's the VOLUME (thickness) of the wool that counts. 2x 2cm panels will perform worse than 1x5cm for example. Just make the wool as thick as possible, and yes you can just add 2 pieces together to get thicker wool traps. That's the whole idea of having more pieces of wool; just to add more volume. In John's design it shows just 2 pieces to make it easier to build it. Else you have to BEVEL the whole piece.

just to have an answer about my idea of the 2 panels in the same wood frame, with air between them so as to act as 2 spring-mass systems. Would it be really more efficient than just a single panel in the wood frame, or it would be just a waste of insulation ?

No, they don't act as 2 sprint-mass systems. There's no (significant) mass in the wool. Just add as much wool as possible; one big piece or multiple smaller pieces together. As long as there's no "barrier" on the pieces of wool (paper/plastic etc) just bare wool.

John wall unit pix show what would be the best solution I think... and I think you agree with it ( no ? lol), but I can't stay without asking stupid things :lol: ... On the John wall unit pix in the red circles, would it makes any comb filtering with all those concave volumes made by the sides of the broadband absorbers ?

no, nothing to worry about.

Cool Ro !! I'm so happy to learn a lot in so short time :D thanks again ! It's okay for the superchunk, I'll recalculate this according to my budget. If it suits, i'll use double insulation panel, so with 75mm insulation panels, it will makes 150mm of thickness ! It will be enough efficient :) I'll be back soon for new questions :lol:

Cool! 150mm sure is a good absorber!

Re So, superchunk are 25% more expensive than a 150mm panel.. but maybe 25% more efficient (?) lol. 2 questions : *The desk will take lots of space in the room and will represent a big and hard surface of 2m square. Is it better to reduce it so as to avoid direct reflexions from the monitor on each side ? (there will be ceiling panel just on top) look on the first schematic on the beginning of this topic. *So as to avoid glass fiber to be free on the air (all the bass traps will be in my bedroom, some very close to my bed), would it be a good idea to coat all the insulation panels with a natural glue for tapestry? all the panel will be covered with a clothe for shure, but it is to avoid any problem of flying fiber in the air.

Phazinhead wrote:

So, superchunk are 25% more expensive than a 150mm panel.. but maybe 25% more efficient (?) lol.

Huh?

Phazinhead wrote:

So, superchunk are 25% more expensive than a 150mm panel.. but maybe 25% more efficient (?) lol.

There have been, ofcourse, some nice tests with suppachunck vs other products (auralex etc). Have to search for the graphs, but it's here somewhere. It originates from another forum (gearsluts??) I'll be digging...

2 questions : *The desk will take lots of space in the room and will represent a big and hard surface of 2m square. Is it better to reduce it so as to avoid direct reflexions from the monitor on each side ? (there will be ceiling panel just on top) look on the first schematic on the beginning of this topic.

Leave the desk, if that's what you need; use it and live it :) Jup, you should build a cloud (hard desk vs soft ceiling) and keep your monitors at the back of the desk.

*So as to avoid glass fiber to be free on the air (all the bass traps will be in my bedroom, some very close to my bed), would it be a good idea to coat all the insulation panels with a natural glue for tapestry? all the panel will be covered with a clothe for shure, but it is to avoid any problem of flying fiber in the air.

no cloth is good enough. http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1742 (it's a sticky)

okay, so if i understand, the desk have to be as small as possible so as to prevent flutter echo and and direct reflexions. in any case, 2 or 3 clouds will placed under the ceiling, where are the monitors, the desk and the mix position. about the idea of the glue, it about adding the glue on the insulations panel in addition to the clothe! i'll never let any ?naked? insulation panel in my bedroom!! ;)

Hi everybody ! I'm back with a new idea. I can't drill any hole in the walls and in the ceiling, so I thought to a solution, which is drawn here : and it gives with the additionnal wall panels : what do you thing about this ? Is it a good idea ? I think to attach the ceiling panels with fine cord pieces.

Actually, that looks like a pretty good idea to me. You could probably make it "portable" too, so that you can take it apart easily and take it with you, if you ever move.

You could probably make it "portable" too, so that you can take it apart easily and take it with you, if you ever move.

yes, this is exactly that, and this is why I can't drill the walls and the ceiling, I'm going to move in 2 years. So, if this design is ok I'll build it. I was just afraid to have structure vibration problem with the long wood beam that support the cieling panels.

If you do cover your whole room with rockwool like on picture your room will be dead. And thats not a good idea. You need to have some liveness in your room and if you go to RT60 standard, reverb should be 500 ms for 60 dB (corect me if I am wrong), and that is pretty live. But, your cloud and side panels will be great.

Hi Tomislav ! Yes, I was exactly wondering about the same thing than you !! I was thinking of using broadband absorber for the 2 sides bass taps, but I fear to have too much side reflexion if I use broadband absorbers made with diffrent size of wood plate. So, I don't know, maybe I should put only 2 ceiling panels... And those panels will be all 75mm thick ! not 100mm

Hi everybody What do you think about using fiberglass rolled as corner basstrap ? I wonder to stack 3 or 4 of them so as to make big colum-basstraps in each room's corner... is it e really efficient solution? could it works as a superchunk ?

Sure that will work. There's paperbacking on the wool so it won't affect the mid/highs too much.

Yes , but will it work as much as a superchunk, of better because of the round shape ? It would need a cloth around it to avoid any flying particles and to lower the high frequencies reflexions. What is the lowest density that can be used for a superchunk to be efficient ?

Phazinhead wrote:

Yes , but will it work as much as a superchunk, of better because of the round shape ?

It IS a superchunk, shape doens't matter.

It would need a cloth around it to avoid any flying particles and to lower the high frequencies reflexions.

No you don't. For aesthetics; yes you might.

What is the lowest density that can be used for a superchunk to be efficient ?

48kg/m3 is the given advice in order to have a broadband aborption. Higher densities will effect low frq a bit better. But density isn't the main thing to worry about; it's the volume of the trap that counts. Bigger=better.

Hi everybody !! I'm back for continuing the project ! I'll be back at home next week so I'll have the time to build all the bass trap and make the work in the next months :D So, some points need to be checked before continuing anything : - I read somewhere that for having a good RT, only 1/3 of the total surface of the room had to be damped... but for what range of frequencies this rule is true ? ( I suppose that for low frequencies, the more bass trap there are, the best it is ?) - for memory my room looks like this (don't pay attention to the layout and the position of the all the bass trap, but the dimensions are OK !) : Because of the position of the monitors and the small dimensions of the room, would it be better to have lots of absorption all around the monitors (the "front" wall and the side wall, around the monitors), and to let the rear wall (behind the listener position, where the bed is) without bass trap? Or would it be good to put only 2 superchunks in the corner behind the monitors, and to put lots of bass traps on the side walls and on the rear wall. In the two case there will have a cloud panel. I'm asking those questions because I read somewhere some "rules" for correction of small room: some people say it is better to put a lot of bass traps on the the wall behind the monitors and to let the rear wall (behind the listener) without bass trap but with a big diffuser (however, I found here in this forum many people saying that a diffuser doesn't work well in small room)... so, what to believe, what to do ?? thank you for your advice guys !

another question : is it good if the speakers are at 50° from the center line, instead of 60° as usually ? The room is 3m wide, and 3.6 m deep. thanks !