Skyline diffusers and more for my living room- advice please

[AdamZuf]

Hi folks,
This is my living room:
ImageShack - Hosting :: livingroomsketchak4.jpg
ImageShack - Hosting :: livingroomphotofv5.jpg

The only treatment I have are 9 portable glasswool 5cm thick absorving panels, and 13 half tube absorvers with wooden back, and they are rotated so what ain't absorved is reflected (dare I say diffused? naaaa.....) to another direction. I found the material on the street, and being poor, I just did the panels with that cheap stuff- yes is tames the highs mostly. I finished sound engineering school and I am aware of frequency dependant NRC and diffusion. We've learned about the skyline and other diffusers. However, It's still hard to put things into practice, so your advice needed.

Look at my workstation and the distance from the back wall, which is actually a never-opened window (sort of), so I covered it with the half-tubes. At current state, running a sine wave at listening levels sometimes causes small vibrations to little things on my desk, just because there are a lot of things there (-: The window never vibrate, the glass is a coarse one by the way, maybe it helps diffusion a bit, from the exposed surfaces, and it's heavier then normal glass.

BUDGET: very small.
DIY ABILITIES: good.
CURRENT POOR MAN'S INVERNTORY: 2 thick blankets, a few pillows and wool blankets.
WILLING TO CHANGE: I don't have a life so I am willing to do whatever is good for my profession. Walls, ceiling, everything. I don't care about the isolation, I can record at quiet hours. However, I still work in a studio (sort of) so remember that I want good results, not world class, critical conditions. The things you see in the right side of the picture will go- the computer, table and will be left empty, as well as anything in the middle of the room, like the 1 man sofa.
Please note that the black area on the bottom of the sketch (where the shot was taken from) is the corridor, and is only seperated from the living room by a thick, double folded theater fabric.

My goals, in this order:

1.In the "lower" side of the living room should enable me to record overdubs. Wheather if it's congas, upright, acoustic guitar etc. I would like to create a more live sounding portion in that area in which room mics won't shame me but make me proud. The table under the small window on the right side of the picture might go.
I want a present, clear midrange that will cut through the mix. I hate veil.

There are several things I could do on my own, but the first thing I'm thinking of is the Skyline diffuser, made of styrofoam.
http://www.bobgolds.com/DifuserKgveteran/home.htm
I have the Acoustic Calculator software.
Acoustic Calculator 1.3

Off coarse I can look at the figures of the size vs. bandwidth all day but experience is needed now, not numbers, and someone that can say: "this is too big and is actually an overkill", and "you should do fine with that no worries". Maybe two sizes of diffusers for different areas or mixed in the same area.

2. I take my portable recording rig to record projects on different locations. Just the same as I can use the acoustical properties of my current panels for certain goals, whatever I make would be best if it could serve for that purpose as well. What sound blockage can I expect (efficiency and frequency-wise) with using the styrofoam diffusers? The current glasswool panels are quite effective, by the way, but of coarse I wouldn't use them to "enhance" the sound of many things...

3. A reasonably neutral mixing environment. I mix on low levels from a pair of Genelec 1029A, and might add a sub later. However, it's just an option. For now, the frequency response measures good and I'm very pleased with how revealing the Gennies are at the current state. However, it's not saying that the panels are as good as it can get for my application. The Gennies have very little response under 70Hz BTW.

Sonex is too expensive, although attractive. The "Rockwool" in Israel is actually a cheaper, less efficient version then the one familiar to you, but it's a standart and maybe should do the drick for lowering the RT60 to a reasonable level around the mixing station, as the sound is quite nice for now.

I'm thinking that maybe it would be wize to absorve the whole ceiling, and not diffuse the "live" portion of it, because if I would like to record 2 instruments together, and seperate them with panels, the panels won't go as high as the ceiling of coarse, so I need the least refections from there.

I am willing to do something that will change the angle a bit on the ceiling in order to eliminate one parallel surface, like putting slightly angled pannels on it.


I can go on forever but now it's time for some of your thoughts and ideas.
Thanks guys!

Adam

[Ethan Winer]

Originally Posted by AdamZuf

I can go on forever but now it's time for some of your thoughts and ideas.

Adam, I think your room is a bit too small for diffusion. Maybe you'd benefit from some on the rear wall behind you when mixing. But the side walls are too close for diffusion. Also, if you do make diffusors, use wood instead of styrofoam. It will last longer and not break the first time someone bumps into them.

--Ethan

[Bob Olhsson]

Rockwool is excellent although nastier to work with than fiberglass. It can be had in a variety of densities. Rigid fiberglass industrial furnace insulation works very well too and is lots less expensive than the stuff marked "acoustical" which I learned to avoid the added expense of years ago.

[AdamZuf]

Originally Posted by Bob Olhsson

Rigid fiberglass industrial furnace insulation works very well.

Can you please post a link for that, so I'll see how it differs from what I know?
From what I've learned, fiberglass has a very non inear NRC graph, which is more efficient as you go up the frequency,so it doesn't sound alive. What are your thoughts about that, regarding the stuff that you're talking about?

Thanks
Adam

[AdamZuf]

Here is what I'm thinking for now:
ImageShack - Hosting :: livingroomwithtreatmentqg4.jpg

Blue is Rockwool (you can see how 120cm wide panels go along the width of the ceiling, sectioned by wood, probably), Orange is diffuser. Maybe because the dimentions are not multiples of 60cm, I'll make different sizes of diffusers.

Still thinking if I should give the ceiling an angle, if so, I guess a wooden back for the Rockwool is needed, right?

Thanks
Adam

[Bob Olhsson]

All insulation absorbs more as the frequency rises. Covering it with pegboard helps a lot with this problem.

[AdamZuf]

Originally Posted by Bob Olhsson

All insulation absorbs more as the frequency rises. Covering it with pegboard helps a lot with this problem.

Indeed, but it's better to use a more NRC linear material in order to use less of the pegboard if we want the absorbtion to be as efficient as possible and keep the RT60 short.

Adam

[Glenn Kuras]

Originally Posted by AdamZuf

Indeed, but it's better to use a more NRC linear material in order to use less of the pegboard if we want the absorbtion to be as efficient as possible and keep the RT60 short.

Adam

FRK will work pretty well for this.

Glenn

[Jason Jones]

I think the skylines could actually help your room quite a bit. I would put them on the back wall as Ethan suggested. And, even though your room width is pretty tight, I would put them on the side walls in the back around the conga. None in the front 1/3 of the room, though.

If you do make the skylines, you really want a more dense material than the foam from the hardware store. Wood is great, of course. But you can also get more dense foam. You will want the metric equivalent of 2 pcf. An EPS molder will have that and usually will sell small quantities. EPS molders make large blocks of foam for freeway underlays, insulation and other architectural purposes. It is easily cut into sheets.

If you don't like the sound of the skyline on the wall immediately to the side, you can put absorbers there and the diffusers on either side of these absorbers - that will still give you some ambiance.

Jason

[Ethan Winer]

Originally Posted by Bob Olhsson

All insulation absorbs more as the frequency rises. Covering it with pegboard helps a lot with this problem.

Just to be technically precise, absorbing material absorbs less as the frequency lowers. That is, it absorbs 100 percent at some frequency and above, but falls off at lower frequencies. Sort of like the difference between a high-pass filter and a low pass filter. But I knew what you meant, Bob.

--Ethan

[Nick_1234]

This is really interesting. I would like to ask a question without interuppting this thread.

What is a good general acoustical set up for any room, I mean should I at least make some to throw up on to the wall behinf the desk, and maybe the back wall?

Acoustics are really my downfall.

Respect.

[Glenn Kuras]

Originally Posted by Nick_1234

This is really interesting. I would like to ask a question without interuppting this thread.

What is a good general acoustical set up for any room, I mean should I at least make some to throw up on to the wall behinf the desk, and maybe the back wall?

Acoustics are really my downfall.

Respect.

Every room is going to be a little different in the set up, but in general you want:

- As much bass control in the corners as possible
- Panels for the early reflections. (ceiling, side walls and back wall)
- Diffusion to help with flutter echo and to give the room a "bigger feel"

Glenn

[Nick_1234]

Glenn

Thanks a lot man, I am gonna make a note of that and start a DIY project to aquire these things

Respect.

[Bob Olhsson]

By far the most common mistake is to use too much absorption.

My experience has been that early reflections that have a flat response are pretty important. This is dictated by both the surface and the dispersion of the speakers. An interesting approach is to actually compensate the off-axis response using the early reflection treatment. You don't get the pinpoint imaging from absorbing the early reflections but you do get better tonal translation which I think is far more important to monitoring and translation.

[SpiderM69]

Hopefully I'm not saying something stupid by not reading the whole thread first, but shouldn't you be careful using diffusers in small rooms? In doing prior research, I read that they're really more applicable to larger rooms, and can actually introduce problems in smaller rooms.

IME, bass trapping, bass trapping, bass trapping.

[AdamZuf]

Originally Posted by Jason Jones

I think the skylines could actually help your room quite a bit. I would put them on the back wall as Ethan suggested. And, even though your room width is pretty tight, I would put them on the side walls in the back around the conga. None in the front 1/3 of the room, though.

Jason

Yup, exactly how I figured it out, didn't you see the see the link on my third post?

Well, I've changed the way I'm going to apply the rockwool.
The panels are going to be made the same as the glasswool pales you see on the photo. portable, both sides covered with carpet. It will be the cheapest way of doing it, just handing them down from the ceiling, instead of doing it like a traditional office-like acoustic ceiling (of glasswool usualy) with a metal frame going along the walls and between them, creating a net. This will also enable me to angle the panels just by changing the wire's length (hopefully yhr sngling will help, maybe the two panels above the desk will have a pegboard back). I can also start doing the panels and see if I reach a good point in which there's no need of more.

On the walls I'm going to add about 5cm deep of wooden sticks (vertically) with.... arrrr darn how's it called in english.. one side coarse to go on the sticks, and it attached to the other, soft side that goes on the panels... I hate not knowing these little things in foreign language..

So, all panels will have reasonable amount of air between them and the wall behind them, so they will be more efficient...

[AdamZuf]

Originally Posted by SpiderM69

Hopefully I'm not saying something stupid by not reading the whole thread first, but shouldn't you be careful using diffusers in small rooms? In doing prior research, I read that they're really more applicable to larger rooms, and can actually introduce problems in smaller rooms.

IME, bass trapping, bass trapping, bass trapping.

Yes but it's the more neglectable (for mixing), 420 wide part of the room, and I think that 567cm from the big window to that back wall with diffusers ain't exactly small. And as I said, I'm pleased with the situation as it is (the monitors sound superb and precise, no bass problms with their small extension), It's more important for me to add the diffusers but I thought what the heck, let's do it right.

I'll get to bass trapping later. Will probably replace some of the half tubes. I can also do something on the ceiling... It will be easy if there will be a need for it.

[Glenn Kuras]

Originally Posted by Bob Olhsson

By far the mist common mistake is to use too much absorption.

.

I totally agree, yes you do need to control some of the flutter echo in the room, but really what you need to address is bass trapping and first reflections.

Glenn

[AdamZuf]

Originally Posted by Bob Olhsson

All insulation absorbs more as the frequency rises. Covering it with pegboard helps a lot with this problem.

By far the mist common mistake is to use too much absorption.

My experience has been that early reflections that have a flat response are pretty important. This is dictated by both the surface and the dispersion of the speakers. An interesting approach is to actually compensate the off-axis response using the early reflection treatment. You don't get the pinpoint imaging from absorbing the early reflections but you do get better tonal translation which I think is far more important to monitoring and translation.

Do you think that the current plan (back wall and side walls of the rear portion covered with diffusers, desk portion all with rockwool) is good?

What do you suggest for the early reflections panels? using pegboard? I never seen someone doing it, but I agree that linear off-axis is important, I also read it in Linkwitz article of the orion and as we all know... he is the man!
Should I measure the current off axis response with a tight cardiod? (the AKG CK-91 has a linear off axis response), and see where I'm heading, or is there a generalized way of complementing off axis response which is adaquate enough for optimal result?

[AdamZuf]

Originally Posted by myfipie

FRK will work pretty well for this.

Glenn

FRK?

[Glenn Kuras]

It is facing that you find on 703 or 705. It will reject some of the highs in the room and act as a membrane which will help absorb more low end.

Glenn

edit... this is good for bass trapping but not good for early reflections.

[AdamZuf]

Materials/objects in the mixing environment that "act like a membrane" are sometimes refered as good, as they absorve the vibration, like what you've saidabout the 703/705, and sometimes asbad, as they act as a second sound source. Well of coarse I can hear that a vibrating glass window is a bad thing, but probably there's a grey area... Can anyone explain?

And about the skyline diffusers, it's time to decide frequency coverage/dimentions... advice please!

Thanks
Adam

[AdamZuf]

ImageShack - Hosting :: livingroomwithtreatmentsj4.jpg
Here is the current design development. You can find a color legend on the bottom this time. The "front" view has only what it takes to understand everything else.
I took the "bass traps, bass traps, bass traps" suggestion seriously this time... But one clarification, is it ok that the trap ain't sealed?

What do you guys think about the way the panel types are spread across the room?

[AdamZuf]

Help?

This is the stuff available here in Israel:
http://www.paz-insulation.co.il/images/acus_h.jpg
The pink line is the most dense 2.5cm thick panel with no frk, 7cm from the wall. Mine will be at least that, probably 10 for the most. I think I'll use that for all the panels, as it is available with backing (forth traps). That way, lots of panels will be portable, as they will be very thin, and I can probably carry about 15 in the back seat of my car.
Going to 5cm thick panel will averagely raise NRC by %5 (the chart looks at 1 NRC as %100), and cost around double.
Is it a good descision?

The backing is quite expensive. If a bare panel cost $5, one with backing cost $8. the difference adds up to about $50. Is there a cheaper, but durable alternative? (maybe appling contact glue on one side or something)

[bpape]

Just to carry on the reflection/response portion...

Unfortunately, the side wall reflections are almost never of the same frequency response as the direct sound. As you go farther and farther off axis, you get serious anomolies in the upper mids and highs. This is part of why we absorb them.

Bryan