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Soffit Layout inquiry Studio Monitors
Old 16th September 2011
  #31
Gear Maniac
 

Quote:
i have followed you for years in your pursuit of a common standard/basis that everyone can adhere to and agree to but it does not seem to be the nature of the art even when the science behind it is improving every year and folks are no doubt trying to leverage it wherever it makes sense to do so in practice.
Thanks for replying Glenn


Well, does that translate into "eye of the beholder" then?heh Sure seems so to me.

Ok, I don't see any sense in carrying on with this now. Thanks everyone.
Old 16th September 2011
  #32
Gear Maniac
 

One more thing Glenn. Just looked at the Sketchups. Nice rendering too.

So, you have a gap around each soffit that allows absorption at the edges, no? Would this amount to a Hemholtz resonator? And for rooms, like mine, where you don't have the space to extend the angled sidewall slat/slot devices, or the depth between the soffits for a slot/slat device, wouldn't it be preferable to have at least a 4" thick absorber there? Like I've chosen to do.

And a few other questions if you don't mind Glenn. In what way do the slats/slots help in that area between the soffits? And are these somehow calculated for depth, slot/slat sizing? And if so, what is the aim? Or are these just arbitrarily sized?

Would it be wise for me to use arbitraily sized slats/slots over my 703 there? I believe John Sayers uses random width slats/slots.

Thanks again Glenn
Old 16th September 2011
  #33
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aackthpt's Avatar
 

Quote:
Originally Posted by fitZ View Post
3. "published standards" As in ISO etc? For non Pro design enthusiasts, these are very expensive to obtain, no?
I believe that THIS is what you are looking for (that post and the one immediately following). Unfortunately it never made it into the sticky thread that thread is discussing, but it IS around, and it IS free.
Old 16th September 2011
  #34
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depends on the room - the use of floating the soffits etc would have to be based on space and best options for getting the room balanced. with your size room the best bang for the buck is the plain old absorption (POA) you have been using to tame the response.

the slats in the render are just the material used, the slats in the SU file are a QRD pattern prime = 23 or 29 with optimize on. John uses a pattern like 25-5-50-10-100-5 (slat-slot) and variations like that, not really random but most times targeting the room response as well as broadband. my slat generator script actually supports PRD, QRD, Sayers, Newell, and Random options for width and depth settings, optimizations, repeats etc so i can rapidly generate them once i figure out the main slat-slot relation i'm looking for.
Old 17th September 2011
  #35
Gear Maniac
 

Quote:
the use of floating the soffits etc
ummm, exactly how does one "float" a soffit face? IF, the monitor box is decoupled from the soffit face, and is supported by a mass, perhaps decoupled mass, then what supports the soffit face? Or IS the face connected and supported by the monitor itself?

Or do you use decoupled structural brackets or something to that effect?

I understand this is pretty proprietary stuff here, but thought I'd ask anyway.heh

As to the slat thing.....well, I think it's time I start decoupling my brain from this whole studio design thing. I've spent WAY too much time on it and the deeper I go the farther away from reality I get. heh Thanks for your input Glenn.
Old 17th September 2011
  #36
Gear Addict
 

Hello Glenn and Fitz,

Glenn, as always, beautiful design work. I'm wrapping my head around the implications of the non-continuous baffle wall. There is some potential of inducing speaker/boundary issues that would otherwise be solved with a continuous baffle wall. I think the newer WSDG rooms have open zones on the outside flanks that would do some of the things you're showing. There is a relationship between the size of the baffle wall, the distance between L & R LF drivers that I'd have to figure out...I guess I'd worry about some level of SBIR or losing the headroom gained from flush-mounting...on the other hand, this method could allow a range of speaker types to work nicely in flush-mount application and should be a tight/punchy room Glenn. Also, I personally very much dig your ceiling treatment:angle of hard surface combined with broadband and diffusion. That would lead to a great response throughout the room.

Fitz, I don't think this is time to abandon the thread but may a good time to take one issue at a time.

Reasons to Flush-mount:
- first note the distinction of term flush-mount from soffit-mount. Flush mount indicates the speaker as an extension of a baffle wall. Soffit-mount indicates "old-school" methods of cramming the speakers up high (for visual reasons) and having alcove space underneath. Both of these implications (to me) are part of the reasons that many pro engineers don't trust "bigs".
- however there is so much done right these days with flush-mount monitors that they should be trust for any/every portion of the audio production/mix process (and not just a show of force to clients)
- ok...back to reasons
- increased sensitivity...up to 6dB which ultimately means less thermal compression of drivers at higher SPL's.
- the speaker/boundary conflicts are greatly reduced both by negating the rear wave cancellation and by geometry of the room which reduces virtual sources. The net result is that the LF response becomes more of a minimum phase nature...and if you damp modes, the control room can have very stable and consistent LF response spatially.
- The baffle wall itself can be either reflective, absorptive or diffusive to better balance the interaction of all room finishes.
- proper flush-mounting is the most direct way toward full-range and high spl response.

The worries are that the baffle wall itself becomes resonant and produces sound sources that reach the listener before the direct sound. Or you place the speakers wrong location.

From these (in my opinion) commonly agreed benefits/concerns there are hybrids. If you don't retain the benefits or deal with the concerns, then a hybrid serves no value because proper flush-mounting takes a GREAT commitment: design, execution, speakers, etc...
Old 19th September 2011
  #37
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Jeff - agreed - the continuous soffit is also my general approach - depending on the absorption on the open areas between the units, it would seem to dictate the effectiveness of deliberately using diffraction as part of the LF trapping strategy. perhaps this results in a reduced depth using a series of tuned/low Q traps running behind. and using this approach may be something (with care) that could "re-shape" out-of-the-box monitors to better fit the room (eg. someone with smaller monitors could use these soffit/cabinets which are designed to extend the response and smooth out any fascia interference to integrate into the room better).

fitZ - floating - as standalone units if you will (maybe cabinets?), or floating as in decoupled from the floor and ceiling - i'd use isolators based on the mass/spring to get the resonant freq down as low as practical.
Old 19th September 2011
  #38
Gear Addict
 

Thanks Glenn...makes perfect sense.

Fitz, just commenting on your room. It appears that the mid/hi drivers are horizontally oriented. Is this correct (kinda hard to see the HF driver but it seems to be black)? If so, I would fully expect that this would limit the practical use of those speakers as their response would have too much variation as you move laterally. As you well know, much of the physical use of your console involves lateral movement. Otherwise, you do really nice work.

I do like the Genelec and Blue Sky stuff that allows the mid/hi pack to rotate for optimal orientation.
Old 24th September 2011
  #39
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Pr.tiouz's Avatar
 

Hello,

i have a very small space ( L4,1 W3,2 H2,2 Meters) where i want to soffit speakers to avoid side walls reflection and gain space, i also want the corner behind the speaker to work as a bass trap.
on the Sketch up you can see the placement of the speaker i'm planning to do, the speaker will be on heavy floor stands and the whole cavity will be filled with heavy weight rockwool panels (120kg/m3 for exemple 705 is 90kg/m3) to have maximum efficiency at low frequencies except for a small tunnel with fan to cool the amplifier of the speakers (S3A).
the large rectangle around the speakers will be the front panel of the soffits and the rest a gap to the bass trap.
is this setup will work as a soffit or does it have to be a sealed cavity to act as one ? or does it is "in between" and there will be a frequency below wich the soffit will not work due to the size of that panel ?
what is the formula to calculate that in relation to the size of the panel?
i need some knowledge on those questions
Attached Files
File Type: pdf Preview 1.pdf (38.3 KB, 216 views) File Type: pdf preview 2.pdf (52.0 KB, 186 views)
Old 25th September 2011
  #40
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i would probably simplify and use straight soffits and use lighter - 48kg/m3 insulation behind the soffits and in most of the other absorption as well. also the S3A are designed for horizontal positioning so vertical might not be correct. a large cloud over the desk and a deep set of absorption on the back wall will be necessary as the S3A also have some serious LF output. the width of the soffits and the side walls should be sufficient for your space. using an opening on the bottom into the back of the soffit and a vent on top should do it. seal the speaker box except for the vent. attached are some ideas for your room.
Attached Thumbnails
Soffit Layout inquiry-pr.tious-control-room-1.jpg   Soffit Layout inquiry-pr.tious-control-room-2.jpg   Soffit Layout inquiry-pr.tiouz-control-room-render-4.jpg   Soffit Layout inquiry-pr.tiouz-control-room-render-3.jpg   Soffit Layout inquiry-pr.tious-control-room-render-1.jpg  

Old 26th September 2011
  #41
Gear Maniac
 

Hi guys! Sorry for taking so long to get back here. Been doing another "get ready for relatives moving in" routine.heh

Quote:
It appears that the mid/hi drivers are horizontally oriented. Is this correct (kinda hard to see the HF driver but it seems to be black)? If so, I would fully expect that this would limit the practical use of those speakers as their response would have too much variation as you move laterally. As you well know, much of the physical use of your console involves lateral movement.
Yea, that's correct and you are absolutely right about the lateral movement thing. I don't think it shows in the pics, but there is STILL a piece of masking tape on the sliding glass door that marks the center of the room. If I move my head ONE INCH, either way, things change...ARRRRRRRGGGGGGGRRRRRRR!


But really, here is the deal on those monitors. As usual, I didn't have the resources to go out and buy REAL good quality monitors. All I could do, was use what I had to build REALLY HEAVY DUTY enclosures, using some old Sansui speakers I had laying around. I had a bunch of 1 1/4" thick MDF with one side laminated with Formica, which I added to the existing box, which resulted in a 2" thick enclosure on the sides and back. I also added bracing to the inside of the same stuff.

Mounting them horizontally was due to 2 reasons. One, when I originally planned this project, I wasn't aware of the concept of vertical alignment of the drivers vs lateral monitoring. And frankly, I still see PRO studios with monitors aligned like this. But yea, it is wrong. HOWEVER, I NEVER intended to keep the Sansui drivers. All along, I was going to gut the boxes, and make a new baffle with Scanspeak drivers and crossovers, with the mid/hf drivers mounted vertically and the woofer off to the side. Which I've seen in many high end monitors. Frankly, I never expected these to perform as well as say Dynadios or whatever...but whattaya want for a home studio.heh

I've talked to a few people on the net who looked at my Sketchups and said the boxes would be fine. So, there you have it. What can I say other than it's the old.."how deep are your pockets" routine. Right now, they perform just like a home studio speaker sounds...I believe barefoot said they have a built in 6db boost with the OEM crossovers...but to my ears..they sound friggen GREAT!!heh

As far as decoupling the boxes here is what I did. My studio is on a second floor so I couldn't add a whole lot of mass. So I did the next best thing. I built a support bracket on the bottom, with Sorbothane decouplers. I didn't calculate anything. I just guessed using the "suggested weight range" on the spec sheet. There are four pads per box on the bottom, and two on the bottom back, and one on the top back bracket. It looks like this.



I used some hi density foam pads to approximate the thickness while building untill I got the Sorbathane pads. Here is one showing one of the bottom pads.


Ok, the baffle itself is composed of a SUB front, which all the brackets are fastened to, and a FINISH front, which is decoupled via floating iso connections at top and bottom, and the two panels are seperated and dampend via a 1/2" hi density foam pad between them. The monitor cutout is precisely 1/8" larger than the box, and actually has a 1" offset between the finish panel opening and the sub front opening. Maybe not optimum for a pro studio...but like I said...it works for me.heh



The pics/sketchups don't show it, but the cavity behind the soffits are FILLED with loose batt type insulation too. The bottom is two layers of 4" 703. So, there you have it...my DIY take on soffit building..right or wrong.heh
Old 27th September 2011
  #42
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Pr.tiouz's Avatar
 

Quote:
Originally Posted by gullfo View Post
i would probably simplify and use straight soffits and use lighter - 48kg/m3 insulation behind the soffits and in most of the other absorption as well. also the S3A are designed for horizontal positioning so vertical might not be correct. a large cloud over the desk and a deep set of absorption on the back wall will be necessary as the S3A also have some serious LF output. the width of the soffits and the side walls should be sufficient for your space. using an opening on the bottom into the back of the soffit and a vent on top should do it. seal the speaker box except for the vent. attached are some ideas for your room.
Thank you very much Gullfo for your reply, it's impressive
i will try to include as much as possible of this to my plans depending on budget
When you say seal the soffit i suppose it's the answer to m'y question about how much a flush mounting would work without the seal. But what is the math behind it, is it just diminishing it's performance below certain frequency ? If yes wich one ?
Old 28th September 2011
  #43
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gullfo's Avatar
 

you could leave the back of the speaker box open as long as you have a really good seal on the face. the idea being to get the LF to move across the face of the soffit before returning into the trapping behind it. this yields the correct LF support in front and causes the diffracted sound to "struggle" through the absorption behind. leaving the speaker box open and not sealing - it would be best to then subdivide the air cavity and minimize the vent patch. this way the space below the speaker is primarily sealed as a single more efficient cavity and the upper portion with the vent, while less efficient is still useful. leaving an air gap around 250-300mm across the bottom and 50-100mm x 300mm on the top should do it.
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