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Discussion Starter #1 (Edited)
Lucky me. I am retired with the resources to build, from scratch, a custom practice building.

This building will be re-purposed as a small garage for the next owner. However, I am sure the interior space can be designed to be acoustically neutral without the need for expensive acoustical treatment.

My concern is the exact INTERIOR dimensions to avoid standing waves and cancelling waves.

Current models are:
8' high x 13' wide x 21' long. (Fibonacci numerical sequence)
8' high x 13' wide x 21' long. (Golden Rectangle of the Greeks)

WTF!! Same result!

Seriously, does anyone know how to crunch the frequencies on these dimensions?

I am fairly confident just relying on these tried-and-true design basics, but it might be wise to see how it works out in engineering lingo. (It wouldn't be the first time I was totally mistaken.)

The two main loudspeaker coils will be positioned from corners using the same ratio.

And oh yeah. A single studio mic (or pair) to capture the room direct to tape for demos.
 

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The best thing to do is ensure that there are no parallel surfaces. After that the golden ratio dimensions become unimportant becasue standing waves will not form at any frequency (golden ratio itself is just a known set of proportions where standing waves are minimised, but not eliminated). The floor should be level, so slant the ceiling; just a few degrees will do. then take 1 interior wall and angle it away from the exterior at one end. This creates a triangular space that is unused - make a door and use it as storage or workshop area etc. Like this (left is top view, right is from the side; Black is exterior red is interior studding/drywall):



The next important consideration is symmetry on the listening axis. The above example is not perfect in this regard but good enough (and the easiest way to not have too much wasted space). The last room I built was in a much larger unit (used for shows, shoots, private parties etc) so I had the luxury to build a weird shape into a corner. This room sounded amazing and I miss it terribly. The only improvement would have been to make it a bit bigger (it wasn't as cramped as my current room, but more space would have been handy; more length than width) but I had to fit it between some columns and I couldn't take too much space away from the moneymakin (read: rent-paying) portion of the unit:



The storage room also had my workbench. Behind that (to the left) was the bathroom (which you'd get to from the the outside the studio area e.g. up from the bottom of the pic). The right edge of the pic is where the performance space was. In the early days I used the studio as a green room since the door was just off stage right, but then some asshole ruined that for everyone. A year or so into running this joint, I cut the corner on the bottom right to improve sight lines from the lounge/chill area to the stage.
 

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Discussion Starter #3 (Edited)
Pretty fancy. Your input is always awesome, GG.

Minimized is OK. Eliminated is unecessary.

I am aware of this info, including the Golden Trapagon design. I considered building it when looking into a quarter-section of land last year. However, I opted for a two-acre lake lot with no electricity, so I am building in town.

This needs to fit into my existing driveway. Even the Golden Cuboid (the A.E.S. Standard) is out. The minimum space according to BBC specs is 1500 cu.ft., so a single car garage beats that by a mile. Dimensions are the only thing left to consider.

Most importantly, when I sell my home, this has to ACTUALLY BE a garage. No, I don't want to explain why the ceiling is slanted. Lol.
 

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I would probably err on the side of 'garage', just from a resale POV. Unless you're planning on tracking some high-level stuff, I think the dimensions you came up with would be just fine. As long as it's big enough to do what you want. You can always reduce reflections with sonic absorption, like Sonex or PrimeAcoustic. And if you want to make it sound larger in any dimension, you could invest in diffusers - but much more complicated and expensive than absorption. Carpet on the floors is cheap. And perhaps bass traps in a few or all of the corners. Easily reversible.

I would consider the garage aspect heavily. If you're dimensions are 1' too small in on dimension for two cars or two doors or whatever, I'd give up perfection to the greater (lor onger term) good and add the foot. A friend of mine bought Jeff Waters' old house out here and it had a two car garage that used to be his home studio. You may have heard that space if you've listened to any Annihilator from the early 2000s. I don't think he tracked drums there, but he played and sang most everything else and probably did most of it in that garage. Being as you want to mic the room and not the instruments/amps up close, you may feel differently about that, though.
 

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Discussion Starter #5 (Edited)
OK. So I got off my butt and crunched the numbers myself. It wasn't too hard.

Dimension times two (to opposite surface and back again), then divided into the speed of sound, equals the resonant frequency. Do this for floor-to-ceiling, side-to-side, and front-to-back.

Height: 8'x2= 16' divided into 1130 ft/sec = 70hz
Width: 13'x2= 26' into 1130 = 43hz
Length: 21x2= 42 into 1130= 27hz

Multiply 70hz x2, x3, x4, x5, x6, x7, x8, x9, x10, x11.
Repeat for 43hz
And for 27hz.

Resulting resonances are
70hz: 140,210,280,350,420,490,560,630,700,770.
43hz: 86,129,173,215,258,301,344,387,430,473.
27hz: 54,81,108,135,162,189,216,243,270,297.

WOW! No duplications. Triples are especially bad. So this is a basically neutral room. This is good enough for me (with some simple, cheap, adjustable acoustic controls.)

You can do this math on your existing jam/recording space, mixing/mastering room. If you are getting triple resonances you can find out how to build specific frequency filter(s) to tame the room. Its all online.
 

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Discussion Starter #6
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The concrete forms laid out to roughly show the location of the garage/studio. Tomorrow put in stakes for the fifteen anchors which were made today and should be screwed in this week. The Golden Rectangle of the ancient Greeks. Pleasant to behold and acoustically neutral.
 

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Discussion Starter #7 (Edited)
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PHOTO: Work has slowed to a halt thanks to antibiotics that prevent me from working in the sun. Gotta dig out some unstable ground on the side with the grass, refill and pack with gravel. Dozen screw piles make the whole thing stable enough to attach to the house and even add a second story, if desired later. And finally, I took HighDeaf's advice and made a better "garage" by extending it to 24'. Notice the 24" chunk added to the closest side. A simple wall inside will return the jam space to the Golden Rectangle/Fibernacci dimensions. Thanks HighDeaf, good advice.

The antibiotics that are keeping me out of the sun, have given me time to continue to research F. Alton Everest's Master Handbook of Acoustics Vol.4. Particularly the section on reverberation.

(For those interested, the calculations for room reverberance are thus:
1. Calculate room volume; length x width x height =2184 cu.ft.
2. Calculate areas of absorption: in my case 273 sq.ft. of concrete floor and 817 sq.ft. of 1/2" drywall.
3. Multiply .049 times the total room volume and divide by [total surface area of material times the average absorption co-efficient of that material]. Do this for the concrete and the drywall at these frequencies: 125hz, 250hz, 500hz, 1Khz, 2Khz, and 4Khz. NOTE: the absorption co-efficient will change according to frequency so you will need to USE THE TABLES ON PAGES 585 to 587. This will give you the room reverb times for those frequencies. Make a graph.)

For those not interested in understanding acoustics, here's the skinny:

Reverb times are acceptably short at low frequencies and high frequencies, but between 500hz and 1Khz the reverb will be too long at 2.4sec. and 2.7sec.

No bass absortion required. This will be provided by the drywall (and insulation, staggered studs). No high end absorption required (but diffusion needs to be considered next). 500 to 1K is best absorbed by drapery. Whoee! Very simple, although 10oz to 16oz velour is quite costly, and twice the width is necessary to produce "1/2" fold coverage.

Basically all I have to do is figure out my speakers/microphone placement to make decent mono/stereo recordings of the room for archive/demo. Treat the walls and ceiling for primary reflections to the mic area. Add drapes, sufficient to lower 500 to 1K to half a second.

Carpet will produce more problems than it will solve as it does nothing but muffle a high end which is already within acceptable specs. Easy enuff to add later if I am wrong.
 

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pourin da pad, pourin da pad

I hope I am missreading, but it sounds like you are conflating acoustic treatment (how things sound to you in the room) with soundproofing; with that no bass absorption required statement. In any case, that can be added later on a very small budget; yopu gotta build the room first.
 

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Discussion Starter #9
pourin da pad, pourin da pad

I hope I am missreading, but it sounds like you are conflating acoustic treatment (how things sound to you in the room) with soundproofing; with that no bass absorption required statement. In any case, that can be added later on a very small budget; yopu gotta build the room first.
Yes, there are so many ways to absorb bass, that won't be a problem. For now I will trust the calculations that I made per the book, and we shall see.

Mr. Everest's Handbook or not -- I am just an amateur, hacking his way through. LOL. As long as I don't make a mistake that can't be undone...
 

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Discussion Starter #10
pourin da pad, pourin da pad

I hope I am missreading, but it sounds like you are conflating acoustic treatment (how things sound to you in the room) with soundproofing; with that no bass absorption required statement. In any case, that can be added later on a very small budget; yopu gotta build the room first.
Lots of time to pour over the numbers. Of course you are correct, GG, about the bass absorption. Although reverb will not be a problem, there could be danger of standing waves at 216hz and 299hz.

After an exhaustive study of all the options, I think I will go with perforated panels upright in the back corners (7/32" holes in masonite @ 6" centres; four inches deep: two inches of air and two inches of mineral wool). These will absorb bass ranging from 200hz to 300hz according to the Handbook. May create a (unnoticable?) dip around 230hz.

On the front wall, traps at the ceiling --one 1.3' deep (216hz) and one .94' deep (299hz) -- both sides. Velour drapes across front wall to shorten the 500hz to 1Khz reverb time.

Staggered acoustic tiles on sides and ceiling just to avoid parallel reflection problems.

ANOTHER WONDERFUL THING ABOUT THE GOLDEN RECTANGLE. If you draw diagonals from corner to corner and select the centre of the room as the prime listening spot (recording mic), placing the speakers anywhere on those diagonals not only places them in the room at the Fibonacci ratio to the walls, it also creates an equilateral triangle with the centre of the room which is ideal for balanced reception of the sound. So many problems eliminated by starting with harmonious dimensions.

In theory anyway. We'll see. Haha.
 

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Fibonacci be damned, the most important spec - is there room for a beer fridge. You're in SK so you gotta have a beer fridge, replete with Rider stickers. All studios have some sort of 'green room' (i.e space for their Rider fridge).
 

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Discussion Starter #12
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Finally well enough to work outside after Lyme and antibiotics which made me hyper-sensitive to the sun.

COMPACTION = WEIGHT + WOBBLE + WATER

Ready for re-bar
 

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Discussion Starter #13
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Forgot to get photo of rebar. The cement finisher said he would drive his loaded gravel truck on it. Bit of overkill on my part maybe. Lol.

It will definitely stay put, if someone wants to add a storey and attach it to the house at a later time. Ten to twelve inches thick at the edges, then tapering, at about twelve inches in, to five or six inches deep inside.

Here is the finished pad. Ready for framing when I get back from holidays in a couple of weeks.

I poured some curbs and sidewalk blocks with the extra concrete. Visible upper right.

The forms for the sidewalk blocks are the correct depth for 300hz bass absorbers and I will use the material from the curb forms to make the sides of my 215hz absorbers. Lol. Lazy and cheap.
 

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Discussion Starter #14
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Finally able to start framing after lyme disease recovery and family vacations.

My suggestion for garage building: keep the windows and lighting on the sides where it does the most good for working on a vehicle.

For looks, the window size will also be the size of some staggered broadband absorbers on the long walls. I will staple burlap without vapour barrier in those spots, and simply cut rectangles out of the drywall. Moisture won't be a problem in a garage with no plumbing or round-the-clock occupancy. The windows will be stuffed with matching "cushions" filled with non-itchy polyester fill. Air conditioner in summer. Sound proofing not an issue in our tiny village.

Running up the centre of the back wall and across the ceiling will be the quadratic diffusion that I will be building from scrap lumber. More about that later.

The movable front wall (fake) will reduce the length to the proper Fibonacci dimension and will contain the two bass absorbers. Possibly more diffusion if it can be non-intrusive to the look and mobility of the wall. More about that later.

Having so much time off has given me the chance to research all the possible acoustic treatments. My level of anticipation borders on ridiculous...
 

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It looks like this is going to be a serious studio. Looking forward to watching the progress and seeing and hearing the final product.
 
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Just wondering, as you are already building one, why didn't you have space for a control room? That way your monitors are out of the recording room.
 

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There are advantages to the one room studio approach (as well as disadvantages).
 

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Discussion Starter #18
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Just wondering, as you are already building one, why didn't you have space for a control room? That way your monitors are out of the recording room.
Not a recording studio. Just a practise space with half-decent acoustics.

"Recording" will consist of a single microphone (or connected pair) into a reel-to-reel. Properly positioned with so-called "quick sound field" (I already have built my own version), this mic will simply record what is happening at one end of the room. For demo and archive only.

Lots of guys around with real recording facilities.

Also, control room treatment is much more demanding. Given that I hate recording, mixing, etc... don't wanna learn it.

Thanks for the interest in my project, guys. Makes it way more fun!
 

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Ahhh... was just curious about it since you are building it. I know what you mean about the recording/mixing aspect of it. I did the same thing originally in my basement, had a single stereo mic to record rehearsals. Later on I got a Tascam US-1641 so I can record each instrument/vocals individually.

Anyway, looking forward to see it when it's finished.
 

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you're doing a great job. I'm very impressed. I'd like to do something like this. I know that it's likely to be a bit personal, BUT the budgeting of something like this really interests me as I'm about to embark, (when time and money permit), on an adventure like this one beside my house only as a recording studio. 20' x 20' or so.

keep up the good work. I hope you're getting the final blood testing for the Lyme done properly in the top spot in the USA. it's known to hide inside cells over time. Just a thought as I'm doing bicom treatment to remove lyme and all the peripheral parasites that follow it along.

anyway awesome work.
 
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