acoustic treatment - bookcase

[Ibvee]

I was thinking about this, and searched somewhat here on GS, but couldn't find anything about it.

The basic idea is, using a bookcase filled with books as a broadband absorber/bass trap/diffusor.
- When you space the books in a random way, leaving some space here and there, it could have some kind of diffusor effect.
- Because books aren't really solid, but still have quite a high density, they might work as a broadband absorber.
- Because the backs of the books arent very soft, the highs won't be to much absorbed.

On top of that, if you take a somewhat old looking bookcase with old books, it looks killer, and is fairly cheap.

Some other benefits: You could put in some magazines for boring artists, you could put your microphones and other small stuff in it, make a safe behind the books just like in the movies, put your surround speakers in it, etc.

But it only works when the acoustical properties are right...

Somebody tried this allready?

[Dave Martin]

You mean like this?

[Scott R. Foster]

Who cares... that looks cool.

[jayfrigo]

Originally Posted by Ibvee

The basic idea is, using a bookcase filled with books as a broadband absorber/bass trap/diffusor.
- When you space the books in a random way, leaving some space here and there, it could have some kind of diffusor effect.
- Because books aren't really solid, but still have quite a high density, they might work as a broadband absorber.
- Because the backs of the books arent very soft, the highs won't be to much absorbed.

This is not a new idea, and does look cool; and it does a bit of good, though not as much as you might hope. The books are more akin to a limp mass, like "soundboard" that is used for resilient channels and such, than an absorber. It's not going to absorb much bass, but depending on a number of factors, possibly including an airspace behind, and how tightly the books fit, it may absorb a bit. Still, it will be neither efficient, nor very broadband, and it will be hard to predict whether it will cover any frequencies that matter in your room.

As for diffusion, it will provide some general scattering, but again, effectiveness will vary, never attaining uniform dispersion over a wide range. Again, predicting the effective bandwidth or diffusion coefficient will be next to impossible, so it's hard to know if it will address what you want it to.

Something like a QRD diffusor works because of a precise mathematical relationship of the number of wells based on a prime number, the depth of each well, and the width of each well. Those factors determine the effective bandwidth, and provide the even diffusion characteristics. Also, effectiveness is greatly reduced when you remove the spacers between the wells. Simply providing an irregular surface is not terribly effective, except perhaps at eliminating flutter.

Still, it is certainly far better than a big expanse of drywall, and does offer some absorption and diffusion. Add to that the aesthetic appeal, ease of installation, and reasonable price, and I wouldn't ignore the option. Plus, I love books and would probably enjoy reading a bunch of them (in my, ahem, copious free time... right).

[Ibvee]

Thanks for the very well explained post! I think I will still go for some nice broadband panels in the back then
However maybe one day in some kind of tracking room it might be cool! Maybe I try something like a sort of library room, surrounded with book cases

@Dave:
That room looks cool man! Does it sound good?

[Ethan Winer]

Jay,

> This is not a new idea, and does look cool; and it does a bit of good, though not as much as you might hope. <

Exactly. A shelf full of books helps a little, but it's not the same as real acoustic treatment - either absorption or diffusion.

I've had a product idea in the back of my mind for a few years now, but there's too little profit to be had as a commercial product so I hereby put it into the public domain:

Cut a piece of 1/4 inch plywood or cardbard into the pattern of a QRD diffusor, such that you lay it flat on a shelf and push it into a stack of CDs to force them into the correct pattern. When you slide the wood or cardboard back out, the CD case depths are aligned properly. If the CDs get misaligned, just push them back in again.

If I thought folks would pay $200 for such a piece of cardboard I'd sell it. But this is probably more suitable as a DIY project.

-Ethan

[jayfrigo]

Originally Posted by Ethan Winer

Jay,

> This is not a new idea, and does look cool; and it does a bit of good, though not as much as you might hope. <

Exactly. A shelf full of books helps a little, but it's not the same as real acoustic treatment - either absorption or diffusion.

I've had a product idea in the back of my mind for a few years now, but there's too little profit to be had as a commercial product so I hereby put it into the public domain:

Cut a piece of 1/4 inch plywood or cardbard into the pattern of a QRD diffusor, such that you lay it flat on a shelf and push it into a stack of CDs to force them into the correct pattern. When you slide the wood or cardboard back out, the CD case depths are aligned properly. If the CDs get misaligned, just push them back in again.

If I thought folks would pay $200 for such a piece of cardboard I'd sell it. But this is probably more suitable as a DIY project.

Cool DIY idea for somebody with a large CD collection or FX/music library, though a pain for regular CD listening!

I had thought about similarly arranging some old, outdated sets of encyclopedias that you can often get cheap. The uniformity of size and number of volumes would allow you to calculate QRD depths and create something that would work.

You'd be stuck with the width of the volumes as your starting point, but at that size it would work in the mid- to upper mid-range, not a bad place for diffusion. Anyway, too much work, not enough return, plus you have the decreased effectiveness due to the lack of well dividers.

[tINY]

I thought somone had a patent on that - RPG, I think they called it.

You'd have to pay a royalty if you wanted to make a comercial product of it.

Kinda hard to sue someone when they don't make money on it, though. Especially when you published in the AES Journal....




-tINY

[Extreme Mixing]

Seems like Ethan's membrane and broad band absorbers are an easier and cleaner solution to acoustic woes. They take up less room, and are probably cheaper. That's what I did.

Steve

[doorknocker]

Originally Posted by Dave Martin

You mean like this?

Aren't books threatening to the average drummer? I mean, I see the sonic reason behind this but what about the intimidation?

[audiovisceral]

Originally Posted by doorknocker

Aren't books threatening to the average drummer? I mean, I see the sonic reason behind this but what about the intimidation?

lol. use dr. seuss.

Java Jive [ a recording studio ] - S t u d i o
^soooo nice

[Old Cane]

Originally Posted by doorknocker

Aren't books threatening to the average drummer? I mean, I see the sonic reason behind this but what about the intimidation?

The look on the drummers face when he asks "what are those?"

PRICELESS.