Sintered microbeads. I would be curious to see acoustic measurements of such a mixer vs. a traditional one.boji said:
DIY diaphragmatic bass absorbers
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boji
Well-known member
Well, not entirely useless if you are trying to locate the worst areas of MH early reflections. Just another point of reference.
What I mean is it's useless when the room is empty and unfurnished.boji said:
Recording Engineer
Well-known member
I think it was just to show what double and triple -leaf actually refers to... As you’re right, this is the first time I’ve heard someone claiming it also refers to acoustics.
moamps
Well-known member
abbey road d enfer said:
It is useful in this situation also because it can be easier to find a flutter echo positions if they exist.
I already answered that; it is useless when the room is empty and unfurnished.moamps said:
john12ax7
Well-known member
PRR said:
Yes we were, but got off on a tangent when the subject of double and triple leaf came up.
Although if sound isolation is not a requirement this could also be used as an advantage for inside the room. Instead of absorbing a room mode you could change the resonance of the wall to allow the trouble frequencies to escape.
moamps
Well-known member
abbey road d enfer said:
Maybe we can agree to disagree.
Any flutter echo that exists in the unfurnished room may disappear or shift when equipment is brought in and acoustic treatment is installed; I don't think you can disagree with that.moamps said:
For example, a flutter echo due to a window facing a hard wall can be made unsignificant if an equipment rack is placed opposite.
I don't need clapping hands to know that I must expect flutter echo from windows and that I must treat or set-up the room in order to minimize it. That should be an evidence at the preliminary stage, when studying the plans.
Clapping hands (or an equivalent measurement) must be done when the acoustic treatment is done in order to validate it.
moamps
Well-known member
When I'm going to measure acoustical characteristics of an empty room I need to determine the best positions (3 or 4) where to place the measuring microphone (and speaker too) for RT vs. freq. measuring. There are two most important criteria to me; axial standing waves critical positions and existence of flutter echo. The standing waves critical positions can be found from the room dimensions before the measurement but flutter echo can't. It should be checked in situ. Using hands or a measuring method.
From my experience, the usual suspects as glass surface-wall combos rarely produce flutter echo because they aren't perfectly parallel. Now days the opposite gypsum walls or gypsum ceiling-wood floor are most critical, today every construction worker has a laser distance meter in a pocket.
This discussion is off -topic here so I will not continue it. Let's agree to disagree.
From my experience, the usual suspects as glass surface-wall combos rarely produce flutter echo because they aren't perfectly parallel. Now days the opposite gypsum walls or gypsum ceiling-wood floor are most critical, today every construction worker has a laser distance meter in a pocket.
This discussion is off -topic here so I will not continue it. Let's agree to disagree.
abbey road d enfer said:
Only one asked for plans. The others didn't bother.
I certainly need to visit before even thinking about anything. One thing is that plans can have errors. Fi, because someone decided to put in a new ceiling. Or made a door. Or...
It's not completely useless. Sometimes, when the room isn't quit, and lacking other means, it can help.
abbey road d enfer said:
I prefer to have a "blank" measurement too, if possible. It shows me how the problems relate to the structure of the building.
You can move gear and furniture around. You can't move walls, in general.
This depends largely on the kind of project. A new theater requires other treatment than an existing home studio. In the case of the theater, you might want to use absorbers and diffraction as you don't want one sweet spot. You probably have the time and the budget to do things very thoroughly too.
In a small home studio, you measure from the sweet spot, to start with.
Ive been considering a timber based structure as a workshop and area to house my recording equipment , sound leaking out isnt any concern , so instead of trying to contain the sound like in a concrete structure , I'd like to try and dampen and defuse a lot of high frequencies and kind of allow much of the low end pass through the structure .
What Im thinking of is a basic structural frame of oak4x4 '' timber attached together with 90 degree steel post brackets and spiked brackets that cement into the ground . What I plan to do is clad the outside with 3/4 inch ply , then using using 1/8 inch ply sheets ,make the inside surfaces curved ,attach the inner sheet to the outer sheet with a flexible mounting right down the middle of the panel. Using an 8x4 foot ply sheets wall sections a bit less of that size could be constructed.The curve could either be put in the vertical or horizontal plane of the wall section and they could be alternated across the number of sections you need . I was thinking of completely filling the voids in sections the with recycled polystyrene beads . It might compact as it gets used but you could always top up each section as needed .Again a raised floor section could be created and packed with poly beads ,heavy plastic lining to make sure you dont cause
From an acoustic point of view ,you would no longer have parallel surfaces ,the thickness is also continuously variable from the middle to either end of the panel ,the beads would be free to move inside the wall to a small degree ,and thus turn more sound into heat . I dont know if the whole thing would sound like a gigantic egg maraca if you had a bass drum in there , or monitors turned up loud. Seems like it would have a good mix of defusion to alleviate boxiness while being more transparent at low frequencies and passing the sound to the outside world , further foam difusers could be used in the usual way at nodes.
Another option would be to clad the ousides with precast concrete 4x8 sheets available here now , its a mix of concrete and poly bead with extra nylon fibres embedded , a lot more mass than plywood , so lower resonance. Around the same thickness as dry wall,a lot heavier and weather resistant after a skim coat and paint . Nothing set in stone yet , but very interested to hear peoples opinions on the above.
What Im thinking of is a basic structural frame of oak4x4 '' timber attached together with 90 degree steel post brackets and spiked brackets that cement into the ground . What I plan to do is clad the outside with 3/4 inch ply , then using using 1/8 inch ply sheets ,make the inside surfaces curved ,attach the inner sheet to the outer sheet with a flexible mounting right down the middle of the panel. Using an 8x4 foot ply sheets wall sections a bit less of that size could be constructed.The curve could either be put in the vertical or horizontal plane of the wall section and they could be alternated across the number of sections you need . I was thinking of completely filling the voids in sections the with recycled polystyrene beads . It might compact as it gets used but you could always top up each section as needed .Again a raised floor section could be created and packed with poly beads ,heavy plastic lining to make sure you dont cause
From an acoustic point of view ,you would no longer have parallel surfaces ,the thickness is also continuously variable from the middle to either end of the panel ,the beads would be free to move inside the wall to a small degree ,and thus turn more sound into heat . I dont know if the whole thing would sound like a gigantic egg maraca if you had a bass drum in there , or monitors turned up loud. Seems like it would have a good mix of defusion to alleviate boxiness while being more transparent at low frequencies and passing the sound to the outside world , further foam difusers could be used in the usual way at nodes.
Another option would be to clad the ousides with precast concrete 4x8 sheets available here now , its a mix of concrete and poly bead with extra nylon fibres embedded , a lot more mass than plywood , so lower resonance. Around the same thickness as dry wall,a lot heavier and weather resistant after a skim coat and paint . Nothing set in stone yet , but very interested to hear peoples opinions on the above.
