Dumb question #342,587

[TBman]

Why make big 4' acoustic absorbant panels (for example) instead of a "sound treated" 3 sided box that a mic can be placed in?

Would it work?

[jim1960]

To my thinking, the box is an attempt to block the problematic frequencies; the room treatment is a way to eliminate the problematic frequencies. What I mean is, if you put up bass traps in your corners, you're going to control those low frequencies that can muddy up your recording by not allowing them to bounce around and build up in the room. If you simply build a box, those frequencies are still there bouncing around and building up, you're just hoping the box blocks enough of it.

Given a choice between the two, I'd rather treat the room than build a box in most cases.

[ChuckS]

If using a 'box' around the mic, I'd assume the box exterior should not be reflective (due to the mic being located close to the box). At most, a box may reduce reflections from the back and sides of the mic (which a directional mic would also do) but will not help with reflections coming at the mic on axis). Still, could be better than nothing. Also agreeing with Jim as this would not be the ideal/optimal method.

[DukeX]

Google "mic shield" and you will see a lot of options (designed for vocals, I think).

I don't know how effective they will be for acoustic guitar.

[Chipotle]

You mean like this?


Or like this?


Or maybe even like this?


They have uses for vocals, where you are close-micing, in some situations. Other times they have the potential to make things worse, if there are are any resonances inside the enclosure itself.

The semi-open ones like the first picture also don't completely get rid of the room. Not only the waves still bouncing back into the front of the mic, but sound from the back still travels around the shield some (if you stick a solid panel between you and another person talking, even outside with little reflection, you don't suddenly stop hearing them).

An acoustic guitar is also a much wider field of sound than a voice. Sound information is coming from the entire guitar all the way to the nut, not just the body. Attenuating sounds going to the side areas of the mic might lose some of the guitar character (just guessing here but I don't think the effect would be beneficial).

Thus for guitar what you want is to use those 4' panels to make essentially a much larger version of a box or shield, so the guitar is inside it. That way you pick up the guitar, but hopefully not the reflections of the room around it.

EDIT: Sound on Sound did a test of the effectiveness of mic enclosures for vocals. Key quote, I think: "The main way in which portable vocal booths reduce room reflections is by absorbing the sound before it can escape into the room." Not by stopping reflections coming back. If that's the case, you can see why it wouldn't really do much for a guitar.

[runamuck]

I've used a couple brands of the foam-type mic shields, one expensive and one cheap. I didn't like either because they seemed to cause subtle comb filtering.

Using 703 or the like would probably be much better but my room is treated now so...

[Doug Young]

There are multiple things going on when people talk about room acoustics. Short reflections is one thing - causing everything from audible "slap-back" echo to just lousy tone, and one of these small shield things may help with that, tho as others have pointed out, they may be too small to work with guitar. You generally fit one mic in them. You could also build your own "box" that is larger - which is usually called a "gobo". See Fran Guidry's site for a demo of what a couple of 2x4 panels placed around you does. There is a danger of comb filtering still, but you'd have to see. This is a reasonable solution for someone who can't permanently install something.

The other issue is room resonances. When I first started recording acoustic, I always got a boomy low G on everything. I blamed the guitar, I blamed the mics, I blamed me for playing the note too hard. Turns out the room I was in had a resonance at that frequency. (There are calculators on the web.) Only bass absorbers (or a different room) was going to solve that problem. I'm not sure that a gobo, small or large will eliminate that, tho it may help a little.

Then, of course there's noise, which is a whole other can of worms. Whether some sort of baffle/gobo/box can help with that depends on the noise, but generally, I doubt it would help much. Even my full-room treatment can't eliminate the sound of an airplane or the TV, or the washing machine running in the house.

[KevWind]

Originally Posted by TBman

Why make big 4' acoustic absorbant panels (for example) instead of a "sound treated" 3 sided box that a mic can be placed in?

Would it work?

First because as has been pointed out for acoustic guitar the commercial ones are too small to be of much use:

But :
Backing up to a more fundamental question , (given often ask the wrong questions).
Perhaps the right question is "Why not,,,, 4 ft by 2 ft by 4" to 8" absorber panels ?"


And ultimately :

Because "Home Recording" is a misnomer----- It's Home Recording and Mixing
And always only mixing with Head Phones presents another set of issues .