Need advice with Small CR design

Hi everyone i trying set up design for my CR in my home studio and after studying Acoustic im getting more and more confused. I have small room (on pic) and im trying figure out how it should be optimally set up. I have to sitting position based on 38% rule and for me looks 1 position as more useful than 2 position. Second big problem is that in this room is wall with open fire (never used) and with two gaps as you see on picture. Window is in centre but with widest size of the room. I had try many ideas but if i use 2 pos tan right speaker will be in part of window in second position i will have large unused space behind desk. Cables from LR are coming from left top corner (bottom left corner from window wall). Walls are from bricks, i have no neighbors near by. I will really appreciate if someone can give me any advice how to sort those problems. Thanks

So i have been little bit experimenting and i have came with this plan. I can fill window from that side because is fixed and i leave only opening part free. I cant reach right ratio for room anyway so i thing tis is best solution i can do in this situation. This is just basic i will now work on back side. If anyone has any idea about corner angles please let me know.

Here is what i design for back wall. Should i stay with this angle or should i use smaller slope as on picture? I had attached SKP of back wall designed trap as in pic

Welcome to the forum Stan! Okay, first a disclaimer: I am just an avid reader, rather than a practising acoustician. I am sure some of the others will be able to chime in, if I put anything wrong. I would choose your second layout for these reasons: - Speakers firing along the long wall (preferable) - More symmetry with speakers and boundaries. In acoustic terms your room is small, which has some implications on how you would treat it: - Absorption is your friend. - The lowest room modes are around 45Hz and 67 Hz, and above 80Hz where they are more dense. - You may need specialised traps to handle 45Hz & 67Hz. - The back wall is too close to the listening position for diffusion. I would make the back wall as absorptive as possible I would suggest you have a look at the following topics: SBIR - http://www.genelec.com/learning-center/ ... cellation/ Speaker placement - http://www.genelec.com/learning-center/ ... estanding/ First reflections and RFZ design And this if you are willing to experiment with a more complicated design to tame the low modes: http://www.gearslutz.com/board/bass-tra ... rbers.html In you diagram you have added yellow 'treatment'. It is important that you specify what this is exactly. Colm

Also, perhaps someone more experienced can comment on the problem of asymmetrical loading from the back wall. Would blocking up the gaps help?

First i want to thank you for opinion and advice thismanysounds. Im still working on design and i did a few changes actually brand new design. In first (second) plan i had big problems with first reflection so i've designed a new scheme with mounted monitors and now are all first reflections going behind me. Other thing a have done is that i have add big absorber above console. Back wall treatment is still open things and i was thinking about only absorbers as well. I will add more info and pictures and if you will have other advice please let me know. This Yellow thing in floor plan is part of window which will be filled with fiberglass.Those gray rectangles on picture with Top Absorber are monitor dismounted amplifiers. Sorry for my English but i do my best :) I will add better floor plan in next post.

Hi Stan, and welcome! :)

after studying Acoustic im getting more and more confused.

Great! That means you are fully qualified already! :) Seriously, acoustics is confusing, since a lot of it is not intuitive at first glance. Sound doesn't actually behave the way we think it should behave...

sitting position based on 38% rule

Don't go too crazy about 38%: it's not really a rule at all, just a guideline. As long as you are not at 25% or 50%, and are in th3 general ball park of high 30's to low 40's, you'll be fine.

1 position as more useful than 2 position.

The 38% rule refers to the distance from the FRONT wall of the room, not the rear wall. You definitely do want your mix position to be closer to the front wall, and far away from the rear wall!

i will have large unused space behind desk.

If I understand you correctly, then yes, that is correct: You do need a large space between your head and the rear wall, and a smaller space between your head and the front wall.

So i have been little bit experimenting and i have came with this plan.

Looks promising!

I cant reach right ratio for room

What are your dimensions like that?

If anyone has any idea about corner angles please let me know.

The soffit face should be angled at 30° in order to give the speakers the correct angle. The angled wall section that joins the soffit to the side wall must be angled such that it directs all reflections well away from your head. The easiest way to figure out the best angle is by ray-tracing.

Here is what i design for back wall.

That looks like two angled reflection panels and a limp-mass membrane trap. You might be able to do that, but it would be much easier to go with a more conventional design: superchunks in the corners, and thick absorption on the rest of the rear wall. - Stuart -

Thank you Soundman2020 for response. Im sorry for delay, but finally here are my Room dimensions. I will keep posted more often now because timber is in garage already. This will be one man job so it will go slowly but i hope than i will finis it before christmas :) I do mini serie about my studio build in my language (czech) on czech audio forum and i will post link on this thread so more people will be able to read opinions of professionals. I have more difficulties in this room as you see, cavities in front corners, window and heating under this window or marble step in front of open fire and doors to close of back wall. I have already changed floor coverage. I had take out carpet and lay down floating floor. Base is concrete witch id covered with 5mm thick foam matt. Floating floor is 12mm thick. I had add a few pictures and .skp for better understanding. I know, its not professional studio like i see here, but maybe one day i will be able to set one as well. :) Like you see i have decided to mount speakers in the wall because i hope that those cavities in corners mass filled with rockwool will little help to reduce radiation low frequencies in to room as my room has bad size ratio. Next i will come with 2D plan of build in walls.

Here 2D plan of new walls size plus angles and their main First reflection.

Hi All im still working on walls to get best possible result but i have still problem with first reflection from last part of walls. Like you see middle part will be just absorption, second part will have soffit mounted monitors, third part will be absorption (or resonators) and last wall resonators. In this scenario are direct middle rays crossed exactly in middle of room. Sitting position will be a little bit close to front wall but monitors are still to close to each other. I have tried 90° position witch give me option to spread them for few centimeters to side wall, but after that will be reflection from last wall to steep and will go straight front of me. I have tried other setup like you se on pic. Line in middle is half of room where green is front zone. I had tried even other angles of walls with monitors but still i have to same problem with last wall (resonator) reflection. I know that in this tiny room i cant do to much, but my question is: will be distance of monitors in my first plan wide enough to get acceptable stereo image. and witch plan is more suitable for my room. With 7 or 5 walls. I had attached .skp as well. Have anyone some idea or advice? Thanks

Uff ive been working a bit on this project again because i was not happy with result and this is i came with. Because i had main problem with last part of walls i started there. I had set up a new angles and i thing than now all first reflection are acceptable. BUT when i measured distance between monitors and sitting position there are not even. Is this big problem or not? Other Q is about RFZ. Is RFZ on picture just green or is blue as well? Can someone explain to me were are exact borders? I thing that RFZ is including both zones but im not sure. Thanks for any response.

What are those angled walls to be constructed out of? Also, what's the point of the short 28° section? I'm working on a similar design but my plan has the 2 adjacent sections continuing their angles til they meet. Easier for construction and a more popular approach. Is there a reason you have your soffits at 35° angle instead of the usual 30° needed for an equilateral triangle?

Hi nms, Those walls will be made from timber frames filled with rigid rockwool. Space behind of this walls will be mass filled with rockwool. Like you see i had tried to do just 5 walls model but i had never get good result with angles of first reflections and space between monitors was to narrow. Problem is that i have to fight with a few anomalies in this room like i have described before. At first this room is almost square which is bad. At second i have big window on left side which i would like to cover and many other aspects i had to fight with. Believe me i have in comp another 50 versions and this last version is i thing the best but i would like to have any opinion on it. Even in this first version of 7 walls construction were monitors to close each other so to get better stereo image i had to move them more to corners and now i got 20cm on each side and space between monitors is now 200cm. This is maximum i can get in this room. Because all of those problems i had to add other angled (absorber) wall. I had read Johns article about 60° or 90°soffits and he says that only difference is smaller (narrower) space for listening. If i had understand correctly there is no rule but 60° is standard. So for my need i had to move soffit walls 5° forward. All decisions i had to made are based on situation in my room.

Like you see i have decided to mount speakers in the wall because i hope that those cavities in corners mass filled with rockwool will little help to reduce radiation low frequencies in to room as my room has bad size ratio.

The basic concept is correct: "flush mounting" your speakers like that is a very, very good idea, since it eliminates many of the problems caused by having speakers close to walls. This is called "flush mounting" and also "soffit mounting", and is excellent. So you have the right idea. However, there are several problems with the way you show it in that diagram: First, the front panel of the soffit must be totally flat: It cannot have those "webbing" shaped things sticking out around the speaker. The reason why this is called "flush mounting" is because the front face of the speaker must be totally "flush" with the front face of the soffit. Acoustically, then become one single panel that acts like an "infinite baffle". So even though your webbed design looks really nice, it would be a disaster acoustically. That needs to be fixed: the front panel of the soffit must be perfectly in line with the front panel of the speaker itself. Basically, the soffit panel is an extension of the speaker box. Next is the tilt angle and height: you show your speakers raised up very high and titled down at a steep angle: once again, that's a bad idea acoustically, even though it looks nice. The acoustic center of the speaker should be located 1.2m above the floor, and the speakers should not be tilted at all. There is no reason to tilt them. Tilting your speakers creates many, many problems acoustically, and should be avoided if possible. If you really have no choice and HAVE to tilt them, then the tilt angle should NEVER be more than 10°, and preferably no more than 7°. I have never tilted speakers more than 5°, since it just complicates things so much. So that needs to eb fixed too.

Here 2D plan of new walls size plus angles and their main First reflection.

That is OK; and will work, but I think you are making it more complicated than it needs to be. You have seven different angled pieces there, from your front wall to your side walls: I never use more than five, and I try to keep it down to three whenever possible, to simplify construction, and also to make the soffit surfaces as large as possible.

but i have still problem with first reflection from last part of walls. ... Have anyone some idea or advice?

Make the last section smaller, and angle it more.

Is RFZ on picture just green or is blue as well?

Just the green zone.

Also, what's the point of the short 28° section? I'm working on a similar design but my plan has the 2 adjacent sections continuing their angles til they meet. Easier for construction and a more popular approach.

Right! :)

Is there a reason you have your soffits at 35° angle instead of the usual 30° needed for an equilateral triangle?

The equilateral triangle is just an ideal, but is not written in stone. You can adjust the angle if you have to, to make the rest of the room geometry work out. You can go up to as much as 45° in extreme cases, but it's probably not a good idea to go beyond 40°, as you start to get "head shadowing" effects beyond that in small rooms. But 35° is fine. - Stuart -

Thanks Stuart to clear problem about soffiting and angles. My problem is that i have NS10's that should be on front (as on pic) and soffited monitors need to be a bit above. If i would not move those up they will be covered by NS10's because there is not enough space to leave both on side of each other at the same level. My first suggestion was to build tight box for monitors from 1'' MDF filled with hard foam. Stand and construction would not be attached to main construction as is in T.Barefoot plan. This mean leave small gap between monitors box and front wall. Those angled stripes on side of monitors was my first suggestion but after that ia was thinking to build QRD skyline instead, to build mass around those angled monitors. I know its crazy and after your explanation i have to reconsider what and how to set both pairs to fit them both on right place. Do you have any suggestion how to sort positioning of both pairs of monitors? Thanks Stan

If i would not move those up they will be covered by NS10's because there is not enough space to leave both on side of each other at the same level.

There are physical limitations to what can be done acoustically in any given room. The smaller the room is, the fewer options you have, and sometimes you have no choice but to sacrifice something. Do you REALLY need the NS-10s in there? Sure, you do need to check your mixes on those, since they are a great reflection of typical poor home speakers, but you could do that just as well in another room...

Do you have any suggestion how to sort positioning of both pairs of monitors?

The only other possibility I can think of is to separate the NS10s as far apart as they will go, and increase the toe-in angle accordingly, so they no longer interfere with your mains. However, in a room that small, they ARE going to interfere with your mains, no matter where you put them, simply because of their size and location. Even they way you had them, down below the mains, is going to be a big problem, since they are in the direct path of the sound from your mains: there would be major edge diffraction, reflections, phasing, and comb filtering going on all around them, and no chance of clear sound from the mains. If your room were larger, then there would be places that you could put them, but in a small room like that, there really just isn't any place you can put them that does not cause distortion for the sound coming form your main speakers. - Stuart -