John Sayers' Recording Studio Design Forum Archive

The last time I built hangers, I stapled 3 1/2” batts of fiberglass to the homasote. I’m getting ready to build some new ones, and remembering what a pain it was, and that overtime the fiberglass tended to become unattached, I had a few stupid ideas.

Would it work to hang rigid fiberglass boards instead. Or what about accoutic ceiling tile?

As I said, I know these are probably not good ideas, but from your answers a to why, I might come to a better understanding of why you build yhem from homasote and insulation. From all I’ve read, there are many of us who are still confused over hangers!

In addition, if anyone can explain a better way to attach, and/ or different types of insulation to use that would give a better result than I achieved last time, I would be very grateful.

The basic concept is that hangers work on several principles at once to do what they do, including absorption, resonance, and impedance mismatch, but the number 1 principle is that they act as waveguides. They re-direct the waves, changing the direction that the were moving into a different direction, and that results in many different good things happening. It also means they are tuned, and basically the rule here is: the bigger, the better! so make them as long as possible in both directions. That's why you often see hangers hung at an angle, instead of straight-on. That allows them to be wider, which implies that they work down to a lower frequency. They also need to be hung such that they don't touch each other, nor prevent each other from swinging gently. And they should ideally be spaced such that each one falls on an important part of the wave, assuming you are using them to treat modal issues. So you want them at the half-wave points, quarter-wave points, eighth-wave points, etc.

Homasote is a good core for the hangers, yes: it is reasonably firm so it provides a good base for the insulation. It is decently massive, so it can deflect the sound well, but it isn't hugely massive such that it causes mid-range reflections. So stick to homasote.

For the insulation, the best I have found is OC-701, or OC-703. 701 if you are making them very big, and shooting for very low frequencies. Otherwise 703 is fine. You can attach it with screws and oversize washers. Here's how Frank did his hangers recently, in the upper part of his speaker soffits: http://www.johnlsayers.com/phpBB2/viewt ... &start=279 Read a few of the comments below the images, for mounting details.

Also, you don't need such think insulation! 1" is fine. 2" would be great, if you have the space to do that, but 1" is quote effective. Look through the full thread for Frank's build, and you'll see how well it works.


- Stuart -