Room test results. What should I do to fix my CR room?

[Skai_Penalva]

Hi everyone!

I just did some tests to measure my room's response and wanted to share it with you and maybe get some guidance

My room has simmetrically splayed side walls with an angle of 12 degrees, the front corners, where the soffits are, are angled at 30 degrees . Rear wall is flat and ceiling is flat. I also have a small diamond-shaped recording booth on the rear right corner. The rear left corner is a regular corner (45 degrees) because there is a door to a bathroom there.

My main problem, I think, is my soffit construction. I soffit mounted a pair of Adam A7's but didn't leave them flush to the front wall, but I did a regular rectangular box which left grooves at the top corners given to the a7s' design. I currently constructed a new wall incorporating the grooves, so the monitor will now be flush against the wall, but given to the +6dB low shelf nearfields experience when soffit mounted, I don't know if I should use the Room EQ knob on the back of the A7 and roll off 150Hz by -6dB, or boost a high shelf of 6k by +6dB, or just push up the volume in the tweeter.


What should I do?

If you see anything else wrong with my room design that might also be causing these results please let me knoe. Thanks guys!

[Soundman2020]

That graph cannot possibly be correct! 154 dB SPL @ 200 Hz? From an A7? I don't think so!!!!

That 157 dB SPL (peak) would have shattered the glass in your windows, and would have practically torn the sheetrock right off the studs! Your whole body would have been in intense pain while you were taking the measurement, and you would now have severe permanent hearing damage (not to mention probable internal organ damage).

That's about the same level you'd measure if you stuck a sound level meter inside the tailpipe of an F-16 at full takeoff thrust with the afterburner on!

Something is just a tad wrong with your measurement. . .

How did you produce that graph?

[Soundman2020]

BTW, yes, you do need to roll off the bass on the A7 if you soffit mount it.

[Skai_Penalva]

LOL!!! i guess something MUST be WAAAYYY off then!! I used a demo of Fuzz Measure, and a Behringer ECM8000 at my listening position to run the test. All I did was place the mic and clicked on the button to run the test. This is the software that Ethan recommended, and mic too for the budget! I'll try the same thing with a friend's computer who owns the ARC software... Maybe that will bring REAL results haha.

The soffit mount DOES add low end.... but not that much i guess... or else I'd be writing this from the other side.

Should I roll off the whole -6dB? Is 150Hz a healthy freq. to shelf off? Seems like a lot of bass and low mid attenuation... but I will give it a try and share my pre and post results.

[Skai_Penalva]

I changed the display type in the software and selected Magnitude which just displays the units as dB's and it seems to peak at around 59 dB's at +/- 210Hz. Does that sound right? The monitors were kind of loud, set at -18dB on the volume knob. Here's the pic.


BTW, Soundman, are you from Chile or just live there? I'm from Honduras haha.

[Soundman2020]

I'm originally from Australia, but I've been living in Chile for over 20 years now, so I'm "casi tan chileno como los porotos!" (Chilean saying).

Anyway, you do seem to have problems with your room if that graph is accurate! You have a 36 dB difference between the lowest dip at around 10 KHz. and your maximum peak at around 200 Hz. You even have a 10 dB difference between 10 kHz and 11 kHz, and another 14 dB between 100 Hz and 150 Hz, plus what might be comb filtering going on in the lows and low-mids.

You are going to need to do a lot more than just roll of the bass response of the speakers by 6 dB!

What kind of treatment do you already have in your room? It looks like you need massive bass trapping and also plenty of reflective / diffusive surfaces to keep your highs.

Could you post your SketchUp model of the room, and a few photos, so we can see what it looks like? Also describe it in detail: What is the floor / walls / ceiling made of, furniture, angles, etc.

Also, how did you set up your test measurement? Position of speaker / mic, settings on the software, test signal used, etc. I'm not familiar with that software, but if Ethan recommended it then it must be decent. Maybe he can interpret your graph for you.

[WayneD]

I think we need to know how the room is constructed. That dip at 150 could be the walls not being built correctly. I had the same problem in the room I just closed. The walls were single GB on metal studs and not secured to the studs very well to boot. More info please Skai.

W

[Skai_Penalva]

Thanx for the replies, guys!

Here is what I got, sorry for not posting it all earlier.

The front and left outer walls are made of brick (pre-existant) and the rear and right wall are made of concrete block 8''. It measures, from inside wall to inside wall,
W 12'11" x L 19'4". The inner walls are a single sheetrock layer with a wooden 2x2 studs frame. In between the sheet rock and concrete and brick walls is R-11 Fiberglass. Not rigid, but the soft type that comes in rolls.

The floor is a concrete slab, but there is a layer of linoleum flooring (fake hardwood) that's just there for decoration really since concrete looks nasty. The ceiling is 8'5" and is parallel with the floor. It's also a concrete slab supported by steel beams. It has wooden 1/2 inch slats screwed on the steel beams that support a sheetrock ceiling. I also placed R-11 fiberglass in between the concrete and the sheetrock in the ceiling.

I placed a cloud above the listening position, which the workers didn't place very symmetrically, it is more to the right then in the middle. They built it with wooden 2x2 studs and used sheetrock for the side walls of it. It's 6 inches deep. Put the same type of fiberglass in it and covered it with black dacron fabric. They left a stud in the center which is where they placed the lights for the front of the room.

Both side walls and front wall have a 2x2 wood stud frame in the front where I also placed fiberglass and covered it with black fabric as well. It covers the majority of the area of the side walls and front wall. I plan to use those frames as slat resonators.

On the right side I have a sofa, regular black fabric with a kind of felt cover. On the left side I have 3 half stack amplifiers, 2 guitar and one bass.

My desk is W 6'6" x L 3'1". It's made with a metal 1/4" inch frame and just a board of plywood that has a glossy finish.

My 3 doors (main, bathroom and booth) are plywood doors filled with fiberglass.

I conducted the test placing a ECM8000 Behringer Omnidirectional Small Diaphragm Condenser Microphone facing straight up towards the ceiling right on my listening position which is 38% of my room length in the front of the room. I used the preamp on my M-Audio 1814 which was modified by Black Lion Audio. I didn't even boost up the gain at all. Just left it all the way down. I used Fuzz Measure for Mac. The software played a Sine Wave Signal sweep of every frequency from 20 Hz to 20 kHz that lasted 10 seconds. It then processed the recorded signal and came up with that result.

There is nothing else I can think of that might help. Here are a few pictures. Here is also a picture of the inside my soffit walls now that I've teared the walls down. The desk is obviously out of place since I needed the room to remove the soffit walls. I am also including a picture of the new soffit wall.

[Skai_Penalva]

I couldn't upload the Sketchup file, I'll try it later on. The soffit walls are at a 30 degree angle each, the side walls are splayed at 14 degrees. The booth is a diamond shaped pentagon. The rear wall is flat and the center front wall which is 4ft long is partially parallel with the rear wall (which is mostly the 2 doors, bathroom and front).

The design is a basic RFZ room. I'll try to upload better pics later tonight. Thanx for the help!

[Skai_Penalva]

OK, this is an earlier post I did. The design didn't end up being the same, but the only differences are the first splayed side walls on the front are now very short but splayed at a wider angle. Also the rear left corner is not a regular 45 degree corner since we had to leave a door for the bathroom. Besides that it's the same design. I hope it helps!

http://www.johnlsayers.com/phpBB2/viewt ... f=1&t=9686


OK, here I did a quick mock up of my studio's design. I tried to do all of the sheetrock walls, but don't have enough time right now so the black lines stand for the sheetrock walls.

[WayneD]

Skai, thanks for posting more info. You said you used 2x2's. That is a very small size of wood not normally used, from my observations on this forum, to build solid Mass walls. Plus, you used a single layer of drywall (GB).

Mass is one of the most important foundational factors in building a good room. Others will most likely chime in on this too. It is early here for me and I am pressed for time, but reading Rod Gervais' book "Home Recording Studio-Build I Like The Pros" (in case you haven't) will describe the Mass Air Mass system and other structural topics. Also, check out any of the builds In the "Other Studios" section of the forum to gain more insight. I believe your problem is solvable. And yes, you have the same wall type as I had in the studio I just closed.

W

[Skai_Penalva]

So basically my solution is tearing down and rebuilding the whole room with better materials? What other options do I have to treat my current room? I can't afford closing down for so long I have many clients currently. If it comes down to that I will do it, but is there a temporary solution?

[WayneD]

Skai, maybe more research would be in order before stopping your cash flow. Look at what others have built and formulate a new plan. Then, allocate a period of time you will be closed to do your repairs. Maybe you can work in another room, temporarily, or work out something with another studio until your repairs are complete. The guys on this forum will always tell you MASS is the key to controlling sound. But you have to do it correctly. I do not believe there is a quick fix. There usually isn't.

W

[WayneD]

Skai, looking back over the drawings you submitted, your room is not symmetrical either. You have that odd shape in the rear of your room. Also, I believe that 14 degrees is to much splay in your side walls.
Please take the advice I listed above and research. The mantra is; 90% design and 10% construction my friend.

W

[lilith_envy]

The vocal booth is just not in a good place. there will be no way for you to get a clear stereo image or stop the comb filtering that is occuring in your room.
Can you move the booth to another room?
Can you use the whole back part as the booth so that your room is symmetrical?