Another Bass Traps thread

[andygabrys]

Hey Jon,

Lots of thoughts posted above here. Would be good to examine all of them.

For me, two things I notice:

1) those pieces of Aurelex are very thin and low density. They are generally thought to deaden high frequencies while doing little to control low midrange and bass. Hence, a room that feels like it has less high end - maybe even dead. While the bass still has nodes +/ - 20-40 dB in size.

2) there is no placement that attempts to trap the bass frequencies. A rectangular room actually has 12 edges and bass trapping material can be placed in any of those 12 edges to help to make it less wild in the bass response. Generally people are using Rockwool or OC703 or OC705 in 4" thicknesses to make a greater impact on bass trapping. Placing these straddling the corners makes use of an air gap and is more effective.


If it were me I would look for those kind of products (which I did and it made a big difference).

Last thought - carpet or no carpet? Sometimes you can make a room extremely dead to the point of feeling like you need to introduce lots of ambience in the mix to try and liven things up.

In general to my ear rooms with carpeted floor tend to sound overly dead, so be careful with how much of the floor the carpet is laying on.

If you have effectively placed a cloud above the working area with some 2" to 4" thick absorbers you will likely be able to take the carpet out of the room.

Anecdotal thoughts based on my setup in several similar sized drywall / wallboard finished rooms with 10 24" x 48" x 4" panels with OC703. insulation.

You can google many of these ideas and find a wealth of information on them.

[Kolstad]

Bit of a difficult room with those large windows.
Bass waves are unpredictable and bounce all over the place. Try to use your ears when testing as well. Dive down in those corners and listen for bass buildup.
You need mass to catch them, so the bigger the better. Big chunks, punching bag size.

Consider heavy curtains on those windows maybe..

[elser]

You know where your bumps are, do you know your dips? RT? A sweep with a dB meter gives you two axes; frequency and level, but a waterfall plot adds decay-frequency and level, over time. Shooting the room with pink noise and an omni condenser would give you a much more detailed read on what your room is doing, but based on your room's dimensions, it'll be tough to tame.

*edit: Modecalc can give you some frequency info based on room dimensions, but dimensions are one thing and materials can be quite another.

Hey Mojo, sorry I let this thread stagnate, some Dr. just took out my gallbladder and now I don't feel so hot. Anyways, I have the ARC software by IK and I think using that would be comparable to shooting the room with pink noise (I think?). I'm guessing you're familiar with the software? When you do that it gives you a graphical plot of the frequency response in the room. If so how would I use that to choose placement and materials? My initial thought is to build corner traps floor to ceiling with rock wool. Seems to me a good place to start. Or is it?

[elser]

A couple more points, I do plan to put heavy curtains over the window facing the yard. But behind the monitors there is no glass, it's just a window space going into the next room. It seems to me it could have a positive effect on the sound of the room? I don't know. I'm thinking of finding some kind of removable glass option so I could put it in for tracking and remove it for mixing, but that's not important at the moment.

Rearranging the room probably won't happen. The mixing position is 2/3s towards one side of the room, which I understand is a good thing. And according to Mike Senior in Mixing Secrets it's better to set up with the monitors facing the short throw of the room, I forget his reasoning, but these seem to me sufficiently strong arguments for keeping the current set up. And the current set up allows quick and comfortable access to all my instruments which is also important to me.

So, I'm thinking the next step is to build 4 corner traps floor to ceiling, straddling the corners as Andy pointed out, and then take it from there. Hopefully the ARC software will help out as well, I use it as an A/B thing, and then reshoot the room and take subsequent steps as needed.

Iz good, yes? Maybe so, maybe no?

[mojobone]

But behind the monitors there is no glass, it's just a window space going into the next room. It seems to me it could have a positive effect on the sound of the room? I don't know. ?

That does change things, cuz generally speaking, a room is a box and a speaker is a box; you hear where I'm going? And yes, the ARC software is very accurate with the JBL LSRs, almost regardless of the room. I couldn't tell from the pics, but it's good you're using the rule of thirds; that can be hard to suss, in such a small space.

I theenk you may be better off using triangular bass traps between the walls and ceilings, so as to conserve floor space, but it's mainly just a gut feeling.

[Danny]

When I did my studio over, I called the guys at GIK acoustics. They are very friendly and knowledgeable.

I drew a diagram of my room on graph paper and emailed in PDF format to them. The will analyze and ask questions about rooms materials, etc.

They didn't even pressure me to buy anything from them.

www.gikacoustics.com/

[fuzzbox]

Danny, I did the same for my room a number of years ago with this company http://www.vicoustic.com/page/project-request..

No pressure to buy and they have a wealth of knowledge and experience with an extensive database of room sizes to draw on.

I recorded some tones before and after... I can easily tell the difference!

[Danny]

Cool! All I can say is that I let the acoustic professionals do an analysis and I got my traps at a great price.

I barely have enogh time to track and compose, let alone do acoustic simulations. .

[fuzzbox]

Totally agree. It's all a compromise anyway as you know. Acoustic treatment is one part of the puzzle! The room analysis is ok to a point. Once you move anything... a bookcase, a table, etc you have to do it all again...

Danny, do you have a soundcloud/Bandcamp page with some of your music?

[waveheavy]

Some of this may sound redundant from what others have said.

You're dealing with a very small room, and small rooms need a lot of bass trapping. You're also dealing with two windows, which glass is very reflective. I can't really tell if you monitoring position is on the long wall, or short wall. Ideally you want your desk and monitors setup on the short wall, meaning the long wall will be running to your sides. This causes how your room's modes get affected.

If your monitors have sound holes in their back, you definitely want them positioned away from the front wall, as close as possible to 1 foot. Bass trap all 4 corners of your room, from floor to ceiling. The cheapest route is to build your own using rock wool like Roxul brand that says soundproof. Roxul makes a 4 foot x 2 foot bat 3.5" thick. With 8 foot ceilings, you'd make two of them for a corner simply stacking them straddling the corner. For the rear wall, same thing, one or maybe two stacks. Usually you need the heaviest bass trapping on the rear wall behind your monitoring station. That's where it should take care of your low bass frequencies, along with the corner traps.

You need an absorber behind each monitor on your front wall, and one or two in between. Then an absorber on each side wall. The way to find out where to position the side absorbers is to have someone hold a mirror on the wall while you sit in the monitoring position. Have them move the mirror until you can see your monitor in the mirror. That's a first reflection point that needs an absorber. The smaller commercial absorbers probably won't work because of the windows. What you can do is build a Gobo absorber using Roxul, a free standing absorder on a 2x4 support frame that would be at the right height and that you could move away from the window if needed.

Only other position is the overhead cloud. Same thing with the mirror. Wherever you see your monitors in the mirror, that's a first reflection point that needs to be trapped.

That's the only trapping I'd recommend for your room. You don't want a completely 'dead' sounding room.