Questions regarding room setup and treatments.

[Mrtie]

So I am in the process of converting part of my basement into a theater room and I am far from an expert on these things so I thought I might pick some of the brains of the vast wealth of experience here. I will be building a false wall with an acoustically tranparent screen and then most likely using AT rose brand speaker cloth as bezel around the screen to essentially make a floor to ceiling false wall. I plane on housing my jubscalas and DTS-10 behind this wall and I have a few questions in regards to both placement and room treatment.

I have gone through and used the RT60 spreadsheet from audiokarma to get a decent baseline of what my room issues may be and it appears to look pretty good with the exception of bass. the room is mostly painted cinder block, and will contian capret with pad, and a RNC .55 ceiling tiles. My RT60 information looks as follows.

Total Absorption (Sabines)
63 Hz	125 Hz	250 Hz	500 Hz	1 kHz	2 kHz	4 kHz	8 kHz
295.8396	366.0055	390.6992	474.011	535.1903	575.4294	534.4023	523.8265

0.31

0.25

0.24

0.19

0.17

0.16

0.17

0.18

Reverberation time being the 3rd set of numbers.

From what I have read it appears most of reverbs are within .05 as is desired except my low end, so I have been thinking that I will use double stacked 3' roxul safe and sound floor to ceiling diagonally across the rear corners to help as bass traps. I also think I may use 3" absorbers both for the first reflection point and bahind the seated listening positon. My question is are these good options, should I look into more/less treatments, difussers, etc? WAF is no factor, but Cash is so DIY is my only real options here, and I'd like to keep treatments to under $200usd if possible.

My second question pertains to jubscalas and their room placement, obviously my diagram is just a rough mock up and I may toe the speakers in as well, should I be trying to back the rears of the speakers directly up to the bass traps or do they need space? How close should they be to side wall, not that I have much wigle room? I know from what I've read of AT screens that I will need like 5-8" of air between the screen and the speakers, so I am basically trying to figure out how much of my room I need to cut off with the screen wall to allow the Jubs the space they need. Also I know that 12.5' isn't alot of space for a pair of K402 horns, am I worried over nothing? How well do jubs image in small rooms, the closest I've ever had mine where about 11' center to center, but the drawn of gettign all this ugly(but wonderful sounding) gear out of my living room and hidden from sight is very appealing to me.

So thoughts on the room,treatments,and placement? Can Jub's be happy this close together? Am I a fool for trying to squeeze that much hardware in such a tight space?

Thanks!

Bonus info Room Modes:

			Axial Room Modes
North to South				East to West				Floor to Ceiling
Mode			Frequency	Mode			Frequency	Mode			Frequency
1	0	0	24.6	0	1	0	44.9	0	0	1	86.9
2	0	0	49.1	0	2	0	89.8	0	0	2	173.8
3	0	0	73.7	0	3	0	134.7	0	0	3	260.8
4	0	0	98.3	0	4	0	179.7	0	0	4	347.7
5	0	0	122.8	0	5	0	224.6	0	0	5	434.6
			Tangential Room Modes
N/S + E/W				N/S + F/C				E/W + F/C
Mode			Frequency	Mode			Frequency	Mode			Frequency
1	1	0	51.2	1	0	1	90.3	0	1	1	97.8
1	2	0	93.1	1	0	2	175.6	0	1	2	179.6
1	3	0	137.0	1	0	3	261.9	0	1	3	264.6
1	4	0	181.3	1	0	4	348.6	0	1	4	350.6
2	1	0	66.6	2	0	1	99.8	0	2	1	125.0
2	2	0	102.4	2	0	2	180.7	0	2	2	195.7
2	3	0	143.4	2	0	3	265.4	0	2	3	275.8
2	4	0	186.2	2	0	4	351.1	0	2	4	359.1
3	1	0	86.3	3	0	1	114.0	0	3	1	160.3
3	2	0	116.2	3	0	2	188.8	0	3	2	219.9
3	3	0	153.6	3	0	3	271.0	0	3	3	293.5
3	4	0	194.2	3	0	4	355.4	0	3	4	372.9
4	1	0	108.0	4	0	1	131.2	0	4	1	199.6
4	2	0	133.1	4	0	2	199.7	0	4	2	250.0
4	3	0	166.8	4	0	3	278.7	0	4	3	316.7
4	4	0	204.8	4	0	4	361.3	0	4	4	391.4

[Chris A]

So thoughts on the room,treatments,and placement?

Just based on my experiences, I'd recommend the side-wall absorption panels, in fact any acoustic reflection surface that is within ~30 inches of the mouth of the K-402s. I assume that you will toe-in your speakers to aim at the middle of your listening position. You can push your Jubscalas back to touch the front wall if you put some absorbing material over the face of the DTS-10 to kill any early reflections above ~400 Hz. This will enable more lf performance from the La Scala bass bins so that you can cross with the DTS-10 as low as possible (more on why this is important if you want to know).

I'd also recommend (strongly) something on your 6.5' ceiling about halfway back to your listening position and at least 24 inches in each dimension. This could be a diffusion panel or absorption pads. I'd aim your K-402s down using the adjustment mechanism to aim them right at your seated position height (use a flashlight or laser pointer to see the throat of each K-402 while seated to get this one adjusted correctly). You're trying to decrease the ceiling bounce issues by doing this. This also means that you need a reasonable carpet depth to absorb added floor bounce from about 400 Hz on up.

Other than that, the room mode thing can be fixed by moving your listening position around and adding a little diffusion/absorption in the places where you have a measurable problem with standing modes.

The bass traps that you show are okay, but I'd recommend putting those at the back of the room across the corners if possible, since they will be a bit too effective right next to the JubScalas, IMHO. A large absorption pad behind your head is needed if your listening position is within 30 inches of your back wall, etc. (or perhaps even more separation distance).

Chris

[CECAA850]

I can't tell from your drawing but try to have your seating position about 2/3 of the way back in the room.

[Mrtie]

I'd also recommend (strongly) something on your 6.5' ceiling about halfway back to your listening position and at least 24 inches in each dimension. This could be a diffusion panel or absorption pads. I'd aim your K-402s down using the adjustment mechanism to aim them right at your seated position height (use a flashlight or laser pointer to see the throat of each K-402 while seated to get this one adjusted correctly). You're trying to decrease the ceiling bounce issues by doing this. This also means that you need a reasonable carpet depth to absorb added floor bounce from about 400 Hz on up.

The bass traps that you show are okay, but I'd recommend putting those at the back of the room across the corners if possible, since they will be a bit too effective right next to the JubScalas, IMHO. A large absorption pad behind your head is needed if your listening position is within 30 inches of your back wall, etc. (or perhaps even more separation distance).

The image got cut off by the forum limets I guess here is the enitre thing http://i47.tinypic.com/10n5m52.jpg.

1. Diffusion is out as it will block the projector path in the already low room. But could I simply make a few 24x48 fabric wrapped absorbtion panels and grid mount them instead of ceiling tiles?

2. Sadly my rear corners are a no go one is an open doorway to the stariway landing/utility room and the other will contian an in wall bookshelf I will be using for vinyl/bluray storage. Will the traps that close to the scalas be that detrimental?

Thanks-Kevin

[Chris A]

But could I simply make a few 24x48 fabric wrapped absorption panels and grid mount them instead of ceiling tiles?

Anything to kill the first bounce of midrange energy will work.

Will the traps that close to the scalas be that detrimental?

You might hear a loss of upper bass, which you can EQ out if it becomes a bit too pronounced. I find that bass traps next to my Jubs take out a bunch of upper bass. I don't have a choice where they reside in my room either, but in my room, I don't mind that loss. However, you can really hear a difference when the bass traps are removed. I'd try A-B comparisons with and without. You can also adjust their angle with the corner in order to increase and decrease their effectiveness.

Chris

[oldtimer1954]

Mrtie- Do not go around adding absorbion/diffusion panals blindly. You first need to measure your room in the time domain. RT60 calculations are useless and should not be considered by anyone with a theater setup in their home. Reverb is not occuring in your room. There is so much bad info going around with regards to room treatments that it totally blows my mind. I highly suggest you figure out how to measure your room/speakers in the time domain and use those measurements to determine where you need to put the treatments.

[artto]

Mrtie- Do not go around adding absorbion/diffusion panals blindly. You first need to measure your room in the time domain. RT60 calculations are useless and should not be considered by anyone with a theater setup in their home. Reverb is not occuring in your room. There is so much bad info going around with regards to room treatments that it totally blows my mind. I highly suggest you figure out how to measure your room/speakers in the time domain and use those measurements to determine where you need to put the treatments.

ditto

Most of the things you've been studying apply mostly to much larger rooms, as in 800 - 2000+ seat concert halls.

[artto]

Mrtie, I can see you've already gone through a lot work, and I don't want to discourage you, and admittedly I haven't looked at all the info you've provided very thoroughly, but from what I have looked at, you really don't have too much to work with, so I wouldn't expect too much if I were you. Hopefully whatever you do will be satisfactory for you, but IMHO, the room is way too long compared to its width and the 6.5' ceilings just aren't going to cut it. And with cinder block and ceiling tiles.......eeeeyyyooooowwwwccchhhh! And forget about $200 for acoustic treatments. That just ain't gonna be enough gas to get you to the grocery store when what you really need is to get from NYC to San Diego.