Placing Panels, Please Advise - Diagram Included

[Perceptes]

Hello everyone,

I am planning to do a treatment of my bedroom studio this summer by making some panels based on Ethan's designs.

My room has a few oddities which make things difficult. Firstly, the entire west wall is a sliding glass door. Secondly, the southeast corner has a little inlet where the door is, so there is no good way to place a corner bass trap. Thirdly, the northeast wall has an open space that leads to the bathroom with closets on each side.

In my current drawing, I have 17 panels (an assortment of each of the three types). I have placed them in the alternating fashion described in Ethan's article. In reality, I won't be able to afford that many. Probably 12 at an absolute maximum and hopefully no more than 8 or 10. I have labeled each trap with a number on the diagram for easy reference. The X marks the listening point.

My questions are:

1) Which of these panels are most expendable if I were going to reduce the total to 8-12 panels?

2) What is the best way to deal with the three problem spots?

3) Is there a completely different arrangement of panels that would work better than what I came up with?

Thanks very much in advance!

 

[Ethan Winer]

Perc,

For a room that small I wouldn't bother with wood panel traps at all. Just use thick, dense rigid fiberglass in all the corners, including the ceiling corners.

--Ethan

 

[Perceptes]

Okay, that will save a lot of time and money. Would you suggest I use both 703 and 705-FRK to try to cover a larger frequency range? And what about the higher frequencies? Will the same sheets of fiberglass be able to dampen flutter echoes? It seems like I'd need something on the wall directly across from the monitors to reduce the echoes. Thanks!

 

[Ethan Winer]

Perc,

> Will the same sheets of fiberglass be able to dampen flutter echoes? <

Use thick, dense rigid fiberglass across the corners for bass absorption, and thinner panels on the walls to catch early reflections. It really is that simple!

--Ethan

 

[Drummer4Life05]

Perc,

> Will the same sheets of fiberglass be able to dampen flutter echoes? <

Use thick, dense rigid fiberglass across the corners for bass absorption, and thinner panels on the walls to catch early reflections. It really is that simple!

--Ethan

I gotta chime in here, as I'm getting ready to do the same thing as Perceptes -- How thick of fiberglass are you talking here? Say, 1" for the bass absorption in the corners, and 5/8" for the early reflections?
Also, should the panels be stuck directly onto the wall, or should they be fastened an inch or so off the wall?

Didn't mean to interrupt, but they seem like relevant questions to Perceptes'.

Thanks!

 

[Perceptes]

Yes, I'd be curious about the answers to those questions as well. I was thinking I'd go for the thickest possible for the bass ones (3" or 4") and thinnest (1") for mid/highs. But if 1" was considered thick, it'd be good to know that I am way off before I go and order some sheets!

 

[Drummer4Life05]

Well, I didn't even know they came in 3" or 4" thicknesses!
I went to Home Depot yesterday, and all they had was fiberglass ceiling tiles, which were 5/8" thick, which I knew was thinner than normal, but I didn't know you could buy them 3" or 4" thick.

 

[Perceptes]

Owens-Corning 703 rigid fiberglass comes in thicknesses up to 4", and 705-FRK comes in thicknesses up to 3". Home Depot does not stock either of these in the store but they can special order it for you. This is what I'm going to do at some point soon.

 

[Ethan Winer]

Folks,

> 1" for the bass absorption in the corners, and 5/8" for the early reflections? <

No, three or four inches thick across the corners for bass trapping, and one or two inches thick on the walls for mid/high absorption.

--Ethan

 

[Drummer4Life05]

Gotcha, thanks Ethan and others.

 

[Perceptes]

Update:

I picked up a box of 2" 703 which I am going to wrap in fabric and put up. There are 12 sheets in the box, as this was the smallest amount they'd sell me. Ideally I will get 3" 705-FRK sheets in the future to use for the corners, but for now I am trying to make use of all the 703 I got. Here are my new plans as to where to place these 12 sheets. Tell me what you think.

- all four corners of the main area of the room
- four panels spaced evenly across the north wall
- four panels spaced evenly across the south wall

I will also move two of these into the northwest corner of my closet when recording vocals to create a mini vocal booth. Would it make more sense to have the two panels oriented in a V shape with the wide end towards the singer, or to have one panel facing them staight on and the other on one side?

i.e.:


singer
\..*../
.\..../.
..\../..
...\/...

(using the periods to represent empty space and the * to represent the mic)
or

singer
|...*...
|........
|........
|-------

The reason for the lack of other side wall is that it is in one end of a wide closet and there is no other side wall to hang the sheet of 703 on. The V idea would mean I wouldn't actually hang them on the walls and would just set them on the ground in order to make a more symmetrical design.

I realize this is kind of confusing and difficult to explain in words so I won't feel bad if no understands what I'm talking about.

 

[Perceptes]

Okay, I finished all the panels and put them up. I put one on the back of the door and three stradling the other corners of the room. Four across the north wall, three across the south wall, and one in the closet for the vocal booth. It has deadened the echoes quite a bit but the room's frequency response hardly improved at all according to the test I did (same as Ethan's test as shown in the Realtraps demo video.) What am I doing wrong?

 

[Ethan Winer]

Perc,

> I finished all the panels and put them up. <

How thick are they?

> the room's frequency response hardly improved at all <

How did you measure? Using the Sonar project from my company's web site?

--Ethan

 

[Perceptes]

The panels are currently all 2" 703. I plan to change up the corner ones with 3" 705-FRK panels at some point when I have more money. Will that really make that big of a difference though, considering I saw little helpful change at all?

I tested the room's response by creating an audio file in Pd that plays a tone for every frequency between 1 Hz and 1000 Hz in 1 Hz increments, one second each. I then mic'ed my listening position with my R0DE NT1-A condenser and played the test. I did this before and after the panel installations and ran a spectrum analyzer on both of the resultant audio files. Here are my results:

 

[Tonio]

You should use a omni mic for the test. Did you record it at the mix position?

T

 

[Perceptes]

Yes, I did record at the mix position. The only mics I have are the R0DE NT1-A condenser and the Shure Beta 58A, neither of which have polar pattern controls. So between the two of them, I figured the condenser would pick up the best sound.

 

[Giganova]

Perceptes -- is there a freebe software for spectral analysis I could use to produce plots like you? I just recorded a sweeping test tone from my mix position I'd like to plot. All I have is this visualization (time vs. frequency; the amplitude is color coded)

 

[Ethan Winer]

Perce,

> I plan to change up the corner ones with 3" 705-FRK panels at some point when I have more money. Will that really make that big of a difference though, considering I saw little helpful change at all? <

Yes, going from 2 inches to 3 will make a difference. I have no explanation for the tiny change, but I will mention that the measuring microphone needs to be in the exact same place for the Before and After tests.

How does the low frequency response sound in the room? Can you hear a difference in fullness and low end clarity? Does the bass seem more even around the room?

I'll also echo what the others said about needing a proper measuring mike. Though I would expect any change in the response to be accurate, if not the absolute numbers.

--Ethan

 

[Perceptes]

is there a freebe software for spectral analysis I could use to produce plots like you?

The one I used for that graph is the spectrum analyzer built into Cubase SX. I just found a free plugin that does realtime spectrum analysis, though: Elemental Audio's Inspector. The PAZ by Waves will do the same job but even better, and you get a 14 day fully functional trial when you install it.

 

[Perceptes]

Ethan,

The mic was in the same position for both tests (within a few inches since I had to move it out of the room while we set up the panels.) There's not much I can do about the mic itself, no more money for another mic at this point.

From my first impression, the bass actually sounded weaker than it did before, but I will have to do another test as far as its evenness across the room. I am also concerned that the high frequencies may have been deadened a little too much. Is 12 panels in one room too many for the room dimensions I describe in the original post? Thanks.