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Post by composerken on Mar 13, 2016 8:44:30 GMT
Hi Ethan and everyone at Audio Expert Forum, Newbie here - been doing a bit of research on treating a project studio. I've read through all of the Acoustics FAQ - to my estimation the most comprehensive guide on acoustic treatment I've found on the web yet! Wonderful stuff. In the next few months I am going to be embarking on a home studio for film composing. The room I will be setting up this studio in is on the smaller side, which has made the information available through your various sites invaluable so far! I would like to treat the room as best I can. I will be investing quite a bit of money into this project and although I can't exactly build a room with dimensions I'd like, budget is available to treat the room. The FAQ basically answered all of my initial questions, and I hope to continue documenting this journey as I go along and will post as I can. I do have a couple questions. The dimensions of this room are 99" H x 119" W x 143" L. In the FAQ you had mentioned: "The only time you might consider making a room entirely dead is when treating a small vocal booth or a very small studio or control room - smaller than, say, ten by ten feet. When a room is very small the reflections are too short to be useful and just make the room boxy sounding. In that case the best solution is to cover all of the surfaces entirely with absorbent material and, for a studio room, add any ambience electronically later."
Considering the dimensions of my room, with it's relatively low ceiling height, would you recommend covering as much as possible? (The ceiling is solid as well as walls) Also, I am slightly concerned about the window on the long wall near where I will be mixing from for first reflections - is this something that I will most likely need to cover?
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Thank you again for this wonderful forum!
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Post by Ethan Winer on Mar 13, 2016 17:23:38 GMT
You don't need to make this room totally dead, covered 100 percent with absorption. It's pretty small, but it's not that small! However, besides bass traps in as many corners as possible, plus reflection absorbers, you should treat most or all the rear wall behind you because that's so close to your head.
--Ethan
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Post by composerken on Mar 14, 2016 20:50:35 GMT
Great, thanks! In the next couple of weeks I'll be running before and after acoustic tests and I'll post my results as I get them.
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Post by composerken on Mar 17, 2016 5:49:42 GMT
I've been researching QRD diffusers to treat the back wall of this room. I would like to make them myself, and wanted to check some math. I determined that I will be using 3 panels that are 24 inches wide (to basically cover the back wall), each with 7 wells with a depth profile like the following: (from an RDQ calculator)  I basically just guessed with the number of wells and well widths by using the RealTraps dimensions as a starting point. Was that a good idea? How critical are tolerances of these measurements? If I'm a quarter of an inch off here or there, will the effect suffer substantially? |
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Post by Ethan Winer on Mar 17, 2016 17:30:18 GMT
If you used a QRD calculator then I have to assume the math is correct. I know of two good ones: QRDudeAcoustic CalculatorAs for tolerances, I honestly don't know for sure. I ASSume being off by 1/4 inch is not a good idea. I'd aim to keep things within 1/16th inch, which isn't really that difficult. --Ethan |
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Post by composerken on Apr 28, 2016 3:03:22 GMT
Hi, just wanted to post the initial test results using Room EQ Wizard for my room. The mic used was the Behringer ECM8000 through a Blue Sky 2.1 System One. These are the results with NO treatment (aside from a small floor rug covering about 1/4 floor behind the listening position). Wanted to get the forum's thoughts, if there were any.   I will be constructing bass traps and panels this week and next. Will post the after pictures as I go along. Also - I purchased your book, Ethan. It is such a clear and wonderfully written manual, thank you! I encourage everyone to buy a copy! |
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Post by Hexspa on Apr 28, 2016 3:17:44 GMT
composerken, that response curve looks averaged. Can you post the non-averaged one?
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Post by composerken on Apr 28, 2016 5:09:46 GMT
Hexspa Sure! By averaged you mean "smoothing", right? That first post was the response with 1/6 smoothing applied. Here are: 1/12 smoothing:  1/24 Smoothing:  1/48 Smoothing:  And no smoothing: 
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Post by Hexspa on Apr 28, 2016 8:23:58 GMT
Now THAT looks like a response graph! Good work. Your low end is almost within spec as it is and those high squiqqlies are due to comb filtering as a result of early reflections. Overall, though, your response is pretty flat. Your room seems to fall in line with the expected modes:  That deep null at 2.8k corresponds to about 4 3/4 inches. Maybe it's the stands your speaker is on or monitor. Your loudspeakers might not be in Ethan's article relating to directivity but many models have considerable side dispersion around 3k: realtraps.com/art_front-wall.htmI predict with some bass traps, RFZ panels and your QRDs behind you you'll be in for a treat. Have fun, -m |
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Post by Ethan Winer on Apr 28, 2016 17:20:44 GMT
I'll just add that I prefer to see two sets of graphs: One for 300 Hz and below with no smoothing, and the other from 300 Hz and above with 1/3 or 1/6 octave smoothing. Smoothing makes sense at higher frequencies because otherwise all the peaks and nulls (which aren't necessarily real) make the response too convoluted.
--Ethan
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Post by composerken on Apr 28, 2016 20:54:48 GMT
That deep null at 2.8k corresponds to about 4 3/4 inches. Maybe it's the stands your speaker is on or monitor. Your loudspeakers might not be in Ethan's article relating to directivity but many models have considerable side dispersion around 3k: realtraps.com/art_front-wall.htmI predict with some bass traps, RFZ panels and your QRDs behind you you'll be in for a treat. Thanks for taking the time to look at and interpret the responses! I'm curious how you're able to deduce what the 2.8K null comes from -- that's really cool to know. (esp. to the 1/4"!) Could it be that the monitors do indeed have considerable side dispersion and it's the window behind them? (I guess I could just throw the curtains up behind, run a sweep and see if there's a change!) Will report as the treatment comes in. |
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Post by Hexspa on Apr 28, 2016 21:51:54 GMT
Well, actually I was wrong. My current understanding is this: If your BOUNDARY is 1/4 wavelength away from your direct source and equidistant to your ears then, by the time the reflected sound gets to you, once it combines with the direct sound it'll be 180 degrees out of phase - thus creating a null. BUT if the boundary is 1/2 or double, then, by the time it reflects and hits your ears and combines with the direct sound it'll be in phase and constructively add to the sound like duplicating an audio track in your DAW. This could stand correction! So your boundary causing the node (if it's real as per Ethan) is 1.1 inch, 3.3 inch, 5.5 inch, 7.7 inch or some other quarter wavelength that isn't half or double. Maybe this article will help: arqen.com/acoustics-101/speaker-placement-boundary-interference/I use this chart a lot: www.phy.mtu.edu/~suits/notefreqs.html But besides, Ethan just schooled us and said that 1/3 or 1/6 octave smoothing IS appropriate for the >300Hz range. Half the time I'm on here making my best, semi-educated, guess and expecting to be corrected sooner or later; I'm here to learn by getting involved. And as per your speakers directivity, I don't remember seeing which model you're using but it wouldn't be unreasonable to expect they're not firing linearly into your ear canal at 3k. Here's Ethan's link again from where you can deduce this same fact: realtraps.com/art_front-wall.htmOr you can see if the polar pattern of your loudspeakers is available. Afaik it definitely is possible to predict nodes, etc using physical boundaries and their relation to wavelength. -m |
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Post by Ethan Winer on Apr 29, 2016 16:52:02 GMT
SBIR type peaks and nulls are shown here: Frequency-Distance CalculatorSo at 1/4 wavelength you get a null, at 1/2 wavelength a peak, then another null at 3/4, and so forth. --Ethan |
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Post by Hexspa on May 1, 2016 5:31:27 GMT
SBIR type peaks and nulls are shown here: Frequency-Distance CalculatorSo at 1/4 wavelength you get a null, at 1/2 wavelength a peak, then another null at 3/4, and so forth. --Ethan Might just be cheaper for me to get parallels or boot camp and a copy of windows than miss out on software or buy Mac-only stuff. |
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Post by composerken on May 24, 2016 7:43:22 GMT
Here's a progress/update on my listening room build. I've built all the acoustic panels, desk and monitor stands.  ![]()   The monitor stands adjust and hold both my Event 8 and Blue Sky System One speakers. Though the Blue Sky are my main speakers, it's nice to be able to switch between the two for reference.  The left wall posed a challenge, having a window directly in the first/early reflection area. So I built a hanging frame apparatus that runs along a track that I can keep it open when I'm not critically mixing.  I constructed the acoustic panels from recycled burlap and fence wood the house had left over. Not sure how much I should be concerned with the sides not being absorbent...they look really nice, anyway. I had a ton of Auralex foam left over from my apartment. I doubled the foam pieces, which ended up filling the panels just perfectly.  I moonlight as a woodworker, and I've wanted to make a desk for the longest time. Since I had a small-ish space, I wanted to maximize the listening area with a little feng class. This desk uses only joinery - no nails, no screws - just wooden pegs and counter weighting.   Top view  The QRD diffusor I built is a standard N7 panel, doubled. I used QRDude for the math. Great resource!  The back wall. Could still use a panel above the diffuser as well as to the left of it. Also, still not quite sure about the closet that is still exposed/open. Since the closet holds a lot of my art supplies (I'm a visual artist), I'm considering keeping it open with large, thick pieces of slotted felt hanging as a "door". Will update when that is in or I've figured out a different solution. Some graphs after treatment...if anyone wants to comment, let me know how I can improve things!:      |
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