Home Theater Forum and Systems banner

Acoustical solution needed...

8K views 48 replies 17 participants last post by  Sonnie 
#1 ·
Below are a few shots of our fellowship hall that we have recently refinished. Unfortunately tile was opted for instead of going back with carpet. We had no echo problems previously with carpet.

We have some pretty picky ladies that are going to be very difficult to please when it comes to taming the serious echo we have created. It's near impossible to carry on a conversation in the room.

We have suggested to the ladies that we build and locate large 3' X 8' or 4' X 8' panels all around the room directly above the chair railing. We plan on using 2" X 2" frames with regular fiberglass insulation and cover with one of the 54 samples of GOM material we have to choose from. Of course they were none to crazy about having the big panels placed around the room... not even in every other open space.

What the ladies are saying that they would accept is for us to build panels to go around the bottom of three sides... all sides except the kitchen area. These would be approximately 30" x 8' panels below the chair railing and between the receptacles. Notice the red block in the last picture.

We have no idea whether this will do the job or not. Obviously we don't want to purchase all the materials, build the panels and then they not be sufficient to work.

We are looking for ideas, suggestions, alternatives. They must be inexpensive, thus our suggestion of building them ourselves. No way we will spend the small fortune it would require to buy panels.










 
See less See more
4
G
#36 ·
Just to reinforce what Ethan Said to some extent.

you CAN make a significant difference using appropriately located wall mounted absorbers, but they'd be muonted much higher up than you were discussing previously... but the most effective and invisible solutions would be ceiling mounted absorption panels... or a False ceiling of acoustic tiling...

note that they should not be mounted hard against the ceiling surface, but hung a little below it... approximately 50% of the flat ceiling space surface area, , in a chequer board pattern would be a good place to start....

Panels can also be hung arranged in the vertical orientation, to act as baffles to control the high level wall to wall flutter echoes... imagine it like a cloud of absorption... taming both the simple floor to ceiling reflections, and some of the more complex floor-wall-ceiling interactions....

this could be done and still maintain the nice open, high ceiling feel of the room, but the simplest answer, and sometimes the most cost effective is a straight forward , flat suspended false ceiling, like you see in office blocks, ,made using acoustic ceiling tiles, some of which are specifically designed and voiced to increase vocal intelligibility, and reduce cross contamination between office spaces.. , (Ecophon is one european ceiling tile name that might be available stateside.. )

If i were looking at the room with a musical eye on it, I'd mix diffusion devices with absorption....


other small but important touches can also make a useful difference... things like using plush deep soft furnished chairs rather than hard surface plastic or wooden hard chairs... seems too simple, but it can make a difference...

throwing the numbers in to one of the room evaluation packages might well give you some idea of how bad it is, but it won't necessarily give you the right answer in terms of choosing and placing acoustic treatment.... better to get a professional out, even if for only one day....
I know of a few who work in the US, but really I have no idea of any of them are geographically useful to you....
I would suggest you contact RPG Inc

http://www.rpginc.com/

I use their products here in Europe (although from their European subsidiary) and IMHO, they're without doubt the best and most comprehensive supplier of acoustic solutions, and they're led by one of the worlds foremost acousticians, with proper research facilities and scientific back up.

Ethan Winer's company, "Real Traps", also supply some useful products, both in the US and over here.... and at pretty reasonable prices... But RPG are the real experts when it comes to complex solutions.... (sorry Ethan, but it's an unbiased reality, even Auralex are newbies compared to the guys at RPG. )

Ethan is however, very much a champion of bringing acoustic ideas to the ordinary joe... in as plain and easily digestible a manner as possible... some acoustics experts criticise him for perhaps simplifying too far now and again, but his intention has always been honourable, to educated the masses and make acoustics at least partially understandable for the average joe on the street.... More power to his keyboard i Say !




.... Can't really help on site, as i'm UK based.... but for the record, I build recording studios for a living... both Live spaces and control room spaces.. and occasionally do a bit of acoustic consultancy for Schools, Churches and Theatres etc.



Regards

Max The Mac

AKA

Max Hodges
Consulting Engineer
Maxtech Audio Services
Oxford
UK.
 
#37 ·
Hi Max and thanks for chiming in. I'm going to mention a few things to our ladies about doing something on the ceiling and high up on the walls. I think they would definitely go for that. As far as installing a complete acoustical ceiling, we tore the one we had out so we could have the vaulted ceiling back to original height.
 
G
#38 ·
I realise you ripped out the old ceiling Sonnie, you did say so earlier.... I thought i'd just subtly hint that that was probably a mistake as far as your immediate problem goes ;) without actually rubbing anyone's nose in it..... :sneeky:
 
G
#39 ·
Have you look at building a Helmholtz's resonator to modify the resonant frequency of the room

they can be painted and made to look quite stylish

also maybe look at http://www.odeon.dk/about.htm
and
http://scitation.aip.org/getpdf/ser...02000002000061000001&idtype=cvips&prog=normal

I also have a colleague who is looking into acoustic room modeling at present i'll ask her some ins and outs

id suggest for standing waves

staggered absorption along the walls

for reflection find the end that will have most of the focus and diffuse the other end with reflective foam and also the Helmholtz

and maybe some corner diffusion as well

rubber shops sometimes sell foam cheap that you can paint and cut to size - I recently bought some for $10/foot
 
#40 ·
Max,

> RPG are the real experts when it comes to complex solutions.... (sorry Ethan, but it's an unbiased reality, even Auralex are newbies compared to the guys at RPG. ) <

No offense taken. Dr. D'Antonio is very much "da man" when it comes to acoustics. Then again, you don't really need Jonas Salk to give you an annual physical. What matters with acoustic treatment is the quality of the products and the quality of the advice you get. If you call RPG to ask what acoustic products you need and where to put them, I promise you Dr. D'Antonio will not be the guy who takes your phone call. When you call RealTraps you get me in person.

> some acoustics experts criticise him for perhaps simplifying too far now and again, but his intention has always been honourable <

That old saw has been totally discredited. As it turns out, I was right all along. :raped: Email me through my company's site if you want more info on that.

--Ethan
 
#41 ·
Hey if you are looking at Guilford fabric, be aware that they have MANY MANY patterns and styles to choose from 54 choices sounds like you've been looking at the FR701 which is UGLY UGLY UGLY.

I phoned GOM and got the number of my local rep - she sent me a few dozen sample pages - each page has about 10 small fabric samples, and often one larger one. From that I quickly narrowed down what I wanted and ordered 'memo' samples from the GOM website - (memo's are appox 8x10)

One fabric you might look at is Anchorage - its a plain fabric (no pattern) but the look has a higher quality about it - and it's available in I think about 50 colors or so. Including many shades of brown that would fit right in with your room.

One possibility I didn't see mentioned when skimming this thread - would be to build a 'false wall' made entirely of fabric - right above the kitchen - IE - frame out your 2 inches or so, put up your rigid fiberglass, and then cover every inch of wall with fabric - at that point - the fabric becomes the wall, and is barely noticeable - and hardly objectionable, as it gets past the whole 'panel' issue.
 
#42 ·
We have 50+ samples to look at.... I'd say they GOM has 200-300 or more. We got samples running out our ears and several of them are very nice.

We are looking at possibly doing something on that wall above the kitchen and high up on all the walls... just not sure yet. The ladies are having a hard time making up their mind what they want.
 
G
#43 · (Edited)
I have found that the best place to start is with trapping troublesome low frequency modes. This is best achieved by using Linear-X which will quickly identify the troublesome frequencies, if that is not available try the Real-traps test tones.

The 3rd and 5th harmonics of the identified modes (booms) will cause continue to cause problems in the frequency range 300 - 4.5kHz if not treated, however much fiberglass you add!

Treat the bass with tunable traps to accurately tame those resonances, then by using Aoustic-X, if anyone still has access to that fabulous product, to calculate the treatment required for a room of that size,. When treating a large area a variety of surfaces are required if you are to keep a flat responcse, ie you do not want to suck all the life out of a room by only having soft absorption.

Ref - Membrane Absorbers in Alton Everests - Master Book of Acoustics 4th edition pp213-4. Also you must factor the absorption of air into rooms of more than 1000 cu Ft. p203 als0 Everest. Then use a Sabine spreadsheet to calculate the existing RT before "treatment" is condsidered.

Good accurate trapping will improve things remarkably if carefully and accurately done, post operative shock syndrome etc!

Another alternative to soft surfaces and membranes is polycylindricals which can look really good, by increasing the surface area relative to the room volume, good for areas that suffer from slapback or pinging.
 
#44 ·
I think I would keep it simple. If I have understood correctly, previously the room had absorption on the floor and ceiling and was satisfactory. I think you need to put back the carpet and/or ceiling absorption.
Ecophon is a terrific ceiling product, can be direct-fixed, but costs $$$.
I have concerns about DIY acoustic panels on ceilings - White fabric dos not have as much light reflectance as a white painted surface so the room may get a bit darker visually. also, fabric is likely to stain and sag over time.
What I have done in some large houses is to fix acoustic panels to the ceiling in certain areas - e.g. running between light fittings - made in this way: 50mm battens fixed to the to the ceiling, absorption material taped in place between the battens, white polyester or acoustic fabric over the front of the batts, then fix perforated plywood or perf plasterboard over the front (fixed to the battens). Paint it all white before installation (don't fill the holes...) & works very well. 25% open area perf is best but even as low as 10% open area with 50mm thick batts will still have more absorption than the carpet that was there b4.
If that is not enough then I would suggest run heavy drapes over the walls between the windows. Only really needs to cover the plane of ppl speaking, i.e. between about 800mm and 2000mm. Personally I think it would look fine above the rail.
 
#45 ·
As all of the walls are solid you are having a lot of reflections between them. I agree with Wayne in saying that you will need roughly the same amount of padding as you had carpeted previously. Try to get materials that have a lot of mass to absorb the sound, have heard that fibreglass is really good for absorbing sound. I'm glad I don't have to install it though i hate working with fibreglass
 
#46 ·
Just wondering how have you got along with this problem? are there any advances yet?
 
#47 ·
Nothing... something tells me we'll never do anything. It's really out of my hands. I've offered to help, but no one is making a final decision and I'm not in a position to be able to make that decision. I've pretty much let it be and if someone asked me about it... I defer to the Elders.
 
#48 ·
Just came upon this. I'm no acoustical expert, but I do lift weights......and one of the things I notice in a lot of gyms (which have most of their walls covered by mirrors, have painted drywall ceilings, and plenty of noises being created from weights clanging and cardio machines blazing) is acoustic panels suspended from the ceiling by wire. The panels are maybe 2'x8' and spaced at even intervals. Seems to work pretty well.
 
#49 ·
That has actually been discussed, but it seems it's pretty much left up to what the ladies want and they can't all agree on what it is they want. We've suggested every possible scenario. I guess one good thing about it is no one is complaining about the echo anymore... :huh:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top