Johns Standard Control Room

While waiting for the primer to dry, I've been playing with the layout. I have a bunch of stuff to store books: manuals, lyrics in binders, CD's, VHS tapes, cassete tapes, mic stands, mics, cables, turntable, vinyl records, old reel to reel tape deck, old 4 track, conga drums, guitar stands, junk, boxes, portable recorders, a theremin, violin, etc etc. I need to buy or make some cabinets. As I mentioned earlier, Brain Gasdson from Recording magazine had a sketch of a wall unit with the top compartments modified into broad band abosrobers, panel traps, etc. I'm not a sketchup artis and never will be. I downloaded a model closest to the idea I could find. I envision something with shelves up top and maybe louvered doors on the lower sections. Maybe there could be absorbant material inside the lower cabinets with still be enough room left to store messy items? The upper shelves could be customized to contain whatever absorbtion in needed based on testing (to be determined) The middle shelves could contain books and the like arranged in a random fashsion for some diffusion. 1. Could this wall unit be all the way across and include enough bass trapping? 2. Am I better off with the corner traps as shown? 3. Any existing furniture thats more suitable to this appplication? Is there a better way to acheive my goals.

that looks like a decent layout -- maybe consider a very heavy drape you could pull across (perhaps segments) the back wall in case you find it too reflective. take advantage of wall-ceiling "corners" to add additional absorption over the TV, cabinets, side walls etc - think open soffit frames which contain absorption - perhaps angled, cover with cloth and/or some slats where you decide to preserve some HF. (drawing of mine not to scale)

Thanks Glenn, I've never seen absorption soffits before. Any photos of existing studios?

you probably seem them in studios all the time since they often look just like the duct soffits except they're basically super chunks in disguise. the framing is really to give the cloth (or whatever you use to cover them) a nice crisp finish. I think if you search fitZ's posts, he has a photo example of his which have some complex angles to fit the speaker soffits and angled out from the wall. basically though, some 2x2 framing should do it.

Glenn, I've searched and searched but could not find the FitZ posts you mentioned, but I get the idea. I prefer not to make built in bass traps....attached to the room....yet...not ruling it out..probably need em. BUT free standing, movable (even tunable bass traps?) acoustic treatments would be a very appealing idea. Not attached - not taxed year after year (cheap bastard) If I move, I can take them with me or sell them. (Red neck shed with wheels on it) :wink: Since storage is important to me, I'd like to talk more about the "sound absorbing wall unit" idea. Here's a concept picture.I'd like to build 3 or 4 of these and place them across the entire back wall. The center unit might have a small built in desk. Any thoughts on design details? Material? Depth 12 inch? 15 inch? Trap inner workings? Am I nuts? Also here are the latest photos. [/attachment]

berry berry nice! on the cabinets - maybe line the back of the slats with 2" cloth covered absorber and leave about 3/4" openings - perhaps a slot panel made from plywood and/or hardwood. on the tops - i'd still consider the soffit approach if only across the top of back room - 12"-14" down from ceiling and 3' - 4' deep or so.

So build that soffit all across the back wall, up under the ceiling.... and forget about aborbers in the upper cabinets?

gullfo wrote:

on the cabinets - maybe line the back of the slats with 2" cloth covered absorber and leave about 3/4" openings - perhaps a slot panel made from plywood and/or hardwood. -

I'm not getting a clear picture on the bottom cabinets. Do you mean to put the 2" cloth covered 703 or 705 immediately right behind the doors? Or all the way back of the cabinet? 3/4" inch gaps between the slats? Is this going to be a Helmholtz (slat) resonator? Can I still use the cabinets for storage?

something like this? maybe angle the fronts a bit so they're not flat. if sealed all around, you will definitely get some HH absorption but you might consider lining the shelves with some anti-slip pads to secure things stored there and avoid rattles.

Glennnnnnnnnn! Way cool looking!!! Thank you!!! Doors angled for diffusion. Hard surface to reflect the highs and some perforation to let some sound in. The cabinet backs are open? Or should they be sealed? Can you shed some light on the design parameters for tweaking the frequency response? Is it a Slat Type Helmholtz Resonator or something else?

the cabinet could be sealed to the wall. it's sort of a HH but not strictly - it's more like one of John Sayer's wall units with opening doors and shelves... :wink: as for the slat/slots 1/2" - 3/4" slots spaced (in this example like a QRD 17 pattern) as you like. better yet run REW to see what the room is doing and make the units more specific to any frequencies that need to be targeted.

gullfo wrote:

it's sort of a HH but not strictly - it's more like one of John Sayer's wall units with opening doors and shelves... :wink: as for the slat/slots 1/2" - 3/4" slots spaced (in this example like a QRD 17 pattern) as you like. better yet run REW to see what the room is doing and make the units more specific to any frequencies that need to be targeted.

What's an "HH". (The search feature on this website rejects 2 letter searches.)

gullfo wrote:

it's sort of a HH but not strictly - it's more like one of John Sayer's wall units with opening doors and shelves... :wink: as for the slat/slots 1/2" - 3/4" slots spaced (in this example like a QRD 17 pattern) as you like. better yet run REW to see what the room is doing and make the units more specific to any frequencies that need to be targeted.

I have downloaded REW (Room EQ Wizard) I have two but questions Master.... 1. What is an "HH" ? (I have searched long and hard for the answer throughout the entire world and even here, but he search feature on this website rejects 2 letter searches.) 2. Will the doors of the cabinets need to be tightly sealed when shut? I await with infinite patience

HH: I think he means HELMHOLZ resonator. ;-)

BriHar wrote:

HH: I think he means HELMHOLZ resonator. ;-)

HH = Helm-Holtz?........he happy having hyphenation hammered halfway in his nHame? :shot: Sorry :oops:

yes, Helmholtz :mrgreen: do the doors need to be sealed? not really. they are much harder to open if they're sealed :shot:

gullfo wrote:

do the doors need to be sealed? not really. they are much harder to open if they're sealed

:roll: Well........I started it. But seriously folks....... All the explanations for a Helmholtz resonator use the bottle analogy....so doesn't the box need to be sealed everywhere except for obviously the slots? If yes, gaskets would be needed around the doors? If not why?

if you want to seal it with gaskets you can to make it work more efficiently i'm ok with that...

I guess, I don't just have a gut level understanding of how these slot resonators actually work. Mechanical systems are much easier to visualize. I done some research but its still not making sense. Does each slot work independently like it's own beer bottle with one particular natural frequency? Why are the slots at different spacing?

The slot spacing (or slat width depending on how how you look at things) plus the varying cavity depth and slot size, all shift the response to a wider Q which is desirable over narrow targeted frequencies (unless you know what they are and need something specific but getting any treatment to target a specific frequency is tough). So broadband tends to be the better approach.

Slot absorbers seem difficult to design with any precision. Experience must make up much of the design process. BTW Glenn, if you're ever in Northern VT you are welcome to stay over. Your help as been so much appreciated. First things first. Room testing. Any good guidelines / tips on doing the room response test? Full audio range or limit to 200 Hz? Should I use my studio monitors, or drag my home theatre subwoofer out to the newly formed control room?

using REW? using the sweeps settings. use your monitors if they're what you're going to use. use one monitor in a lower corner and the omni mic in the upper opposite corner to get the full room response, then set them up in their approx (or exact) positiion and the mic in the listening position and repeat.

gullfo wrote:

use one monitor in a lower corner and the omni mic in the upper opposite corner to get the full room response

Yes I'm using REW. ? Speakers "lower" = on the floor? ? Mic = very close to ceiling? ? Should I test the room empty or put as much the equipment, furniture, instruments, etc in the room first? The room is VERY live right now.

The interior of the room is done except for treatment. Does it make sense to move the equipment and furniture in, then do the response test? Or should I build the big ceiling soffit first? (get the dusty construction done first) Anyone?