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window behind monitors.... best way to treat this??

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window behind monitors.... best way to treat this??

Postby DoeZer » Tue Dec 21, 2004 6:33 pm

Hi everyone...

I'll be setting up the equipmebnt in my new place along the front wall, facing down along the longest dimension...

I dont have a choice of using the other end wall cos the door is there...

so, the problem here is I have a window on the front wall, approx 4ft wide (the wall is only 8ft wide)... I will have my monitors either side of the windows but as far away from the corners as possible... and the window will be in the middle.

I know thats not the best acoustically, alotof the photos you see of for example foam based setups have ALOT of the absorbtion placed BEHIND the monitors right across the back wall

eg the photo of the front wall on this link here...

http://www.auralex.com/sound_control_project2/sound_control_project2.asp

anyone got any ideas how you approach this with a window there?? Maybe, fit a heavy timber frame in front of the window and mount the panels on that??

anybody??

thanks
D
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Re: window behind monitors.... best way to treat this??

Postby Scott R. Foster » Tue Dec 21, 2004 6:39 pm

Why not just make some cloth covered mineral fiber panels to fit inside the window opening - then use the panels elsewhere. No need for a heavy frame regardless.
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Re: window behind monitors.... best way to treat this??

Postby Ethan Winer » Tue Dec 21, 2004 6:41 pm

DoeZer,

> I know thats not the best acoustically <

I see no inherent problem with a window on the front wall, and if anything it may release a little bass energy that travels in the front/rear direction of the room. Since a window has less mass than a wall, it reflects bass frequencies less which is a good thing. It also gives you a nicer view of the outdoors!

To my way of thinking the most important "echo points" that need treatment are the first reflection points on the side walls and ceiling, and also the rear wall if that wall is not far behind your head. I know that treating the front wall is common, so I'll be interested in hearing what others have to offer.

--Ethan
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Re: window behind monitors.... best way to treat this??

Postby Steve Hill » Thu Dec 23, 2004 7:58 pm

I'm with Ethan on this. What's the problem with an arrangement which more or less reflects what happens in lots of pro control rooms having a central window looking into the live room?

Treat everything else as best you can and ask yourself, seriously, is the window actually a problem at all? If so, I'd start with nothing more ambitious than heavy lined curtains to start with, andonly if that fails move on to worrying about de-mountable panels etc.
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Re: window behind monitors.... best way to treat this??

Postby Doublehelix » Fri Dec 24, 2004 3:54 am

Is it not a pretty common thing to have a studio window behind the monitors anyway? (One that views into the studio from the control room)
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Re: window behind monitors.... best way to treat this??

Postby Paul Woodlock » Fri Dec 24, 2004 4:23 am

Steve Hill wrote:...Treat everything else as best you can and ask yourself, seriously, is the window actually a problem at all? If so, I'd start with nothing more ambitious than heavy lined curtains to start with, andonly if that fails move on to worrying about de-mountable panels etc.

I agree with Steve.

Unless it's a problem don't worry about it :)



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Re: window behind monitors.... best way to treat this??

Postby DoeZer » Fri Dec 24, 2004 10:28 am

great!

Just to be clear here. Im not LOOKING for problems know what mean?! I just reckoned that the glass would be highly reflective and I might get alot of bounce back towards the listening position, but if all of you folks are saying dont worrty bout it, well then great, thats exactly what I wont do then!!! plus, the point about a window into live rooms from the control rooms is a very good one. never thought of that :)

cheers
D
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Re: window behind monitors.... best way to treat this??

Postby Martin Walker » Fri Dec 24, 2004 2:33 pm

Yes, there will be some 'bounce back', but as Ethan has said, far less at mid and low frequencies than from a solid wall. Since it's these reflections that cause most acoustic problems, the fact that the glass is less massive than the wall is a good thing (unless of course it lets out so much sound that your neighbours complain ;)). it will only be highly reflective at higher frequencies (above 500Hz let's say), and these reflections are easy to deal with (If necessary) using a curtain.

In my opinion it's also lucky that your window is at the front - if it were at one side your room would be acoustically asymmetric, which could make one speaker sound different from the other one (stereo imaging problems).


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Re: window behind monitors.... best way to treat this??

Postby Ido » Fri Dec 24, 2004 8:06 pm

My experience is that an untreated front wall causes the sound to be muddy, it reduces imaging quality.
In the pro studios with front windows, these windows will usually be at a relatively bigger distance from the speaker/listner than in the typical home studio, so the effect is greatly diminished (not to mention the angled windows for higher frequencies).
This also depends on the reflective area, so a small area window in an otherwise absorptive wall probably won't matter.
I would check by doing a listening with/without absorbent in front of the window, and take it from there.
The treatment advice given before is highly effective, you CAN make a very good acoustic curtain, which can stand up to the better treatments (suitable fabric, multi layers, airspace, folds etc.).


Ethan Winer wrote:
...and if anything it may release a little bass energy that travels in the front/rear direction of the room. Since a window has less mass than a wall, it reflects bass frequencies less which is a good thing.
--Ethan

The above statement is highly inaccurate to say the least, but maybe let's not go there for now..
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Re: window behind monitors.... best way to treat this??

Postby Ethan Winer » Fri Dec 24, 2004 9:43 pm

Ido,

> The above statement is highly inaccurate to say the least <

Rather than just say it's "highly inaccurate" you'll be much more convincing if you explain why it's inaccurate. Assuming normal 1/8 inch window glass as found in homes, I'd love to see some hard data from you showing the "crossover" frequency at which a window, versus a standard wall with sheetrock on both sides, transitions from reflecting to passing.

--Ethan
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Re: window behind monitors.... best way to treat this??

Postby Ido » Sat Dec 25, 2004 1:20 am

Ethan Winer wrote:Ido,

> The above statement is highly inaccurate to say the least <

Rather than just say it's "highly inaccurate" you'll be much more convincing if you explain why it's inaccurate. Assuming normal 1/8 inch window glass as found in homes, I'd love to see some hard data from you showing the "crossover" frequency at which a window, versus a standard wall with sheetrock on both sides, transitions from reflecting to passing.

--Ethan


OK,

The innaccuracues I see in you’re posts are as follows:

1. All the basic partitions we normally know between rooms or between inside-outside (windows, wall of whatever kind etc.) will reflect the vast majority of incident sound energy back into the room. Even a lowly 10 dB TL means that only 10% of the overall incident acoustic energy got transmitted through the partition.
2. The smaller the specific partition area (as in this window), the less significant this specific TL.
3. The smaller the window area (as in this window), the stiffer the window, thus relatively higher TL.
4. As a general rule, a window doesn’t have to have the same mass as a wall in order to have similar TL.
5. The term “release” that you use has no relation to the scientific definition of transmision loss as I know it.
6. Never heard of the term “crossover frequency between reflecting and passing ” , TL is TL, for a given partition it will have higher and lower values, but it doesn’t go from “reflecting” to “passing”. At the most, one could talk about resonance, but that is not a crossover point between reflecting and passing. Could be you mean some kind of intuitive explanation?
7. You made a general decisive rule for “window on the front wall” . There are many possible window configurations, some which can surpass standard wall TL’s.
Glass is material/matter, just like brick or gypsum.
8. Bass energy travels pretty much omni directional, and not front-rear.

That being said, since you gave what comes off as “absolute” explanations for the physical mechanisms mentioned, I believe it is you who need prove them.
Now for the record, I have no problem with intuitive physical explanations, just as long as they aren’t misleading, and as long as they are reserved (stating their limitations).
In this case, one could be led to believe from your statements that implementing more windows in a room will take care of LF absorption, which is a wrong notion.

I have responded to you’re request, how about giving me the same courtesy?
I asked you twice about that 1/3 octave measurement claim of yours (should I bring you’re quote again?), and you never answered. I’m still not sure where you stand on this.
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Re: window behind monitors.... best way to treat this??

Postby Hugh Robjohns » Sat Dec 25, 2004 11:08 am

Ido, It's Christmas Day. Lighten up! Go unwrap some presents. Ethan's post was a simplification but one that was -- as I read it -- helpful in a generalistic way. You are nit-picking in way that adds nothing significant to the context of the thread, and seems to me to be entirely aimed at point scoring off Ethan.

Ido wrote: 1. All the basic partitions we normally know between rooms or between inside-outside (windows, wall of whatever kind etc.) will reflect the vast majority of incident sound energy back into the room.


Obviously this is true in general terms, but assuming an ordinary single pane window (or even a thin double glased window for that matter), it will allow some of the low frequency energy to pass through -- and much more so than a brick wall, which is the point Ethan was making. This can be easily demonstrated by standing outside a closed window and listening while loud music is playing inside.

Your points about the affects of the window area are obviously true, but don't conflict with what Ethan said.

6. Never heard of the term “crossover frequency between reflecting and passing ” , TL is TL, for a given partition it will have higher and lower values, but it doesn’t go from “reflecting” to “passing”.


I agree, the 'cross-over' term may not be one normally used in this context, but once again, the meaning is clear and it is blatently obvious that a wide range of materials used inthe contruction of rooms do change their characteristics from predominantly reflective, to predominantly aborptive (or transmissive) at different frequencies. A large pane of glass installed in a solid wall and supported only at its edges will reflect the majority of mid and high frequency sound, but will allow a significant proportion of low frequency sound to radiate through, primarily because the glass pane will vibrate in sympathy. There is, in effect, a crossover region from the former condition to the latter.

7. You made a general decisive rule for “window on the front wall” . There are many possible window configurations, some which can surpass standard wall TL’s.


What do you hope to gain from this sad point scoing exercise? Yes, it is possible to design multilayer windows with phenomenal isolation. What relevance has that here? The topic concerned an ordinary domestic window.

8. Bass energy travels pretty much omni directional, and not front-rear.


Ethan said nothing to contradict this. What I undertood him to mean was that some of the relected LF energy moving in the general direction of back wall to front wall would pass through the window.

In this case, one could be led to believe from your statements that implementing more windows in a room will take care of LF absorption, which is a wrong notion.


Incredible!

I asked you twice about that 1/3 octave measurement claim of yours (should I bring you’re quote again?), and you never answered. I’m still not sure where you stand on this.


Not in this thread you didn't. Please try to stick within the bounds of the thread, otherwise it looks like you are simply out to score points and sling mud. A rather sad position to be taking at this time of year, don't you think!

Merry Christmas to all our Sound On Sound friends. I'm going back to see what Santa has brought me....

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Re: window behind monitors.... best way to treat this??

Postby Ido » Sat Dec 25, 2004 11:57 am

Wow, Hugh, I‘m sorry for this.
I originally said I DIDN’T want to get into this, my last post was in response to Ethan’s request.
Only reason I made the original remark was that my personal “sense of accuracy” thought it right to put a “reservation” on Ethan’s statement.
I am sorry, but I also don’t agree with some of the “acoustics” you said too :) :protest: :) , but hey, on you’re command, I’m off to find something to unwrap... :D.
(If this would ever be of your’s or group interest, say the word).
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Re: window behind monitors.... best way to treat this??

Postby Hugh Robjohns » Sun Dec 26, 2004 11:26 am

Ido wrote:Wow, Hugh, I‘m sorry for this.
I originally said I DIDN’T want to get into this, my last post was in response to Ethan’s request.

Sorry if I came over a little heavy handed ido. I was very disappointed to discover that although there were only two posts in this forum on Christmas Day morning, both were attacking Ethan.

Only reason I made the original remark was that my personal “sense of accuracy” thought it right to put a “reservation” on Ethan’s statement.

I share your 'sense of accuracy'. However, it is both possible and preferable to correct technical inaccuracies without the post coming across as a personal attack.

I am sorry, but I also don’t agree with some of the “acoustics” you said too.

Fair enough. Let's debate the issues, but not the personalities. What specifically don't you agree with?

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Re: window behind monitors.... best way to treat this??

Postby Doublehelix » Mon Dec 27, 2004 3:22 pm

I am in the process of making a control room in my studio, that is going to have glass between the rooms. So in one of Ido's earlier posts, he suggests that most pro studios that have glass partitions have more room between the speakers and the glass. What do you suggest in my situation?
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