Poor control room dimensions due to amount of gear!

Hi to all... GREAT forum! Due to the size of the console, and the "excessive" amount of rackmount gear, I've been forced to make the control room at what I believe is considered a poor ratio. With finished walls, the height is 7 ft. 10 1/2 in. the width is 11ft.9 1/2in,with a depth of 16ft. 7in. My thought for room treatment are to use up to 2 feet(depth) and completely treat the rear wall with broadband absorbtion, no slots. The front wall I plan to use John's corner absorber designs. I'm very undecided as to how to treat the front wall between the corners. As far as the side walls go, on my right side is the "wall of rack gear" and on the left,the sliding glass doors into the tracking room! Probably not a lot I can do here!! John, Steve(knightfly) or barefoot, am I going in the right direction or totally lost?? Thanks to all who reply!!! Tom

How much wall space is on those side walls? Is the sliding glass door right next to the mix position, or slid forward or back? I'm thinking about the sidewall reflections... if the door is right next to you, you're ok because sound from the speakers that hits those glass doors will go past you and (hopefully) get caught by your rear wall absorber. If these doors are slightly ahead of the speakers, you might have trouble there. On the same token, try to place the huge rack-o-gear aligned with the mix position, across from the doors. Yes, it'll goof up sound for people standing behind you, but if it comes down to them-or-you, well... whaddya do? With good absorption in the front corners and back wall, you should be ok. What's the ceiling treatment like? Absorptive or diffused, or just flat reflective (hope not)? Kase www.minemusic.net

Hi Kase, Thanks for the reply. At the moment there's nothing on the ceiling, I do plan to hang a "cloud". As far as your question about the doors, they start approx 2 inches behind where I sit. The racks will also be in the same location. I posted this at the design forum, because I wasn't sure if it was a "design" or an "acoustics" question. Thanks again Kase, for the response, all input is greatly appreciated!! Tom

As far as your question about the doors, they start approx 2 inches behind where I sit. The racks will also be in the same location.

That's even better. All the hard reflections off them will go past you. Hey Steve, if you're reading this, I just had a thought... would a rack full of gear count as a decent diffusor, even if just for high freqs? I mean, with all those odd knobs and lights and switches and stuff, it's a pretty irregular surface... Anyway, as far as the side walls go, you've probably got some room left on the side walls for treatment. Just make sure there's something absorptive wherever the reflections from the speakers would be coming at you. Good luck! Kase www.minemusic.net

dymaxian wrote:

.. would a rack full of gear count as a decent diffusor, even if just for high freqs? I mean, with all those odd knobs and lights and switches and stuff, it's a pretty irregular surface...

It seems to me like the front of the gear would diffuse, but what kind of rack is holding the gear? If its open then you'll have all the flat surfaces of each piece of gear reflecting straight back up <slightly diffused> towards the mixing position. If its a cabinet then much worse. If there is some reflection there aiming back up then you'll want to think about building a corner absorber. Just my thoughts. Ron

"Hey Steve, if you're reading this, I just had a thought... would a rack full of gear count as a decent diffusor, even if just for high freqs?" - Probably a little, at around 8k and up - mainly, the down side would be screwing up the rest of the frequency band. That's why you see "producer's desks" behind the mix position that are no more than about 36" or less. The early reflections are NOT your friend... Steve

"My thought for room treatment are to use up to 2 feet(depth) and completely treat the rear wall with broadband absorbtion, no slots" - Tom, if you have that much space available at the rear you can do a pretty decent "gradual impedance" sort of trap - Phillip Newell diagrams one on page 171 of his book, "Project Studios, A More Professional Approach" - Speaking of diagrams, it would make things MUCH easier if you could post one of your floor plan, with the items marked that are taller than 36" - otherwise, I feel like I'm answering things like "what kind of vehicle should I get", not knowing whether I'm talking to a truck driver, a housewife, with or without kids, whether or not a farm is involved, horses or pigs to transport, planning to first learn how to drive and then winning the Daytona, etc. I'm not trying to be mean here, it's just that there are so MANY factors that enter into acoustics that it's really difficult to answer questions without first asking a few hundred of them myself... Steve

Steve, thanks for the reply. I fully understand any questions you might need to ask before answering! Sorry, but I am unable to post a drawing at this time. As far as items taller than 36", the 4 racks together, side by side are approx 5 and a 1/2 feet wide, and are 5 foot 8 inches tall. Similar to the racks that can be seen in the picture of Ocean Way Hollywood's Studio D. Each rack is 36 spaces. The console is approx 6 feet wide, with the top of the meter bridge about 40" from the floor. The racks will be directly across from the sliding glass doors. Hope some of that helps!! I'll have to do some further research, I'm not sure what you mean by a "gradual impedence trap". I figure with the room my dimensions I'll have problems at 70Hz, 141Hz, 236Hz, 282Hz(?) and at 375Hz. Thanks again for your precious time, GREAT forum! Tom

Juxtaposition is all-important in acoustics, and I'm not seeing your room in my head as far as console, speakers, your head, racks, sliders, front wall, etc - if there's ANY way you can find to post even a crude scanned in drawing... The "gradual Impedance" thing is my paraphrase of Philip Newell's comments in his book - in it, on page 171, he diagrams a rear trap wall that's over two feet deep (and quite involved) that, from the attending text sounds like it would be close to a "black hole" for any frequency you'd care about. One of hundreds of details I'm "stockpiling" while designing my new facility. Your comment about using a couple of feet at the rear is what brought up my comment on that wall. With the racks and sliders both slightly behind you, you have less of a problem than if it were the other way around - As far as modes, your dimensions actually look pretty good - Bonello distribution curve shows no glaring problems, other than a slight "hole" at around 40 hZ. If you can do the "super wall" thing at the rear (I definitely recommend buying the book, and not just for that), then do the front part of the side walls with false splayed walls and put a cloud over your mix position, you should have a pretty usable space... Steve

Steve, I have ordered the book. Thanks for turning me on to it! I'll check out page 171, before making any final acoustical treatment decisions!! Tom First Bass Audio

Steve, I've read through the book, especially Chapter 11! I believe the rear wall absorber system, detailed in the 11.5 diagram, is exactly what I need. It's not to hard to built and I have plenty of space to do it. I let you know how it works out!! At the moment, I'm still hanging drywall (only on the first layer) and as you know, there's never enough hours in the day. Any idea where I can get a couple of months of 28 hour days?? Thanks for turning me on to the book and the idea!! Tom First Bass Audio

Tom, glad to help - BTW, if you aren't sure what Newell calls "dead sheet", as near as I can tell he's referring to loaded vinyl (such as Auralex Sheet Blok) - that stuff is expensive, but I've not found anything less expensive that sounds like it could replace it. Closest thing so far (absolutely NO research to back this up yet) would be cushion vinyl floor covering, but I doubt it would be "limp" enough to work the same. Even the thick vinyl Shower Floor Pan vinyl carried by Home Depot, etc, runs about $5 per lineal foot for 4 foot wide stuff, and it's not as thick as the Auralex stuff. Been looking for that length days (and the energy to use them without all that time-wasting sleep crap) for quite a while now... Steve

Steve, Standard roofing can replace it at normal indoors temperatures (careful with fire properties). In the industry more bitumen like foils are used than vynil. There are mass loaded bitumen type materials. They are much cheaper than vynil. The fire properties of vynil are better, but the gas when it burns by an external source is at least or even more poisened (chloor). This is valid if the vynil is PVC as I assume. Eric

Eric, Thanks for your post, here and elsewhere, on this and other forums!! What do you mean "standard roofing"? Here in the US, standard roofing usually means, a "tar paper underlayment with asphalt/fiberglass type shingles". Are you thinking the "tar paper" is a possible substitute for the "deadsheet". It certainly is cheaper!! Tom First Bass Audio

Tom, How do you call that: that black foil on rolls to burn on top of a roof? The standard roofing as we call it, made from bitumen. Please give me the correct English name, that I'm sure other people will understand this too. I've a small technical English dictionary: it sais it's the same in English as in my language. Bituminous materials have an internal damping which can even be better than the vynil foils. For resonance absorbing purposes, such materials are also made in special versions with added minerals (the mass loaded thing) and sometimes with added weakeners to make the material more flexible at low temperatures. Acoustically mass loaded vinyl is not better (even a bit the reverse) than bituminous foils. The advantage of mass loaded vinyl is that it works better at very low temperatures, is a nicer material to work with, and has better fire properties. Note that the acoustic effect of such visco elastic materials is very temperature dependent. Note: the use of such materials is dependent on the application. So I don't say a thing now about the fact if it sensible to use it or not. My idea is that in the studio world people often have wrong expectations of this material Regards Eric

Eric, the materials I'm aware of here (home construction types) are 30 pounds per 100 square foot "tar paper", usually called building felt or roofing felt, and 90 pounds per square foot "roll roofing", similar stuff but usually comes with gritty stuff embedded in one side (the side one would walk on) - it sounds like what you're referring to may be similar but for fusing together with heat after application, to form a continuous layer? As always, I appreciate your inputs - if I'm not careful, I may actually LEARN some of this stuff :? ... Steve

It's this stuff on top of this roof: But only the top layer has this gritty stuff. Such roofs are made of more than 1 layer. The bottom layers don't have this gritty stuff and are sold in all kinds of qualities and thicknesses. Acoustic versions are based on this stuff, with possible additives to increase density and keep it weak at minus temperatures (In centigrade). The acoustic quality is defined by the internal damping which is very temperature dependent. PVC can't beat those properties. So PVC is used for it's other mechanical properties when necessary. For the industry those bituminous acoustic versions are used in enormous amount. It exists in self adhesive versions and so on. Industrial steel noise enclosures seldom use PVC to improve the acoustic steel properties. Ducting insulation (this alu sheeting you see round all those huge ducts in the chemical industry) based on metal or alu sheeting is in 95% done with this stuff. The automotive industry (busses, trains etc...........) use it. Just to insulate the vacuum ducts for cooling compressors of one medium large power station I once used > 35000 sft. Best regards Eric

Eric, I believe the materials we are all talking about, are the same. As Steve has said, we call it "tar paper" and "asphalt shingles". Both are available in different thicknesses, such as 30 pound and 50 pound. "Asphalt shingles" is the material with the grainy "stuff" on the side facing the sky , so to speak! The "asphalt shingles" are also available in roll form. In talking with a roofing contractor, the roll form is mostly used on a flat roof having no pitch (or very little). Sometimes used on a pitched roof to save cost. This contractor prefers to roof homes and buildings during the US summer months. Though it can get very hot up on the roof as we know, his thoughts are to "shingle" in the early morming hours, so the crew has done the days "work" by 11:00 am. The two reasons for this being the shingles will mold or glue themselves to one another from the heat of the sun, and to NOT walk on them when hot, so the grainy stuff is not disturbed. After typing all this, I just realized that you probably already know this! My apology to you if so. I will check further in to using this material. Thanks again, Tom First Bass Audio

Tom, To make this sure: If I call it "Tar paper" than every English speaking guy understands it correctly? Bit surpriced since I don't see where the paper comes in (there's no paper involved). TIA Eric

I used the stuff eric is describing in my outside walls. Because the exterior walls are cladded with OSB I wanted to increase the mass so I put 2 layers of roofing felt between the studs and caulked it all around and then added a layer of 5/8 drywall on top of that. The roofing felt comes in rolls - a fraction of the cost of mass loaded vinyl (something like $12 a roll) - each roll is almost too heavy to carry by hand - I think I had to use a wheelbarrow. It has lots of little stones on the surface of it. Each roll did 5 or 6 stud widths 2 layers thick. It's also class A firerated. I did a test with a blow torch and it melts and burns if the flame is on it but take the flame off and it instantly stops burning (doesn't propogate fire) - so I felt ok using it. It seems to work. My inside walls have 3 layers of 5/8 drywall. Playing drums as loud as possible plus guitars on max volume - faintly can be heard directly outside the building. 10 feet away - can't hear a thing :D

Eric, the name "tar paper" is an old one, from when similar materials were used to wrap houses before the exterior siding was applied - it was used for a vapor barrier, and really was tar coated paper at that time. Since then, this (lighter weight than the outer layer of roofing stuff) "tar paper" is usually found in what is called 15 pound and 30 pound weights - these are weight per "square", which in US is 100 square feet - so weight per square foot would be 0.15 lbs and 0.30 lbs respectively. The actual exterior roofing material is made similarly ( bituminous impregnated felt) but is typically 90 pound (0.9 lbs per sq. foot) - the 15 and 30 pound stuff is normally used either as a vapor barrier under siding (instead of Tyvek) or for the same purpose under heavier, 3-tab roofing shingles for pitched roofs. Sorry for the non-metric numbers, I'm just getting off graveyard shift with two more 12-hour nights to go... Steve

Very old thread, but... Is this what you are talking about as a Sheetblok alternative: http://www.homedepot.com/Building-Mater ... ogId=10053 ...or the lighter stuff: http://www.homedepot.com/Building-Mater ... ogId=10053 Thanks, Seamus

seamus wrote:

Very old thread, but... Is this what you are talking about as a Sheetblok alternative: http://www.homedepot.com/Building-Mater ... ogId=10053 ...or the lighter stuff: http://www.homedepot.com/Building-Mater ... ogId=10053 Thanks, Seamus

Nope. He's talking about Modified Bitumen roofing. It's sometimes called "torch down" here in the states. It's fairly thick, 3/16"-1/4"in thickness. You can get it granulated or without granules. It needs to be applied to the roof with a torch, and therefore not widely available to the general public. It's usually only available at roofing contractor supply houses.

Ah ha. Thank you. Seamus.

One more thing about this stuff... If you were to use it in some sort of bass trap configuration.... Doesn't it stink like hell?