Discussion in 'Room Acoustics / Studio Design' started by mikezfx, Dec 8, 2002.
That is a very confined space. The ceiling is low and the room is narrow. Perhaps we can prevail upon James (Knightfly) to run the dimensinons in his computer program and let us know if it is useable or if shortening the room would help? I just don't know what to add to the info you have already read in the oterh studio treatments thread other that I suspect your going to need a massive amout of bass trapping and you are never going to get accurate bass response in a room like that. A 20 Hz bass tone wavelength is 14' and to have a "legal" listening enviornment you need a minimum dimension of..... you guessed it 14'. It might be possible to deal with a room that has one dimension less than that but when tou have two, as you do it just gets damn near impossible. We may be able to get it to where it is useable but I don't think you are going to be able to get full bass response in that situation. One thing I would definately say is you should be thinking of monitors that only reach down to about 60 Hz., that will help eliminate some low end "loading" in the room. Let's see if we can get Knightfly to run those numbers and then revisit this once we have that information.
thank you very much for the reply.
i figured this would the problem going in. unfortunately there are no ceilings in the house taller than 8' .
if the space is unuseable, i can investigate other spaces in the basement where i could easily achieve 14' in two dimensions.
my monitors are KRK V6's (6" powered nearfields, silk dome tweeter).
Mike, I just lost a post to you that was my typical, about two pages - I'm so pissed at Earth Stink for going comatose on me that this one will be more concise than usual. (my own fault for not saving everything BEFORE I ask my incompetent ISP to do it's bleedin' job...
Your room dimensions are as good as you'll get with a low ceiling. Splayed walls will cost you over 10% of your limited floor area if done at 12 degrees, which is minimum for any useful function (getting rid of flutter echo, minimising standing waves) There is a slight bass starvation at around 40-50 hZ, which your V6's can't do anyway - If you later decide to add a sub, it should go against the wall behind the mix desk, a couple feet OFF center, or in a front corner. (This from Genelec's recomendation for sub placement)
Your budget will keep things simple - glue two layers of sheet rock up against the upstairs floor from underneath, between the joists, getting it hermetically sealed with glue/caulk. Use either non-hardening silicone or butyl caulk. Add 4-6" of rockwool insulation in between the joists, get some Resilient Channel and run it crossways of the joists every two feet, screw two layers of 5/8" sheet rock onto the RC, making sure you do NOT put any screws into the sheet rock that line up with a floor joist (this "shorts out" the flex effect of the RC, which is NOT good) Glue and screw everything, caulk everything airtight, and you will lose only about 1.5" of ceiling height which does nothing bad to the modal response of the room. This method will get you around 47-50 dB of STC rating if done right.
You may need to enclose and foam treat the stairwell to act as an airlock, with doors at both ends. Where the walls will NOT be load bearing, you can save some money and get better STC ratings with metal studs than with wood. Do NOT use RC on metal studs, it's a total waste of money.
Re-read the posts on Double Helix' thread, 99% of that will apply in your case too.
Sorry for the terse reply, I'm still chewing nails over losing 25 minutes of typing because some idiot can't maintain a decent server... Steve
thank you very much for the help.
i am looking to add a sub to my setup in the future. will this cause major problems?
my main question is -
other than splayed walls, are there any other structural aspects I can implement to reduce the cost of acoustic treatment after the room is completed?
also, whats the best homemade diffuser approach? i can spend some money on it to make it look nice and i have decent wood working skills.
I think a lot of low in the room may be a problem but Knightfly thinks it's ok.. he has got the computer analysis program so he has a better grasp on that. My approach is more of the poke and hope nature. Splaying the walls in your situation would rob you of valuable floor space and room volume, the worst thing you can do. Just follow the instructions I gave DH in the previous thread and pay attention to the Live End, Dead End part and symmetry!!!. Let us know about your progress and I will help step by step. Give a shout when you get started. Fats
It's my opinion, I'll play with it if I want to!
excellent, splayed wall idea ditched. the simpler the better, the more room the better.
wheres the best place to get resilient channel from? i know Auralex makes the stuff, but is there a cheaper source?
last thing i have to figure out is how to do the HVAC on a budget, then im ready to go.
once again, thanks.
Is transfer noise going to be a problem for you? That is do you need to contain sound inside the room and keep sound out? If this isn't an issue then you don't need to worry about the RC channel and all the sheetrock stuff. The basement walls are cement so they are plenty stiff enough. What is the ceiling made of? Is it the stringers for the floor above or has it already been finished? As far as HVAC, that is a very difficult issue to deal with in a room where mics are to be used. There are some panel type AC units that work on the heat pump theory but these can be expensive.. Perhaps someone else can contribute some good solutions..I don't know everything after all. You may need to consult a heating and AC contractor for some ideas. ....... Fats
It's my opinion, I'll play with it if I want to!
situation with noise control is that i mainly want to keep sound contained in the room, and especially contained from the upstairs so I can edit/mix/ record softer instruments with out disturbing upstairs. the floor above is caprpeted and low traffic so I am not too worried about foot traffic.
the ceiling currently is just a layer of 1/2" sheetrock attached directly to the joists of the floor above, with pink insulation stuffed in between.
so i will defintely do the resilient channel / double sheetrock thing on the ceiling. i dont think i need RC on the walls.
i also need to put a floor of some sort down, i was thinking (perhaps not clearly) to put down 2x4's on top of Auralex U-boats, covered with a couple layers of plywood and then carpet.
amp i wasting money here, what can i do for a floor?
You may want to adopt a wait and see attitude about the ceiling. What you have already may do the job. The floor is going to cost you some of you height in the room which is already an issue. The up side to that is you can run your cable bays under the floor...makes for a nice clean install. The u boats are a good thing, but does the floor really need to be floated? If transmission isn't an issue, then it's needless. There are lots of other places to find acoustic matierials besides Auralex. IMO they are very expensive. I don't know what justifies their pricing. Their stuff isn't any better or worse than a lot of others in the market. ........... Fats
the cable runs under the floor will probably be worth the *slight* height loss. hadnt even though that far ahead yet (!). maybe i can even put the floor on 2x4's turned sideways. i also would like to get some clearance from the ground just in case there is ever a water/moisture problem.
auralex is way overpriced. especially after you posted the link to Marketek (sp?).
Check out http://www.foambymail.com ....... Fats
woah - thank you! finally a company that feels "foam is foam".
Mike, I hate to burst your bubble on the cheaper foam, I don't like paying any more for things than anyone does - still, I looked all over foambymail's site for info on specs for their foam, and only came up with density and fire rating. Compare that to auralex' specs page -
I'm not saying that the cheaper stuff isn't as good, I'm only saying that we DON'T KNOW... If I were you, I'd call or write them and ask for NRC specs like Auralex posts, just to see whether the two products will give you anywhere near the same results. You're going to need the 4" foam for the most part, because of the better low freq. absorption - I'd concentrate on specs for that mainly.
Fats is right about trying things before you sink money into them - I'd hook a CD player to your V6's, place them as close to the position and conditions (stands, etc) that you intend them to be in,
Go to your nearest Radio Shack and buy the ANALOG version of their Sound Pressure Level Meter (about $40, and the most useful $40 you will ever spend on your studio), bring it home, set up the meter on "C" weighting, fast response, place the meter about where your head would be during mixing, then adjust the CD player volume so that you get a reading of 85 dB average, with peaks to maybe 90 dB - let the CD play, go upstairs, and see if the level is objectionable. If it is, have the person who will be most upset at high sound levels upstairs, listen from upstairs while you turn the level down slowly. Have them stomp on the floor when the level is low enough, and check the SPL on the meter at that point. The difference between 85 and where the upstairs level is OK, is the amount of NRC in dB you need to shoot for.
If you're lucky, 85 dB downstairs won't cause ANY problems upstairs - if so, you're done.
BTW, you'll use the SPL meter CONSTANTLY, not just for this test.
As far as floating the floor, that's a complete waste of time and money unless you plan on a larger facility with separate drum booth, vocal booth, tracking room, control room, etc - Besides which, its' nearly impossible without serious acoustic engineering help, to get the right durometer spec for rubber used for floating floors. You have to figure the total weight of the floor, and walls if they are built on the floated floor, you can't contain the rubber sideways or it doesn't compress the same, the total area of rubber needs to be part of these calculations, it will rob you of at least 4 inches of valuable headroom if done even slightly right, and probably 100 other reasons that temporarily elude me at the moment.
Keep in mind that in order for a floated floor to work, you need major MASS in the floated part so its movement is damped by the rubber. Typically, the LEAST floor that is used over rubber would be 1-1/2 inches of particle board or concrete, more is better. What you're trying to do is to eliminate floor transmission into the floated area, by having a heavy mass supported on springy stuff so that the mass won't be affected by what few vibrations get thru the springy stuff. Rubber, or neoprene, is nearly rigid if not compressed to its ideal percentage - this is a really tricky calculation as I said.
There are companies
that can provide what you need for floated floors, but not in your budget - even the auralex U-boats aren't cheap, and again the loss of headroom... The U-boats are designed to support a 2x4 on edge, not flat - the durometer spec on the rubber would have to be completely different for them to work with flat runners, even if they WERE the right size.
If you're on concrete right now, and concerned about moisture as you mentioned, I'd consider ripping pressure treated 2x4's in half, to so-called 2x2 - put the sawn edge toward the upper floor, rest the bottoms of the 2x2's on a couple layers of 30 pound roofing felt (tar paper only thicker) - you can cut a roll of this stuff with a long sawzall blade, into mini-rolls or, if you're really concerned about moisture, cover the entire floor with it, overlapped by about 6" , THEN put down the 2x2's and fasten the floor (3/4" plywood minimum, or 1-1'8" T & G flooring even better - use plenty of construction adhesive when putting the floor together, and long decking screws countersunk slightly so you can put whatever floor covering down - basic vinyl flooring is probably the least expensive wear surface that will look good and sound OK - You can add throw rugs to taste when tuning the room later. (re-read the other thread about the mirror trick)
There are more opinions about subwoofers than there are subs to choose from - I've had good luck in a small (10x12) room using K-ROK's with a Yamaha 120 watt dual 8" sub - the trick is finding a reasonably priced decent quality sub with a Linkwicz-Riley crossover (24 dB/octave)so you minimize the "mud" caused by both speakers trying to reproduce the same frequencies, and not necessarily in phase with each other. If you try to buy the matching one for your speakers, KRK wants about $1k for it - Mackie is even prouder of theirs - the Yamaha costs around $350, and has 24 dB filters. I had mine set so people coming into the room didn't say "where's the sub", but more "how the hell do those little speakers put out such full sound" - The next setup for me will be even more scientific, been reading some of Bobby Owsinski's stuff and plan to get his calibration kit for surround.
This post is getting a bit long, and I'm nog getting any closer to beddy-bye, so I'm gonna chop it off for now - Hope I gave you a little more to think about... Steve
Mike and Steve,
It seems I recall seeing the NRC ratings on foamby mails page and it was comparable to other foams... I'll look again. Some good points about floating the floor Steve. When I had tile installed on a cement floor in my studio they came out and did a test to check for moisture content in the slab.. I'll bet you could get some info from a tile place on how to check for that...If the moisture content is acceptable you could just lay some soundboard down and sheet over that with some plywood and carpet or tile. This would float the floor ... sorta ...and provide a surface that isn't hard and cold in the winter. ......... Fats
steve and fats,
once again thank you for all of the suggestions.
i like the direction the project is going - less complex and less expensive. more money for mics and pres
steve: i was planning on looking at other sub options that the way overpriced KRK one. 350 sounds perfect for that yamaha. how does it connect to the V6's (or any speaker)? it is powered?
as far as the flooring goes i think i will go the 2x2 method steve suggested because once, ten years ago, water did make its way in and there was a good inch of standing water.
newbie to flooring question: how do i affix the 2x2's to the cement floor/ roofing felt, or do i not?
another question about flooring: i can spring for a little more than the vinyl tile, id either like to wall to wall carpet it, or do a wood tile floor (the interlocking kind you can buy at home depot and put some throw rugs down. does either option offer an advantage acoustically?
Mike, I'll have to get back to you on using the Yamaha sub with powered speakers - I've only used it with the passive K-ROK's. I don't remember whether it's a simple connection change, or worse. They have a couple of newer versions of mine, currently being packaged (or not) with MSP-5's - Those, since they're being used with ACTIVE speakers, might have a line level crossover (what you need) I'm not sure if mine do, and they're buried in mounds of gear in my old studio right now...
Flooring - use the parquet if you can - you can always deaden it selectively with a throw rug, but you'd have to put wood OVER the carpet to brighten it back up...
If you have the chance of standing water, I'd definitely put the roofing felt down first, after using a good sealer on the floor. If possible, build the walls so you can see under the floor between the roofing felt and the bottom of the false floor - (put the wall on TOP of the false floor) - that way, if the water comes back you can aim a big fan under the floor and dry things out. I would overlap the roofing felt such that there are two layers under each 2x2, it will help with cushioning the 2x2's so they sit more solid. I would just place them and screw thru the new subfloor to hold them - once it's together, gravity and mass will take over and nothing will move unless you find a need to hold a WWF event for elephants inside...
An added avantage of this floor is that if you go with only the 3/4" ply for flooring (this is also available in t&g, do it) is that the thinner floor will act as a partial bass trap which won't help noise TRANSMISSION but will help the INSIDE response.
I just read through all of the above. Mind bending.
If you don't mind, please give me some input on what to do with this space. We just got it in a friends basement. We have permission to build as needed. Its solid newer construction. Solid concrete walls and floor. Neighbors not an issue. And the owner is 90% deaf. No, really.
Space available to us is 26' wide and about/up to 30 or so feet long (the full basement is about 50' long) .
Here's the hang up : There are posts supporting the center joist that runs length-wise down the house. They are about every 8 feet. I am thinking that one room- LEDE set up- will allow listening/mixing and recording as needed. Although we really like the idea of a separate room (just to be cool...)
I have Everest's book, have read thousands of pages, and am ready to go. Plan on lots of DIY with 703 and R19 insulation. Diffusors- QRD style that I designed- are also available.
We do anyting from rap vocals and midi to rock.
much appreciate it
OH, the ceiling is 91" at center, 92" at edges.
steve - would love to hear about the sub stuff. i really need one, my v6's are great but i end up making bad decisions for bass guitars and kick drums cuase i cant hear them that well.
the plan for the floor you gave is perfect. this is starting to come together. what does t&g stand for by the way, or is just a brand??
i bought a radioshack dB meter after reading the other posts last week, ill do the NRC tests with a sensitive family member this weekend.
more to come.
Tongue and Groove
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