New Studio (With Measurements)

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landocommando
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New Studio (With Measurements)

Postby landocommando » Sun, 2019-Sep-29, 00:55

Hey Everyone,

I've uploaded the MDAT files for my new studio. Anyone care to take a crack at what audio treatment I could use? It would be much appreciated! Thanks in advance.

-Landon
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Soundman2020
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Re: New Studio (With Measurements)

Postby Soundman2020 » Sun, 2019-Sep-29, 01:18

Hi there "landocommando", and Welcome to the forum! :) :thu:

I'm looking at your REW data now, and there's a lot that needs doing in your room! For example, you have some pretty big modal issues at around 43 Hz and 110 Hz, as well as a possible SBIR dip or floor bounce dip, and you also have some very strong reflections happening within the first few milliseconds: that suggests that you have reflective surfaces close to the speakers, or close to the mix position... or both.

However, you haven't really given us enough information to work with... Please post more details about your room, such as the dimensions (length, width, height), the locations of your speakers and mix position in the room, locations of other large objects, such sa the desk, chair, couch, etc.... and posting photos of the room would also help us understand it better, so we can offer better advice on treating it. The more info you provide, the easier it is for us to help you figure out what you need to do to make the room great.

Also, please check the rules for posting! app.php/rules It seems you missed something important there... :)

- Stuart -

landocommando
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Re: New Studio (With Measurements)

Postby landocommando » Tue, 2019-Oct-01, 16:37

Apologies for the delay, but I have read through the rules and have come back with more information and pictures.

Room Dimensions: 11.5' x 10' x 8' (With an additional space back left measuring: 3.5' x 2.75' x 8')

The front of the monitors are about a foot from the back wall and 2.5' from the side walls equidistant. There is a wooden desk, which holds my laptop and second monitor, located in front of the monitors which may cause some reflections (see attached pictures). There is also a 3' x 6' vinyl flooring which is laid onto a sheet of plywood to roll the chair around on (see attached pictures). Also a couch on the right side of the room against the right wall (see attached pictures). Let me know if there is anything else I can supply in terms of information, and thank you in advance for your help.

-Landon
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Re: New Studio (With Measurements)

Postby Soundman2020 » Thu, 2019-Oct-03, 11:25

Great! That makes it much easier. So, with dimensions of 11.5' x 10' x 8' , or 15' x 10' x 8', the actual results do not match the predicted results! That's strange... everything is off by a few Hertz from where it should be. For example, your first lengthwise axial mode shows up at 42.9 Hz, but according to the measurements, it should be at either 37.7 Hz (if we take the length as 15' 0"), or 49.1 Hz (if we take the length as 11' 6"). To be at 42.9, the room would need to be 13' 2" long. Likewise, your first width mode should be at 56.5 Hz, but it is actually appearing at 58.8 Hz, as though the room were only 9' 7" wide, instead of 10'. Your first height mode should be about 71 Hz, but you'll be in the null for that at half the room height, and there is a null around there, but its more like 76 Hz... which would be right for a ceiling at 7' 6"!

landocommando-REW--WF--12-500-LRS.png
So that's rather strange.... I'm not sure what the cause of the discrepancy is.... But anyway, clearly the largest initial problem that you have, is the lengthwise axial mode, at about 43 Hz. That's hard to treat, but it's a bit problem so it will need treating. The second largest issue is at around 108 Hz, which I'm assuming is your second width-wise axial mode.

Now, the good thing is that both of these problems are triggered by the sub AND ALSO by the mains, so it should be possible to reduce the intensity by careful placement and tuning of the sub. I would start by placing the sub up against the front wall, one quarter of the width of the room, turned sideways so the speaker cone faces the side wall furthest away, then try two tests like that: one with the sub phase switch set to 0°, and the other with the phase switch set to 180°, and see which of those produces the best results. Then try to tweak it a bit more by moving the sub left or right in small steps, just a couple of inches each time, to see if there's a better spot.

But before doing that, I would suggest that you improve the layout of the room, to make it symmetrical and properly balanced. The left half of the room must be a mirror image of the right half, but right now you have a large TV on one wall, and a couch on the other wall. I would change that, to put the TV on the front wall, between the speakers, and put the couch across the rear of the room, instead of up one side.

Also, your chair has a high back, and is rather "solid": it would be better to replace that with a low profile "open" chair, something like this:
CHAIR-open-mesh-back-2.jpg
. As you can see, it is open and "airy", and presents much less solid surface area to the room, so less effect acoustically.

In your case, I would also try placing the speakers a bit closer together, so that the middle of the front face is at 25% of the room width, to see if you can avoid triggering the second-order axials across the room, then place your chair so that your head will be about 49" from the front wall, and turn the speakers so they are both pointing at a spot about 16" behind your head (in other words, 65" from the front wall. Then set up the desk so that it is at a comfortable location in front of you. About the desk: see if you can find one that is lower profile, acoustically, with fewer flat surfaces, and less chunky. As small as possible, so that it does not affect the room acoustics too much.

With that arrangement, take everything else out of the room, and do the above procedure for locating and tuning the sub, testing with REW at each point, then post your results here again. If you can get those first two modes under better control, then it will be much easier to treat them room, acoustically.

- Stuart -
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landocommando
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Re: New Studio (With Measurements)

Postby landocommando » Sat, 2019-Oct-05, 00:19

I sincerely apologize, my measurements were incorrect. You were indeed correct about the length being 13' 2". I will make the necessary corrections and take some new measurements. I don't think I'll be able to move the TV or the couch, but I can make the rest of the corrections to make it as close to perfect as possible. Thank you in advance.

-Landon

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Soundman2020
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Re: New Studio (With Measurements)

Postby Soundman2020 » Sat, 2019-Oct-05, 03:28

No problem! It happens... simple mix up with the tape measure, I guess?

At least the mystery is solved, and we know why the measured results didn't match the predicted results! So all is good.

Please post the new results when you have them.

I just posted some instructions on how to do some additional testing in your room, of you feel like it. You might find it interesting: http://www.digistar.cl/Forum/viewtopic.php?f=9&t=24

- Stuart -

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Re: New Studio (With Measurements)

Postby landocommando » Sun, 2019-Oct-06, 21:54

I made the adjustments to the room! I tried the sub at the 25% width facing the opposite wall but I think the desk might be messing with the audio frequencies, so I moved it to the middle of the room against the wall facing to the back wall. I also lowered the speakers a bit so the tweeters are about the height of my ears when listening. I also moved the speakers closer together and pointed them 16 inches behind the listening position. Overall I think it sounds better, the curve still shows the axial modes but they have decreased slightly.
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Re: New Studio (With Measurements)

Postby Soundman2020 » Tue, 2019-Oct-08, 13:57

The levels seem to have changed between the initial "baseline" tests that you did, and this new set of tests. The new one are several dB quieter. It's hard to say exactly how much, since they aren't the same, due to all the changes you did, but it looks like about 3 or 4 dB difference. Its important that you keep the levels the same, always: if not, then it's hard to compare the graphs.

I tried the sub at the 25% width facing the opposite wall
I didn't see that measurement in the new REW file: Please post that one too. You don't need to do a full set of tests each time, for setting up the sub: just one single LRS test (Left speaker, Right speaker, and Sub all going at once).

but I think the desk might be messing with the audio frequencies,
It,s possible, yes, but probably only with mid and high frequencies, not much with lows. There's a basic principle in acoustics that objects can only have a significant effect on sound waves where the wavelength is smaller than the object. At 100 Hz, for example, the wavelength is 11 feet, so any object smaller than about 11 feet wide won't have much effect. At 225 Hz the wavelength is 5 feet, so assuming your desk is 5 feet wide, it could start having an significant effect on frequencies from 225 Hz up.

so I moved it to the middle of the room against the wall facing to the back wall.
A single sub should almost never go in the middle of a wall, as that means that it will trigger all second-order length-wise axial modes very strongly, since it is at the pressure peak location for all of them on the front wall. And since it is also at the center of the FLOOR, it will also trigger all second-order height-wise axial modes. You'll get a very strong modal response from having the speaker in the middle of the front wall. That's not a good location.

Please try the 25% locations again (both 25% left and also 25% right), and do REW tests like that. Also, at both of those points do a second test with the phase of the sub flipped to the opposite setting.

Locating the sub in the room is a slow process: it's not as simple as just trying a couple of places, then leaving it in one. The process STARTS with trying the 25% locations, with both normal phase (0°) and flipped phase (180°), then moving it in very small steps, just a couple of inches at a time, and testing in each location with REW, and keeping careful notes of where each test was done. Then you can compare all of those, to see which one is giving you the smoothest response in the TIME domain, as well as the frequency domain. It is similar to doing the "walking mic" test (see here: viewtopic.php?f=9&t=24 ), except that you are moving the sub, not the mic.

I also lowered the speakers a bit so the tweeters are about the height of my ears when listening.
That's probably a bit too low. It's not the tweeter that should be at ear-height (that's a common myth, unfortunately), but rather the acoustic axis of the speaker. Some manufacturers state the location of the acoustic axis in their manuals, others just publish it on their website, and others don't bother. If you don't know where it is for your speaker, then image a line that joins the middle of the woofer to the middle of the tweeter: the acoustic axis will be half way along that line. That's the point that should be at ear height, or slightly above. The "standard" height for speakers in studios is to have the acoustic axis 120cm above the floor, which is 47 1/4". However, it is also common to raise the speaker a little higher than that, maybe an inch or two, maximum (3-5cm), for more complex acoustic reasons.

I also moved the speakers closer together and pointed them 16 inches behind the listening position.
You can do a similar procedure as above for finding the best location for the speakers, in terms of separation: start with them very close together, then do a REW test like that, then move each speaker 1" out (in other words, increase the distance between them by 2", since each speaker moves 1") and to another REW test like that. Then keep on moving them in 2" increments, until they are nearly against the side walls. Then look at all the tests, and find the location that has the smoothest time-domain response while also having good frequency response. in this case, you need to do the L-S and the R-S and the LRS test at each location, assuming that you already have the sub positioned in the best spot, or if not, then do L, R, and LR tests.

Getting the speaker and mix position layout optimized is a long, slow, tedious process. It takes time: not something that you can do in a few minutes with just a couple of moves. When you look at the animated graphs in the "Walking Mic" thread (see link above), you can really see that even small changes in position of the sub, main speakers, or listening position can show large differences.

- Stuart -

landocommando
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Re: New Studio (With Measurements)

Postby landocommando » Sat, 2019-Oct-12, 20:27

So I took all the measurements you requested. I've attached them here along with descriptions in REW. It seems like the right side facing left is the best bet for my room currently. Let me know if you feel differently/if there is anything else you need from me. Thanks in advance.

-Landon
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