problematic room

Dear forum-users, I hope I may get a little help here. I´m really a little helpless at present and don´t know what to do. First of all I would like to tell you something about the story of my room. A friend of mine and me have invested a lot of time, money and work in our studio. This time, after having worked in a lot of acoustically difficult rooms for a longer period of time, we tried to accomplish everything correctly this time. That´s why we decided to take an acoustician to plan the rooms. We found an empty hall in which we could have realized all kinds of room dimensions. The most important thing for us was a good translation in the bass. Regrettably I´m only able to post these design plans in a rough form. After having worked for about a year at the control room and the studio we experienced that the control room did´nt sound as we had expected. After a measurement we quickly noticed that the reverberation time was much too long and we had similar strong problems with the bass than before (+-15db). We would have had each option with the dimension of the room and even a ceiling height of approx 4m would have been possible. Later on we more and more optimized the room by the help of with further acoustians. Even after that we still had continuing translation problems in the bass and indeed an EQ did´nt solve the problem either. There were still some strong dips below and above 100Hz. Meanwhile I had tried to work-in this matter here in the forum, by the help of some books and asked here for some advice. A forum user recommended me to cover the complete anterior half of the room, strongly absorbing (20cm Rockwool+20cm wall distance). Below the ceiling we hang up a thick cloud (20cm). Months later, after several measurements and thousands of speaker positions, we finally thought having found the best position. Based on the thick rockwool there are at least no strong dips any more. The dips in the bass were presumably caused by low ceiling and the nearby walls. Actually there aren´t any bigger problems regarding modal ringing.

Hi Michawave, and welcome! You certainly do seem to have a sad story there. I'm curious about one thing on your floor plan: You show some free-standing "slats" in the room with 20 cm of insulation behind them, but they are not sealed, there is no cavity containing the insulation. In other words, on your plan there is no "box" surrounding the insulation at the back: it appears to just be the slats, and then the insulation, and nothing else. Why is that? I'm trying to understand what effect that is supposed to have. Also, you have two large red triangular areas marked "3 x Helmholtz". What are they supposed to be doing, and what frequencies are they supposed to be tuned to? What are the dimensions of those? I'm no expert at all in this area, but to my eye, the layout of your treatment seems rather strange, and does not seem to follow any of the common principles, such as LEDE or DEDE. Did the acousticians tell you what they were basing their designs on? To me, it looks like you have reflective surfaces right behind your speakers (the slats), with no absorption, it seems like you have no absorption at your first reflection points, your entire back wall is dead, and the slats don't seem to be working as slats at all. Have you considered soffit-mounting your speakers? From what I've read, that really does help to tighten up the bass and improve imaging. Have you considered some form of diffusion on your rear wall? The studio isn't that big, but it looks like you have around 4m from your head to the back wall, so it might be worth a shot. What about the ceiling? What is it made of, and how is it treated (apart from the cloud)? But to me, the strangest thing is those slats standing up in the middle of the room, with no sealed cavities behind them. Maybe if you could post some photos of the room and close-ups of the treatment, so that folks here can get a better idea of what you have there. - Stuart -

Hello Soundman, thank you for your fast answer. the slats at the front are only to reflect some highs and mids back into the room. That is not a slat resonator with a closed cavity. We´ve constructed the slats because i often get a feeling of pressure in my ears, because there was to much absorption. I know its not perfect....for me its more a temporary solution that i can work in this room. The Helmholtz are tuned to 3 different frequencies which ring to long (between 40 and 120hz). But at the moment i closed the wholes at the front with some fabric, because the insulation(wall) is standing in front of them and i don´t know if they would work. They were build bevore we put all the insulation in. I think the original design is based on the reflection free zone principle. (imagine the room without the insulation at the front which we build a year later on, to control the strong dips in the bass). Later it got more and more a Lede room. Yes....the spaced slats (behind the speaker) (spaced with 5cm) only reflect some highs back into the room, so that speech etc. is not to dead. The slats at the sidewalls are angled to prevent reflections. Actually the complete front is variable build. Yes, i considered suffit mounting but i feel more comfortable with near or midfield listening and working from my personal experience. But that shouldn´t mean i dislike suffit mounting. Perhaps its a possible solution?! Ah yes...its not in the drawing; at the moment i placed some self build diffuser/reflector at the rear wall in front of the insulation to get a longer rt60 so that it will not get to dead. (angled so that it does´nt reflect back to the listening spot). By the way speakers are Genelecs 8050. kind regards and thx so far

I would diffenately be asking for my money back from the "acoustician" The angles in the outer wall seem strange too, with that little kick half way down? When you say "stone", do you mean brick? You saud you had the option of a 4m ceiling height, what did it end up being? And why did it not get built with a room ratio in mind? It's very sad lil

Yeah...thats true. It was a long process and we got some money back. The last chance was to bring it before the court but then we had to select statutory consultee etc.... With this little payback we builded some helmholtzresontor and bought some basotect to prepare the bad angled walls and the reflection points and in order to bring the reverberation a little down. The problems in the bass still remained. Based on a tip we decided to build the complete front with very thick insulation to nail these deep dips from sidewalls an ceiling. yes it´s brick...with some insulation(5cm) and than two-part gypsum board on it. Ah...the average ceiling height is 2,7m. The ceiling is slightly angeld and build of gypsum. Perhaps its a sulution to place the speaker near the frontwall and reduce the increased bass with an eq? or is this a bad idea?

I hope Ethan or Rod or Andre or someone like that can offer their opinion on what you should do here. I have some ideas, but they would just be educated guesses, whereas those guys really know what they are doing. But anyway, one comment:

Perhaps its a sulution to place the speaker near the frontwall and reduce the increased bass with an eq? or is this a bad idea?

For what it's worth, Genelec dos NOT recommend using any kind of EQ with their speakers, except for the EQ controls on the speaker itself (if any). They sent me a lot of very useful info when I asked, while I was designing my soffits, and among that was advise to never use EQ in you monitor speaker path, do to the possibility of introducing phasing issues. Genelec does sell soffit mount kits for some models of speakers (not sure about yours), and they told me that those speakers that can be soffit mounted already come with bass roll-off controls. Placing your speaker up against a SOLID wall is similar to (but not the same as) soffit mounting. However, I'm not sure what it would do with those slats of yours, since they are not a solid wall! I doubt they would work anything like an infinite baffle, or even an ordinary wall. I can't tell you what to do in your room, but I can tell you what I'm planning for my room, and maybe you can take some of that and apply it in your room: My Speakers will be mounted in concrete soffit panels, angled at nearly 45 degrees (towards the mix position) and tilted down by roughly 12 degrees. In my case I need those angles, as my room is much smaller than yours. In your case, you can probably use 60 degree angles and zero tilt (depending on your console, desk, etc.). The concrete might be covered with acoustic cloth, or I might just leave it bare. The space between the soffits will be deep absorption, several inches. The space under the soffit panels, below the desk will have bass traps in it, probably hangers. The side walls will be splayed, with slats on them, and deep absorption at first reflection points. The floor will be laminate over concrete, and the ceiling will be 100% absorption (several inches of mineral wool, with acoustic cloth for aesthetics). There will be two large bass traps in the rear corners, diagonal, floor to ceiling, and the rest of the rear wall will be absorption. I might cover the mineral wool with thin plastic of sort, after testing the room, to return some of the highs. I might add or remove slats on the walls, as needed. I might add extra bass trapping in the rear wall/ceiling corner and other corners, if needed. I might make a few other minor changes, as needed. That seems to be the general consensus here for a good-sounding room, and seems to have been implemented successfully in many studios built by folks here. That's about all I can suggest, with my limited knowledge. But it seems to me that your solution will be along the lines of removing a LOT of that stuff (perhaps all of it), since it obviously isn't working, then starting again from bare walls, using one single design philosophy, instead of the hodge-podge mixture of stuff that these "acousticians" have dumped on you. A question about your floor: What is it made of? Is it floated?

as shortcut...(i will read your post again tomorrow with a clear brain) :) yes, the floor is floated and is made of parquet.

yes, the floor is floated and is made of parquet.

Ahhhh!!!! Now that IS interesting! I'm wondering if that might be a large part of your problem!!! Can you post details of EXACTLY how that floor is built, layer by layer, starting from the ground upwards? I have a hunch.... - Stuart -

the floor buildup(from the bottom up) ..... a)cement floor... b)1,5cm insulation c)floating floor plates (image) d)glued parquet (on the floating floor plates) to give less resonanz greetings

OK, that's not the kind of floating floor I had in mind. It might be part of the problem, but not the kind I was imagining.

....are there no further ideas to fix this room a little?? :|

Take out the floating floor and glue the parquet right to the cement.