[Skye]

Hello, everyone. I'm new to the Audio Circle, but I see from some of the other topics on the front page in just this circle that I'm going to love it here!

This is a topic that I started recently over on the Asylum, but I've found some of the responses there less than constructive. Since this site has a reputation for more gentleman-like conduct, I thought I'd give it a shot!

I'm shopping for a home right now, and naturally, the listening room is somewhat high on my priority list. However, money is tight, so I can't afford to build new or buy a mansion with an appropriate room. In fact, I'm even having trouble finding homes with unfinished basements in my price range!

Well, I found a home I like a bit more than some of the others. The neighborhood is fantastic, condition is good, and I feel I could live there for 8+ years. There is a pair of broadcasting towers 4.5 miles away, is this an issue?

The master bedroom is 15' long by 10'10 wide, with a sloped ceiling that is 8' tall at the front and 10'4 at the back. Side walls are perfectly symmetrical. There is one large window in the middle of the front wall, which I could cover with mdf and absorption. The rear wall of the room is taken up with accordion style wooden closet doors and the doorway to the room in the back corner. So no bass trap in that corner. 

No fancy outlets, no angled walls, and the width concerns me. But at least the side walls are symmetrical, there is only one window to control, the front two corners are intact for bass traps, and the sloping ceiling is a plus.

My inexperienced eye gives it a 6.5/10, and since all the other places I've looked at rate a 3/10 or lower, this seems like a step in the right direction.

How do you rate a room like this for listening? What concerns you about it? What attributes that is has do you find most significant, and what attributes that it is lacking do you find most significant?

Thanks so much!
Skye

[Ethan Winer]

High-power radio towers can be a problem, but 4-1/2 miles away is far enough that you should be okay.

That room shape is good, though larger would be better. With enough acoustic treatment you could definitely get excellent results. I wouldn't worry so much about the front window because your speakers don't face that way. A far more important source of "early" reflections is the side walls, and the wall behind you.

As for bass traps, rectangle rooms have 12 corners, not just four where walls meet walls. Corners at the tops and bottoms of each wall are equally viable. Further, bass traps can go on the wall near to a corner, if not straddling.

--Ethan

[bpape]

Doesn't sound like a bad room at all. Sure, a little wider would be nice but the rest sounds like it will either be neutral or working to your advantage.

Bryan

[Skye]

Thanks for the replies, I hope to do business with both of you as soon as I can. 

Those are good tips about bass traps near the corners instead of in them, I hadn't thought of that. I think I could plan on treating the front two corners from floor to ceiling, and maybe the back of the room where the rear wall meets the ceiling as well.

Do you think the imaging would be too poor in this room because the room is too narrow?

I have the idea that having symmetrical side walls is more important than having well spread-out bass modes (although the modes in this room do calculate to be spread out well). The imaging and soundstage are important to me. What do you think?

Do you think absorption at the first reflection points and diffusion in the rear of the room? Based on the room size, is this appropriate?

[Skye]

Using the advice on George Cardas's website the speakers should be 2'11.875" from the side walls, 4'10.125" from the wall behind them, and the listener should sit 4'10.125" away from each speaker. This seems very near-field to me. I guess it's going to be one listening seat only, haha.

[Ethan Winer]

Do you think the imaging would be too poor in this room because the room is too narrow?

No, as long as you have absorption at all of the reflection points.

I have the idea that having symmetrical side walls is more important than having well spread-out bass modes

It's all important.

Do you think absorption at the first reflection points and diffusion in the rear of the room? Based on the room size, is this appropriate?

Yes, and that's also appropriate for all home-sized rooms.

--Ethan

[youngho]

Hi, I think it would be helpful to know what sorts of speakers you are planning to use (I might consider controlled directivity speakers, alternatively dipolar ones, to ameliorate ipsilateral sidewall effects).

Is it possible to swap out the closet doors or else mount treatments on them? Just out of curiosity, any pics or diagrams?

[Skye]

Speakers are two-way bookshelf speakers with 6.5" woofers. My friend and I built them, and they sound fantastic. 

No room diagrams or pictures yet. I could work up a crude diagram, but it would only show what I've already described. Unfortunately, pictures could be tricky. I may have to schedule a visit with the realtor specifically for it. Otherwise, I could take pictures late next week during the inspection, but that may not provide enough time to withdraw my offer fairly based on feedback here.

Any changes in the room are fair game. I'm not concerned about the aesthetics of treatment within reason (no cinder-blocks or exposed fiberglass, for example, that's just too tacky). I could replace the closet doors or hang treatment on them or stand floor-mounted treatment in front of them. It's all fair game.

[youngho]

Hi, I was just curious. Are you planning to use it for any other purpose other than listening to music? How about the closet space? Do you usually listen by yourself? Do you have a budget for acoustic treatments? Are you pretty handy/DIY? Do you think that you might try different speakers in future?

The room is narrow. Because of this, you'll probably end up having the speakers a little closer than usual to the sidewalls, so they'll need to be significantly turned in towards the listening position. You'll likely want pretty thick (3-4" minimum) absorption on each sidewall nearest the closest speakers, otherwise the bass may sound a little tubby. Unfortunately, absorption is not uniform, and it becomes more variable at more oblique angles, especially if covered with cloth (to get a sense of this, check out page 483 at http://books.google.com/books?id=sGmz0yONYFcC&q=fiberglass#v=snippet&q=fiberglass&f=false). However, since the speaker will be turned away from the nearest sidewall,  it'll basically be the sound power response that basically bounces off that wall, with bass reinforcement resulting from the nearby boundary, especially <1 kHz (except for the cancellations that occur because of proximity effects, but that nearby absorption will help with that, at least a little). Of course, the speakers would be pulled forward off the front wall significantly. You'd want some absorption flanking the window, and you could use thick velour curtains/drapes, as well.

Closet would probably be used mostly for absorption, maybe a little diffusion off towards the sides.

The primary issue by far will be the width of the room. Length won't be nearly as much of a concern with some placement and the closet absorber. Height is fine, the ceiling slants in a favorable direction. You'll also want to have a thick rug, maybe shag, between you and the speakers.

These are just the idle thoughts of an enthusiast.

[Skye]

Idle thoughts from an enthusiast are welcome!

Room is only for listening. I'm fortunate to have enough space in this new place to have a dedicated room.

The budget is going to be tight, initially, but I certainly plan to place treatment. I keep going back and forth on buying it or building it. Since I've never built them before, the first few pieces could turn out a little wonky; I'm only somewhat handy. But then again, purchasing is pricey. I've entertained the idea of 2' by 4' fiberglass wall traps, superchunk bass traps, and maybe even a batch of skyline diffusers. But this will all come in time. First step is simply putting in the speakers. Sadly, I don't even have room to plug them in where I am now.   

It may take me a year or two of planning and saving and building/buying and placing, but I'm confident I'll make the most of any room I'm in. And since I plan to be there 8+ years, I want to make sure it is the right room. There's no sense in starting with a bad room. The gear I can change, but the room I'm stuck with for a longer time.

I do wish the room was wider, but it is the best I've found so far, assuming that symmetrical side-walls are more important than volume and ratios (assuming that imaging is more important than a flatter bass response, and I think it is). If you think this is not the case and have experiences to back it up, I may re-ignite the search for a home and let this one go to some other buyer. However, it is my experience from the past two months of looking that all rooms with symmetrical sidewalls are small, squarish bedrooms. All the living rooms are too open and irregular, and none of the homes in my price range are extravagant enough to have bonus rooms.

I was considering putting an mdf board over the window and then covering it with absorption. However, reading Ethan's post on another thread gave me the idea of using thick wooden blinds as diffusion. If it works well, I wouldn't mind the natural light. But since the primary focus of the room is sound, I'm willing to cover up the window.

I usually listen by myself. I'm considering a loveseat with one side centered in the room. Maybe I'll change my mind upon using a loveseat, but I have the idea it would be nicer not to be in the middle of a couch. Of course, furniture stores do sell chairs as well. 

I'll investigate removing the closet doors and shelving. A rug sounds good. When it comes to it, I'll want to investigate a thorough game-plan of whether each essential (all first reflection points and the back of the room) has absorption or diffusion, and then the benefit and preferred placement of non-essential pieces. However, as I said, my goal in the next week is to see if this home has the right room. If it's not as good as I was hoping, I should let the seller find another buyer and then keep looking.

[youngho]

Hi, the room sounds like it's the best compromise that you've found.

A sofa would likely be too wide for a 10'10" wide room. I would start with a single comfortable chair that does not have a headrest.

Wooden blinds or shutters might act more like diffraction elements than true diffusion, if one considers diffusion to be relatively uniform scattering over a broad range of frequencies. It would certainly be a shame to board up the window. I would still consider the curtains (highly draped or pleated, with at least a few inches air space behind them) as one potential element of the front wall treatment.

I would suggest looking at these links that WGH has so kindly assembled, particularly parts 1-3 of "Loudspeakers and Rooms, etc". I would also look at http://www.rpginc.com/Technology.cfm and download the studio, listening room, and acoustics integration PDFs. If you can buy Toole's book that I linked earlier, it's really a great resource, but the above links will get you most of the way there. Some of the recommendations in the book and from RPG may be somewhat at odds with those you may get elsewhere.

The plate resonators from RPG look quite interesting, but they are expensive. In terms of DIY, if you're extremely patient or have access to a CNC router, you could possibly make the BAD panels yourself. Otherwise, fiberglass is cheap. Unfortunately, the cloth covering can be a little unpredictable, as shown in the link from Toole's book.

Best of luck.

[Skye]

As I mentioned, the dimensions of the room are 10'10" wide, 15' long, with a slanted ceiling from 8' to 10'4".

Front wall of my future listening room:


Left front corner:


Left side wall:


Left back corner:


Back wall:


Right wall:


Right front corner:


Closet system:




I was hoping it would turn into banana bread:

[Skye]

Model render of the bare room:


Render of the back of the room:


I think I can take off the closet doors and remove the closet systems (was too hard to draw anyway).

Owens Corning 703 Rigid Fiberglass, 2'x4'x2":


703 cut for super-chunk bass traps:


703 cut for super-duper-chunk bass traps!:

[Skye]

View of the treated listening room from the doorway:


My very attentive listener? Who doesn't believe in the sweet-spot but prefers the edge of her seat?:


View of front 1D quadratic diffuser:


Design is from QRDude based on prime 53, effective down to 565 Hz. Boards are 1.2" thick (the actual thickness of 1.5" lumber, the narrowest that can be bought that is more than 1"). Period width is 4'5.

View of rear 1D quadratic diffuser:


Same design as the front. I wanted to use a bigger prime and bigger period width, but it can't be done if I intend to leave the room after it is installed. Unless I can change the door to swing out?

Front 2D prime root diffuser (unfinished model):


Based on the prime number 947, it is 22 rows wide and 43 columns wide (22x43+1=947, and since 43 is prime also, the only number both dimensions are divisible by is 1). Well depths were generated on http://www.oliverprime.com/prd/ with well depths quantized to 1 cm. It is effective down to 1,200 Hz.

Front super-chunk bass trap:


Floor to ceiling Owens Corning 703 cut into triangles, 24"x24"x34". Covered with black fabric.

Rear ceiling super-duper-chunk bass trap:


It covers the back wall where it meets the ceiling. It is composed of Owens Corning 703 cut into a polygon the dimensions of three of the above triangles. Polygon dimensions are 24" height, 48" width, 24" on the top with a 34" slant to the bottom.

Side wall first reflection point:


It is a broadband absorber made from 4 sheets of 703 held together by fabric stapled to a rear frame. It is 8" thick of absorption held 1.5" out from the wall by the 1.5" wood frame (which doesn't cover the entire back of the panel, only around the edge).

Ceiling first reflection points:


Same design as the wall mounted ones, 8" of absorption held 1.5" or so away from the ceiling.

View of the sloped ceiling:


View of the closet behind the rear diffuser:


This could be filled with low-frequency absorption as well?

[youngho]

Hi, a few thoughts from me:

0. Sorry, I think the room as modelled would be unattractive.

1. Front window: instead of diffusion, you could make two absorbing panels using 2x4 framing and rigid fiberglass panels, covered with cloth. These could be sized to the windows and mounted on the frame, basically like shutters. This would be less visually intrusive, if that matters at all. Later, you could try replacing these with custom RPG BAD Panels or Arcs to see whether you prefer the center diffusion or absorption.

2. Corner traps: I wonder if someone could point me to good data regarding the Superchunk method, as the little I've seen has not been convincing? You may better off building a diaphragmatic absorber using thin plywood, framing, and fiberglass (perforating the plywood with a grid of holes would make it more like a Helmholtz absorber but could also be worth considering). Some measurements and math would be needed. Gearslutz and studiotips.com has some information, as does Alton Everest's acoustics book. You could also use something like I describe in #3.

3. Sidewall absorbers: Instead of an 8" thick absorber, I would consider 3-4" rigid fiberglass with a 1/4" airgap in front of a (possibly perforated) plywood panel mounted on framing, then either fluffy insulation or another rigid fiberglass panel with a little airgap. If you do use the fluffy insulation and are feeling creative with a band saw, you could build these so that one side is deeper and the other shallower so that the depth of the cavity behind the plywood is variable. If you made a bunch, you could mount a series of them on each side wall (deeper towards the front of the room, shallower towards the back) and have a reasonably attractive setup, like a lower-end version of http://www.avguide.com/blog/robert-harley-visits-transparent-audio-and-discovers-210-miracle-upgrade.

4. The rear: I would aim for symmetry, hence 3-4" thick absorption on the room door and the left closet door, maybe diffusion on the right closet door--something like the RPG BAD panel would work (you could drill the pattern through the door itself and put fiberglass in the closet behind the right door/panel, then use the other side for storage).

5. Ceiling: make sure you use a mirror, as the slope of the ceiling makes it a little trickier. 3-4" absorption would be fine, 8" is frankly overkill. You might consider the use of some diffusion on the ceiling.

6. Floor: The pictures suggest thin carpet. You might consider a thick fluffy rug or carpet between the speakers and the listening position.

[tomytoons]

Great drawings, my room is similar being 11 X14 (bedroom) hardwood floors. I don't think your room is ugly as shown.
I have a sloped ceiling on the equipment, speaker short wall and my window is to the left. Heavy drapes on window, tied back. Speakers are 7 feet apart and 3 feet from that short front wall, 4 feet from side walls. Listening position is about 10 feet. All approximate. Thick Oriental over Hardwood floor. I can post some picts.

Now, I don't know jack about most of this. I use a MG Room Tunes kit ($200 on sale) this for a long time in 3 different configured rooms and many different speakers. These were placed as advised in the instructions. At all reflection points in corners etc. People may have something to say about that, but hey it works. Perfect, no, but pretty damn good for the cost involved. None of my rooms have been problematic especially since I went to full range speakers eliminating the large Sub I was using. It just over loaded the room at certain loudness settings. My vinyl suffered, naturally.

You may have too much and too many $$ not needed, involved in your drawings.

My 2 cents worth.