Thanks John and guys for the thread. I'm totally blind, and most of the sites I've been visiting to get a grip on room treatment uses graphs and images that mean nothing to a blind guy. Throw that on top of a ton of technical specs that I really don't understand and you end up with one confused puppy. However, this thread actually makes some sense to me. I'm just getting serious about my room and listening environment, so I have several questions. Before I go too much farther then what I have here, I'm wondering ... Should I start a thread independent of this one and dedicated to my ongoing build? Last thing I want to do is get off topic or high jack a thread.
You're welcome and thanks! Sorry it takes a while for me to answer... We're very busy.. but that's good thing.
With that said, I would like to address something brought up in this thread. Using the 38% (or .375%) rule for listening position let me make sure I'm correct before starting to talk about treatment. The room I'm in is 14' 7/8" x 11' 2-1/4" and totally untreated at this time. So let's call it, for math's sake, 169"x134". So I should set up facing the 11' wall and .375% out in the room. 169*.375=63.375 or roughly 5'4-3/4" - am I correct so far?
Okay, First - don't call it a rule. It's very, very good starting point. but as rules go.. it's meant to be broken.
I would highly recommend that you always face the short wall. Doing so will put the longest dimension front and back and as far as the forward to back acoustic reflections go, (modal activity - axial modes and harmonics) if you sit at about 3/8 of the room length, you will NOT be in a large peak or dip where these waves coincide. 3/8 is basically an odd multiple of the room length & any odd multiple (within reason) can work fine. So... Ideally, you want to have as large a sweet spot as possible, therefore a longer distance will equal a larger sweet spot.
The operator must move around a bit and will want to stay in an area where he can hear properly as he moves to adjust an EQ, mic pre, or patch in an effect, etc.
So sitting behind my desk at a comfortable reach, it is 3' 9" (45") for my ears to the back edge of the desk, which leaves 18" between my desk and the wall. Ok, I need to be set up where it is a equal triangle from my speakers side to side and distance to the center of my head. If that is correct then my speakers need to be 45" apart, not wanting to take up desk space I'll want to place them on stand just behind my desk. They are JBL LSR305, which are 9.88" deep, so that leaves just over 8" between the back of the speaker and the wall. So is that too close to the wall? Do I need to have them over the desk? Maybe on short stands, or build a stand where the platform hangs over the desk?
As I said above; change your room orientation (if the room will allow) and start with the speakers close to the wall. Test and adjust, test and adjust, etc., until you get the 'best position'.
Ideally you should have them as close to the boundary as possible to mitigate the effects of SBIR (Speaker Boundary Interference Response)
I'm certainly interested in this thread. I have a small room. Lots of bass trapping, and the whole issue of having to place my speakers close to the front wall is of interest. I would like to know what the Schroeder value is all about. Couldn't find a good description of it. My room is 10' 5" x 11' 8" x 8' . The whole rear wall is bass traps. Front two corners bass traps, and 1st point reflection as well. Sheetrock ceiling and carpet floor. Small... yes...
Saddle, what's the ceiling height? The Schroeder frequency of any enclosure is calculated by the room volume with Sabine equivalents (absorption). My Room mode calculator has this integrated. It is available from my publications page.
An issue I have is if I set up facing the short wall, the wall behind me has a total of three doors. (I'll try to post pics later,) in one corner is isn't an issue because the door is three and a half feet from the corner. However, the other corner has a door leading to the hall, and a closet it door. One door is only three inches from the corner while the closet door is only seven inches from the corner. I don't see how I can place a base trap in this corner, and setting up facing this wall is not possible either. I do understand why it is best to set up facing the short wall. What are my options here in my room. 14'4" x 11' 6" x 8'. Countless primmer's I've read say if I set up facing the long wall, so I have corners that can be trapped, that I'll never tame the sound in here at all.
Chip, Try it anyway. As Ash said... a rectangular room has 12 corners
We deal with strange and wonderful rooms all the time. - And trap where we can. It's always a compromise. But the trick if determining the direction and priorities.
This is a really interesting thread. I'm stuck with a really small studio space at the moment, measuring 7' by 9' with a 7' ceiling. I have bass traps in the front corners (on the short wall), behind the monitors, and on the walls to the side of the monitors. The rest of the studio has equipment lining the walls, except for the door at the back.
John, you mentioned bass frequencies "folding around" the monitors, and it made me wonder whether I need to treat the walls behind the equipment (i.e. keyboards and racks). I had been under the impression that the profusion of gear would break up most of the reflections from the side walls behind me and the back wall, but now I'm wondering if that really applies to bass frequencies.
Should I be thinking about 703 panels behind the equipment (particularly the keyboards, I guess, since the racks are flat surfaces unto themselves)?
Yes, if you can, treat all the walls. NOTE: thin treatment will only get the mids and highs. Read my paper "Room Acoustics Design and the Frequency-Power Spectrum". There I describe the 'missing-link' in many treatment articles. Like my wife tells me, 'It's something that you didn't know.." LOL (She's Indonesian and speaks with an exotic accent)
If the racks are only about 3 to 4 ft high, you don't really need reflection treatment.. BUT you will need treatment to the floor if possible on all the walls. This is where those wall/floor and ceiling/floor corners come in handy.
This is a pretty common situation, and while I'm not an expert, I think I can offer a little advice that I've picked up around the net.
1) There are 8 other corners in your room. Look for places at the wall/floor and wall/ceiling corners where you can put traps. Putting things on the floor tends to make a small room even smaller, but you could maybe go under your desk and other gear. You'd have to figure out how to hang them across the ceiling corners. The doors on the back wall will be in the way of this also, but it still opens up a lot of places to stick traps.
B) What's in the closet? Can you put bass traps inside there? You could leave the door open. I'd probably just remove it altogether, but unless it's a real heavy solid door the bass will blow through it anyway, so you could probably just leave it closed.
III) The hallway itself is a kind of bass trap. Leave that door open (or not, unless it's actually heavy enough to block the sound) and the bass freq's just keep going down the hall instead of bouncing around inside your mix room.
In fact a small, poorly insulated room where you can hear everything that happens in the next room is actually a bigger room in terms of low frequency response. We always talk about isolation and trapping - keeping the sound in the room and then trying to stop it bouncing around. But if you just let the sound out, it cant bounce around, right? I am sure that this is an important part of the reason my mix room sounds so good. Even at reasonable levels, you can hear my monitors (especially the subs) everywhere in the house.
[Emphasis Added]
Yes, It's always a challenge and a compromise - Isolation vs. Acoustic response. In our big commercial builds, I actually prefer concrete walls, both for the interior partitions and exterior/structure. THEN we go about to control the waves INSIDE the rooms.
But with the usual home studio in the US and Canada, we are talking about interior partitions of 1/2" drywall on un-insulated 2 x 4 studs and another single layer of 1/2" drywall on the other side. This type of partition will have a resonance of about 70 Hz. A partition like this begins to pass low frequency at 100 Hz. So.. THERE'S your bass trap. My friend, Andre calls this "Invisible Alpha". haha!
So, be aware of all of the aspects of the construction of the space that you plan to treat. The more information you have, the less testing (and guessing) will be needed.
- and I really hate guessing.
I also have testing data posted on my publications page - ir761 from the Canadian research council.. great stuff! Worth over a million dollars if YOU had to do it yourself. It's there for your information. Use it.
Cheers,
John
