placement of panels / symmetry issues / HF overabsorption

Hi around! I been already inquiring on the subject but the appropriate thread got locked here. Anyway, I've learnt that spacing the panels from the walls is a doubtless benefit, so that's what I did. Considering limited studio space, I decided to leave an air gap of only 50 MM (~2 IN) behind the absorbers except for the ceiling corners bass traps (obviously). The layout I came up with is very rough and simple: The ROCKWOOL sacks are of ROCK-BATTS SUPER brand, each sized 0.6 x 0.5 x 1 M (~2 x 1.6 x 3.3 FT) and here is their absorption chart: The ECOPHON CEILING / WALL are sheets of ISOVER ECOPHON TECNO TAL-H 50 MM (~2 IN), placed horizontally and vertically respectively. The sheets are sized 0.6 x 1.2 M (~2 x 4 FT) and their front side is covered with coloured glass tissue or aluminium laminate (not specified) but I don't think it reflects much of the highs, here's the chart again: I've got few questions here, though. Hope it's an easy answer for those in the know-how. a) Is symmetry significant in relation to ceiling and floor? Cause there's a sack of Rockwool in each corner on the floor while on the ceiling there's a completely different layout of different material. b) The doors are placed asymmetrically as you can see on the picture. Does it play a big role on placement of the panels? By now there's one hanged directly above the doors (note: doors are covered with a huge blackout curtain which is most likely going to be removed during the summer). c) How about panels on the back wall? I did read about "reflection free zone", would it be better to cover this whole wall with the panels? d) I've already installed the panels on right wall of the room and have 2 Rockwool sacks in the corners behind -- and it feels like there might be overabsorption of high frequencies. Would covering panels with some plastic or special paint help here? Or should I just reduce number of panels? And it looks like this.. Panels on right wall. The huge doors and the corner trap above. Thanks to everyone, ===zee

z99 wrote:

a) Is symmetry significant in relation to ceiling and floor? Cause there's a sack of Rockwool in each corner on the floor while on the ceiling there's a completely different layout of different material.

No, that's fine. > b) The doors are placed asymmetrically as you can see on the picture. < That's fine too, but the panel placements should be symmetrical left and right if possible. > c) How about panels on the back wall? I did read about "reflection free zone", would it be better to cover this whole wall with the panels? < If the wall behind you is closer than 10 feet then those reflections are considered "early" and should be absorbed or diffused. Also, the rear wall is yet another good place for bass trapping. > Would covering panels with some plastic or special paint help here? < You'll have to experiment to find that answer. > Or should I just reduce number of panels? < You want as much bass trapping as possible. Always. Also, your mix position is not well placed. It looks like it's too close to the back of the room. See this article: http://www.realtraps.com/art_room-setup.htm --Ethan

> b) The doors are placed asymmetrically as you can see on the picture. < That's fine too, but the panel placements should be symmetrical left and right if possible.

This may not always be the case. Sometimes, slight staggering can reduce flutter. If you notice an annoying "boing" between parallel areas of flat wall, you might wish to stagger a little bit. Shifting panels on one side forward slightly and on the other side backward slightly - "slightly" being less than a foot, typically - it should be enough to reduce flutter without sacrificing imaging.

Also, your mix position is not well placed. It looks like it's too close to the back of the room.

I would concur. But I see the doors are probably going to prevent you from moving forward in the room. Any chance you can consider rotating 180°?

re Thanks for the elaboration! Since the total room's lenght is 14 ft, I don't think it's possible to move the mixing position 10 ft forward.. However I'll try to obey 38% rule here -- the desk is not properly placed in the plan yet (also cause I'm using a temporary table at the moment, the real one is yet to be made). The panels will be placed more/less symmetrical but not exactly, more like with an error margin of 5%.. 180° rotation would leave me starring at the wall -- while behind the door there are huge windows, so actually I've made made those big doors with a purpose so I can see outside world while working. Ofcourse it'll bring in some extra noise too etc but from my experience it's worth it. So, for the RFZ I'd have to hang a "cloud" and put more absorption on the rear wall? :idea:

re-hi! there's still a question or two i'd need an advice on. taking in consideration deskspace and monitors, it's really not possible to locate the mixing position at 38% counting from the "front" wall. as much as i gather, the only other worthwhile choice would be placing it 38% from the "rear" wall, in which case much more early reflections related problems are to be expected. what would you recommend for the definite cure? should i cover most of the rear wall with absorbers? will there be more reflections from the ceiling and floor as well? is cloud above mixing position a must? thanks once again, ~~~

z99 wrote:

the only other worthwhile choice would be placing it 38% from the "rear" wall

The most important point is to not be near the center of the room front to back.

should i cover most of the rear wall with absorbers?

Yes, but a room this size needs that anyway no matter where you sit. If the wall behind you is less than 10 feet away, those reflections are considered "early." Even when the wall is farther, bass reflections are a problem. See this short article and calculator program: http://www.realtraps.com/sbirlbir.htm

will there be more reflections from the ceiling and floor as well?

Yes.

is cloud above mixing position a must?

The ceiling reflections points are halfway between you and the speakers, not directly overhead, as explained in the Room Setup article I linked above. This is not to say that absorption over your head won't help in other ways. For example, if the cloud is four inches thick (or more), it can add useful bass trapping. --Ethan

thanks once again. unfortunately i can't figure out what the program is doing and how can i make use of it.. looks like not into deeply enough :roll: i've decided to do what i am able to at the moment though, including covering rear wall with quite some panels. my questions this time would be: how high should those RFZ panels be placed, i guess around same height as my ears? also is it ok to have some spacing between them (since i dont have enough material to cover whole wall, just 4 pieces of 120x60 cm), or is it better to lay them next to other without leaving any gaps yet covering more of most reflective area? ~~~

z99 wrote:

how high should those RFZ panels be placed, i guess around same height as my ears?

Exactly.

or is it better to lay them next to other without leaving any gaps yet covering more of most reflective area?

Right.