Help on design and more...

Hi everyone, :mrgreen: first of all pardon my english and thanks John for the site, incredible info here, i`ve been a reader here for more than a year and reading Rods book and also master handbook of acoustics a lot... I am form Argentina and materials here a very limited, for example: the thicker gypsum board i could find here is 12.5mm.. :cen: Ok lets get into The situation: I am about to have a space for my new Studio which will be like this: 7.6mt X 8.3mt ceiling: where it is the entrance the height is 3,5 mt At the back it is 4,5mt Theres one column than cant be moved (red) Exterior walls are made of bricks the weak spot is the ceiling, is made of iron sheets, wich I believe that dont count as a leaf..

John Sayers wrote:

shingles or sheets of iron wouldn't be considered a leaf as they aren't airtight so don't cause a spring in a MSM setup.

from viewtopic.php?f=1&t=14332 the GREEN boxes in the image is only furniture Bass traps are YELLOW(yellow) and BLUE are windows. (the skp file is very large..) Zone: the zone is calm, or i think so... (been in the place only a few times) I bought a Sound Level Meter (with A & C frequency curves) so ill make some measures of the area noise and post them. I dont share wall with any neighbours, the closest one is 2 meters away. (from the back wall) neighbours backyard on both sides and on the front a long hall. My Goals: g1. Have a "big" (for my dimensions) Live room g2. Have nice control room, not smaller than 4 meters long (because of sound, and the possibility of geting 2 or 3 clients feel almost.. "comfortable") I was aiming to reach Sepmeyer mode 1/1.28/1.54, or something near.. g3. Able to record drums without disturbing neighbours. g4. Have an iso booth g5. have some place for clients, outside the working space(LR CR ISO)... where they can sit.. g6. I know that STC are not good for measuring music frequencies, but... for attenuate as much as i can drums on the outside i need walls with high stc AND high TL on LOW frequencies, how much... i dont know, I was thinking on calibrate my ECM8000 with the SPL meter and record some drums at a distance of one meter.. check the lower frequencies levels and aim for a TL according to those levels... g7. No spelling mistakes in the post.... im shure ive already f :cen: Planning: p1. I will make a room inside a room, (NOT inside out, maybe the iso i can make it inside out) p2. Gypsum board will be 12,5mm thick (cant get thicker) p3. Metal studs of 69mm p4. no green glue here.. p5. two layers of gypsum board in each wall (Check q3.) Budget: I would like to spend less than 7k (dollars) Not much.. i know possibly.. I might get some wood plates for free.. but dont know yet how much or the dimensiones, hopefully ill get enough for adding mass to the LR leaf (obviously walls AND ceiling) Questions: q1. Is my design ok? q2. Is the "g6" approach correct? q3. In order to achieve "g6" (TL low frequencies for drum....) What would be the best approach: make both, exterior ceilling and LR ceiling and walls using two 12,5 GBs (OPTION A) or leave the ceiling with one GB and the LR ceiling and walls with 3 GBs (OPTION B) for more mass thus more low TL? cant afford both walls with three GBs :( q4. about the GB problem (p2.) Ive been reading ir761 on page 361 where the TL on 50hz is low (15,6), and when a 16mm GB is used the TL for 50Hz is 18,1 (page 364) how much TL in that frequency range could be practical for a drum recording situation? :shot: I will have 69mm studs and air gap between studs of 150mm, and no cross brace, will this improve the TL in low frequencies? how can I calculate it? Well, Thanks very much for your time. I wish I could be clearer, and had more money.. jaja Thanks for reading :!: :mrgreen:

I could make the Sketch Up file smaller :mrgreen: its only the floor plan, once its ok i ll continue with the design See U :D

overall the design looks good. are you considering soffit mounting the monitors? on the isolation - assuming the walls and ceiling are decoupled - you're better off with the more mass inside if you have to make that trade off. if you go to studiotips forum and find the MSM spreadsheets from Eric Desart, you will be able to make reasonable calculations on the best allocation and spacing for the walls and ceiling. the steel framing for the ceiling though is going to be a challenge unless you can suspend that weight off the primary structure using isolation mounts.

gullfo wrote:

overall the design looks good. are you considering soffit mounting the monitors? on the isolation - assuming the walls and ceiling are decoupled - you're better off with the more mass inside if you have to make that trade off. if you go to studiotips forum and find the MSM spreadsheets from Eric Desart, you will be able to make reasonable calculations on the best allocation and spacing for the walls and ceiling. the steel framing for the ceiling though is going to be a challenge unless you can suspend that weight off the primary structure using isolation mounts.

Thanks gullfo! I read and learned a lot from you in this forum, thanks for your time, I was planning on standing the monitors, not soffit, because i think its much more difficult to soffit and if i make it not so good its more difficult to correct it, at least thats what i think.. :? just to get it clear, about the mass question you mean that the option B is the way to go, no? for the ceiling Im goning to use independent metal beams for the CR and the LR, and hung the steel framing from those beams, I was thinking on using "C" type, (at least thats how they call it here), ill make a SU and post it for a more graphic explanation. the spreadsheet you mean is MSMresonance03.xls? Im trying to compare the walls, dont know if i did it ok correct me if im wrong: in "relative dbs- build up metric" i entered in table 1 (reference): 25 mm 1300 kg/m³ 160 mm 25 mm 1300 kg/m³ (each GB 12,5 mm 650 kg/m³) 2GB air 2GB table 2 wall 1: 37,5 mm 1950 kg/m³ 12,5 mm 650 kg/m³ 3GB air 1GB but this shows 0db at 230mm cavity with and -1.5 at 160 mm, it means that with the "3GB air 1GB" design im loosing 1.5db of TL? or I entered something wrong? even if the TL falls 1.5db, it doesnt mean that im loosing that TL on the lower frequencies, or it does? By the way Gullfo, how far do you think i am from isolating a drum with two walls made of 2GB 12.5mm each? Ive read in ir761 page 12 that when non-loadbearing walls are ar 600mm oc the resonant frequency is lower, but What does it means 600mm oc? it means that studs are spaced 600mm? or on the center of the GB the screws must have a spacing of 600mm? (on the sides 305mm) or both? this is done ONLY when nothing needs to be hung from there? Thanks again gullfo, if you (or anyone else) needs information on anything about my design or the place im dealing with, let me know, im willing to help you help me :mrgreen: :D

the density seems off since each layer doesn't increase the density, just the overall mass. so if all walls are composed of GWB, just use the 650kg/m3 density. the 600mm "On Center" (oc) means the wall studs (or in the ceiling joists) are spaced so the center line of each member is separated by 600mm. correspondingly, the spacing of the drywall screws would be 600mm across the spans and 150-200mm along the spans depending on the fastener schedule.

gullfo wrote:

the density seems off since each layer doesn't increase the density, just the overall mass. so if all walls are composed of GWB, just use the 650kg/m3 density.

Ok, so then for the same cavity with I would be gaining 0,8db on the Total TL.

gullfo wrote:

the 600mm "On Center" (oc) means the wall studs (or in the ceiling joists) are spaced so the center line of each member is separated by 600mm. correspondingly, the spacing of the drywall screws would be 600mm across the spans and 150-200mm along the spans depending on the fastener schedule.

Sooo, studs should be spaced 600mm oc, ok Ive been reading this post viewtopic.php?p=20003 where knightfly said "Place the first layer, using half-schedule fastening (screws twice as far apart as normal)" but i tried to find exactly the distance with no success, and ended with a few more doubts... how much is twice as far apart as normal? on the second layer, screws should: pass trough the 2nd layer, the 1st and also the studs always? I made a SU with an example, with screws, backer rod, caulk, etc to see if its ok the way i think things should be done? if not please point me the way :wink: Thanks!

so if the normal spacing is 200mm along the stud or joist, then you could put them 400mm apart on each layer and stagger so ultimately you're penetration ends up being pretty much the same 200mm. usually on the edges you would increase the frequency to 175mm/350mm. also, staggering the seams of the drywall - sealing each layer and criss-crossing.