Rearrange room layout or enclose space?

[sh0]

I have a small basement room with the listening area basically in a rectangle with a fairly large opening in the right wall to another small room (creating a shape more like an H or an I depending on how you look at it). I've attached a basic drawing (in PNG or PDF - same file).

OR
View attachment RoomLayout_2006-05.pdf

Currently my main speakers are on the 139" wall with the windows. The windows are at the ceiling and small though. The frequency response is much worse on the FR speaker than the FL - it's no surprise that their responses are different given a full exterior wall on the left and a very small interior half wall on the right. I assume the asymmetry is also effecting the imaging of the system.

I'm trying to decide what options I have to improve the space. I'm considering the following:

1) Should I add a door at the room entrance at the base of the stairs (the 35" opening in the top left of the drawing)? I'm pretty sure I want to do this since it will also help with sound isolation.

2) Should I add a wall to opening between the rooms to enclose the listening area in a rectangle (where the I-Beam is)? This seems like a good idea for symmetry but I don't want to spend the money and effort if it won't necessarily make an improvement. The total volume of the space with the rooms open is only about 2200 cubic feet so it's not like I have a lot of space to fill with sound as it is (enclosing the space would drop it to about 1200 cubic feet). Knocking out the half walls entirely isn't really an option because the one half wall with the ducts also contains a support pole for the I-Beam which would probably defeat the purpose of opening up the space.

3) Assuming I do add the door (#1) and don't add the wall (#2) mentioned above, should I consider orienting the room in the other direction with the listener facing the longer 169" wall? It seems like this would have the advantage of a more symmetrical front soundstage although I've read that facing the longer wall is a bad arrangement.

I'd appreciate any advice!

 

[Ethan Winer]

> Currently my main speakers are on the 139" wall with the windows. <

You'll do better to have the speakers at the top of the drawing, facing downward. That will give you left/right symmetry which is very important. It will also put the wall behind your head much farther back, which is equally important.

> Should I add a door at the room entrance at the base of the stairs <

Yes, not only for isolation as you mentioned, but also for symmetry. Symmetry is important in the front of the room, and especially the left and right side walls between your ears and the loudspeakers. Rotating your setup 90 degrees counter-clockwise and adding a door will improve both.

> Should I add a wall to opening between the rooms <

If you rotate your setup you won't need a wall, and in fact you're then better off without it.

--Ethan

 

[sh0]

Thanks for the response Ethan!

Oriented in the way you suggest (with the mains on the wall at the top of the drawing), the primary listening position would be lined up with the opening to the other room so as far as a wall directly behing the LP, it would be much further. However, can I ignore the partial wall around the opening that could actually be closer to the listening plane in this orientation? The space from the "top" wall to the opening is about 11.5'. Can I have the listening position closer to the partial wall with the opening than one would normally do for a full wall?

I realized in my original post that I referred to the wall with the opening as "half walls" which probably implies half-height. In fact they are full floor to ceiling "walls" with a large opening roughly in the middle.

Conveniently , if do rearrange my room in the suggested way, I'll need another MicroTrap for the additional sidewall it will create (the opening in the current arrangement was at the first reflection point so I felt no need to treat it). No problem there though.

Thanks again for the input!

 

[Ethan Winer]

> Oriented in the way you suggest ... the primary listening position would be lined up with the opening <

Yes, and that's a Good Thing.

> can I ignore the partial wall around the opening <

That's not ideal, but it's a lot better than what you have now. With no wall directly behind you the severe peaks and nulls caused by comb filtering are minimized. As I said, it's a Good Thing.

> Can I have the listening position closer to the partial wall with the opening than one would normally do for a full wall? <

The ideal distance back from the front wall in a "normal room" is 38 percent. Since the partial wall blocks about half the width I can't predict what will be best in that room. You could experiment by placing the speakers as I suggest, then play some bass-heavy music and walk forward and back listening for where the bass sounds most even.

> In fact they are full floor to ceiling "walls" with a large opening roughly in the middle. <

Yes, I understood that from the drawing.

--Ethan

 

[~JC~]

>
The ideal distance back from the front wall in a "normal room" is 38 percent.
--Ethan

Sorry to butt in, but I assume that you are referring to audio, not a theater listening recommendation?

 

[ScottMayo]

What Ethan said - turn the room 90 degrees. Then fill the shelves with books (simple source of diffusion and some very deep bass absorption), maybe put a heavy curtain up over the opening in what will now be the back, and put a door on the left-hand opening.

Don't hope for much sound isolation from the door. But it will help a little with the acoustics in the room.

 

[Ethan Winer]

John,

> I assume that you are referring to audio, not a theater listening recommendation? <

Both! The "38 percent rule" applies anywhere the goal is for accurate bass response. Understand that this is not the be-all end-all of room set-up. You can get great sound other than 38 percent back, and even at 38 percent the response will be terrible in an untreated room or a room that's poorly proportioned. Further, the "optimum" response at 38 percent back also depends on how high up off the floor you're considering. But 38 percent is a good starting point because it gives the best average where the inevitable peaks and nulls are the least damaging.

--Ethan

 

[~JC~]

Ouch!

Thanks for the response, but I guess that just isn't going to happen. For my 8' wide screen, I would want to be 12' back (1.5X) If 12' was 38%, the room would need to be 31.5' long!. I have 18', and will be at ~14'. I guess I'm going to see what happens if you flip the ratios! Thanks again for the reply.

 

[Ethan Winer]

John,

> I have 18', and will be at ~14' <

Being 38 percent from the rear wall is good too. See THIS drawing.

--Ethan

 

[~JC~]

Thanks Ethan

Thanks for the drawing. I think I will be very close to it, with the way I have things arranged. I will have 4 - 2X4' - 2" panels on one wall, 3 on the other (door precludes 4. And 2' wide, 4" thick floor to ceiling bass traps stradling the corners. Oh, yes, front wall will be covered with 1". Haven't planned anything for the ceiling, may wait to see how it sounds first. I can always add ceiling panels at a later date. Thanks again for the drawing. John

 

[sh0]

I finally got around to rearranging the room this weekend as suggested. I'm still playing with placement of the mains and listener position. Since there isn't a door by the front left speaker yet, the two mains still measure differently (oddly the front left seems to measure better than the front right). The front right speaker seems to have significant problems - perhaps this will improve when the door is added (?).

Here are 2 different measurements of the front right speaker.



Position 1 is about 2.5 feet from the back wall and almost 3.5 feet from the side wall. Position 2 is less than 2.0 feet from the back wall and just under 3.0 feet from the side wall. Neither seem too good but it seems to improve closer to the walls unless I'm interpreting that incorrectly. I will play with it more this evening. 3.0 feet from the side wall doesn't seem that close but it's creates a pretty wide stereo image given that the listening position is around 9 feet from the front wall.

I have a few questions about how to place bass traps in the new arrangement. There isn't a corner by the front left speaker and even when I add the door, I still can't straddle the corner with a bass trap panel. Will having a panel in the corner by the front right speaker and not by the front left speaker cause symmetry issues? Is there something I can do to address this (if there is an issue)? Perhaps using tube traps for the front corners would work (with the one by the door positioned away from the corner to allow the door to open). I suppose that wouldn't be symmetrical either. The concept of closing the door and then straddling a panel across the corner has occurred to me but that is far from ideal.

Also, do I need to worry about treating anything in the small adjacent room through the opening - like the very back corners? I currently have 4 bass trap panels (2 large 7" thick and 2 small 4" thick) and 2 HF panels. I have the 2 high frequency panels on each side wall at the first reflection points but is there an obvious / recommended way in which to distribute the bass trap panels or do I need to measure all the different possibilities using waterfall plots to find the combinations which reduce ringing most significantly.

Oh and my wife likes the heavy curtain across the opening idea. I assume it will reduce any high frequency reflections from the surfaces in the opening but if it improves the appearance as well even better! Also, is there any reason I couldn't put my equipment in the space between the 2 rooms (behind the curtain)? Ok - way too many questions, I'll stop now ...

Thanks again for the advice guys!

 

[Ethan Winer]

sh0,

> Will having a panel in the corner by the front right speaker and not by the front left speaker cause symmetry issues? <

Symmetry is less important at bass frequencies, but I have a better solution. If you can't straddle that front corner, put a bass trap flat on the wall but adjacent to the corner. It's not quite as good as straddling, but it's a lot better than not having any trap there at all. Or just skip the door and leave it open.

> do I need to worry about treating anything in the small adjacent room through the opening <

It's difficult to say without being there. As an experiment, play some bass-heavy music and walk back there and stand near the corners. Do you hear the bass build up more in those corners? If so, that's one sign that bass traps there will help.

> do I need to measure all the different possibilities using waterfall plots to find the combinations which reduce ringing most significantly. <

Yes, measuring is the best way to know for sure.

> is there any reason I couldn't put my equipment in the space between the 2 rooms <

How will you then go from one room to the other?

--Ethan