egproductions
Veteran
Do people use blimps (without the front) for off axis rejection indoors? Are there any drawbacks?
Blimp for Off Axis Rejection?
- Thread starter egproductions
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Bruce Watson
Veteran
Blimps are acoustically transparent. They don't block sound, no matter what direction it's coming from. What they block, is air movement. That's what they are actually used for.
Any one using a blimp indoors (except in very very very rare exceptions) is screaming out at the top of their lungs BIGGEST NOOB EVER
If you need to move to follow the sound source then some form of wind protection can be useful to prevent LF noise as the mic moves through the air.
Ever heard of using a BBG on a hyper indoors. Maybe not a blimp, but it is a mini-blimp or a zeppalina. ��
egproductions
Veteran
That makes sense. I saw something about the rycote cyclone and off axis rejection and it got me thinking that maybe tha would be a good non conventional use for a blimp.
And a full size blimp is totally over the top overkill for that purpose when indoors.
cpreston
Veteran
Newer blimp designs are asymmetrical and involve more acoustically transparent materials in order to get better sound. This actually has more to do with allowing less distorted sound to get to the interference tube rather than blocking sound from getting to the mic. Anything that blocks side axis sound is actually going to cause more of a problem with allowing a directional mic to function correctly than actually increase side axis rejection.
So you agree a moving mic needs some protection from air movement? Foam slip on shields are often ineffective, Super softies are very good but not everyone has them for all their mics, a blimp is very effective, a blimp + deadcat would certainly be overkill and it's not acoustically transparent.
GaryNattrass
Veteran
Your body is also useful for protecting a mic in wind.
I haven't used a blimp for a few years now and a softie is the compromise for inside and out although a foam windscreen can be enough for most inside jobs and also has a second use if you pop some white or visible tape on the very end as the camera crew can then see when it is in shot.
I haven't used a blimp for a few years now and a softie is the compromise for inside and out although a foam windscreen can be enough for most inside jobs and also has a second use if you pop some white or visible tape on the very end as the camera crew can then see when it is in shot.
egproductions
Veteran
Would some sort of housing for the mic that blocks sound from the rear/sides but not from the front be usefull in reducing off axis rejection? It could be that simple right? What am I missing?
egproductions
Veteran
Why don't they just design the mic like that to begin with? Or sell an accessory that eliminates off axis rejection?
Bruce Watson
Veteran
No, alas, it could not be that simple. Engineers around the world have been studying this problem for many decades. There was a fair amount of effort put into baffles in the 1950s by Decca, as they researched what eventually became the "Decca Tree" system for recording classical orchestras. There are some interesting pictures on the 'net. But they soon gave up on the idea because they got better results without the baffles. By the 1960s even the Decca Tree configuration was dropped by Decca in favor of other techniques.
An interesting example of a baffle that really does work well is the Jecklin Disk.
The problems I'm seeing with your proposal is two fold. First, it will likely cause a near step-function change in loudness between objects not blocked by your baffle and objects that are, and this will likely be very audible and difficult to fix in post. Second, it will likely introduce nonlinearities into the frequency response as a function of whether the sound is baffled or not. Said another way, things that are off-axis will sound "colored" compared to things that are on-axis. This is usually highly noticeable, and you can't easily or at all correct this in post. You may be able to beat this with proper design (it does work for the Jecklin Disk, mostly), if your baffle attenuates linearly across the frequency spectrum. Which is unlikely for cheap materials and would probably be expensive for well engineered materials.
But you know, try it and see. Can't be that hard to cobble together a test. Who knows? You might like the result.
If you want audio tracks that are totally isolated then record them in isolation. What then; add room tone and other stuff back in?
The question is how much rejection-isolation is desired. Think about a hyper or shotgun versus and omni pattern. How they roll off from the sweetspot is the artistic part of the science of good location audio.
The question is how much rejection-isolation is desired. Think about a hyper or shotgun versus and omni pattern. How they roll off from the sweetspot is the artistic part of the science of good location audio.
cpreston
Veteran
So, basically a mic capsule surrounded by a huge amount of sound deadening material that isn't reflective. A portable sound booth. They make those, although they are meant for close recording.
Noiz2
Sound Ninja
The hollow sound of recording with a mic at the end of a tube.
It's not off axis rejection. It's off axis attenuation. We have to be careful with these terms because people see "rejection" and think it means that sounds that are off axis will completely go away. I talk with people every single day about this.
The short of it is that doing something like what you ask would sound pretty unnatural. The smaller the space you are in, and the with not a lot of acoustic treatment, the narrower the pick up pattern, the funkier it can sound....sometimes... You have to find a good balance between pickup pattern and the space. Honestly, a mic with non-colored off axis attenuation is really the goal, and there are several mics out there that do this, but they aren't cheap.
What Scott said about the hollow sound of putting a mic in a tube is exactly what you'd get. I did this very thing back in college when recording vocals for a song, but it was the desired effect. It's an old technique that we stole the idea from the Beatles on, but lots have people have done it. For video projects, it's not what you'd want at all.