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

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

Postby Eric Desart » Thu Jan 06, 2005 10:49 am

Doublehelix wrote:
It is the same combatants fighting over the same childish crap.
 
While I respect the knowledge of Ethan, Eric, Paul, Foz, etc., all this petty bickering is so damn frustrating! The only ones left reading the thread are the ones doing the arguing!!! Take it somewhere else!
 
Arguing over semantics, and getting into a technical bees-hive does nothing to answer the question of the average musician or studio owner.
 
Pathetic really...


You have no idea about the energy involved. But I agree it is frustrating.

What you call semantics is a basic and principle myth misleading for the average musician or studio owner.

But don't worry. I will not bother when you get this kind of misleading advice.
It really is more fun to fight for people who appreciate the energy others put in for them.
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Re: window behind monitors.... best way to treat this??

Postby Marky » Thu Jan 06, 2005 2:48 pm


...says the guy who has publicly announce leaving the forum at least three times now, yet keeps re-appearing.

Like Double Helix, I don't doubt any of your scientific knowledge of the subject but your intentions are obvious.

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

Postby Eric Desart » Thu Jan 06, 2005 4:21 pm

First part: I humbly agree I sinned, but take you gentle hint into account.

Second part: Leave this conclusion about intentions to you.
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Re: window behind monitors.... best way to treat this??

Postby Paul Woodlock » Thu Jan 06, 2005 6:31 pm

Marky wrote:
...

Like Double Helix, I don't doubt any of your scientific knowledge of the subject but your intentions are obvious.

- Mark

Greetings Mark :)

Eric's intentions are no secret. His intentions are to keep the Internet free from misleading and incorrect acoustics info. He has the knowledge and experience to do this. Rather than question Eric, you should question the information from folks Eric is trying to correct :)


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

Postby Scott R. Foster » Thu Jan 06, 2005 7:14 pm

Eric:

Bwaahahahahaha!

You are foiled again.

Nice try, but your clever tricks didn't work on those two cunning fellows... Marky and Helix are obviously too sly to fall into your trap and have avoided all the thinking and learning you tried to force on them.

No stop using your mind control beam to force them to read your posts.. or I shalll taunt you a second time!

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

Postby Paul Woodlock » Thu Jan 06, 2005 11:32 pm

Your Mother was a hamster and your Father smelt of elderberries!!!

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

Postby Doublehelix » Fri Jan 07, 2005 3:07 am

It is sooooo obvious to anyone on the outside-looking-in that you guys all have a personal agenda, and can't wait to prove each other wrong, and to prove how great you are, when you really have very little desire to help the original poster. (At least it seems that way to me)



I was pretty frustrated when I wrote that, and now in retrospect, it is pretty strong. I do believe that you guys desire to help, it is just that sometimes the need to prove each other wrong (or yourselves right!) clouds your intentions.

I also understand your need to correct incorrect information, and think it is a worthwhile thing to do.

It just gets frustrating to read all these flame wars arguing over the same things, between the same people.

I apologize if my original post was a bit harsh, I have actually learned a lot from each of you over a long time on several different forums.

Like I said, I was pretty frustrated at the time.

Still, I wish you guys would stop with petty bickering!!!

Pistols at 20 paces should take care of it once and for all!!!
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Re: window behind monitors.... best way to treat this??

Postby Paul Woodlock » Fri Jan 07, 2005 5:10 am

Doublehelix wrote:
It is sooooo obvious to anyone on the outside-looking-in that you guys all have a personal agenda, and can't wait to prove each other wrong, and to prove how great you are, when you really have very little desire to help the original poster. (At least it seems that way to me)



I was pretty frustrated when I wrote that, and now in retrospect, it is pretty strong. I do believe that you guys desire to help, it is just that sometimes the need to prove each other wrong (or yourselves right!) clouds your intentions.

I also understand your need to correct incorrect information, and think it is a worthwhile thing to do.

It just gets frustrating to read all these flame wars arguing over the same things, between the same people.

I apologize if my original post was a bit harsh, I have actually learned a lot from each of you over a long time on several different forums.

Like I said, I was pretty frustrated at the time.

Still, I wish you guys would stop with petty bickering!!!

Pistols at 20 paces should take care of it once and for all!!!

Thanks for being understanding :)

Without a care for the peeps who look to forums for infomation, these flames wars wouldn't have started. It is with a care for the newbie that people like Eric, who with a lifetime of experience and knowledge seek to pass on that experience to others. And also of course correct any misinformation that appears. A DIY studio/Acosutic treatment is reasnably affordable, but it ain't 'cheap'. So Internet misinfomation can cause wasted £££££.

Also the now proven baseless allegations of Studiotips falsifying data to make a ccertain commercial membrane absorber add much fuel to the fire. I'm sure you'd be a little hurt if you'd been accused of sauch? :)

Anyway, that's been done and dusted now. On a positive note there's some great acoustics info buried amongst the shrapnel which might not have appeared otherwise.

I've certainly laid down arms and have got back on with building my studio. Much more fun! :)

cheers !


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

Postby DoeZer » Fri Jan 07, 2005 11:30 am

Hi Foz...

do you mean set up a LF sound source and close up the room pretty tight... then go around the OUTSIDE of the room with my "nanu-nanu" rubber tube and see where the sound is coming from? obviously this must be what you mean. yeah, maybe i'll fix up the door and then check that out before doing any more...

btw, if you have small holes in the room (due to plumbing pipes coming in or whatever) then whats the best way to seal around them acoustically speaking... would the usual mastic sealant have any effect here..??

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

Postby Hugh Robjohns » Fri Jan 07, 2005 12:44 pm

Paul Woodlock wrote: It is with a care for the newbie that people like Eric, who with a lifetime of experience and knowledge seek to pass on that experience to others. And also of course correct any misinformation that appears.


I thoroughly approve of correcting misinformation -- and we all know the Internet is full of it (as are some respected printed texts... but that's a different story).

Regulars to all of the SOS forums will know that the SOS staff, moderators and many learned contributors endeavour ceaselessly to provide clear explanations and to correct misunderstandings or misinformation at any and every opportunity -- and I hope this continues to be the case.

Sadly, though, it has sometimes been the case that some participants get so bogged down in the details that they overlook the bigger picture. Whether the intention or not, such dogged determination to argue a specific detail can often appear to be little more than point scoring, particularly when it has little practical relevance to the original question or questioner's interest or abilities to understand.

There are times when simplistic analogies are more useful and informative to some people than technically precise academic answers. There is room for both, though, it's just a case of realising which is more appropriate for each situation.

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

Postby Scott R. Foster » Fri Jan 07, 2005 3:00 pm

DZ:

Acoustic caulk... its dense and non-hardening... Paul probably has a UK source.
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Re: window behind monitors.... best way to treat this??

Postby Paul Woodlock » Fri Jan 07, 2005 5:41 pm

Foz wrote:DZ:

Acoustic caulk... its dense and non-hardening... Paul probably has a UK source.

http://www.decoratingdirect.co.uk/viewprod/s/SIRSSLMA/

Have fun! :)


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

Postby JamieB » Thu Jan 13, 2005 12:48 pm

Hehe. Funniest thread I've read for ages!

Personally I too find the physics interesting. Would love to see more of this kind of in depth discussion, preferably in a specific thread though.....

DoZer, hope the studio works out for you.
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Re: window behind monitors.... best way to treat this??

Postby Brian Ravnaas » Fri Jan 14, 2005 5:59 pm

hi everybody,

as this is my first post, perhaps an introduction would be prudent. I'm a studiotips member, and my professional work crosses into the area of transmission loss. I'm not an in-room acoustics guru by any stretch, and i do not have part in any of the arguments hereabouts.

but a friend mailed me a link to a thread here, and i've enjoyed reading bits of the forum for a few weeks now... and i have a small number of thoughts that i think might be interesting (although they aren't an answer to DoeZers question in the most direct sense - i'm not the fellow to answer that)

i'll enter them in separate posts so as to not create one immense un-readable gargantuan rambling.

the first relates to the discussion of modal problem abatement stemming from walls with poor transmission loss behavior. the second relates to ETF as an absorber assessment tool.

with respect to low transmission loss corresponding to "absorption" being observed in a room. This is, of course, true - a real phenomenon. Imagine an open window or door - open into free space. That would have zero transmission loss, and it would have 100% absorption at all frequencies - all incident sound could escape. A door open to the outside might make one heck of a bass trap, perhaps, i haven't seen discussion relating to this.

But it was commented above that the transmission loss of real walls, windows, etc. is sufficiently high to render this phenomenon essentially moot with respect to room acoustics... I took the liberty of making a couple of pictures reflecting the transmission loss of windows in practice and calculated, and the worst wall imagineable.

(here's hoping that i'm clever enough to run the html)

Image

And here are the corresponding absorption coefficients, based upon transmission loss. They were calculated based upon 10^(-TL/10) where TL is the transmission loss.

Image

The point of all of that is that even the worst imagineable walls would not exhibit large levels of absorption DUE TO POOR TRANSMISSION LOSS. I'm open to correction if my math was incorrect above.


Now, walls do exhibit higher absorption than that at times... But think of a panel trap for a moment. It exhibits a bell curve of absorption (or a sharp peak if damping is low, i believe) centered on the resonance of the trap. And a cavity wall - like a double-pane window - will exhibit similar behavior, and the absorption around that resonance may well be vastly higher than for a single panel.

like this:
Image

The double-glazing may exhibit a fairly large level of absorption at ~400hz, but it's a resonant phenomenon, not one related to poor transmission loss behavior. The resonance yields poor TL, but i think that the absorption may be higher than the still fairly high TL of 20dB would imply.

This pic Image

shows resonant dips in two walls measured by National Research Council, Canada, and a hypothetical transmission loss plot for a bass trap. In the case of the concrete block, even at the resonance point the transmission loss remains fair (20db), but one could reasonably expect the absorption in the room to be much much higher than the formula i offered above would imply. The TL remains fair due the mass of the concrete, and the in-room absorption would be high due to the resonant behavior.

the common figures for various walls that one finds here and there on the web for absorption are suspect (IMO). they vary widely, and the peak in absorption would likely relate to some resonant behavior.

i think that is what was meant above when the comment about wall absorption generally relating to spring effects was entered.

whatever that's worth, and i 110% realize that many persons offer the thought that poor walls will mitigate modal behavior, i doubt (based far more upon the general math than experience with room modes) that a poor wall or window will alleviate your peak at, say, 81.5hz. Unless it happens to resonate at 81.5hz. :)

take care,

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

Postby Brian Ravnaas » Fri Jan 14, 2005 6:19 pm

i fear the thread where this discussion occured is locked, so begging the pardon of all for putting it a bit out of place... I wish everyone to understand that i enter this out of a love for discussion more than any form of expertise in the area of room mode measurements. :)

there was discussion of using ETF in lieu of 1/3 octave decay measurements to observe/assess the performance of bass traps at very low frequencies. the 0.7hz resolution was touted as an advantage, and various counterpoints were offered.

i think that concept has merit. With the type of measurements that Ethan offered, you can observe the behavior of a single mode. With the reverb room method, you measure the average of many modes. I believe that the standard relating to absorption measurement via the reverb room method issues it's minimum volume criteria based upon ensuring that XX number of modes exist at the relevant frequencies. This XX - this minmum number of modes - finds it's way into other standards as well, such as ASTM E-90 for transmission loss.


Halliwell abd Warnock of Canadas NRC, (in "Sound transmission loss: comparison conventional techniques
with sound intensity techniques" JASA 77, 1985 ) make a very interesting commentary on this criteria that's worth reading for anynoe who is very interested. They also offer that if broader frequency ranges (like octave bands) are to be measured, then the minimum modal criteria can be met to much lower frequencies.

anyway, back to Ethans thought and why i think it has merit. It's analagous to measuring the resonant boost of, say, a wall with an accelerometer. It really can be very handy to observe the specific mode or behavior in a more discrete way, and you can via that technique conclude very precisely where a mass-spring-mass resonance is located, and what factors affect it's severity and location.

and so i think you could also use the ETF technique to say "well it looks like my slab of 703 is definitely doing something on this 77hz mode", and that can mean alot.

neither are substitutes, of course, for the applicable standards. but i do think it's a nice idea.

i disclaim again that this isn't my area of prowess. you guys are all my superior when it comes to room modes, i've little doubt.

:)

Brian
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