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 Post subject: Re: Soffit mounting?
PostPosted: Fri Sep 02, 2016 3:11 pm 
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HI Guys, my 1st comment/post, not sure if this thread is to old to receive an answer now, my question is, the "acoustic hanger" in your diagram here John, is that "empty space" or is there some sort of acoustic treatment in there?

Cheers

Ashley


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 Post subject: Re: Soffit mounting?
PostPosted: Mon Sep 12, 2016 2:27 pm 
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katalyst wrote:
HI Guys, my 1st comment/post, not sure if this thread is to old to receive an answer now, my question is, the "acoustic hanger" in your diagram here John, is that "empty space" or is there some sort of acoustic treatment in there?

Cheers

Ashley

Hi Ashley, Welcome!

Inside the area marked "acoustic hanger", are acoustic hangers! :) That is the treatment: just like the name implies, there's a series of acoustic hangers in there, built and spaced in the normal manner. they are excellent for bass traps.

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 Post subject: Re: Soffit mounting?
PostPosted: Wed Aug 09, 2017 12:44 pm 
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Hi All,

First comment on this forum after a few weeks of excited reading :D

I know this thread has been inactive for several months, however, I have just joined, finished reading it and have some initial queries re John's flush mounting design (which I am sure will form the start of a whole slew of questions I will cover in my own thread when the time comes for me to get some feedback on my 5.1 writing room design).

My first question is to do with the compromise of making the lower baffle panel an absorber of reflections from the back of a mixing console or desk as was discussed only a few comments previously. I was wondering if there would be any negative effects on the effectiveness of the baffle if a separate panel was mounted in front of the lower baffle panel. That is to say, that the lower baffle would be constructed completely the same way as the upper baffle panel and both would be mounted flush. Then, separate absorbing acoustic panels would be attached to the front of the lower baffle panel. Would there be any negative effects to the baffle if there was an acoustic panel mounted "unflushly" to the baffle itself?

It is entirely possible that I am misunderstanding the design of the entire bottom cavity here, and that everything from the speaker down is one big broadband absorber - still, would what I have described above negatively affect the performance of either the baffle or broadband absorption of reflections from the back of the desk?

I have attached John's original design for ease of reference.

Secondly, with regards to using active monitors with switches located on the rear of the speaker cabinets, can one just use a standard power bar with a switch on it to switch on and off power to the speakers?

I have my eyes on Hans Zimmer's monitor of choice the Quested VS2108. I presume that these would make suitable candidates for flush mounting due to their shape, front porting, low profile heat sink and the ability to attenuate low frequencies to deal with correcting the power balance issues associated with flush mounting. I believe the options are only -9dB, -3dB, 0dB and +1dB of low-frequency adjustment at 40Hz as this feature is designed for when using a subwoofer. I believe and hope this should still be fine.

Finally, will I find any problems with flush mounting the Left, Centre and Right speakers in my front wall, but placing my Left Surround and Right Surround monitors on stands? My room dimensions are L 6.85m, W ~ 3.2m, H ~ 2.5-3.5m (I will be building an interior ceiling.

I know I am probably covering too much information in this simple query my main curiosity is whether my first idea has any merit. Rest assured that I will be making my own thread to discuss specifics of my room design shortly, so please feel free to ignore the questions regarding the monitors! :)

Thanks very much!

Love this forum

Karim x


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 Post subject: Re: Soffit mounting?
PostPosted: Wed Aug 09, 2017 1:29 pm 
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Hi Karim, and Welcome! :)

Quote:
I was wondering if there would be any negative effects on the effectiveness of the baffle if a separate panel was mounted in front of the lower baffle panel.
You could do that if you wanted to, yes. It wouldn't look so neat as with John's system, but it would still work OK acoustically.

Quote:
and that everything from the speaker down is one big broadband absorber -
That's correct: It is! :) The entire section under the shelf and behind the absorber box, is a bass trap, where the active elements are "hangers".

Quote:
Secondly, with regards to using active monitors with switches located on the rear of the speaker cabinets, can one just use a standard power bar with a switch on it to switch on and off power to the speakers?
Yes, you can do that too. Not a problem. Just remember to turn your speakers on AFTER all your other gear is already running, and to turn them off BEFORE you turn of anything else.

Quote:
the Quested VS2108. I presume that these would make suitable candidates for flush mounting due to their shape, front porting, low profile heat sink and the ability to attenuate low frequencies to deal with correcting the power balance issues associated with flush mounting.
Speakers do not have to be front ported in order to be soffit-mountable. It is entirely possible to soffit mount rear-ported speakers. Here's an example: www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=20471 Those are Eve Audio SC-407s, which have rather large ports on the rear. And yet, there they are, soffit mounted and performing spectacularly... :) So you don't need to limit your search to just front-ported speakers or sealed boxes. As long as the soffit is designed correctly and the right precautions are taken, there's no problem with that.

The heat sink is also not an issue. You just need to leave enough space at the rear of the speaker enclosure box (inside the soffit) to ensure that there is sufficient airflow over the heat sink, to keep things cool.

The V2108 does indeed have a low cut switch on the back, but it does not do what you need for soffit mounting. That switch is meant for use with a sub, as you pointed out, and it rolls off below 40 Hz., according to their documentation, it seems (although it's not very clear!). But that's not what you need. With a speaker that size, the baffle step response enter frequency will be fairly high, probably a few hundred Hz, and that's where you need to start the roll-off, in order to correct the power imbalance (or rather, in order to "uncorrect" the power imbalance correction that is no longer needed!). So that switch won't do what you want.

However, there's more than one way of skinning a cat, as the saying goes! Any good quality parametric or semi-parametric equalizer that has a low shelving filter on it will do the job. As long as it has enough adjustment in the frequency setting to cover the likely range, and at least 6 dB of roll off, that should be fine. If you also get to select the steepness of the roll-off, that's a nice bonus.

Quote:
Finally, will I find any problems with flush mounting the Left, Centre and Right speakers in my front wall, but placing my Left Surround and Right Surround monitors on stands?
Ahhhh! So this is a 5.1 room! Hmmm... that's a little more complex... You'll need to treat the room rather differently, and design your soffits and the geometry for the surround speakers with great care, to prevent rear-surround reflections from getting back to your ears from in front if you... 5.1 control rooms are just a tad harder to design than plain old 2.0 and 2.1 rooms.

Will you be running a bass management system?

(The answer to your question is "yes". You can put your surrounds on stands, as long as the stands are massively heavy, and correctly located, and you have the right treatment on the walls next to them, and the front walls.

Quote:
My room dimensions are L 6.85m, W ~ 3.2m, H ~ 2.5-3.5m (I will be building an interior ceiling.
That's rather confusing! So what will the height of the "interior ceiling" be? Will it be 2.5m, or 3.5m? ANd how will you prevent it from acting as a three-leaf system, in combination with the real isolation walls (which I'm assuming will be two-leaf MSM walls?).

Quote:
I know I am probably covering too much information in this simple quert
, actually, not enough info! A diagram of your room, showing the proposed layout, the proposed isolation system, the proposed treatment, and the proposed soffit design would help a lot to understand what you are trying to do. So please do start your own thread with that information in it, as well as all the other information. I look forward to seeing that!


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 Post subject: Re: Soffit mounting?
PostPosted: Thu Aug 10, 2017 2:21 am 
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Soundman2020 wrote:
Hi Karim, and Welcome! :)

please do start your own thread with that information in it, as well as all the other information. I look forward to seeing that!


- Stuart -



Thank you very much for your answers, Stuart! The reason I have no exact height for the interior ceiling is that it is an aspect of the design which I am searching for advice on The ceiling could be anywhere from 2.35 to about 4 meters high in this particular room! (It is a converted barn with an attic space I could make use of for a higher ceiling) Having said that, the main reason I am not starting my own thread yet is that I do not know if I will definitely be in this room yet. When I know exactly where I am going, I will be sure to inform you all of what the details are so I can properly design my space :)

Much love,

Karim

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 Post subject: Re:
PostPosted: Tue Dec 05, 2017 7:35 am 
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John Sayers wrote:

Anyone know the link to the new SAE site for this material? Or any similar material whatsoever? Or maybe someone has it saved in any way or form and can share? John, maybe you have it uploaded somewhere to download?

Thanks.

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 Post subject: Re: Re:
PostPosted: Sat Jan 20, 2018 4:10 am 
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diedushka wrote:
John Sayers wrote:

Anyone know the link to the new SAE site for this material? Or any similar material whatsoever? Or maybe someone has it saved in any way or form and can share? John, maybe you have it uploaded somewhere to download?

Thanks.



Here you go:

http://johnlsayers.com/Recmanual/index.htm

A little late, but better late than never! :)


- Stuart -

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 Post subject: Re: Soffit mounting?
PostPosted: Thu Feb 07, 2019 4:26 am 
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Soundman2020 wrote:
Quote:
is there really any point in attempting to enclose the rear panel of the mounting box
For acoustics and cooling: No, no reason at all. But for structural integrity there's a good reason: that's the only piece that keeps the box square. That might or might not be an issue, depending on the overall design.

- Stuart -


Two questions:

1)With open back box, any special requirements to decrease leakage to Live Room?

2)I've seen a couple well known studio builders have boxes enclosed except for the front. Those monitors are passive. Cooling is not an issue in these designs?

-Mark

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 Post subject: Re: Soffit mounting?
PostPosted: Thu Feb 07, 2019 9:19 am 
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Quote:
1)With open back box, any special requirements to decrease leakage to Live Room?

Do you mean speakers with ports on the back side of them?

The leakage to the live room is resolved by building decoupled inner and outer leaves. The soffit mounting of the speakers is inside of your inner leaf and therefore the speaker design will not change the isolation.

Quote:
2)I've seen a couple well known studio builders have boxes enclosed except for the front. Those monitors are passive. Cooling is not an issue in these designs?

The designs you're mentioning are soffit mounted speakers. Cooling IS an issue and if you scroll up in this thread and see an image posted of John's soffit design, you'll notice the ventilation arrows in the image.

Greg

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 Post subject: Re: Soffit mounting?
PostPosted: Thu Feb 07, 2019 9:56 am 
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Gregwor wrote:
Quote:
1)With open back box, any special requirements to decrease leakage to Live Room?

Do you mean speakers with ports on the back side of them?

The leakage to the live room is resolved by building decoupled inner and outer leaves. The soffit mounting of the speakers is inside of your inner leaf and therefore the speaker design will not change the isolation.

Quote:
2)I've seen a couple well known studio builders have boxes enclosed except for the front. Those monitors are passive. Cooling is not an issue in these designs?

The designs you're mentioning are soffit mounted speakers. Cooling IS an issue and if you scroll up in this thread and see an image posted of John's soffit design, you'll notice the ventilation arrows in the image.

Greg


Greg,

Thanks for answering. Yes, I am speaking about flush/soffit mounted monitors. In designers that build CR and LR with say a window between. Wouldn't not having MDF on the back increase leakage (since there is not a true inner/outer leaf? Also, yes I understand about John's image. What about someone like Wes where no ventilation is visible and he uses completely enclosed MDF box (except front). How is that happening?
-Mark

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 Post subject: Re: Soffit mounting?
PostPosted: Thu Feb 07, 2019 2:39 pm 
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Quote:
In designers that build CR and LR with say a window between. Wouldn't not having MDF on the back increase leakage (since there is not a true inner/outer leaf?
There is ALWAYS a complete inner-leaf and a complete outer-leaf. It's a matter of perspective: If you stand in the control room, looking towards the live room, then there are two "leaves" between you and the LR: the first one is the inner-leaf of the control room, and the second one is the inner-leaf of the live room, but from your point of view that second one is the OUTER-leaf of the CR. So, two leaves.

The speakers are ALWAYS mounted completely inside the control room. So, you have the complete CR wall around the room, then you have the speaker "soffit" in the room, butting up against the inner leaf. The speaker is mounted in the soffit, poking through the front baffle of the soffit, but behind the speaker, is the inner-leaf wall of the room.

Quote:
What about someone like Wes where no ventilation is visible and he uses completely enclosed MDF box (except front). How is that happening?
There is ALWAYS ventilation, even for passive speakers. It might not be visible, but it is there. Take a look at the corner control room thread, for example. Here's a view of his almost-completed control room, showing the soffits:

Attachment:
FRANK--finished-soffits.jpg


As you can see, there is no visible ventilation, but those things certainly are very well ventilated! There's a ventilation path that starts in the hnager section below the speaker shelf, then goes up past the rear face of the speaker, and around the sides, then continues up out the top, through the upper hanger section, and into the HVAC return vents, which are directly above the soffits.

An earlier view of the soffit interior, before the insulation went in and the baffles were put on:

Attachment:
FRANK--partial-soffits-interior-SML-ENH.jpg


You can see the ventilation path up the rear of the soffit. That remains open, even when the insulation is in.

So even though the ventilation might not be visible, it is still there. It must be. You can't have a device that is dissipating hundreds of watts of power as heat, without ventilation to remove that heat...

That's all part of the soffit design: it's not just about speaker acoustics, but also about room acoustics, mechanics, ventilation, and isolation, among other things.

- Stuart -


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 Post subject: Re: Soffit mounting?
PostPosted: Fri Mar 29, 2019 10:39 pm 
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Sorry, i dont kow if i missed something.
Why there is a relative thin frontplate on the shematics like a plywood panel ?
Is more mass better for the soffit wall ?
So maybee three layers of gypsum or more wood ?
Or whats the reason to only use 5/8 plywood ?


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 Post subject: Re: Soffit mounting?
PostPosted: Sat Mar 30, 2019 12:54 am 
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StudioDE wrote:
Sorry, i dont kow if i missed something.
Why there is a relative thin frontplate on the shematics like a plywood panel ?
Which schematic are you referring to? The thread is 15 pages long, with over 200 posts in it... Are you referring to John's diagram on page 1? If so, I'm not sure what you mean by "thin frontplate". The front baffle on that is 1 1/4" thick (about 32mm), with one layer of plywood plus one layer of solid timber. That doesn't seem "thin" to me.

Also, that's just a basic conceptual outline, showing the minimum that will work: Most soffits are built heavier than that.

Quote:
Is more mass better for the soffit wall ?
Yes.

Quote:
So maybee three layers of gypsum or more wood ?
Personally, I don't like using drywall (gypsum board) for soffit baffles, because cutting the hole in it leaves a brittle edge that can flake more over time, with the vibration and pressure. I know some people have done that, but I prefer to use tough materials, such as MDF and high density solid wood.

Quote:
Or whats the reason to only use 5/8 plywood ?
It does not HAVE to be only 5/8" plywood! You can use whatever wood you want, as long as it will do the job. As I mentioned, that's just a conceptual design, which can be modified to fit specific cases.


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 Post subject: Re: Soffit mounting?
PostPosted: Sat Mar 30, 2019 4:56 am 
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Quote:
Which schematic are you referring to? The thread is 15 pages long, with over 200 posts in it... Are you referring to John's diagram on page 1? If so, I'm not sure what you mean by "thin frontplate". The front baffle on that is 1 1/4" thick (about 32mm), with one layer of plywood plus one layer of solid timber. That doesn't seem "thin" to me.


I was refering to the soffit picture posted from John on site 1 and also on the 3rd post on this site (15)
There is written 5/8" Plywood wich is about 1,5 cm. The bottom part of the soffit under the speaker
So i thought maybee its to thin to hold the bass frequency inside.

Quote:
Also, that's just a basic conceptual outline, showing the minimum that will work: Most soffits are built heavier than that.


Ok thank you, i thought maybee there is a reason to not go with more mass.


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