more
Image not preserved: bass mic position.jpg
Image not preserved: piano mic position.jpg
Image not preserved: kick drum mic position.jpg
timogiodeson MEASUREMENTS THREADS! Tracking Room Acoustic
Originally posted at johnlsayers.com, topic 9383.
more
CORNERS BASS TRAPS MEASUREMENTS STARTS FROM HERE
Low frequencies measurements
I made the following measurements with the sub woofer in the floor tri-corner and the mic in the opposite ceiling tri-corner.
there is two measurements in each graphic, one of the two, shows the room without acoustics treatment.
the type of treatment it's listed on the file name.
whats interesting is the 6 mineral wool panels do almost the job of the 20 auralex lenrds... obviously the 30, 60 and 150-160hz need some further adjustment - maybe some panel traps for the 60hz and some lenrds for the 150-160hz.
Thanks Glenn,
Here more measurements
sub woofer and speaker in the floor tri-corner, mic on listening position.
4 different kind of acoustic materials floor to ceiling in 3 of the corners.
Aur. Lenrd bass traps, (12) 2x1x1 Lenrd , 4 in each corner.
4" tick 8 pound mineral wool, (6) 2x4 panels 2 in each corner
5/8 thin generic ceilings tile, (6) 2x4 panels 2 in each corner
plywood cylindrical diffusers ( not sealed Poly..) (1) 2x8 in each corner.
Also a combination of 2 materials (Lenrd with 8 pound mineral wool in front), and 3 materials ( lenrd plus 8 pound mineral wool and cylindrical diffuser in front)
here 3 different measurements,
Yellow line: (20) Aur. Lenrds
Blue line: same (20) lenrds with additional (6) 8 pound mineral wool panels in front of the lenrds, floor to ceiling in 3 of the corners.
Pink line: same (20) lenrds with additional (6) 8 pound mineral wool panels in available corners "non in front of the lenrds."
Some more...
here the difference between 8 , 12 and 20 Aur. Lenrd bass traps in the room corners.
8 lenrds green line
12 lenrds red line
20 lenrds black line
here more,
8 , Lenrds in the room, two in each corner (blue line)
4 , 2x4x4" 8 pound mineral wool panels , one in each corner (red Line)
Combination , 8 Lenrds two in each corner plus 4, 2x4x4" mineral wool 8 pound panels one in each corner in front of the lenrds.
here one more
(Pink line)
20 Lenrds, I made a gigantic mega Lenrd foam bass trap made by 12 Lenrd all together in the floor tri-corner where the drum is... there is additional 6 Lenrds, one in each room Tri-corners.
Some how :D with this gigantic tri-corner bass traps I can finally hear some improvement in the bass drum sound, and the room is not too dead jet...
(Green Line)
same 20 lenrds combination with 6 additional 8 pound density 2x4x4" mineral wool panels in available corners.
Probably because the ceiling treatment...? The room tend to become dead very easily even with only corner traps.
Also, regular size floor to ceiling 2x4x4" mineral wool or 2x1x1 foam bass traps do not absorb low enough for my instruments I guess.. especially for the bass drum, however, 4 inc 8 pound mineral wool floor to ceiling in all 4 corners plus regular Lenrds in almost all ceiling/wall corners, do effect the bass drum a little but at this point the room sound already too dead...
what happens if the lenrds are placed around the room and they have a gap between them (instead of end to end)? make the gap 30cm. also, the 2'x4'x4" absorbers - hang them off the ceiling or wall by 4" and also make a checkerboard pattern of them instead of side by side. on the walls - leave space between them of about 60cm or so. this lets the edges work for you and should keep it from getting too dead.
The Lenrd are end to end only if 4 of them floor to ceiling... otherwise there is always a gap in between ...also yes the absorbers are off the walls and spaced . I'm in the middle of some very interesting measurements right now. I will post everything tonight, Including pictures ! thank youwhat happens if the lenrds are placed around the room and they have a gap between them (instead of end to end)? make the gap 30cm. also, the 2'x4'x4" absorbers - hang them off the ceiling or wall by 4" and also make a checkerboard pattern of them instead of side by side. on the walls - leave space between them of about 60cm or so. this lets the edges work for you and should keep it from getting too dead.
CORNER BASS TRAPS MEASUREMENTS WITH PICTURES STARTS FROM HERE
Thanks Glenn, here all the new measurements and pictures.. sub and speaker still in the corner , for reference I tested various absorbers only in the corner behind the drums, floor to ceiling , the rest of the room corners and walls are untreated, the mic is in the drummer listening position. my goal is to reduce the booming bass drum and electric bass sound, (6 strings and deep cannon bass drum with Evans Emad head) , also nulls in the grand piano lower range.... (now with the new position the piano sound much better than before probably OK) upright bass and small jazz kick maybe OK too. With the few absorbers I have, everything tend to become too dead and booming , .. It is difficult to perform in such dead and booming room. There is some long flutter echos going back and forward between the two short walls (long way of the room) that I almost like ...will be better to diffuse this instead absorbing? The acoustic material I have, is almost transparent below 100hz I guess... the measurements show very little changes below 100hz unless I'm missing something... Isn't 100hz and below the most important frequencies for bass drum, bass, etc? P.S. The big corner cylinders you see in one of the measurements it's not a Poly, it is unsealed and without insulation behind it, it is just a diffuser.. question: The real corner Poly, "if sealed" will be more effective below 100hz than the porous absorbers I have measured ?what happens if the lenrds are placed around the room and they have a gap between them (instead of end to end)? make the gap 30cm. also, the 2'x4'x4" absorbers - hang them off the ceiling or wall by 4" and also make a checkerboard pattern of them instead of side by side. on the walls - leave space between them of about 60cm or so. this lets the edges work for you and should keep it from getting too dead.
...
...
...
...
Ceilings Tile...
8 pound with FSK Foil toward the room, toward the corner etc .
two combinations of 8 pounds absorbers in the corner with lenrds behind.
Gabriel,
Thanks for the postings. That's some amount of work ! Is there a subjective better option from a musician's point of view ? Beside that, it looks like your sub is a bit too loud.
I would go for damped heavy wooden panels, suspended from the ceiling all around the room. The walls are first covered with industrial style high density 2" mineral wool faced with a glass tissue. Then the wood panels are suspended with hooks and chains or ropes from the ceiling. They should not touch the floor or the ceiling. It would be a good idea to vary the thickness of the panels to get a broader absorption. You might have to experiment a bit with the placement of panels.
The hard wood surfaces will maintain a live sound in the room. The panels will vibrate to absorb bass frequencies. That should work for the type of sound you are looking for.
If the room is still too boomy in the 250 Hz region you might have to swap some of the panels for more expensive perforated ones.
Thank you very much msikio that look very interesting, and also simple to build... I agree plywood vibrate! I can feel it with my hand wile I play the bass drum!! My sub sweep level is loud because I thought real instruments like drums etc, sound louder than 75db.. , so I set up the sound level meter at about 85/90 db instead the standard 75db recommended for speakers. I plug my ear with my fingers during measurements.. :) just two questions please, 1) plywood thickness 1/8, 1/4, or ticker? full 4x8 size? you said heavy wooden panels, hope not to heavy... also you said damped, how ? 2) the mineral wool in the walls can also be 1 inc for economy? or maybe R fluffy insulation 3'1/2 tick or similar?Gabriel, Thanks for the postings. That's some amount of work ! Is there a subjective better option from a musician's point of view ? Beside that, it looks like your sub is a bit too loud. I would go for damped heavy wooden panels, suspended from the ceiling all around the room. The walls are first covered with industrial style high density 2" mineral wool faced with a glass tissue. Then the wood panels are suspended with hooks and chains or ropes from the ceiling. They should not touch the floor or the ceiling. It would be a good idea to vary the thickness of the panels to get a broader absorption. You might have to experiment a bit with the placement of panels. The hard wood surfaces will maintain a live sound in the room. The panels will vibrate to absorb bass frequencies. That should work for the type of sound you are looking for. If the room is still too boomy in the 250 Hz region you might have to swap some of the panels for perforated more expensive ones.
Quoting a PM of B.D.R. alias Gabriel :
I figured out this design based on your requirements, my own experience, theory and tips from various people and acoustician... but I never built such a design yet. There is no way to be sure such a design will work as there is no equation that I know of associated with it. It relates to know principles : MSM and so on but it doesn't follow the usual recipes. As you feel experimental here's my "gut feeling" to reply to your questions : The panels should be 1/2 inch plywood with 0.72 lb/ft2 limp mass completely glued to it with contact adhesive. The overall weight of the panel should be about 2.3 lb/ft2. Yes, I would go for full size 4 x 8 panels. You might experiment with one panel, play a slow sweep in the room and record the vibration with a (cheap) contact mike. I think it should work... but as I said... no guarantee... I would stick to 3.5pcf 2' glass tissue faced mineral wool. Much easier to work with. In case you feel the room is too live you can easily remove some of the panels and your don't have to face non covered mineral wool. Still be careful, the glass tissue is quite fragile. You don't necessarily have to buy the limp mass from acoustic suppliers, some roofing or floor damping material can sometimes do the trick for less money.your design make sense, no parallel wall, the plywood will absorb bass , the fiberglass will absorb mid high and a little bass...the angles will diffuse the sound etc... please feel free to share , my life is an experiment any ways..! if the plywood need to be really heavy probably will be to expensive and also heavy for my ceiling , but if it is 1/8 or 1/4 or similar probably OK... also I don't know what is a damped panel
Gab wanted some input from me offline. I was happy to offer some opinions; what I would do in his situation, as it were. Here are excerpts from the PM exchange:
OK here the list of the materials I presently have. (20) auralex lenrd bass traps (36) auralex 2x2x2" studio foam (12) Armstrong ceiling tile (6) 2'x4'x4" 8 pound density mineral wool /fabric panels one box of (6) 8 pound density mineral wool boards 2'x4'x2". (1) 4'x5'x4" 2.5 pound density mineral wool/fabric panel. 40 sq. F of fluffy R11 3" 1/2 tick fiberglass 2 moving blankets 8, 2'x6"x 6" cylindrical plywood diffusers (12) 2x2x6" cylindrical diffusers 2 Auralex 2x2 diffusers 50 sq. f. of 3" tick solid foam . ----------- room info: dimensions 19.4x12.1x8.7 floor 100% coverage vinyl on concrete walls 100% coverage drywall ceiling 100% coverage two layer of 5/8 generic ceiling tile, glued to drywall sealed and painted. No airspace. One regular size entrance solid wood door, no windows. tracking and practice room
Gab, ...some preliminary suggestions. This is stuff you can try without having to place anything permanently - just try it and listen for what kind of difference it makes: 1. For the (wall/wall) corners of the room, I would suggest stacking four LENRD in each. Then place 4" of (8 lb) mineral fiber boards over the LENRDs, spanning the corner. This technique - 4" panels over LENRDs - has been shown to be extremely effective for controlling bass. I helped Mitch Gallagher do it in his - significantly smaller - recording booth and it helped considerably. (He discussed this in his book. Measurements are provided.) 2. For the rest of the walls, I would suggest using the 2" Studiofoam on the walls. If you can, place the panels over a 2" air gap. Coverage should not exceed about 30% for each wall, should be more or less centered on the wall, but panels should be spaced and staggered to minimize parallel flat surfaces. 3. Finally, use the diffusers you have on the ceiling. I usually suggest placing diffusive areas over instruments - in your case, over the piano and drums. Minimum area for these diffusive areas should be 4'x4' over each instrument, but more cannot hurt. If you can, start with the stacking LENRDs and mineral fiber panels over the wall/wall corners (#1 above), then evaluate. If that is providing ample bass control in the room (it won't be perfect, but it should be much better), then you can move on to the Studiofoam and diffusers. I hope this helps. Also, please let me know how you would feel about posting this publicly. I generally prefer not to offer advice privately through contacts made on public forums. I would feel more comfortable if this advice were...made public. Feel free to copy the above to a post in the appropriate thread if you like. Otherwise, I would like to do so at some point.
Will be relatively easy for me to follow the suggestions you provided and let you know how that sound, I can also take measurements if necessary. I already tried similar approaches with the auralex material but I never spaced the studio foam from the walls also I never had all 8 pound + lenrd on the 4 corners + spaced studio foam in the walls at the same time. my impression with the traditional Auralex application is that my room become to dead and booming, but probably spacing the foam and adding 8 pound in front of the lenrd will make the difference.. I don't mind to try that! I have just two questions please 1) You said that you haven't had time too look to my room info... but I hope you noticed that my ceiling it's 100% covered with glued (rigid mount) ceiling tiles sealed and painted) right? do you think this need to be taken into consideration? my room tend to become too dead because the ceiling? drywall and hardfloor for the rest. 2) about spacing the foam, in one of your articles in Auralex web site you said that the foam can be spaced using furring strips only, or furring strips with thin plywood or pegboard on the back of the foam for stability or cardboard etc.. what you suggest in this case? I have the feeling that thin plywood some how will improve the low absorption by resonance or similar, I experimented talking inside a studio foam wile varying the airspace from the foam to the wall , if the foam is in contact with the drywall or any other rigid surface even if the rigid surface is spaced from the drywall my voice sound kind nasal... if the foam doesn't have a rigid surface in the back my voice doesn't sound nasal. Of course my voice doesn't sound nasal with a 4 - 6 inc tick foam absorber no meter if the absorber is connected directly to the wall or with an airspace. thank you very much Jeff.
Above should about cover how I would start approaching Gab's room, were it my own. I do have one question for Gab: Did I interpret your "talking" experiment correctly? I took it to mean you were standing near the foam/wall and talking into the panel, evaulating the difference in mounting methods. Is this correct? HTH. All the best,I took all this into account. In fact, having tiles on 100% of the ceiling is even more reason to use the diffusers over instruments. The more you use, the more "life" you could potentially "add back into" the room.1) You said that you haven't had time too look to my room info... but I hope you noticed that my ceiling it's 100% covered with glued (rigid mount) ceiling tiles sealed and painted) right? do you think this need to be taken into consideration? my room tend to become too dead because the ceiling? drywall and hardfloor for the rest.Any of those ideas should work. In theory, furring strips alone should be the best. Personally, I don't think the pegboard is a bad thing - and you can mount it on a few nails! I've used this approach a LOT and I've never been disappointed with the results.2) about spacing the foam, in one of your articles in Auralex web site you said that the foam can be spaced using furring strips only, or furring strips with thin plywood or pegboard on the back of the foam for stability or cardboard etc.. what you suggest in this case? I have the feeling that thin plywood some how will improve the low absorption by resonance or similar,I don't know what this type of test would prove. It is rare that a source or microphone would be so close to the absorber. It's the effect in the room that counts. If you mount the foam a certain way and observe an effect when standing in the room that you don't like it, do something else. :)I experimented talking inside a studio foam wile varying the airspace from the foam to the wall , if the foam is in contact with the drywall or any other rigid surface even if the rigid surface is spaced from the drywall my voice sound kind nasal... if the foam doesn't have a rigid surface in the back my voice doesn't sound nasal. Of course my voice doesn't sound nasal with a 4 - 6 inc tick foam absorber no meter if the absorber is connected directly to the wall or with an airspace.
I was going to say that ;) Also, about the measurements : it would be interesting to see the LF decay as in a practical situation a good LF decay is really what makes a room easy to work with.3. Finally, use the diffusers you have on the ceiling. I usually suggest placing diffusive areas over instruments - in your case, over the piano and drums. Minimum area for these diffusive areas should be 4'x4' over each instrument, but more cannot hurt.
:...some preliminary suggestions. This is stuff you can try without having to place anything permanently - just try it and listen for what kind of difference it makes: If you can, start with the stacking LENRDs and mineral fiber panels over the wall/wall corners (#1 above), then evaluate. If that is providing ample bass control in the room (it won't be perfect, but it should be much better), then you can move on to the Studiofoam and diffusers.
thank you Jeff, I'm done with step 1 and measurements already. 4.09 am, ... I stacked Lenrds and mineral fiber on all 4 corners, floor to ceiling 16 lenrd and 8 , 2x4x4" 8 pounds absorbers, in one of the corners with FSK foil toward the room, no fabric yet, the rest of the absorbers are regular 8 pound without FSK. do you think this provide ample bass control? Can I move on to studio foam? can you please help me with the evalution you suggested? P.S. About the talking experiment.. yes I was talking into the panel, evaluating ....it's very interesting.. you can axially hear what kind of sound come back into the room :oops: measurements:I do have one question for Gab: Did I interpret your "talking" experiment correctly? I took it to mean you were standing near the foam/wall and talking into the panel, evaulating the difference in mounting methods. Is this correct? HTH. All the best,
..