Room is gonna kill me and my sweet spot

[David17]

Ok here we go again. I am in a 13.5 x 11.3 room with an 9 foot ceiling. I upped the carpet and went with a floating wood floor.Speakers are isolated from the floor with foam and rubber steel feet. I then added 5# 2x4 ceiling traps and 2# extra 6" bass traps on the front wall thinking this would tighten up my sweet spot. Also side walls are treated equally on both sides. Amost 2/3 of room is treated up front. Now I did build a diffuser that I put on back center wall which reflects too much in the room since it is only 7ft from my chair to back wall. Bummer.
So I am thinking about adding 2 bass traps on center of back wall. I had 4 on the back wall not including corner traps but my ears were so sucked out and fatigued they had to go.
My speakers currently sound a bit mid bass heavy. And honky on some bass notes. Does adding 2 traps on the center wall sound correct. This room is gonna kill me!!
Thank you
Sidenote. I am also using jbl 305 speakers with rear bass port so I didn't know if this could pose a problem if I have to move closer to wall.

[Soundman2020]

I upped the carpet and went with a floating wood floor

Do you mean "floating floor" in the acoustic sense? (New concrete slab poured over decoupled pad, acoustic isolation springs...). Or do you mean laminate flooring, sometimes very incorrectly called "floating floor" by manufacturers who don't have a clue about what a real floating floor is? I hope it's the latter, not the former...!

Speakers are isolated from the floor with foam and rubber steel feet.

Are they set up in the correct geometric layout for that room? Are the stands massively heavy?

extra 6" bass traps on the front wall

6" is not a bass trap: That's just a broadband absorber that goes down to the low mid range. In fact, I don't see any bass traps at all in your room. At least, I can't see anything big enough to be a bass trap in the photos, but maybe the photos don't show all of the room.

Also side walls are treated equally on both sides. Amost 2/3 of room is treated up front.

Why? I mean, why are you killing the front of the room, when it should be kept mostly live, and why are you not treating the back of the room, where all your problems will be? The treatment plan seems to be flipped around backwards here...

Now I did build a diffuser that I put on back center wall which reflects too much in the room since it is only 7ft from my chair to back wall.

Right. Not surprising. The room is too small to be able to use most forms of diffusion.

So I am thinking about adding 2 bass traps on center of back wall. I had 4 on the back wall not including corner traps but my ears were so sucked out and fatigued they had to go.

Then you did not build them correctly. It's that simple. Without proper bass trapping on the rear wall, that room will never sound acceptable. The rear wall is pretty much always the source of the majority of big problems in any small room. Untreated, the room won't work.

My speakers currently sound a bit mid bass heavy. And honky on some bass notes.

Right. Not surprising. That's because you have no bass traps in the room.

Does adding 2 traps on the center wall sound correct.

Nope!

I am also using jbl 305 speakers with rear bass port so I didn't know if this could pose a problem if I have to move closer to wall.

How could you possibly move them closer to the wall? If you have the room set up correctly, then there rear of each speaker is only 4" from the front wall, and there's 4" of OC-703 in that gap. It is physically impossible to get them closer to the front wall...

And to answer your question: No, the rear ports are not the problem here. The problem is the lack of bass trapping.

I would suggest that the best course of action here is to take out all of the treatment, furniture, and general clutter, leaving only the speakers, the desk, and the chair. Then set up those correctly, with the right geometric layout for that room, and run a test using REW. Upload the MDAT file from that test to a file sharing service, such as DropBox, then post the link here so I can download it and analyze it, then give you some pointers on how to start treating the room. But the room must be completely bare for this test: nothing at all in it. Just the speakers on their stands, the desk, and your chair.

- Stuart -

[David17]

Sorry for two posts. It has been a hellacious couple of weeks with this room and projects waiting to kill me. I have stands at 4" with 4 inch absorbers behind.
Stands are super heavy filled with sand setup triangle correct. Floor is wood laminate on concrete.
My 6" bass traps are actually 15 " fiberglass. The front is covered and lfet to hang over like a huge pillow.
I have superchunks in corners. 22 inches for depth. These reach ceiling.
Can you suggest a better bass trap? I found these as dYI online like most. I really liked Ethan Weiner's Traps with the wood cover on them.
I will get a room run for you Stuart.
Thank you for all your expertise!!
David

[Soundman2020]

My 6" bass traps are actually 15 " fiberglass.

I don't understand: How can they be both 6" and also 15"? Are you saying that you compressed 15" thickness of insulation down to 6"? Is that it?

setup triangle correct.

Please describe that triangle: What are the following distances:

- Distance from each speaker to closest side wall (measured from acoustic axis of speaker to wall face)
- Distance between speakers (measured from acoustic axis of one speaker to acoustic axis of the other speaker)
- Distance from speaker to head (measured from acoustic axis of speaker to center of head location)
- Height of speaker (measured from acoustic axis of speaker to floor surface)
- Distance from rear corner of speaker to front wall (closest distance)
- Distance from front wall to center of head location.

I have superchunks in corners. 22 inches for depth

What is inside them? What insulation did you use, and how did you place it within the traps?

I really liked Ethan Weiner's Traps with the wood cover on them.

Those are probably panel traps. No use for your room. Do you have a link to the exact product? Ethan makes quite a few different products...

I will get a room run for you Stuart.

Make sure you fully calibrate REW correctly before you do that! Especially with regard to setting the levels. Calibrate at 80 dBC for each individual speaker, so you will automatically see 86 dBC with both running. Run three tests: one with just the left speaker, one with just the right speaker, and one with both. Label then correctly. Do not change any settings between tests, after you calibrate.

- Stuart -

[David17]

Are you saying that you compressed 15" thickness of insulation down to 6"? Is that it?

Yes. I should not compress the fiberglass right?

- Distance from each speaker to closest side wall

45 1/2 "

- Distance between speakers

44 3/4"

- Distance from speaker to head

44 3/4"

- Height of speaker

46 1/2"

- Distance from rear corner of speaker to front wall

23" I did have 4" of absorber on front wall and speakers butted up to this. Sounds was worse thus the move out.

- Distance from front wall to center of head location.

61 1/2"

What is inside them? What insulation did you use, and how did you place it within the traps?

Safe and sound cut to triangles. I built a frame that is a triangle with simple 2x2 wood. This measures 8 ft tall.

Those are probably panel traps.

Yes

Make sure you fully calibrate REW correctly before you do that! Especially with regard to setting the levels. Calibrate at 80 dBC for each individual speaker, so you will automatically see 86 dBC with both running. Run three tests: one with just the left speaker, one with just the right speaker, and one with both. Label then correctly. Do not change any settings between tests, after you calibrate.

I will give.

- Stuart -[/quote]

[Soundman2020]

Yes. I should not compress the fiberglass right?

Right! No wonder they are not working as bass traps! The density is way too high to be much good for bass trapping, and the impedance mismatch at the boundary is probably reflecting most of the highs and mids.... You'll have to take those apart, throw away the insulation, buy proper, new stuff, and use that. Once we find out what the problems are, we can decide on what the best insulation will be to deal with them.

- Distance from each speaker to closest side wall
45 1/2 "

- Distance between speakers
44 3/4"

- Distance from speaker to head
44 3/4"

That's what I feared: So your speakers are not set up correctly...

- Height of speaker
46 1/2"

Ditto.

Notice something? The distances are practically all the same! 45".... So you will have a major dips and peaks in the frequency response, associated with roughly 75 Hz, 150 Hz, 225 Hz, 300 Hz, 375 Hz etc.

- Distance from rear corner of speaker to front wall
23"

Ditto.... and you therefore have large dip in your low end response at roughly 130 to 150 Hz. That's the first SBIR cancellation frequency. And you therefor also have the comb filtering associated with that artifact, going all the way up the spectrum....

And notice that your distance here is perfectly related to the other distances: it is almost exactly half of the wall/speaker, speaker/speaker, floor/speaker distances.... You have set up the perfect storm for low frequency mush!

I did have 4" of absorber on front wall and speakers butted up to this. Sounds was worse thus the move out.

The reason it was "worse" is because the layout was not correct, and the rest of the room treatment was not correct.

- Distance from front wall to center of head location.
61 1/2"

But the room is 13'5" long?

Those are probably panel traps.

Yes

No use for your room.


- Stuart -

[David17]

I see that now on the speakers. I did have the triangle at speakers 3 ft apart and myself of course 3 feet and 4 inch of absorber on wall then speaker butted up to it. I cleared out the room and will run a test now.
David

[David17]

I have test for you at dropbox but I need an email to invite you.

[Soundman2020]

I did have the triangle at speakers 3 ft apart and myself of course 3 feet ....

That's actually a myth.... You do NOT need to have your speakers the same distance apart that they are from your head. Yes, you DO have to have them both the same distance from your head, but it is not necessary that the distance between them must also be the same.

Yes, you do see that myth repeated all over the place, everywhere, even in text books, and there's a good reason for it: it makes setup simple, and works reasonably well for most cases. But it is not written in stone! You will not get arrest by the "Speaker Triangle Police" if you set up your speakers differently! In the vast majority of rooms, it is entirely probable that there is a better layout. Although that famous "equilateral triangle" might work OK, it won't be optimal. In your case, for example, that forces you to set things up equidistant from the walls, floor, ceiling, and front wall, which is bad all around. So forget that. We'll do some stuff next time to find the correct geometry for your room.

I have test for you at dropbox but I need an email to invite you.

Just make that file public, and post the link here so anyone else who is interested can download it.

- Stuart -

[David17]

WOW. I did not know this. Ok will do.
here ya go:
https://www.dropbox.com/sh/s64oy8616644 ... Tnp2a?dl=0

[Soundman2020]

There are four files at that dropbox location, but the seem to contain duplicate data. "Leftmds" appears to contain two tests, which are duplicates of "left" and "right". "rightmds" contains a duplicate of "right". Very confusing!

For anybody else following this thread, you do NOT need to download all of them. Just get "left.mdat" and "right.mdat". There's no point to getting the others.

Anyway, first conclusion: the room is almost empty! That's good. The overall decay time is nearly 600 ms. However, it does not seem to be completely empty. There still seems to be something that is absorbing high frequencies, and some low mids. Are you SURE you took absolutely everything out of that room?

Second, you did not calibrate at 80 dB. You calibrated at 70 dB. So for next time, you'll need to re-calibrate and run the tests at 80.

Third, most of the modal activity is clear, but because the test was done 10 dB too low, there are likely several modes that were not triggered. Also, the room appears to not be very well isolated, as there's quite a bit of background noise. Your noise floor is around 40 dBC, which is pretty high for a studio. You probably wont be able to do accurate treatment and room tuning, because it isn't possible to measure accurately, as there's too much background noise.

Forth, there's too little energy in the low end. It's almost as if you have the bass-roll off activated on your speakers. The level below about 200 Hz rolls off by about 6 dB. If you have adjusted the settings on your speakers, then please set them back to flat response for the next test.

Fifth, there's something asymmetrical about the speaker response. They are not the same. It might be the speakers themselves, or it might be that they are not set up identically in the room, or it might be that the room itself is not symmetrical, but something is causing a lack of symmetry. It's not huge, but it is noticeable.

So lets' deal with the above issues first, then set up the speakers in the best theoretical locations, and see what happens from there!


- Stuart -

[David17]

The room does have a weird alignment. When we measure out the speakers from the front wall, it looks like the speakers are not 100% equally placed in the room by about 3 or 4 inches. It is weird. Noticed while laying floor tile come to think of it.

Sorry about the dropbox. I deleted the other two files so no confusion.

No bass roll off on the speakers. Never messed with this.

The only thing left is big leather couch on back wall that we need four people to move and only had 2 : )
Computer and small glass table for keyboard/mouse.

The right side of room has the french doors with no treatment on them now?

The Dr's diagnosis here is sounding like I have a very bad room. Don't tell the wife. It has so many holes in the wall it looks like termites moved in.

[David17]

I have to throw this out there Stuart and all.
My window is 64" wide by 70" tall and sits offset from wall. Then the french doors are almost all glass. Thus I only really have 2 full walls and 2 smaller walls due to the french doors and the big window.
I know everyone says from alot I have read it is a no no to reverse my room since you can use the full wall to put traps on but can you shoot the speakers at the glass after it is covered with curtains for the high bounce back? I ponder this still because the glass lets bass travel through? I have recorded in some pretty odd studios with great results on transfering to other playback devices. I also did get the speakers better centered so the numbers are not so conflicting. Ears are open and ready to complete this room DR Stuart.. : )

[Ethan Winer]

So I am thinking about adding 2 bass traps on center of back wall. I had 4 on the back wall not including corner traps but my ears were so sucked out and fatigued they had to go.

I got your email. I don't visit the forums any more because I'm very busy, and I don't do consulting by email for free. But I'm glad to offer a little here, though you're already getting plenty of advice.

The rear wall behind you is perhaps the single most important place to treat. Reflections from the well behind are strong, and early (in your small room), and the harm all frequencies down to DC. If you did to the rear what you did in the front you'd be on the right track. I don't know what "sucked out and fatigued" means, but REW measurements will tell you everything that matters.

--Ethan

[David17]

Thank you for your input Ethan and I truly appreciate your time as well as Stuart on this. I hope I can give back in the form of helping others as well as maybe a few traps being purchased ; )