Room/Mic Problem

  • Thread starter Thread starter Ed Fones
  • Start date Start date
Why not hang the duvets, then put some nice fabric covered frames over them to prevent people seeing them - if they work, keep 'em.

My temporary audio space in my video studio is making me think I need to invest in some decent monitors for there, because it's more convenient to work in there. The speakers in there at the moment are awful, so a pair of proper balanced mons should be good
 
rob aylestone said:
Why not hang the duvets, then put some nice fabric covered frames over them to prevent people seeing them - if they work, keep 'em.

My temporary audio space in my video studio is making me think I need to invest in some decent monitors for there, because it's more convenient to work in there. The speakers in there at the moment are awful, so a pair of proper balanced mons should be good
Click to expand...
Rob, 18 months ago I made acoustic panels and put them on walls and ceiling. Obviously now I use this room we have found out there isnt enough of them. To make them again would cost almost twice as much.

So the wall panels are coming down and going up on ceiling with others. The wife has found 7 duvets and they are almost going to obliterate 2 walls. The other 2 walls will have acoustic panels. Hopefully this will work.
 
Ed Fones said:
Rob, 18 months ago I made acoustic panels and put them on walls and ceiling. Obviously now I use this room we have found out there isnt enough of them. To make them again would cost almost twice as much.

So the wall panels are coming down and going up on ceiling with others. The wife has found 7 duvets and they are almost going to obliterate 2 walls. The other 2 walls will have acoustic panels. Hopefully this will work.
Click to expand...
Hi Ed, I know a lot more about valves than I do acoustics but, if possible hang the duvets 200mm or so away from the walls. The mechanism is, AFAIK that the sound goes through twice as it bounces off the wall plus the absorbers work down to a lower frequency.

You also need a good deal of the absorbers BEHIND the subject.

Dave.
 
ecc83 said:
Hi Ed, I know a lot more about valves than I do acoustics but, if possible hang the duvets 200mm or so away from the walls. The mechanism is, AFAIK that the sound goes through twice as it bounces off the wall plus the absorbers work down to a lower frequency.

You also need a good deal of the absorbers BEHIND the subject.

Dave.
Click to expand...
Thanks Dave. I am a chippy and can turn my hands to almost anything so hanging duvets anywhere I want is possible, but at this stage the least work and expense is the better for me. Behind the subject is a green screen approx 14ft long presently with 4 x 4ft x 2ft acoustic panels behind it. Soon there will be 5 acoustic panels there and I couldnt fit anymore.

All in all at present there is 19 panels fixed to wall and ceiling. I have 21 all together. So the new plan is to have 5 on two opposite walls = 10 panels and the other 11 on the ceiling. I have enough rw3 left to make a 12th.

The other two walls which have two doorways will be covered with duvets. Be like a padded cell when done. Probably quite apt.:-)

One day my endless work will stop! I must have been a really bad person in a previous life.
 
ecc83 said:
if possible hang the duvets 200mm or so away from the walls. The mechanism is, AFAIK that the sound goes through twice as it bounces off the wall plus the absorbers work down to a lower frequency.
Click to expand...
This advice has been around for ages, but in my mind, I don't understand it. The soundwaves that make it through the panel will bounce off the wall (behind the panel) regardless of the distance of the panel from the wall, and then pass through the panel again - again, no matter the distance from the wall.
 
mjbphotos said:
This advice has been around for ages, but in my mind, I don't understand it. The soundwaves that make it through the panel will bounce off the wall (behind the panel) regardless of the distance of the panel from the wall, and then pass through the panel again - again, no matter the distance from the wall.
Click to expand...
Like I said Mike, my acoustics knowledge is poor but I THINK the answer is that absorbers work because the air particles lose energy by converting motion to heat. By definition, the particle velocity at a solid surface is zero. Some distance away it has speed. I dare say there is an optimum distance? A combination of the material depth, frequency and practicality?

I do know it was proved by the grandfather of speaker design, G A Briggs that cabinet absorbents on walls are far less efficient than those in the centre part of the cab.

Dave.
 
ecc83 said:
Like I said Mike, my acoustics knowledge is poor but I THINK the answer is that absorbers work because the air particles lose energy by converting motion to heat. By definition, the particle velocity at a solid surface is zero. Some distance away it has speed. I dare say there is an optimum distance? A combination of the material depth, frequency and practicality?

I do know it was proved by the grandfather of speaker design, G A Briggs that cabinet absorbents on walls are far less efficient than those in the centre part of the cab.

Dave.
Click to expand...
My acoustical property knowledge isn't what it should be, either. But I AM an engineer - and Wave Physics was my most-hated physics class at McGill!
We have to remember that sound waves don't move the air particles in a 'velocity' sense (if they did, every sound would make a breeze or wind we would feel - when we feel the air move from a loud subwoofer, we are feeling the physical moving of the air from the physical movement of the speaker, not the actual soundwave, although they are in synch for a short distance), the air particles 'vibrate' - the louder the sound, the more they vibrate, and yes, sound absorbing material converts that energy to heat. The speed of the wave is based on the density of the medium it passes through so the denser it is, the slower the wave propagates (with different frequencies having different speeds in different mediums).
So, if there is no air space at all between the absorber and the wall, the wave moves at a slower velocity out of the absorber, bounces off the wall and back into the absorber at the same velocity. If there's an air gap, the wave 'speeds up' as it leaves the absorber, bounces off the wall, then 'slows down' as it goes back into the absorber. At least that's how my old brain sees it! So, yes, space between absorber and wall means more air particles get vibrated by the soundwave, which does absorb a very small amount of the energy, but I don't think it would be very noticeable.
I wonder if anyone has does measurements of the same panels (at different frequencies) directly against a wall and with air gaps of various amounts?
 
Yes Mike, I was being too simplistic in saying air particles "had a speed" they are as you say, vibrating back and forth in waves.
It is further complicated by the fact that air particles have a range of speeds in totally random directions. At temperatures and pressures that suit us human beings that average speed is about 340mSec. Perhaps therefore, particles hitting a wall bounce off with fewer particles at the higher speed and thus the wave as a whole spends more time in the absorbent?

As for measurements? What Briggs was doing was trying to remove as much of the cabinet resonance* 'colouration' as possible and found that he needed much more material if attached to the wall to achieve a result than if a 'curtain' was hung top to bottom with a single twist in it. He reasoned that this was because the standing wave 'motion' was greatest in the centre of the cabinet.

* Not BTW, the movement of the actual cabinet structure. That was/is yet another can of wriggly things!

Dave.
 
I may have forgotten what this was all about, but it seems like a lot of treatment for recording a voice track in a very large room. Panels and such do not insulate against external sounds, especially things like HVAC and such. (Seal your doors and windows first.)

Of course, it [treatment] will reduce the amount of reflected sounds, i.e., once they get into the room, but I did not hear lot of reflected source sound in that bit of recording I listened to, way back. Maybe there are other plans for this space, or the vocal sounds will be really loud??
 
I recently ran across this video of Jamie Fox doing some voice over work. Notice the treatment which appears to only go part of the way around him. The wall of treatment should deaden things quite a bit.

 
Keith...........The room is well insulated from outside. It is the internal walls which are the problem and being rectified.

Rich...........We have a separate purpose built soundbooth. This room is for video and in this instance greenscreen work. This cannot be done in the booth.
 
I lined the room with Duvets.

Then I tested the Rode NTG2 overhead in different positions no more than 600mm away.

The Rode Lavalier 11 in her hair and clipped to the overhead boom.

And the Rode NT-1A on a mic stand ending up 4ft away in front.

The worst for the deep room type stand was the NTG2, hardly any improvement. Next was the Lavalier 11 which was just useable. The NT-1A is the one we used and it was far better than the others.

So the least practical was the best and in this situation the NTG2 is shite.

Totally surprised and only ever used it outside before.
 
You must log in or register to reply here.
Back
Top