Little mixing room

Hi, my name is Thomas and i'm from Düsseldorf, a nice town in Germany. First of all, i want to apologize for my crappy english, i'm a bit out of training :oops:. I finally moved to a new apartment and got a room, in which i like to build a small studio. My goals: I would like to use the room primary for mixing, and secondary for doing some overdubs, if necessary. Ouverdubs could be a guitarr directly plugged into my mixer, or a vocaloverdub. Drumrecording is not planned. My room The room has a size of 4,45m x 3,81m x 2,43m. I hope it's not a problem, that i use the metric length system. All the walls are ferroconcrete, exept the ceiling, which is meade of plasterboards. (i hope that's the right description). I got the luck, that there is only a terrace over my room. The weather sucks generally, so my neighbors won't be there a lot :P . My buget As a student, i don't have much money, so 500€ would be the maxim that i can afford. The plan I already designed two different options with ScetchUp. I think, the easiest way to show you what i'm planning to build is to upload these files. I'm not shure about the angles. I've never done something like this before. I tried to mind all the things that are posted in this forum, but i need help, i think. Btw, next week, i will be able to mesure the room with a test mic, and i will post the results here! And here the skp files. They were to big to upload... http://www.speedyshare.com/files/239612 ... zimmer.skp http://www.speedyshare.com/files/239612 ... mmer_2.skp

Hi Thomas, Welcome! The dimensions of your room are reasonable: your room ratio works out to 1 : 1.57 : 1.83, which is not bad, and you have a reasonable volume, at about 41 m3. But the first thing you need to do is to rotate your layout by 90°. Right now, you have the speakers firing across the room (on the short axis), but you really need to get them firing down the room (long axis). It looks like the best way of doing that is to have the desk facing towards the window, with the speakers on each side of the desk. With your current design, your head is on the worst possible place in the room: Right in the middle! You need to try to get your head positioned at about 38% of the distance between front and back walls (that's just a guideline, though), then arrange the speakers so that they form an equilateral triangle with your head. The basic layout of your treatment in the first plan looks OK, so all you need to do is to adapt it to the new orientation of the room. You also need to add treatment at the first reflection points on the side walls. Make those changes, post the updated SkethUp, and we'll take another look! - Stuart -

Thanks for your quick respond Stuard, i really appreciated it! I've done a new designe of the studio, but i got a few questions first: 1. You recommend to rotate the room about 90° clockwise. But if i do that, it won't be possible to build the back absorbers at the two corners, because there 's the door to enter the room. isn't that a problem? 2. In the new plan, i push the whole workingdesk to the wall, so that my head is positioned at about 38,29% of the distance between front and back walls. Would that be enugh? 3. In the actual plan, it is only possible to place an absorber at the right wall, because of the window at the left wall. But i've planned to hang a heavy weighted curtain in front of the window. Would that be enugh absorption? Don't get me wrong, i'm not to lazy to change the plan, but i'm really worried about the back wall. But if it is more important, that i rotate the listening position then having some absorber in the back corners, then i will change the whole plan! Thanks, Thomas! And the .skp file: http://www.speedyshare.com/files/241484 ... mmer_3.skp

1. You recommend to rotate the room about 90° clockwise. But if i do that, it won't be possible to build the back absorbers at the two corners, because there 's the door to enter the room. isn't that a problem?

Well, you still have place for the one on the right rear corner, and you could probably build a "gobo on wheels" type trap, that you simply wheel in front of the door when you need to do critical listening. That would be one option. But a room has twelve corners, so if you can't get bass trapping in the two best ones, then you can go for the other ten as well.

2. In the new plan, i push the whole workingdesk to the wall, so that my head is positioned at about 38,29% of the distance between front and back walls. Would that be enugh?

That should be fine. The 38% figure is only a guideline, a rough starting point. You don't need to hit it exactly: as long as you are in the general ballpark, you'll be fine.

3. In the actual plan, it is only possible to place an absorber at the right wall, because of the window at the left wall. But i've planned to hang a heavy weighted curtain in front of the window. Would that be enugh absorption?

A really heavy curtain, pleated, would probably work fine. Or you might be able to build something on wheels here too, or even make a "plug" that fits into the window frame and can be taken out if you want to natural light in the room, or put back for critical listening.

Don't get me wrong, i'm not to lazy to change the plan, but i'm really worried about the back wall. But if it is more important, that i rotate the listening position then having some absorber in the back corners, then i will change the whole plan!

Well, it's not a "life or death" kind of thing, but overall I think there are more advantages to rotating the room than there are to leaving it as is. Acoustically, it makes more sense to have the speakers firing down the long axis, and you have an issue of symmetry with the current layout: your doorway looks to be right at the first reflection point on the left wall, and the window is recessed on the right. Once again, those won't make a huge difference, but to my way of thinking, making a whole lot of little changes can actually add up to some big improvements! - Stuart -

Here's a new version of my room. I've changed a lot of things, especially the 90° subject. I added a pivotable absorber in front of the door, so that it is possible to enter the room form outside without knocking it over. Also, i've put some absorbers on the sidewalls to prevent flutterechos. Once again, i'm not pretty shure about the angles for the absorbers. Are they ok? Just check my pictures and the .skp files! Thanks, Thomas! And the skp. file: http://www.speedyshare.com/files/242738 ... mmer_4.skp

That looks much better to me! However:

Also, i've put some absorbers on the sidewalls to prevent flutterechos. Once again, i'm not pretty shure about the angles for the absorbers. Are they ok?

For flutter echo, you should probably "checkboard" the panels, such that each panel is opposite a section of blank wall. The way you have it now, there are sections of blank wall opposite each other, and you will probably get flutter echo on those. Also, look at the image below: I drew a couple of lines to show one possible reflection from the right speaker off the left wall: As you can see, this reflection will get to your left ear, causing problems. You need to treat those first reflection points with absorption. < edited to add the missing image!!! :oops: > - Stuart -

Mhh, there's no picture... :cry: can you post it again? Thomas

I've changed the plan: I think that will work! Thomas

Looking good!!!! :) - Stuart -

So, i finally constructed some of my pannels and i'd like to share some pictures with you. So far, i just completed the framing and attached some molton to it: You may notice the holes at the side of the frame. I've planned to place the Rockwool between two webs of cord, so that it can't deform the molton. Which brings me to my next problem: i went to the building supplies store to buy some Rockwool, but there's plenty of different kinds of it, like 'Formrock', 'Cliprock', 'Flexiroc', etc. The guy at the store told me, that there's even so called 'Sonorrock', which is specialized for arcustic needs. And it's expensive, too. So, what kind of Rockwoll do i need for my needs? Is it really necessary to buy special, expensive Rockwool, instead of buying the 'normal stuff'? What kind of Rockwool do you use in your projects?? Thanks for your help, Thomas!

Hi folks! After nobody responded to my last reply, i had done some research by myself :mrgreen: . After browsing on some websides which contain informations about building a house, the most importend 'thing' for a arcustic absorber is the 'spezielle Ströhmungswiderstand' (specific flowresitance). Its unit is (kPa*s)\m². The webside (http://www.baunetzwissen.de/standardart ... 47753.html) advised a specific flowresitance (Rs) of 40 (kPa*s)/m². Is that true? Has someone a different opinion? The only Rockwool that satisfied this value is the socalled 'Thermarock 100' wich has a Rs value of 43 (kPa*s)/m². But it's very expensive and heavy. Is it really necessary to have this big Rs value? Greets, Thomas

After nobody responded to my last reply, i had done some research by myself

Well, the information you were asking for is actually in numerous places, all over this forum. The same question has been asked many times. I guess that's why nobody answered: folks get tired of repeating themselves over and over, when the information is readily available right here, and only needs a brief click on the "search" button to find it. As Glenn just demonstrated. :) - Stuart -

TomessAI wrote:

Hi folks! After nobody responded to my last reply, i had done some research by myself :mrgreen: .

Buy a man a fish and you feed him for a day, teach a man to fish...and he can build his own studio with less dependency on the will of others :)

Hi everyone! I resurect my old thread, because i want to change my roomthreatment. I was satisfied with it as long as my demand was just for hobby. Here are som Pictures of the actual 'design': But i was lucky to get some freelancing jobs with my mixes, and now i'm at a point where i could make some money out of it. So, first of all i mesuerd my old room at the hearingposition and was quiet shocked by the results. But see for yourself: As you can see, there is alot to do...it explained alot of the 'mistakes' i've made in it. After that i thought it was a good idea to mesure the empty room. So i put everything out of it and mesure again. So right now i'm at the point of planning a new design for my mixing room. There are certain limitations, because i live there for rent. Another bummer is the ceiling: it's made out of plasterboard and hollow. Over my room is a roof terrace from my neighbours. I assumed that there is some isolation between my ceiling and the concrete above it, but as you can see in the mesurements, there are some resonances, which could result out of it. And it limits me to hang heavy clouds or other things at the ceiling. I've read alot in this forum and really like the slat absorber design, because you are able to 'tune' certan heights to certan frequencies (if i understand it right). Can you give me some extra informations so i can calculate them? (if this is even possible...) So with that in mind i mesure at 3 different heights (bottom, middle, top) in all corners and in the middle of each wall. then i messured at the planned hearing position, the middle and 4 differen points (middle middel middle) The frequency responce below is the average of all mesurements. I would really appreciate your ideas for a suitable design! Cheers, Tomess!

i mesuerd my old room at the hearingposition and was quiet shocked by the results. But see for yourself:

It's hard to see anything useful from just those graphs. You'll have to post the actual MDAT file somewhere that we can download it and analyze it. You should also do the tests at a level of about 80 dB, not the 60 dB you are using right now. What is clear from the graphs (and the photos) is that you are going to need a lot of bass trapping in your room. The good thing is that the treatment you already build looks like it should be useful... But how is it built? What are those panels made of? - Stuart -

Hey soundman, thanks for your reply and sorry, that it took me so long to answere... Here is the mdat file: https://www.dropbox.com/s/8k7tl94vddhpq ... m.rar?dl=0 And yes, i mesure at 60dB, because i don't know it any better...my mistake. Is it really so bad? Beacuse i think i can't redo the mesurement in the near future... The pannels are made out of 8cm Rockwool Sonorrock (40 kg/m³), packt in 7µm plastic sheet. The cover is made out of Molton. And yes, basstrapping is my goal, but i want to make it right!

Hey, did someone had the time to take a look at those mesurements? It could really help if someone have a opinion...i'm a bit stuck here, don't really know where to start with the treatment. I would love to have some formulars to calculate some absorbers etc... :oops:

I took a look at the REW data, but I'm not exactly sure what I'm looking at! There are 20 different measurements in that file, with cryptic names that don't mean much. I assume that the refer to locations in the room where the measurement was taken, but but "bottom front edge L" doesn't tell me much about that.... Also, the levels are still too low: there seems to be a lot of noise in the measurements, so I'm not even sure if they are 100% valid. By increasing the level to around 80 dB, you will be greatly improving the signal-to-noise ratio, and removing doubt about the validity of the readings. There's no calibration file in there, so I assume that you didn't calibrate REW either. So what you should do is to first calibrate REW, both for the actual sound level in the room (using a hand held sound level meter), and also for your sound card, then take a new set of measurements with the mic located at the mix position, exactly 1.2 meters above the floor, on the room center line, and pointing upwards at 45°. Do one test with just the left speaker at a level of 80 dB, then do another test using just the right speaker, also at 80 dB, then one more test with both speakers on, and without changing any levels at all. Post that new MDAT file, and I'll take another look at it. - Stuart -