Hangging bass panells Hidley traps

Is the angle of the panels part of the procedure, a space constraint or both?

for this study the angle is important and thy did not do any varitions with measurmentes would need more tests separation between them also is a factor

I found it interesting that they angled the ceiling panels toward the speakers - I've never seen that done.

I found it interesting that they angled the ceiling panels toward the speakers

Could you clarify what those "ceiling panels" are, John? You mean hangers in the ceiling, or something like clouds on the ceiling? And they were angled to point edge-on at the speakers, or face-on towards the speakers? Either way, it sounds unusual.

This is their hanger layout.

Thanks John. I'm trying to get my head around that, but not understanding it. How can they work if they are facing the speakers head-on? But I'm not surprised that resonance of the panels themselves accounted for less than 1% of total absorption in that configuration, since I can't see how the panels would be able to resonate at all from direct sound, if they are deliberately aimed edge on to the speaker. It's almost as though the idea is to use them as some king of combination diffraction grating and wave guide, but I still don't get how that would do the job: Where are they "guiding" the "waves" to? Is there a whole bunch of absorption behind those panels, or is it just drywall? I guess I'm just not getting the principle of operation. :?: - Stuart -

I think the intended idea is that hopefully the energy of the wave is used up by the time it goes between the angled panels and hits the back wall, supposedly it has lost the energy to be reflected back out through the angled panels, thus it is 'trapped'

mike0370 wrote:

I think the intended idea is that hopefully the energy of the wave is used up by the time it goes between the angled panels and hits the back wall, supposedly it has lost the energy to be reflected back out through the angled panels, thus it is 'trapped'

Yes - that's what they saying - but why did hidley hang them behind walls and ceilings? Hidley originally built what were called "compression ceilings" where the ceiling over the console was solid timber with hangers behind in the ceiling cavity. In his Quad rooms there were two ceilings with hangers behind. In his live room at Paradise studios in Sydney, which I watched being built, he had hangers behind the 1/2" glass mirror walls. He never appeared to take into consideration the direction of the sound as this article suggests.

There is a lot of info on hangners and hidley's design in the "recording studio design" book by P.Newell. The control room design shown in the pict is a non-enviroment studio where every surface exept the front walls and floor are made as absorbent as possible to the lowest range possible. Here's a rough "resumé" of some findings made by Mr newell in a studio of that kind during construction. The first thing that he says is that those panel do not work by themselves but rather in an array. The hangers on the side have almost no effect on low freq. but a huge effect on higher freq. Array of Hagners on the rear wall yeild better low end absorptions if they are angled about 45 deg from the source. The angle toward the speaker of the ceiling hangers is not a dominant factor but the size and angle play an important role. I might also add that hangner made by M. Newell in his numerous studio are made from chip board covered with deadsheet and rockwool or felt. Also the walls behind those hangners are not just double 5/8 gypsum board on 2X6 structure but rather a deadsheet in a double 1/2 gypsum sandwich, that itself act as a low freq absorber. There is often a curtain of deadsheet suspended in front on the walls. The good low frequency response of a room like this is a result of a multitude of construction technique to get there, not just the hangners. They are a complement. There is a section where some test where made to measure their effect but to be quite honnest i'm not sure i undestand it quite well so i won't get into that. My 2 cents

the AES papper is based in a none enviromental room made by Newell I have newels book and he discribes this tecnic but the this tecnic has been used for many year without nowing exactly what is happening this papper helps a bit

orangenumerik wrote:

There is a lot of info on hangners and hidley's design in the "recording studio design" book by P.Newell. The control room design shown in the pict is a non-enviroment studio where every surface exept the front walls and floor are made as absorbent as possible to the lowest range possible. Here's a rough "resumé" of some findings made by Mr newell in a studio of that kind during construction.

the non-environment studio design is P Newell's not Hidley's. This is just Newell's interpretation of the Hidley system as I know for a fact Hidley used homosote and fiberglass not chipboard and rockwool, and as I said before, he had them behind walls so the theory presented in the paper was not the theory Hidley used.

i agree too some degree John but it is the frist seruis study i have seen on this type of trap it like talking about difragmatic trapas and the difrent matarial that can be used too my opinion Newells and Hidly are the same type of trap and this study brings a good aprouch of what is realy happening

It would be good to have a real life measurement of a room without hangers, and then with hangers installed on the back wall. to see its change on frec response. Also, if you were to put hangers on your back wall, would you also put rockwool panels behind the fabric that covers them? In other words, by placing hangers on the real wall will somehow treat low frecs, but it also has to behave for rear wall reflections as well... :?:

t would be good to have a real life measurement of a room without hangers, and then with hangers installed on the back wall. to see its change on frec response.

That test have been done by Newell and documented in the second edtition of his recording studio design book.(P.648)

I know for a fact Hidley used homosote and fiberglass not chipboard and rockwool

I agree john , i was just pointing out that some designer use chippboard and felt as their panel core. Since a lot of peoples wonder what is best. The more i read about hagners, (every bit of info i can find) seem to show that panel core is not a determining factor but rather the fact the each hangner is part of an array.

...he had them behind walls so the theory presented in the paper was not the theory Hidley used.

absolutely right, my guess is that those hagners behind walls are for damping of the resonant cavity.

orangenumerik wrote:

absolutely right, my guess is that those hagners behind walls are for damping of the resonant cavity.

that's what I've always assumed also. ;)

In that case it means that the material used to hold each piece of insulation doesnt really matter at all. It could be even a piece of wood! Am i right? (because finding homosote or similar gave me a big headache)

My guess is as long as it is "lossy" or damped it is OK. A plywood covered with dead sheet should do the thing imho, or anything that would damp the panel. homosote is a quite "dead" material wich probably makes it ideal for the job.

Why you need a damped material in between if the insulation already do that job on both sides?

Why you need a damped material in between if the insulation already do that job on both sides?

My guess is that you need it to help damp resonance in the panel itself, which the insulation probably wont do well enough by itself. Just a guess though. I might be wrong... - Stuart -