New space - studio in Athens

will do!!! :thu:

The diffuser's dimension were calculated in order to tune it specifically for my room taking into consideration it's LF and HF cutoff, listening position (regarding SBIR, measurements and practical position), ISD gap, etc.

Have you considered modifying it into a fractal type design? This is a cool read that might inspire you to glue HF diffusers onto the LF diffusers. http://arqen.com/acoustics/acoustic-diffusers/download/ Greg

Gregwor wrote:

Have you considered modifying it into a fractal type design?

Not really, do you think it would be beneficial to do so? I mean my design works now for the low and high frequency cutoff of my room so what it is that would change if converting it into a fractal type? I don't know if I am missing the point here..I will download and read what you sent. Thank you!!!

Not really, do you think it would be beneficial to do so?

I think so.

I mean my design works now for the low and high frequency cutoff of my room so what it is that would change if converting it into a fractal type?

How did you sort out what your cutoffs should be? The change is that the fractals allow it to diffuse at very high frequencies which is never a bad thing. Greg

Gregwor wrote:

How did you sort out what your cutoffs should be?

Hi Greg and thanks for your time! :) J.H.Brandt has a spreadsheet available for all on his site which calculates these along with many other things. He also describes the best way to calculate it yourself and I quote: Low Frequency cut-off: 1. measure the distance from the listening position to the wall where the diffusor is to be mounted. i.e.; room length X .625, for the back wall. 2. calculate the frequency of the wavelength at that distance. i.e.; frequency = speed of sound / (room length X .625) 3. multiply that by 4. High Frequency cut-off: 1. Find the Schroeder Frequency of your room and multiply times 4. 2. The result of #1 will give you the start of the 'Ray Region' of the room. 3. Multiply the frequency of the beginning of the Ray Region times 4.  --- You can always go a bit higher than the recommended HF cut-off, but don't go lower than the recommended LF cut-off

Photo updates of my place. Steel framing for housing the face insulation: Framing and covering with LPDE (for insulation's dust free use) of the diffuser and the inner door cavities: Face insulation in place: Adding wooden slats for LPDE and/or fabric stapling: Finishing diffuser's cavity:

photo update part 2. Finishing inner door's cavity: Building inner "hangers" door: Back wall complete:

Attaching the measurements for the room as of now. Frequency responce got a lot better. Rt also getting close to 267ms target with the low end being partly there. ETC looks good even without first reflection treatments, back wall reflections kicking in lowered by 30db around 35-40ms later. Next move is building 3 ceiling clouds, 2 big ones for the front and middle part that will be 3 x 1.7m and a smaller one for the back 2 x 1.3m. Placed between the ceiling's concrete joists (which are coming down off the ceiling 37cm), will not cover the whole ceiling but leave a gap of 15 to 25cm on every side. Hardbacked with 20mm thick plywood and attach 10cm rockwool of density 40Kg/m3 (GFR=15KPas/m2) All 3 tilted down the same (at the front of the room) dealing with the reflections, also breaking modes and sending everything on back wall.. Will raytrace for exact angles. Sounds good? Still so much to do, clouds, first reflections treatment, front wall panels and behind speakers, side parallel walls treatment for flutter, possible reflective materials on spots to bring back what needed. Its been 2 years since I started..working alone on weekends takes time :) One step at a time, measuring and moving forward in respect to the results. Also sold my ATC20's to fund the purchase of ATC50's as the room is now bigger. Currently measuring with a pair of Events. (good thing FR is similar-not the flatness though..) The mdats:

Ray traced the hard back clouds. 25° angle for the front, 9° for middle and back seem to work in favor Nice having 4 meters high ceilings, some limitations due to ceiling joists, they are surrounded with insulation rolls as seen on previous posts. Plan to add a 80x50cm trap on horizontal front wall to ceiling corner, seems to be really important for a series of modes on lower spectrum (20-100Hz)

Wondering if it's better to add 5cm insulation 50kg/m3 (gfr=30kpas/m2) on cloud instead of 10cm 40kg/m3 (gfr=15kpas/m2), given that the RT is looking good on low end and I am just using the insulation up there to primary treat ceiling's first reflections. The hard back 2cm plywood will help breaking/redirecting some vertical room modes. The combination will help the flutter I have especially on middle part of the room. I know ceiling cloud isn't as effective as the rest of my bass traping so can't see a reason to make it deeper, especially if I don't want to end up too dead.. because I have more insulation panels to add like on first reflections, sides for flutter, for sbir (behind speakers), possibly center front wall.. also the front ceiling superchunk. RT needs to get down mostly on mid and high regions: Absortpion curves: Custom mix: :) Maybe someone who took a look on my measurements can help..? :)

I've tried to open your measurement files with REW 5.19, but it says that your .mdat file is not a .mdat file. :? Did you use the beta version 5.20? I'm on windows 10 latest updates...this happen bevor with other files from this forum and I can't figure out what's wrong... :roll: And I would love to see those measurements. :mrgreen:

TomessAI wrote:

I've tried to open your measurement files with REW 5.19, but it says that your .mdat file is not a .mdat file. :? Did you use the beta version 5.20? I'm on windows 10 latest updates...this happen bevor with other files from this forum and I can't figure out what's wrong... :roll: And I would love to see those measurements. :mrgreen:

Hi there, yes I am on 5.20 but I also opened these with 5.19 without problem..

And I would love to see those measurements.

If that happens to you I suggest you download the 5.20..some cool new changes and looks nicer too :)

The front cloud will be tilted down 80-90cm so I think I can extend the front horizontal upper corner trap by adding more insulation under the one I already have. I tested that and seems to work in favor judging from the frequency responce, reverbaration time, spectrogram. That's what I did, the before: And After: Some graphs: And the mdat:

To say that I'm impressed simply wouldn't do your work justice. I'm especially impressed with your hanger door!!! Wow! Your mdat loaded up fine on my computer and it look awesome. You're right that even the IR shows 1 reflection point to tame and the rest looks killer. You're on the right track and I can't wait to see things shape up even further. Did you consider lowering your first cloud and angling it differently in an attempt to prevent reflections from the ceiling beam? Greg

Gregwor wrote:

To say that I'm impressed simply wouldn't do your work justice. I'm especially impressed with your hanger door!!! Wow! Your mdat loaded up fine on my computer and it look awesome. You're right that even the IR shows 1 reflection point to tame and the rest looks killer. You're on the right track and I can't wait to see things shape up even further. Did you consider lowering your first cloud and angling it differently in an attempt to prevent reflections from the ceiling beam? Greg

Hey Greg, thank you for your kind words! yes I am pleased with the progress! And the hanger door turned out great! The hangers can even move freely but without getting crazy movement upon opening-closing. I managed to fit 5 pieces of 2 meter high hangers in there, the biggest is around 80cm wide and going down to 10cm steps. They all have 1cm core and 3cm insulation on each side of the hanger. Reg: the cloud, I tried different scenarios but this one worked best. The beams are not a problem because there are 40-50cm deep horizontal traps covering all ceiling beams (and the rest of ceiling corners). Especially on these front ones will add a 5cm insulation face panel, one to three layers of garden felt for particles protection and finally the fabric. So not many reflections will make it back down..It's also 4 meters high ceiling so that helps too!

Some progress on front wall to ceiling horizontal corner trap.

Making the Steel frames for the clouds: Painted: Damping the insides with polyurethane expanding foam: Drilled so I can attach the 20mm boards: Attaching the boards: The three hard backs for the clouds are ready:

But before hanging the clouds I needed to make the frames for the wall to ceiling corner traps so that the fabric can "sit" on and take a shape.

Hanging the clouds! On these guys: Front cloud, above listening position: Middle room section cloud: Back of the room cloud:

Adding the insulation. Custom spacers for attaching the insulation's frame: Front: Middle: Front and middle clouds view: Back:

And measuring. Any ideas how to tame this 19Hz axial? :roll:

You've been very busy! It's looking great so far, are you happy with how it's going? The metal work for the clouds is excellent, how do they compare weight wise with timber frames? Paul

Yes, and I am doing this by myself... Thank you! I am so and so because I see I have still lot of problems to deal with so.. The weight for the hardback alone is 80Kg. That is for 3 x 1.7 meters cloud made of 1.5 mm thick steel tubes 20mm thick wood and all the bolts and hanging stuff. Not sure what would be with timber.

Any ideas how to tame this 1-0-0 axial mode? I've got close to 1" decay time at 18.2Hz... Measurements attached It affects the sub low spectrum in a bad way... Sounds like a low passed reverb tail in a cathedral :lol: I am considering all options like limp mass, diaphragmatic, vpr, slatted helmholtz but I am finally confused which way to go. The helmholtz probably can't reach down there given my available space. But I am open to possible suggestions! As you can see, back wall is already treated with the huge hangers, front wall has the two big superchunks and the wall to ceiling trap. So I got the following space available for front wall treatment: If I go for porous absorption I got a little more than 3x3 meters and max depth of 48cm. If I go for tuned traps I got 70x145cm and 145x170 and a max. depth of 24cm. I can also extend the depth for these but I prefer not to if possible. It's either one or the other

So I will finally use Limp Mass Absorbers tuned at 18.25Hz. Place directly on front wall. That's the layout. Grey are LMA'S, green are porous absorbers 10cm to 1.4m deep. That's LEFT, RIGHT, L+R (purple), unsmoothed.