wall reflections off glass worse than drywall?

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Rob S.

wall reflections off glass worse than drywall?
« on: 15 Dec 2007, 09:16 pm »
Is having numerous picture frames on walls to a dedicated audio room any worse than having the same space exposed with drywall?   I'm mostly done with treating my room with about 15 pieces of room treatments from Realtraps and GIK and like the way the improvements have helped the overall sound.  I'm wanted to put something else on the walls.  Would a handful of large type glassed frames set me back some sound wise?

Thanks,

Rob S.

PaulHilgeman

Re: wall reflections off glass worse than drywall?
« Reply #1 on: 15 Dec 2007, 09:30 pm »
Remove the glass maybe?  Then you will at least have some diff/abs properties in higher frequencies

TomS

Re: wall reflections off glass worse than drywall?
« Reply #2 on: 15 Dec 2007, 09:42 pm »
Is having numerous picture frames on walls to a dedicated audio room any worse than having the same space exposed with drywall?   I'm mostly done with treating my room with about 15 pieces of room treatments from Realtraps and GIK and like the way the improvements have helped the overall sound.  I'm wanted to put something else on the walls.  Would a handful of large type glassed frames set me back some sound wise?

Thanks,

Rob S.

Rob,

As Paul said, those glass surfaces are best avoided due to HF reflections they will likely cause.  They really won't negatively affect the gains you've made with the existing bass treatments AFIK.

How about some fabric and/or canvas art, possibly an interesting variety of some smaller wall mounted sculptural objects and break up the surfaces a little?

Tom

JLM

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Re: wall reflections off glass worse than drywall?
« Reply #3 on: 15 Dec 2007, 09:47 pm »
Actually you're comparing glass to paint (a thin, but hard surface).  Bare drywall versus paint in a room makes a huge difference.

How about oil paintings or lithographs?

richidoo

Re: wall reflections off glass worse than drywall?
« Reply #4 on: 15 Dec 2007, 11:16 pm »
If the glass is not on a first reflection point, you probably wouldn't notice a difference between glass and sheetrock. If the wall opposite the glass pics is parallel and reflective, you may want to put something cushy on that opposite spot, to avoid high freq slap, but only if the beam is near where you are sitting. To absorb high freqs you don't need much cush, a curtain, tapestry, whatever. But it's not a big deal, as long as you have some cush in the room. Bass freqs won't be affected by glass vs. sheetrock.

If the pictures aren't very large, you could put a thin padded upholstery behind them and get a very slight little bit of amplitude diffusion. If they are big big, probably wouldn't work. You can hang them by wire, allowing them to tilt facing downward slightly to avoid slap with parallel wall.

I have a lot of glass windows in my room, it's just more hard surface that needs some cush elsewhere to offset.  Congrats on the room treatments Rob!!
Rich

Rob S.

Re: wall reflections off glass worse than drywall?
« Reply #5 on: 16 Dec 2007, 03:46 am »
I was hoping to fill in some spots between the panels.  Yep, wasn't going to mess with the 1st Reflection points,  maybe some additional wall decorations or such before and after the panels.

Good suggestions guys.   Thanks.

Rob S.

bpape

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Re: wall reflections off glass worse than drywall?
« Reply #6 on: 16 Dec 2007, 02:37 pm »
Actually you're comparing glass to paint (a thin, but hard surface).  Bare drywall versus paint in a room makes a huge difference.

How about oil paintings or lithographs?

Sorry but I've got to jump in here on this.  The difference between painted and unpainted drywall is unmeasurable and basically zero.  Picture frames on the wall are a different story as they're forming a cavity that can resonate and are not recommended.  Removing the glass is a good idea.

Tapestries and such are touchy as they'll give you some high frequency only absorbtion which you may or may not want.

Bryan

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Re: wall reflections off glass worse than drywall?
« Reply #7 on: 17 Dec 2007, 03:04 pm »
If the glass is not on a first reflection point, you probably wouldn't notice a difference between glass and sheetrock.

I agree with this. People obsess over glass, which does reflect the highest frequencies more than sheet rock. But it's not that much more reflective, and it's only at the "zing" frequencies. It's the difference between echoes in a tiled and untiled bathroom.

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JLM

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Re: wall reflections off glass worse than drywall?
« Reply #8 on: 17 Dec 2007, 04:27 pm »
Brian,

Just walk into a drywalled room before and after painting.  Its undeniably different, much more reflective.  Even bare drywall to drywall that's been primed is different.  And the difference between primed and painted is an even bigger difference.  It has worried me in the past on various projects, but adding carpet/furnishings brings it back to a more normal acoustical nature.


bpape

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Re: wall reflections off glass worse than drywall?
« Reply #9 on: 17 Dec 2007, 04:38 pm »
To each their own.  Next time I'm in an unpainted room, I'll try to remember to take some measurements before and after painting.  I just can't see how a layer of latex that's maybe 0.010" thick is going to impact anything.  Carpet and furniture, absolutely.

Bryan

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Re: wall reflections off glass worse than drywall?
« Reply #10 on: 17 Dec 2007, 05:10 pm »
Brian,

Just walk into a drywalled room before and after painting.  Its undeniably different, much more reflective.  Even bare drywall to drywall that's been primed is different.  And the difference between primed and painted is an even bigger difference. 

Then, which paint have you found to have the best acoustical properties?

Cheers

bpape

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Re: wall reflections off glass worse than drywall?
« Reply #11 on: 17 Dec 2007, 05:54 pm »
If I'm reading his posts correctly, his assertion is that the paint actually hurts the sound and makes things even more reflective.  I'm not sure how that little thin layer covering another thin layer of paper bonded to what equates acoustically to rock is going to change anything. 

Now, if we were talking about sealing a porous surface which was bonded to a material which was absorbtive in the high frequencies fiberglass, mineral wool, cotton, etc.), then I'd agree 100%.  But, the drywall isn't absorbtive much at all in the high frequencies and the paper is already mostly reflective.

Bryan

Ethan Winer

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Re: wall reflections off glass worse than drywall?
« Reply #12 on: 18 Dec 2007, 05:18 pm »
I'm not sure how that little thin layer covering another thin layer of paper bonded to what equates acoustically to rock is going to change anything.

When recording studios build "live" reverb rooms, they typically coat the interior surface with shellac or varnish to make the surface even harder and thus more reflective at high frequencies. The paper used on sheet rock definitely absorbs something at very high frequencies. It's similar to the difference between a bathroom with painted sheet rock and ceramic tiles, as I mentioned earlier. Not a huge difference, but it's there. I'm sure you could measure it too.

--Ethan