Design of control room for project/home studio asymmetry..

Thats nice! :D Thanks a lot Stuart :!: I hope these Genelec Soffit mounting kit is worth its money^^ I tried to come up with something like a design for the soffit. Trying do get the geometry right in sketchup was somewhat hard for me, but I hope I made it: sketchup file Did I get the general idea? How big does the cavity with the speaker box need to be? I thought, the smaller it is, the more place I have for using hangers. The actual Soffit-Mount Box (from Genelec) which holds the speaker is not yet included in the design. How big does the gap in the lower part for sound entrance need to be? How to build the fake soffit wall? Maybe drywall, and laminate flooring on top? (can look nice, and laminate is quite cheap^^) Should I build the soffit throughout the whole corner, like I did in my design? Or just a small part, and the rest just cavity hidden by cloth? Doing the framing right will be not easy, it is also hard to simulate it in sketchup... :oops: I will ask a carpenter friend or my father on how to do this, they have more experience than me -_- One more time, thanks for your help stuart! Peter

Did I get the general idea?

Looks good to me! :)

How big does the cavity with the speaker box need to be? I thought, the smaller it is, the more place I have for using hangers.

Small is fine, but I wouldn't make it any smaller than that. Also, don't forget that you need a cooling path past the back of the speaker, for air to circulate. You don't want your speakers overheating.

How big does the gap in the lower part for sound entrance need to be?

John recommends around 12" (30cm).

How to build the fake soffit wall? Maybe drywall, and laminate flooring on top? (can look nice, and laminate is quite cheap^^)

I would use something a bit more massive for the base layer: At least one layer of 3/4" OSB, MDF, plywood, or some such. It needs to be very massive, heavy, rigid. You'd probably be fine with laminate flooring glued firmly on the front, as the final finish. That could look pretty good, I think! Nice idea. Just make sure that the laminate is very firmly attached, 100% glue coverage (no air gaps in the glue).

Should I build the soffit throughout the whole corner, like I did in my design?

That's the way I would do it, yes. Barefoot once commented that it is possible to switch to absorption once you get far away from the speaker, but I'm not too sure where you would draw the line, or how deep it would need to be. I reckon its better to keep the soffit all hard, then put thick absorption on the side walls, as normal, at the first reflection points.

Doing the framing right will be not easy, it is also hard to simulate it in sketchup...

Yup! Framing compound angles like that is a nightmare, with or without SketchUp. Things never seem to fit quite right... - Stuart -

Soundman2020 wrote:

Small is fine, but I wouldn't make it any smaller than that. Also, don't forget that you need a cooling path past the back of the speaker, for air to circulate. You don't want your speakers overheating.

Would I benefit from making it a little bigger? This is what the Genelec Flushmount Kit says about cooling: "The frame has openings covered with felt and is designed to leave a gap above the loudspeaker top when installed correctly. These are essential for the functioning of the loudspeaker’s reflex port and amplifier cooling. They must never be covered in a way that would restrict airflow. No paint or other treatment that may alter the characteristics of the felt may be applied to it." Sounds like I don´t need to care about the air circulation. But the whole idea is somewhat contrary to what people say about flushmounting on this site ^^ Maybe I should give the people at genelec a call, there are not many information about the system out there...

One more question :roll: In Johns design there is a little absorption panel in front of the lower part (right above the sound entrance gap) Should I do that? Or just wood all the way?

But the whole idea is somewhat contrary to what people say about flushmounting on this site

I agree! I've always wondered about the way their kit has the speaker sticking half way out of the baffle, and curious about how that can be considered "flush", since it sort of contradicts the meaning of the word! But I guess the engineers at Genelec know what they are doing!

Maybe I should give the people at genelec a call,

That's an excellent idea! It would be great to get their explanation of WHY the speaker is not flush, and also if that can be modified to a more traditional fully flush mount, with proper ventilation.

In Johns design there is a little absorption panel in front of the lower part (right above the sound entrance gap)

That provides additional balancing of the overall room absorption, and also deals with reflections from the back and sides of your desk, console, video monitors, etc. But I don't think it is critical in your case, as the soffit is so tight up against the desk. So if you can fit it in, then it would by good, but not essential. - Stuart -

Hey Stuart, again some more questions coming up here^^ About the hangers this time From what I´ve seen, John uses the front corner only for the mid sized Hangers under the soffits. Will the big hangers in the corners work properly with just a 30cm gap? I`m imagining the bass building up in the corner at my fake-wall, an not enough sound entering the hanger-cavity to mak it work properly? But maybe it would work just fine, I´m unsure there. I can get "weichfaserdämmplatte" wich seems to be a good replacement for homosote. John suggests 12mm homosote with 25mm insulation on both sides. Will 20 or 30 mm of insulation do as well? What about the spacing of the hangers? John suggests 20 cm, but then i cannot put in a lot of them. Can I hang them a little closer, so that i can fiddle in a few more?

From what I´ve seen, John uses the front corner only for the mid sized Hangers under the soffits.

True, but he doesn't normally have rooms shaped like yours! :) I'm just trying to make the best use of the additional space to the outsides of the soffits.

Will the big hangers in the corners work properly with just a 30cm gap?

Yes, they will work fine. Not as efficient as if you had more space, but still good.

I`m imagining the bass building up in the corner at my fake-wall, an not enough sound entering the hanger-cavity to mak it work properly? But maybe it would work just fine, I´m unsure there.

Bass does build up in corners... including the floor/wall corner, which is why you need a large gap into the soffit down at floor level, where the bass is. John recommends a 12" gap down there.

Will 20 or 30 mm of insulation do as well?

Yes. The thickness is not critical.

What about the spacing of the hangers? John suggests 20 cm, but then i cannot put in a lot of them. Can I hang them a little closer, so that i can fiddle in a few more?

As long as they don't touch each other, and have enough space to swing freely a little bit each way, then you will be OK. Just don't cramp them up too tight! - Stuart -

Wow, sometimes it is unbelievable how time is flying :shock: It took me until autumn to finally start working on my room... But finally I´m almost finished and was able to do some measurements today and come back to this site :D Stuart, I hope you are allright, its good to see that you are still around here helping people :D As you can see on the pictures, there are still some (mainly optical) things left to do, but the treament is installed. (I also have some pictures of the building process, but not too many, my sd-card with the pictures broke...) I finally decided to not go with the hanger/flushmount idea because it is not only complicated to build and eating up much space, but also I found no realiable information on Genelecs flushmounting system and I have heard of no space actually using it. So I feld on the save side to use your first suggesstion, which was using superchuncks and absorbers at early reflection points and behind the speakers. I built my superchuncks in every available corner of the room. It was not so easy to do it on the ceiling corners but had to be done, as I can´t really use my rear corners (because of the door and window...) I also build a big absorber on the rear wall. I angeled it, so that I don´t loose to muche space for seating can still adress more deep frequencies. What still has to be done is building a cloud, but you suggested to wait for the first round of treatmend to be installed, so here are the files: :wink: Here is my measurement file: https://www.dropbox.com/s/nnxc3jhn0hros ... .mdat?dl=0 Here is the old file for comparison: https://www.dropbox.com/s/ynfl0psqnllww ... rrect.mdat The RT60 is looking much better (mainly between 0.2 and 0.3), The lo freq. response and symmetry seem better, too, but I don´t know how much I might be able to improve them more. Please have a look at that graphs and tell me its not totally messed up :wink: The listening test was quite good, the bass and clarity are much better than with my old treatment. The stereo image is also much better, more defined and realistic. The almost 90° setup makes the stereo field quite wide but the stereo image is still stable and working for me. The sweetspot is not so big, but I think thats one of the disadvantages of the 90° setup... But no problem, I can live with it :wink: Please let me know what you think about the measurements, All the best, Peter

I'm really sorry to have to tell you this, but unfortunately, the hosting service for the forum screwed up when they moved us to a new server last week, and they somehow managed to lose all photos that were uploaded between the 15th and 21st of December... including yours! So if possible, please could you upload those again. Just edit your post and re-insert the photos in the correct place. That should fix it! Sorry about the problem!!! :oops: - Stuart -

hmm, actually this whole post had been deleted. Then I wrote a completely new one which has been deleted too, then the old one came back, just without pictures... :? Here are the pictures, but these are not so interesting, there are still some things to do (including changing some colors) to make it look good. Picture quality is also not so great, I will make better ones after I finished everything. But what do you think about the measurement? https://www.dropbox.com/s/nnxc3jhn0hros ... .mdat?dl=0

That's a pretty good improvement! Much better. There's still some modal ringing going on at around 51 Hz, which might be difficult to treat further as you don't have much space left in the room for that! But it's nowhere near as bad as it was originally. What do you have on the side walls right now? I'm pretty sure that mode is related to the roof width, so if you could get some 703 on the side walls, that might help. I know you don't have a lot of space there, but anything is better than nothing! There's also a slight issue with the decay times in the high mids, so you might want to consider doing something about that. I can't believe I'm going to say this, since I practically NEVER recommend it, but in this case it is what your room needs: carpet. Ordinary commercial thick-pile carpet should do what you need there. So you could try a throw rug on the floor, and see if that helps. Normally carpet is not used in studios, but in your case, I think it will do the trick. But the room is way, way better than the first time! Major improvement. - Stuart -

Hi Stuart, thank you for your comment :D , I hope you had a good start into 2015 I´m happy to be on the right track with my treatment Actually I have some space left at the sidewalls. I hoped to keep some free space there for video equipment / instruments. But if some more treatment will help with the modal issues I will do it. I also think there is still a small flutter echo between the sidewalls, especially because I have not treated the window/radiator and door yet(which are opposite to each other). I was thinking about maybe using thick curtain to adress that? Or maybe the flutter echo is from floor to roof (the roof isn´t treated at all yet), in this case the carpet would do the trick. Or maybe some kind of thin ceiling panels on the roof? Originally I planed to build a cloud, wouldn´t this also help with the modal ringing if it´s hard backed? Maybe I could also build a tuned panel absorber for 51hz mode. The room is not THAT small, I still have enough space left. Maybe a panel trap could even be built on the ceiling?

Actually I have some space left at the sidewalls. I hoped to keep some free space there for video equipment / instruments. But if some more treatment will help with the modal issues I will do it.

You could test it out without actually building anything: Just put a couple of panels of 703 up against those walls, and do another REW test to see if the effect is worthwhile.

I also think there is still a small flutter echo between the sidewalls, especially because I have not treated the window/radiator and door yet(which are opposite to each other). I was thinking about maybe using thick curtain to adress that?

You could attach acoustic absorption to the back of the door, probably. If that's not enough, then a really thick, heavy, lined curtain on the window would probably fix it.

Originally I planed to build a cloud, wouldn´t this also help with the modal ringing if it´s hard backed?

Yes, it probably would help a lot.

Maybe I could also build a tuned panel absorber for 51hz mode.

Not a good idea. It's MUCH harder to tune such a trap than the text books tell you about. Yes, in theory you could do that, and you'd probably get a reasonable effect, but hitting exactly 51 Hz with a panel trap isn't as easy as it sounds: The depth would need to be pretty big, so it would take up a lot of space, plus you'd have to place it in the middle of one of the two surfaces that is causing the mode. Having a very large, deep box sticking out into your room might not be very pretty! I'd just go with more bass trapping.

The room is not THAT small,

It is acoustically! The wavelength of a 20 Hz tone is about 17 meters, so in order for your room to not be small acoustically, the shortest dimension (height) would have to be at least that big, and the other dimensions (length and width) would need to be proportionally bigger. Only things like concert halls and aircraft hangers are not acoustically small.... :)

Maybe a panel trap could even be built on the ceiling?

Only if the 51Hz mode is related to room height... If it is related to the width or length axis, then placing the trap on the ceiling would not be very effective. It needs to be at the point where the pressure node is located for that mode. I didn't check back, but I don't recall which axis your 51Hz mode is related to. Is it a vertical mode? - Stuart -