Mini-Prod Studio - Finished

:oops: thank you phybeau. I'm doing my best. 38% is in my design (right now) relative close to the 3rd axial mode (when I'm getting this modal stuff right). as you can see in this sketch the theoretical ideal position would be closer to the speaker or a little closer to the middle. i guess when all is done (some day) I will have to carefully listen and measure to what is really happening. and that could end up somewhere around 38%. from the theoretical point of view (see idealized sketch) it should be sth about 44%. there are sooo many things one has to take into account that it is nearly impossible to get everything right in terms of "right". if i would get my speakers closer together I would lose the "ideal minimum distance between speakers rule". also: the speaker would sit exactly on an axial mode widthwise. (if I would long for the 38% rule...) I hope I get all this stuff right!? and for the record: this is one thing I'm really a little scared of when building the soffits. IT ALL MUST BE PRETTY ACCURATE. it would be easier to have speakers on stands: to find the right positions for the speaker simply move the stands. a soffit is fix and for perfect symmetry both speakers must have an identical angle. in every direction. :? puh...man, that will be a challange. but on the other hand building soffits will have a lot of pros. floating floor: I've read paul's thread several times. I've searched for and read loads of eric desart's posts. I know that a floating floor needs mass. and i know that an elevated wooden floor isn't a good choice. :cop: but it is annoying to record an acoustic guitar in the tracking room while one cannot walk or step the beat or displace a chair in the ctrl room without the risk to record it also. this is my only concern and reason why I thought "I have to do sth!" "what about a floor?" maybe simple parquet underlayment and parquet on top will make a difference. for drums I'm planning indeed a "poor man's floating floor" also for the bass. but that's it. I don't need and I don't want a "real" floating floor (as I said above). I want to get rid of this tic tic when someone walks through the ctrl room while I'm recording a sensible signal in the tracking room... (maybe I should buy felt slipper for the artists) greetings, carsten

but it is annoying to record an acoustic guitar in the tracking room while one cannot walk or step the beat or displace a chair in the ctrl room without the risk to record it also.

That truly is annoying...! So if it is more the other way around (CR noise into TR onto recording) would several layers of mdf with GG in between not give any relief? They specificaly mention impact noise on their website. And maybe as a last resort, dare I mention it:.... thick carpet on the floor??? About the soffits, I'm sure you'll find a solution, just keep at it! You should maybe invest time in a simple try-out with your speakers: Stack the four corners with Rockwool, hook up the speakers and find out...

Hey Phybeau,

Phybeau wrote:

dare I mention it:.... thick carpet on the floor???

hehe...noooo way. I don't like carpet. I will buy a pack of cheapo uargh laminate and an underlayment just for the sake of trial and error. this will cost about 15,-€ maybe less. I'll put it on the floor and hear what happens...if it's fine (I guess it will) I can go (literally) this way. otherwise I'll have to research a little more. No GG! It is really and only to reduce walking noise. And this can be handled without mass I think. anyway. I'll let you know when I've tried it.

Phybeau wrote:

You should maybe invest time in a simple try-out with your speakers:

If it would be that "easy"... I already measured and tested a lot and have to admit that ideal and real are closer together than I thought. (at least from the simple modal point of view in an empty room...) But a soffit is like a wall and will change - I guess - a lot. also: the backwall isn' t build right now. and I'm really curios what will happen to the modes if the slanted backwall is in place. Since I'm here I learned a lot and this will never end. In the past 3 months I also tried to figure out how I could treat the live room and was amazed how much changes when you simply put 2 bags of rockwool in a corner. I wonder, I really really wonder, how the pros are able to predict what which treatment and where installed will have what effect? It's like a chain reaction. you put the 2 bags in the left corner and suddenly a peak in the right corner is gone BUT another peak (frequency) arises... this is soooooo :cen: damn too much for my little walnut brain... but I'll keep at it. I will crack this nut! :horse: so long, carsten

me again... :roll: I was wrong with my assumption that 38% is close to the 3rd axial mode...it's close to the 4th axial mode. It would be nice if someone with more knowledge than me (nearly everyone here ;)may eventually check my approach: Step 1: I need a new solid backwall due to circumstances I haven't recognized before (the original backwall is a brickwall with lousy isolation.) Good thing is that I can slant the wall in order to hopefully tame the modes a little. new dimension will be the average of longest+shortest length divided by 2: 446cm (it was 463cm originally) step 2: I used Bob Golds finest Room Mode Calculator with my dimensions: Length: 4.46 meter width: 3.63 meter heigth: 3.34 meter hit the calculate metric button et voilà: step 3: first (1,0,0) mode: 38,6 Hz -> 8.92 : 4.46 : 2.23 meter (Wavelength, 1/2, 1/4) to copy this in sketchup I simply measured with the Tape-Tool 2,23m (8,92 is out of bounds, 4,46 is the room length) from the frontwall and drew a line: step 4: second (2,0,0) mode: 77,1 Hz -> 4.47 : 2.23 : 1.12 meter again I used the 1/4 wavelength (1,12 meter) measured from the front, drew a line AND NOW I took the 1/2 wavelength (2,23 meter) and measured from the just drawn line (not from the front) and drew a line: (this is correct, isn't it?) step 5: third (3,0,0) mode 115,7 Hz -> 2.98 : 1.49 : 0.74 meter first line is 0,74 meter from front second line is 1,49 from first line third line is 2,98 from first line step 6: fourth (4,0,0) mode 154,3 Hz -> 2.23 : 1.12 : 0.56 meter first line is 0,56 meter from front second line is 1,12 meter from first line third line is 2,23 meter from first line fourth line is 1,12 meter (1/2 wavelength) from third line! step 7: fifth (5,0,0) mode 192,8 Hz -> 1.79 : 0.89 : 0.45 1st: 0,45m from front 2nd: 0,89m from 1st line 3rd: 1,79m from 1st 4th: 0,89m from 3rd 5th: 1,79m from 3rd :?: are step 5, 6 and 7 correct? thanks! carsten

aaahhh...hmmm...yes...the floor: I need a floor. impact noise between ctrl and live room is unbearable: 30mm compressed rockwool. 1 layer 22mm particle board. finish will be 22mm real massive spruce deal board - no laminate. no parquet.

That should work reasonably well, but you'll probably need more than just 2 layers of wood in there: By "particle board", I guess you mean MDF? You need it as dense as possible, and you need several layers. You are doing this for the impact noise, not trying to float the floor, correct? Also, by "compressed rockwool", I guess you are referring to something similar to 703?

and like always::: every little bit has already been discussed and explained: the famous: Floating Floor Thread

But it seems like what you are trying to do is more like a drum riser than a floating floor. There's no reason why that shouldn't work, since you are not basically just trying to stop the transmission of impact noise into the floor.

I wonder if this kind of transmission would also happen if the concrete would be directly on solid earth (ground level)?

I reckon it would, but to a lesser extent since it would be damped by the entire planet! So you'd still get some impact noise, but at a lower level, and the "ringing" would be gone.

About the floating floor. I have to agree with Mika. In order to make it work, the topfloor will have to weigh 'tons' in order to make it's own (resonance) frequency very low. Paul Woodlock had some excellent research on this in his build diary, if I'm not mistaken. And it would work best if the separate walls were attached to those separate floors./quote]Yes, but Carsten isn't really talking about floating his floor! He's talking about isolating it from impact noise, basically what a drum riser does.

I've never seen anybody make a 'floating floor' with just a couple of layers of mdf (or similar) and GG in between.

Maybe you should take to Rod Gervais then! viewtopic.php?f=2&t=13361&p=93011&hilit=floating+floor#p93011 OK, granted, he does say that you need multiple layers of wood to accomplish that, which is more than Carsten had in mind, but it can be done.

It might be that GG doesn't work very well on these low frequencies, but you could try a search..

Actually, GG works BEST at low frequencies! That is exactly what it is designed to do, and exactly what it has been shown to do in independent lab tests. It doesn't do much at high frequencies, but it absolutely shines in low frequencies.

a soffit is fix and for perfect symmetry both speakers must have an identical angle. in every direction. :? puh...man, that will be a challange.

Yup! That's why I'm designing my soffits to be adjustable.... Think: "threaded bar and nuts" ... :) I'll have some limited ability to rotate the entire soffit once it is already in place, and also to adjust the soffit tilt slightly. Not much, just a couple of degrees max, but enough to compensate for my construction errors. I'm still working on how to also get a bit of adjustment in speaker distance as well, but I don't have that nailed yet. Like you say: So much to get right, and so many ways to get it wrong! - Stuart -

thank you stuart, what a great idea to build adjustable soffits :idea: I guess I should re-read your insanity-thread. Sorry, my thread's a little messed up (and also my english) with all my questions and blah blahs. with "impact noise" I simply mean "walking noise" -> when you tap (and tap means tap - and not: stamp to the ground like an elephant) on the ctrl floor you can hear it in the tracking room (when doors are closed). I don't want to stop heavy elephant's stamping bass ('cause I don't want to build a real floating floor) I just want to stop or reduce walking noise (High Heels clicking on concrete e.g. - not that I wear those...I'm thinking of my girlfriend...). That's why Phybeau mentioned thick carpet. -- particle board is a little lighter (700kg/m³) than MDF (740kg/m³) but has grove and tongue at it's sides. It's cheaper than MDF. "compressed rockwool" is (in this case) especially for floors (it's called floorrock in germany and rockfloor in the UK:). you can use it under concrete or the lighter version if you want a lighter floor with particle board or chipboard or OSB or Gypsum: the english datasheet direct from rockwool I don't know if this is comparable to 703. to be honest neither a drum riser nor a floating floor is my real demand for the ctrl room. I'm only longing for a slight damping. I hope this was a little clearer now?! thanks & greetings, carsten

me again... :oops: will building a soffit wall for flush mount speakers alter the room modes especially in front of the soffit wall? as you can see in the sketch the speakers would sit right on top of 1/4 of the width (mode 0,2,0) and that is known as bad - a no go! would a solid soffit wall anything change? btw: the red line marks 38% from front and is nearly exactly the 4,0,0 mode. the green line will be the listening position... the grid represents the axial modes (length and width). today I read this great thread started by mr. eric desart on studiotips.com: The 38% Rule from Wes Lachot and felt a little approved that I wasn't too far off the road with my considerations to have the listening position not exactly @ 38%. on the other hand: 44% was a little too much. right now I'm heading for 40-42%. cheers, carsten

as you can see in the sketch the speakers would sit right on top of 1/4 of the width (mode 0,2,0) and that is known as bad - a no go! would a solid soffit wall anything change?

I don't think it will change very much at all, since I recall reading that a speaker in a soffit will theoretically excite ALL modes that terminate on that panel, not just the ones that happen to be exactly where the speaker is. So I don't think it will make much of a difference. You seem to be very concerned about room modes, Carsten! Maybe you are taking them a bit too seriously? Modes will always be there, you have a good ratio (don't you???), and the treatment in the room should be designed to damp them anyway, so I wouldn't get too tied up in moving things around by millimeters to try to get away from bad modal positions. You already seem to ave good positions for everything (AFAICS), and I don't think you'll make dramatic improvements by sliding a speaker 1/64" here or a soffit 1/32" there... :)

on the other hand: 44% was a little too much. right now I'm heading for 40-42%.

Cool! That's roughly where I am with my design, too. So if that turns out to be bad, then we'll BOTH have bad rooms!!! :) Seriously, your room, speaker and soffit geometry seem to be fine, from what I understand of the subject, so I wouldn't get too hung up on polishing that very much more But maybe André or Ro or someone could chime in with some pointers??? - Stuart -

hmm, I was refering to - or rather had in mind - the drawing in f. alton everest's master handbook of acoustics (fourth edition) page: 283, figure 13-10, 13-11. it's about the modal pattern in rectangular rooms and how the sound field distorts in non rectangular rooms. and I thought the massiv front of a soffit wall might work similar in terms of distorting/shifting the modal pattern... btw: am I allowed to post these figures here (copyright)? but i guess you're right. don't worry - be happy... stop thinking - start building. c.

and I thought the massiv front of a soffit wall might work similar in terms of distorting/shifting the modal pattern...

I agree that it sure will change the modal pattern in the room: No doubt about that, I reckon. But the speaker will still excite ALL the modes that terminate on the surface, so the way I see it, it doesn't really matter of there is a peak or trough lining up exactly with the speaker, or if it falls several feet away: it will still be excited, since the entire surface acts as a baffle, and excites all the modes anyway. I think!?

btw: am I allowed to post these figures here (copyright)?

I'm no lawyer, but I reckon that it might fall under "fair use", as long as you provide full credit. I've seen others post pages like that here, so it's probably OK: But like I say, I'm not a lawyer, so I could be quite wrong. - Stuart -

stuart. I know what you mean and I agree. modes are modes and will stay modes. but I think I'm not able to properly articulate my thoughts. last attempt and for the sake of completeness: this is a simple copy of the figure I mentioned in my last post from f. alton everest's master handbook of acoustics, fourth edition, page 283, fig.13-10: on the left side you see the 1,0,0 mode in a rectangular room (5 x 7 meter) on the right you see the same 1,0,0 mode in a nonrectangular room of the same area. the sound field is distorted. now imagine what this may look like in front of a soffit wall?!?! wouldn't or couldn't that eventually solve my "speaker is in a null" problem? who knows... anyway. I should stop my guesswork. thanks for your patience, carsten

Regarding room modes and speaker location in your room, the speakers will be NEAR the 2,0,0, mode, not right on it. In addition, the non-rectangular splayed walls of the speaker walls will shift the location of the modes. It will be fine as you are proposing it. Andre

I replied in the thread. You are in good hands with Stuart and the others. Good luck and enjoy your studio! Andre

Andre, thank you very very much! carsten

hey folks, just a short one: I'm alive and building... the ctrl room looks great and sounds good. a little too dead imo. but i'm not finished at all...so let's hear what will happen in the following weeks. piccis will follow when I found my camera. two major issues: @ ~ 50 hz @ ~ 115 hz the 50 hz is something i don't know where it comes from. it's from somewhere in the building. maybe an air compressor... it's not from my system! i can still hear it when all my stuff is switched out. i have no clue. it's not too loud but annoying the closer one comes to a corner. the left corner/rear wall seems to be the spot with highest pressure. you can't really see it on the graphs and it seems that it ain't a big problem but it is really really annoying to sit and work in a substantial tone. (i haven't heard it until i build the rear wall with metal studs, 10cm rockwool and two layers 12,5mm gypsum) whereas at the right corner/rear wall 115 hz has an enormous pressure. and this ~ 115 hz is a major peak @ the listening position. so my plan is to use a slot resonator for the 115 hz hidden behind cloth (right corner/rear wall) and a panel trap hidden behind the murder chunk in the left corner/rear wall. is the slot resonator a good idea? it has been said that one should avoid reflective parts at the rear wall especially in a small ctrl room like mine (length roundabout 435cm - 455cm). i thought fabric on a frame in front of the slot resonator might tame the reflections...or am i wrong? the cloud isn't installed and no fabric. just rockwool behind thin plastic foil. measurements were made with room eq wizard, motu 828mk2 and a behringer ECM8000 mic piccis will come! thanks, carsten

me again =) i found some older piccis. enjoy. don't forget to read my question in my previous post concerning slot resonator in rear wall covered with fabric... thanki you carsten

here are two montages of my ctrl room as it is right now. still looking for a hint 'bout my question in the pre-previous post. cheers, carsten

That is looking great! A covered slot resonator should be fine for what you what acoustically. Andre

thank you very much, andré (with an e or an é?)! great. than i can go ahead. carsten

Carsten, I have been watching and waiting for you to get on with the finish work. Your famous door hinge router job told me this was going to be a nice finish job when all was said and done. And it is truelly looking very nice indeed. nice work Tom

wow. :oops: thank you tom! that's makin' me really happy! after a long break from october last year to february this year caused by a giant lack of planning and a couple of tours plus some kind of burn out I managed to start the last big 'n long building session. right now it's festival season so I am only able to work 3-4 days/week...long enough to get some things done and too short to see big progress happening. apart from that I'm still doing everything alone. just me and my brain. I really hope that I'll find some time to sort my trillionthousands of pics to share 'em with this superb forum^^ see ya =) and again: thank you very much! carsten

I really hope that I'll find some time to sort my trillionthousands of pics...

You know the rule here, Carsten: "No pics means it didn't happen!" :) So until we see the pics (and like Tom said, we are all DYING to see them, and turn green with envy at the quality of your craftsmanship), then you just didn't do a thing yet.... :lol: - Stuart -

carsten_d wrote:

thank you very much, andré (with an e or an é?)!

With an e. My parents were Estonian and Andres is the Estonian version of Andre and my maternal grandfather's name. When I was named, my parents wanted a Canadian name, hence Andre. It is not French, it is Canadian. Andre

Andre, you would have been Andy in Australia :)

And here's me spelling it "André" all the time! :oops: Sorry Andre! :oops: - Stuart -