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PostPosted: Tue Mar 19, 2019 5:25 am 
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Andre,

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I suggest you save the RD/PUBS URL as it is a goldmine of data.

I'm having troubles getting to the main directory. Every URL I try (deleting the end of the URL) takes me to an Error 403 page. Do you have a directory link you can share?

Thanks!

Greg

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PostPosted: Tue Mar 19, 2019 5:33 am 
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Gregwor wrote:
Andre,

Quote:
I suggest you save the RD/PUBS URL as it is a goldmine of data.

I'm having troubles getting to the main directory. Every URL I try (deleting the end of the URL) takes me to an Error 403 page. Do you have a directory link you can share?

Thanks!

Greg


Try these.

https://www.bbc.co.uk/rd
https://www.bbc.co.uk/rd/publications


Andre

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Last edited by AVare on Tue Mar 19, 2019 12:25 pm, edited 1 time in total.

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PostPosted: Tue Mar 19, 2019 10:04 am 
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Thank you so much Andre!!!!

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PostPosted: Fri Apr 12, 2019 4:44 am 
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Have you guys already seen this new article written by Ethan?

http://ethanwiner.com/speaker_isolation ... 0_lCKO2Udk

Both he and John Brandt agree that speaker isolation provides no audible benefits if the speaker is designed properly such that no vibration is transmitted through the cabinet itself. There was a facebook post about this in which I asked if this also applied to flush mounting (soffit mounting) to which the answer was the same. I remember Newell also mentions the very same in his book.

Therefore it seems spending time and money on sorbothane or other isolation systems is a wasted exercise - it won't necessarily do any harm, but it is also not required.

Let me know if any of you disagree,
Paul


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PostPosted: Fri Apr 12, 2019 6:56 am 
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Let me know if any of you disagree,
Me. :)

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PostPosted: Fri Apr 12, 2019 3:03 pm 
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Such speakers weigh hundreds of pounds. What does this mean for the average reader?,

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PostPosted: Fri Apr 12, 2019 7:31 pm 
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AVare wrote:
Such speakers weigh hundreds of pounds. What does this mean for the average reader?,


A bad back and a hernia?

The article mentions products designed to be put under small “near field” monitors, which is what the average reader is most likely to have. According to Ethan and John B any competent speaker designer would build a cabinet that does not transmit vibrations, and any potential problems that could arise will
Be from airborne vibrations from the cones themselves. Therefore speaker isolation products or homemade are snake oil and not required. Here is a quote from John B in response to a comment that isolation is still required for soffit mounting or larger speakers:

“isolation? For what purpose?

We have already shown that a 10 gr mass effect on a 25000 gr mass will have extremely little effect. This effect (0.0004 %) can not possibly be heard.

This is an example of a speaker weighing 25 kg.

Larger speakers will have larger cone masses, yes. But the percentage actually grows smaller with the larger units.

Banter about opinions is useless and therefore we must require Empirical Evidence to be the judge.
And, sorry to be so brutally honest, but those who do not accept empirical evidence are simple fools and deserve to be ridiculed.”

Paul


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PostPosted: Sat Apr 13, 2019 2:41 am 
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According to Ethan and John B any competent speaker designer would build a cabinet that does not transmit vibrations, and any potential problems that could arise will
Here's a simple thought experiment (Einstein loved those "thought experiments, I hear!), but you can also do this one in real life. Get out your favorite studio monitor, set it in the middle of your dining room table, then play loud, contemporary, bass-heavy music through it, at around 85 dBC. Gently touch the sides, top, bottom and rear faces of the cabinet with your finger tips Can you feel vibration? If the answer is "yes", then the manufacturer of your speaker did NOT do what John B and Ethan W say they should have done.

In my experience, it seems that most manufacturers of good studio monitors are somehow unable to do that...

Now turn up the level to get maybe 110 dBC (not unheard of in control rooms, when the engineer wants to "check the bass"!). Try again with your finger tips... Got vibration?

Your honor, I rest my case! :)

OK, so the article you mentioned seems to be talking about speakers on desks, not for proper flush-mounted speakers, so it's not really applicable. It's also not that new: it dates back over 3 years, and I had seen it before, but dismissed it as not very useful for typical home-studio situations.

The truth is that, for flush mounting (soffit mounting), decoupling speakers from framing is rather necessary, Either that, or you need an extremely massive, very rigid, vert tight-fitting enclosure box to hold the speaker, and very rigid, massive framing, so massive that the typical sound levels cannot make it vibrate... Those are the two basic approaches here: massively massive mass (redundancy is not redundant here! :) ), or properly tuned resilient decoupling on all axes. Both approaches work, and they both have their pros and cons.

The only thing I'd agree with from Ethan's article, is that the devices he tested were of no use, and personally I would not waste my money on any of those. But the way he tested them is not the way monitors are usually mounted in most of the studios you see here on the forum.

When done properly, resilient mounts do work, and they work well. I probably have some real data from real-world tests done in one of the places I have designed, where the speakers were mounted like this. I'll see if I can find something.


- Stuart -

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PostPosted: Sat Apr 13, 2019 3:00 am 
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Soundman2020 wrote:
Quote:
According to Ethan and John B any competent speaker designer would build a cabinet that does not transmit vibrations, and any potential problems that could arise will
Here's a simple thought experiment (Einstein loved those "thought experiments, I hear!), but you can also do this one in real life. Get out your favorite studio monitor, set it in the middle of your dining room table, then play loud, contemporary, bass-heavy music through it, at around 85 dBC. Gently touch the sides, top, bottom and rear faces of the cabinet with your finger tips Can you feel vibration? If the answer is "yes", then the manufacturer of your speaker did NOT do what John B and Ethan W say they should have done.

In my experience, it seems that most manufacturers of good studio monitors are somehow unable to do that...

Now turn up the level to get maybe 110 dBC (not unheard of in control rooms, when the engineer wants to "check the bass"!). Try again with your finger tips... Got vibration?

Your honor, I rest my case! :)

OK, so the article you mentioned seems to be talking about speakers on desks, not for proper flush-mounted speakers, so it's not really applicable. It's also not that new: it dates back over 3 years, and I had seen it before, but dismissed it as not very useful for typical home-studio situations.

The truth is that, for flush mounting (soffit mounting), decoupling speakers from framing is rather necessary, Either that, or you need an extremely massive, very rigid, vert tight-fitting enclosure box to hold the speaker, and very rigid, massive framing, so massive that the typical sound levels cannot make it vibrate... Those are the two basic approaches here: massively massive mass (redundancy is not redundant here! :) ), or properly tuned resilient decoupling on all axes. Both approaches work, and they both have their pros and cons.

The only thing I'd agree with from Ethan's article, is that the devices he tested were of no use, and personally I would not waste my money on any of those. But the way he tested them is not the way monitors are usually mounted in most of the studios you see here on the forum.

When done properly, resilient mounts do work, and they work well. I probably have some real data from real-world tests done in one of the places I have designed, where the speakers were mounted like this. I'll see if I can find something.


- Stuart -


Thanks Stuart.

The facebook thread has comments from both John and Ethan stating that isolation is also NOT necessary for flush mounting. The quote in my post above was in response to whether or not isolation should be used as part of a flush mounted installation. Here's another from from the same thread from Ethan:

"Even soffit mounted speakers shouldn't benefit from isolation. Why would they? This is such a common myth almost everyone believes it. As far as I know I'm the only person who ever actually tested this."

Also regarding your vibration test, as you have read the article, did you also see the youtube link? There's a sub putting out 117db at 38hz with a glass of water resting on top of the cabinet with absolutely no movement or ripples.

I am not saying that you are wrong and that Ethan and John are correct as firstly I am not experienced enough to be able to do so and secondly I suspect it all depends on the speaker being used. I am just presenting it as it may be useful.

In my case, my monitors are extremely solid and heavy, they weigh over 70kg (150lbs) each. There is absolutely no vibration that can be felt in the cabinet when they are maxed out. Therefore I do not believe I would gain much from sorbothane isolation.

Paul


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PostPosted: Fri May 24, 2019 11:10 pm 
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Progress has been slow lately due to some family problems taking priority, but I have managed to put my wiring troughs in. They're constructed from a re-purposed hardwood cabinet and roofing batten. As they'll be embedded in concrete I will cover them in polythene before the pour.

The goal with the troughs is to enable me to have as much flexibility as possible with easy access to any cabling changes that need to happen. There will be a removable lid with some of the finish floor stuck on top to disguise the troughs into the rest of the floor.

Paul


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PostPosted: Thu Aug 29, 2019 9:07 pm 
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I've been quiet lately but I do have some updates for you all.

I finished the cable troughs and yesterday we finally poured the concrete down inside.

I'll write a post with some pics tomorrow as today is our wedding anniversary.

Paul


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PostPosted: Sun Sep 01, 2019 8:10 am 
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Hi guys,

To all those of you who are more experienced, I have a question regarding the BBC R. Walker "No integer multiple within 5% rule" when it comes to vaulted ceilings. Does it still apply, or is it only for rectangular rooms?

To remind you, my room is L 24' 1" x W 19' 9" with an average ceiling height of 10' 7.5" these dimensions all comply to the 5% rule.

The ceiling is vaulted; 8' 9" at the lowest - 12' 6" at the peak.

Between 8’ 9" - 9’ 4" it passes the 5% rule.

Between 9’ 5" - 10’ 5" it fails the 5% rule.

Between 10’ 6" - 11’ 5" it passes the 5% rule.

Between 11’ 6" - 12’ 6" it fails the 5% rule.

How much of an issue is this likely to be? I chose my dimensions based on the most amount of volume I was permitted, this meant that I needed to use a vaulted ceiling. I used the average height while inputting my dimensions into various room calculators to check and double check that my ratio would at least be decent enough, but I did not consider until now that due to the angles caused by the vaulted ceiling it would at certain heights fall below recommendations.

For example, the actual height at the peak is just over half the length, which fails the rule, despite the average ceiling height being very good.

Am I panicking about insignificance? I am planning to treat the peak like any other corner and fill it with a superchunk, below which I could put hangers etc. But I am worried I have not given myself the best start, acoustically, before treatment. I would even move a wall now rather than later if it's worth it.

Any advice/reassurance appreciated.
Paul


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PostPosted: Sun Sep 01, 2019 10:24 am 
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To all those of you who are more experienced, I have a question regarding the BBC R. Walker "No integer multiple within 5% rule" when it comes to vaulted ceilings. Does it still apply, or is it only for rectangular rooms?
Room ratios only apply to rectangular rooms. To a lesser extent, they can be useful in providing some info about rooms that are not quite rectangular, such as when a wall is angled slightly. But a vaulted ceiling is rather different: that's some pretty steep sloping, usually, and there are two surfaces up there, not just one.... so the room now has seven sides, instead of just six. That implies that ratios are not really valid measurements.

Quote:
I chose my dimensions based on the most amount of volume I was permitted,
:thu:

Quote:
this meant that I needed to use a vaulted ceiling. I used the average height while inputting my dimensions into various room calculators to check and double check that my ratio would at least be decent enough, but I did not consider until now that due to the angles caused by the vaulted ceiling it would at certain heights fall below recommendations.
Don't sweat it too much! You will need to put treatment on the ceiling in any case, so the only real difference is the type of treatment, and how much of it. In the worst case, you might need to cover a large portion if the ceiling with thick absorption. That's about the only consequence.
Quote:
Am I panicking about insignificance?
:) You could say that! But it's always good to ask if you have any suspicions! NOT asking would be a big mistake.

Quote:
the actual height at the peak is just over half the length, which fails the rule, despite the average ceiling height being very good.
Think of it this way: Most of your ceiling does not have that problem! It's only for one specific strip if ceiling (range of dimensions) that you "fail" the test.... so worst case, you are only "off" by a small fraction of the total ceiling area.... Plus, the ceiling is angled steeply in two different planes, so it is not even parallel to the floor! It's most unlikely that there will be any problem here. And if there IS an issue, then just put treatment on it! :)

Quote:
Any advice/reassurance appreciated.
Reassurance! It's not a big issue. Don't sweat it.


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PostPosted: Sun Sep 01, 2019 11:18 pm 
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Quote:
Any advice/reassurance appreciated.
Reassurance! It's not a big issue. Don't sweat it.


- Stuart -

Thank you as always Stuart, now I can sleep at night :yahoo:


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PostPosted: Mon Dec 09, 2019 1:15 am 
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Hey guys,

What do you guys think about turning my rear inside out wall into a massive membrane trap? I'd have to shoot the room and see if it's needed and at what frequency range, but as a potential idea for treatment it might work quite well. Porous absorption or hangers could also be placed in front of it, especially in the corners as well as a diffuser in the middle if desired.

My vision is using the stud bays as the cavity with insulation, and then fixing the membrane to the studs. If a bigger cavity is needed then more studs can be placed in front of the wall studs to increase the cavity, and then the membrane could be either plywood, MLV or whatever is needed to target the desired frequency range.

Has anyone ever tried this?

Paul


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