Acoustic hangers

[John Sayers]

definitely Stuart, excellent research paper material.

I remember that thread with Eric - no one could actually say how they worked.

I mentioned watching oyster cages hanging in the bay and watching the wake from the boats wash into the cages and disappear. I suspect that's kinda how they work.

[Soundman2020]

Now there's an idea! Oyster-cage acoustic bass traps! The aesthetics might be a bit strange, though....

Seriously, that sounds like a good explanation. I'd never really thought of it like that, but it makes sense. The energy is somehow dissipated and/or diffused, and/or maybe even diffracted by the hangers.

John, maybe this is a question that you don't want to answer (understandably!), so just ignore it if that's the case: but in your experience, does changing the orientation and separation of the hangers change the amount of absorption, or the peak frequency of absorption, or some other parameter? And if so, how? I mean, does increasing the spacing between hangers make them absorb better at lower frequencies, or higher, or no change? Do they absorb better when the are "face-on" to the incoming waves, diagonally across their path, or oriented "in-line" with the waves?

- Stuart -

[John Sayers]

Stuart - as I see it there are two ways to use them, thus mount them.

In the model I gave the corner hangers is the corner trap method where the sound goes into the corner and the hangers get bigger and more massive as you go into the corner and the sound has to to return the same way.

The other use is in a ceiling where I place them in the modal points - ie. one in the middle (1/2) then one in the 1/4, 1/8, 1/16 till you run out of room. Plus you may also be going in two directions at once for opposing walls.

[Soundman2020]

Thanks John! That makes a lot of sense, and gives me a first "empirical" rule about hangers: If they work best at modal points, then they must be velocity-based, not pressure-based. Interesting! That certainly does shine a little light on an otherwise dark subject. It makes me think they must be acting something like wave-guides.

Much appreciated.

I'm going to have some free space up in the rear ceiling-wall corner of my room, and I'm thinking about hangers for there. Either hangers or a large horizontal superchunk: I haven't quite decided which.

- Stuart -

[John Sayers]

the hangers are cheaper

[Soundman2020]

I like "cheaper"!!!

A quick question: Are hangers more (or less) effective in tri-corners (wall-wall-ceiling) than they would be in normal wall-wall corners? I guess they should get the normal extra 6dB boost (18 total), like any other tri-corner treatment, right? I'll have some nice deep spaces in my rear tri-corners, that would be ideal for hangers, I think.

- Stuart -

[John Sayers]

I'm not sure what you mean Stuart - wall wall ceiling v wall wall - there must be a ceiling.

[Soundman2020]

Yeah, I guess I wasn't to clear about that! I'm thinking out loud about my room, but not explaining my thoughts too well...

What I mean is this: Imagine a bunch of hangers that don't stretch all the way from the floor to the ceiling, and are only 50% of the room height. So if the room is 2m high, then let's say that the hangers are only 1 m high, for argument's sake.

Is it better to have that "bunch of hangers" located part way up the wall, away from the ceiling and floor? Or is it better to put it at the top of the corner, next to the ceiling?

I suspect that the best position would be up top, where I expect it would get the extra 6 dB boost in effectiveness due to having the ceiling there too.

The reason I ask is because of the HVAC ducting that I need to get into and out of my room: The only place I can bring it in is in the rear corners, which limits the size of the space where I can put hangers, and thus limits the maximum length of the hangers. But I can move the ducting up or down slightly, if the hangers would be more effective in one location than another.

I guess that still isn't very clear! Maybe I should just do a quick sketchup to explain it better, but that will have to wait. It's way past my bedtime, I still have work to do!


- Stuart -

[John Sayers]

oh - ok - I've always understood the bigger the hanger the lower the frequency. Tom Hidley would build a 35ft square room (so much for modes) and then add an inner shell (cloth covered most of it) with a 3 -4 ft space behind which he would fill with hangers of all sizes. Same for the ceiling. He was claiming flat response i.e. flat reverbtime @ .4sec down to 20hz.

check this out

GF_PLAN_PROMO.jpg

[Soundman2020]

Thanks John! That makes sense. OK, so I guess I'll see if I can re-figure how to make my hangers as large as possible, but a depth of 3-4 feet at the back would be nearly half the depth of my entire room! I really need to get a bigger house... I have maybe 4 inches to spare across the back wall, widening out to maybe 18" at the top (above head height). That's where my hangers will go, but I also have to have HVAC ducts in there...

I think I need to post an updated SketchUp model, so you can see where I am right now...

Tom Hidley was also the guy who pioneered concrete soffits, so I guess that makes him something of a role model for me! Concrete soffits and hangers.... hmmm... Now if only my room would end up sounding even half as good as one of his....

- Stuart -

[John Sayers]

yes - but the concrete soffits housed twin 15" drivers - is that what you'll be having??

[Soundman2020]

I wish! It will just be a pair of humble Adam A7's, and a Sub-8 down on the floor.... If I tried to put 15" drivers in there, I'd be out of soffit already!

But say, if I'm using 8" speakers, and he used 15", does that mean mine will sound a bit better than half as good?

- Stuart -

[John Sayers]

actually - I suspect the quality of the new 8" drivers is superior to the old 15" crankers

[micmic]

Hi John and all of you.

A attached some pictures of the hangers I made for the studio I designed.
There are seven on each site. 2.5 Meters high and the width varies from 30 cm till 75 cm.
I'll hope that's enough....
Don't mind the HVAC outlets hanging there. They gonna be mounted in the ceiling.
In the middle comes a diffuser.

[Kaj]

Hi all, thanks for the....(I hope).............Sticky to be!!!!
Two and a half question-statement(s), only to stimulate all you experienced people on this forum to share your visdom once again!

Q1
Wouldn't a RealTrap work as a hanger if arranged in the same way?
(Ethan, have you tried to place them like hangers?)
Q2
Would it be possible that the soft particle board is selected only due to its low density but still strong enough as a core supporting hanging assemby and to carry fluffy insulation glued to it?