A question about the first reflection points

[Danny_79]

Hi everybody! In many ways, my room is designed and built in such a way that it makes acoustic treatment very difficult. For example, i can only treat the reflection points behind the speakers, the rear wall and the left side of the speakers. On the right side the reflection point is a balcony door which i off course need to use sometimes, so no bass trap there. And in the ceiling, there is a light bulb hanging close to the reflection point so i don't dare drilling there, don't wanna risk drilling into the power cables. However, my question is this: Will it do any good if have a bass trap somewhere near the the reflection point on the right side, even if it's not at the exact point? I guess the same question could be asked for the ceiling. Thanx in advance!

[PedroTheThird]

You can build your own broadband absorbers and put them on rolls, making it possible to move them out of the way if you're not working. Attaching ceiling absorbers is possible without drilling holes if you use beams on stands (like an upside-down U) but it depends on how large your room is.

[Drew Stephenson]

I think we've got some confusion between bass traps and broadband absorbers going on. Bass traps are best positioned in corners, broadband absorbers are what you want for your mirror points.
I'd echo Pedro's suggestion about building an absorber on a frame so you can move it in and out of position as required. Likewise a ceiling cloud on a frame is simple enough to build - it doesn't have to be as complex as mine (which is on wheels!):
https://imgur.com/gallery/main-frame-complete-RemSWJ3
https://imgur.com/gallery/main-frame-co ... ng-hd0818e

[Edit to correct and say build a frame, not build on wheels]

[PedroTheThird]

Nice framework Drew. That's a good example of what can be done without drilling holes into walls and ceiling. The frame also provides spacing between absorbers and walls/ceiling because porous absorbers work best where particle velocity (of the lowest target frequency) is the highest.

[Danny_79]

I think we've got some confusion between bass traps and broadband absorbers going on. Bass traps are best positioned in corners, broadband absorbers are what you want for your mirror points.
I'd echo Pedro's suggestion about building an absorber on a frame so you can move it in and out of position as required. Likewise a ceiling cloud on a frame is simple enough to build - it doesn't have to be as complex as mine (which is on wheels!):
https://imgur.com/gallery/main-frame-complete-RemSWJ3
https://imgur.com/gallery/main-frame-co ... ng-hd0818e

[Edit to correct and say build a frame, not build on wheels]

You're right...the absorbers are broadband but my understanding is that they do absorb some low end too(?) Interesting pictures...i'll see if i can work something out of them...cheers!

[Sam Spoons]

Lots of ways round the problem, as well as the suggestions above have you considered using two panels for the cloud*, one either side of the light fitting? And how about putting a panel actually on the door?

Mirror points are not really negotiable, panels placed elsewhere simply won't address the first reflections.

* The lighting cables in the ceiling will run between and possibly through the joists if there is a floor above, if not they will run over the joists so little risk of drilling into them, you can but a stud and cable detector for not a lot of money too.

[Danny_79]

Lots of ways round the problem, as well as the suggestions above have you considered using two panels for the cloud*, one either side of the light fitting? And how about putting a panel actually on the door?

Mirror points are not really negotiable, panels placed elsewhere simply won't address the first reflections.

* The lighting cables in the ceiling will run between and possibly through the joists if there is a floor above, if not they will run over the joists so little risk of drilling into them, you can but a stud and cable detector for not a lot of money too.

I have in mind to build something i can place the absorber on so it can be in front of the door when needed, and then removed when i don't need it. I am not sure how, since i don't have alot of carpenting skills, but that's what i am thinking. The door is made of mostely glas, and some wood so placing an absorber on it will probably be tricky, but we will see. I have such a detector. It's not 100% reliable but i may give it a chance

[Sam Spoons]

Could you build an absorber onto a frame hinged just outside the door frame? Or take Drew's approach and make it free standing, it probably doesn't even need wheels as it will be light enough to lift?

Is you ceiling plasterboard? If so these plasterboard fixings barely pierce the board and will just push a cable out of the way with negligible risk of piercing the insulation. https://www.screwfix.com/p/easyfix-self ... pack/3685h. Slightly trickier if it's plaster and lath but find the joists and the wires are usually close to the floor above or on top if no floor.

I have posted a design for a very easy to build broad band absorber, if you can wield a drill, screwdriver and staple gun (and can buy 2 x 1 PAR cut to length) you will be able to make them very cheaply. Or, assuming it is not the main/only* door just put some hooks on the door so you can hang a commercial panel on there and lift it off when you need to use the door.

* Or even if it is, attach some legs and lean it against the door when you are mixing and record in a part of the room where you can put panels**

** Or rearrange the room so your mirror points fall where you can put panels. 80% of the improvement made when adding acoustic treatment in a mixing room comes from the first three panels on the side wall and ceiling mirror points.

[tacitus]

Yeah, I couldn’t do it the standard way as I have windows down one side. They’re all curtained (currently a bit too light, but heavier ones will follow); the other side has tall bookcases filled with irregularly-sized books and stuff. Thick rug on the floor and the ceiling’s open to the pitched roof (13ft apex), so although there’s reflection going on, it seems to disperse somehow. Having stuff at the reflection points is definitely 80% of the job. And however feeble my curtains and bookcases are, the difference is, for once, night and day!

One downside is that the thick hairy rug is a magnet for things like cartridge screws from the hifi side. When it gets moved, heaven knows what’ll fall out!

[Danny_79]

Could you build an absorber onto a frame hinged just outside the door frame? Or take Drew's approach and make it free standing, it probably doesn't even need wheels as it will be light enough to lift?

Is you ceiling plasterboard? If so these plasterboard fixings barely pierce the board and will just push a cable out of the way with negligible risk of piercing the insulation. https://www.screwfix.com/p/easyfix-self ... pack/3685h. Slightly trickier if it's plaster and lath but find the joists and the wires are usually close to the floor above or on top if no floor.

I have posted a design for a very easy to build broad band absorber, if you can wield a drill, screwdriver and staple gun (and can buy 2 x 1 PAR cut to length) you will be able to make them very cheaply. Or, assuming it is not the main/only* door just put some hooks on the door so you can hang a commercial panel on there and lift it off when you need to use the door.

* Or even if it is, attach some legs and lean it against the door when you are mixing and record in a part of the room where you can put panels**

** Or rearrange the room so your mirror points fall where you can put panels. 80% of the improvement made when adding acoustic treatment in a mixing room comes from the first three panels on the side wall and ceiling mirror points.

It's definitely light enough to lift without problems. I just need something to keep it standing stable at the reflection point. No need for wheels, just some kind of stand/support. I could put some hooks at the door as you suggest but then the panel will probably not have a big enough gap to the surface to absorb low end if i have understood it correctly. To be honest, i am noot sure what my ceiling is made of but i have drilled a couple of holes in it.

[Danny_79]

Yeah, I couldn’t do it the standard way as I have windows down one side. They’re all curtained (currently a bit too light, but heavier ones will follow); the other side has tall bookcases filled with irregularly-sized books and stuff. Thick rug on the floor and the ceiling’s open to the pitched roof (13ft apex), so although there’s reflection going on, it seems to disperse somehow. Having stuff at the reflection points is definitely 80% of the job. And however feeble my curtains and bookcases are, the difference is, for once, night and day!

One downside is that the thick hairy rug is a magnet for things like cartridge screws from the hifi side. When it gets moved, heaven knows what’ll fall out!

Sounds like you have a simmillar problem to mine.....my right side of the speakers is mostely windows and curtains too

[Sam Spoons]

It's definitely light enough to lift without problems. I just need something to keep it standing stable at the reflection point. No need for wheels, just some kind of stand/support. I could put some hooks at the door as you suggest but then the panel will probably not have a big enough gap to the surface to absorb low end if i have understood it correctly. To be honest, i am noot sure what my ceiling is made of but i have drilled a couple of holes in it.

Just screw a couple of pieces of 2x1 to the back to get the height right and lean it up against the door, that will give you some space behind and with the feet about 6" away the space behind will average out at a couple of inches which will be fine.