Help with Treatment in Bedroom Control Room

[Matt C.]

Hi, I am hoping to get some help with acoustic treatments in my little basement control room. my guess is the answer will be "go make a bunch of bass traps with OC 703 and put them in the corners", but i wanted to get some explicit advice before i went ahead and did it. I'm amazed at the amount of expertise on this forum, and any help at all would be greatly appreciated!

i attached a layout (sorry it is so crude...) and pictures of the room below. the room is:
9'7" wide
9'1" long
6'9" high (mostly...)
along the north side of the room, (above the mixing board and monitors) the ceiling drops to two different levels (6'6" high on the right, and 5'7" on the left), which makes things a little weird.
walls are all gypsum, floor is carpet. nothing really fancy about the general construction of the room, pretty basic basement bedroom.

right now i have two 2'x4' absorber panels (made with 3" ultra touch cotton insulation) mounted against the rear wall. right now I'm concerned that they are not effective (they don't seem to make a noticeable difference in listening tests or my crude frequency analysis tests)

my budget is probably $200-250 max. i'm hoping for a relatively simple DIY solution.

my questions:

1. if i make more panel absorbers, should i stick with ultra touch cotton (cheaper and easy for me to get locally), or should i send away for some OC 703/705 instead? like i said, i'm concerned that the cotton traps i have now are not as effective as i need them to be, but maybe i'm wrong.

2. is this just a matter of making as many panel absorbers as possible and putting them in as many corners as i can? or is there some other option i should be looking at instead?

3. my monitors are very close (within a couple inches) to the front wall. is it worth putting 2" panel absorbers between them and the front wall?

4. if i'm going to put an absorber cloud on the ceiling, it should be placed about half way (horizontally) between the monitors and the listening position, correct?

5. i was thinking about putting "superchunks" in the two front wall corners, but i can only spare about 12" on each wall around the corner (making the corner chunks about 12"x12"x17" triangles). is this thick enough to be worth doing?

6. i've thought about rearranging the whole setup so the mixing board etc is up against the East wall instead of the north, however the room is close enough to square that i doubt it would make a difference acoustically. anyone think this might be worth doing?

thanks very much, any help or advice would be greatly appreciated!

[Matt C.]

one more thing: here is the result of my pretty crude attempt at measuring the frequency response of the control room. i played pink noise through the monitors and recorded with an Oktava 219 at the listening position (equilateral triangle with monitors). then i fed the recorded signal through Waves PAZ analyzer. not sure if i'm going about this testing the right way, but this is all i've got at the moment.

thanks for looking!

[Soundman2020]

If that really is your room response, then you have some major issues to deal with!

[full_bleed]

Is that an accurate method of testing a rooms freq response?

[Soundman2020]

Is that an accurate method of testing a rooms freq response?

If it is done correctly, then yes, it is one way of doing it.

But there isn't anywhere near enough resolution on that graph to be useful in the low end. That looks more like a 1/3 octave approximation of a rough outline of the room response, which is probably OK for the mids and highs, but not the lows. In the low end, you need much, much better accuracy than that.

Having said that, assuming that the graph really dos show the response of the room, even at 1/3 octave resolution it is clear that the room has major issues! When your lows are about a thousand times more powerful than your highs like that, then you have a problem! It needs major bass trapping to start with, without touching the highs, then perhaps some additional treatment for specific regions.

However, since the speakers are just resting on a thin shelf, at various distances from the walls and ceiling, the room is badly asymmetric, has strange shapes inside it (HVAC?), is rather small, has a very low ceiling, and is laid out sideways (instead of lengthways, which is the correct way to do it), I suspect that a lot of what you see on that graph might be related to all kinds of comb filtering from the walls, console and furniture (sue to the speaker positions), plus resonance from the shelf and other furniture, plus resonance from the room, plus modal issues with the room geometry itself, combined with the small size and low ceiling.

If that were my room, I'd turn it around to face the right way (speakers firing down the long axis, not across the short axis), get the room set up symmetrically, get the speakers off the shelf and onto some massive decoupled stands, replace the furniture with something more solid and massive (less likely to resonate), install tons of deep bass trapping in the corners (superchunks), treat the first reflection points, then measure again, more accurately to see where the remaining problems are. The way it is right now, I doubt you could do a decent mix in that room at all, and certainly not one that translates!

IMHO


- Stuart -

[Matt C.]

thanks for the input. your advice brings up a couple questions:

- because of the size of my desk, it will be hard to have my monitors on seperate stands on each side and still have them forming an equilateral triangle with my head - i would need to be near the back of the room, nowhere near close enough to reach the desk. is it a big deal if i don't form an equilateral triangle, and the monitors are about 75" apart, but my head is only about 55" from each? (having the speakers placed too wide?)

- is it important to have completely seperate monitor stands, or can i just buy those foam platforms that are supposed to absorb the vibration? are those effective at all?

- in researching superchunks for corners, it seems like they are usually made so that the front face of the triangle is either 24" or 36" wide. i might be able to do 24", but obviously my room is really small, so is it wrong to consider making slightly smaller superchunks?

- i'm up for making a bunch of fiberglass/ultratouch absorber panels. is that the main treatment option i should focus on, or is there another sort of abosrber i should consider making.

- if anyone has insight into whether rigid fiberglass is significantly more effective than ultratouch cotton, i'd love to hear it.

thanks again for any help! i did another frequency response test in the room today, this time using voxengo span as an analyzer. seemed to give a much more detailed picture of what is going on. i'll post it soon.

[cadesignr]

Don't have much time but heres what "'I'd" do.
1. Reverse your monitoring station to allow symetry in back wall and build bass trap in cavity as shown.
2. Build 4 Corner Traps using Ultratouc(I'll show you how to build these if you are interested.
3. Build 3 Broadband traps for Front, Cieling and Rear walls.
4. Build 2 sidewall absorbers.
5. Get rid of desk. Its basically a resonance generator with closed ends
Build simple mixer support as shown( I'll give details later)
6. Mount shelf under front absorber.
7. Paint(that blue looks old fashioned and cheap, at least to me.)
Materials(your cost is approx. $300. I'll give you list and cutting bill if you want.)
I'll provide lighting details later. Plus, there are a bunch of details that I had no time to address today.

Anyway...............heres the ideas.
With your existing colors, desk, etc. Note, I didn't have exact dimensions for what appears to be a Tascam M520...If you want me to proceed, please provide dimensions of mixer and monitors.





Now for a color change.



















Believe me, this stuff is EASY to build. And cheap. I'll show you how if you so desire.

Its late. Gotta go. Happy New Year!
fitZ

[cadesignr]

Oh, btw, Ultratouch is fine.

ABSORPTION COEFFICIENTS @ OCTAVE BAND FREQUENCIES (Hz)
R- in. (MM) 125 250 500 1,000 2,000 4,000 NRC / STC
R-13 3.5” 89 0.95 1.3 1.19 1.08 1.02 1.0 1.15 NRC

R-19 5.5” 140 0.97 1.37 1.23 1.05 1.0 1.01 1.15 NRC

[Matt C.]

wow! that is incredibly helpful! thank you so much for all the help. of course, i have more questions:

1. i am concerned about reversing the layout of the room like you suggest, for two reasons: one - the only place for other people to sit down in the studio would be directly under the super low ceiling/new bass trap, which would be awkward (but maybe workable), and two - i can't seal off the closet with a corner bass trap like you suggest, since that closet has to remain accessible (unless i can build an effective corner trap that is easily movable. my roommate uses that closet for storage). would it be feasible to do the same huge bass trap over the lowered ceiling like you suggest, but leave the mixing board etc in the same spot it is in now? do you think that massive amount of absorption would make up for the irregular shapes there?

2. is there a difference between "broadband traps" and "sidewall absorbers"?

3. regarding the shelf for monitors (and probably my computer monitor too), anything special i should do with this to decouple the speakers from it/the wall? is it worth buying those (auralex?) foam speaker pad things, or can i just use, say, a thick piece of rubber? should i mount the shelf in any special way?

4. i would love to see more detailed plans for both the superchunk corner traps and the simple mixer support (the tascam m520 is 43"wide x 33"deep x 10" at its highest). i get the general idea of both, but seeing the details would be much appreciated.

if it's helpful, my monitors are 16"h x 10"w x 13"d (although i will hopefully be replacing them soon anyway)

and again, thanks.

[xSpace]

Good looking room work Fitz.

What do you think about the shelf that support the speakers becoming a flanking path to the desk support?

Maybe cutting the speakers loose from the hard mounting to the wall would be the answer?

[Soundman2020]

- because of the size of my desk, it will be hard to have my monitors on seperate stands on each side and still have them forming an equilateral triangle with my head - i would need to be near the back of the room, nowhere near close enough to reach the desk. is it a big deal if i don't form an equilateral triangle, and the monitors are about 75" apart, but my head is only about 55" from each? (having the speakers placed too wide?)

Having the speakers far apart is not too much of an issue.: it will just widen your stereo image a bit, and squash the sweet spot slightly. Equilateral triangle is also not a huge issue, as long as you maintain good symmetry and your ears are equidistant from the speakers. The 60 degree axis intersect angle can go up to 90 degrees if you need to. The 38% mix position point is also just a starting point. It isn't written in stone. In a small room you really don't have much choice but to adjust the geometry. If you didn't adjust the geometry, you wouldn't be able to get where you need to go. "Compromise" is the name of the game, keeping your priorities in order. The way I see it, what you need first and foremost is room symmetry, then keeping your mix position and speaker positions out of "bad" places, then take care of mountings, treatment, and angles, then the rest of the details.

So I'd say get your room symmetrical first (at least the front half), then play around with the geometry of speaker / head locations to get it as good as you possibly can and as close as possible to the EBU recommendations, then figure out how to mount things in the best possible way, then figure out what type/where you need to put the treatment to go along with all of the above (first reflection points, clouds). Then, with the space you have left, worry about putting in the biggest possible bass traps you can. Then test the room properly, and based on that you can decide what further treatment might be needed.

Regarding the speaker mounts, they need to be massive, solid, and decoupled. The idea is that the speakers cannot directly transmit any of their own vibrations to anything else, so they need to be "decoupled" from everything else (by neoprene/rubber/foam/etc pads), and whatever it is they do rest on needs to be extremely heavy/massive so that it is very hard to make it vibrate (stone, rock, concrete, thick metal. thick wood, etc).

- is it important to have completely seperate monitor stands, or can i just buy those foam platforms that are supposed to absorb the vibration? are those effective at all?

Foam pads are good, but are only part of it. You also need something massive under the foam, that cannot vibrate. Those shelves can vibrate, even with pads. Like xSpace said, you need to decouple the speaker mounts (shelves, stands, whatever) from the walls/floor as much as possible, and also decouple the speakers from the stands. If you use a thin wooden shelf, even with foam pads it will only be an inch or so away from the speaker, so it will still pick up the low frequencies through/around the pads, and will "resonate" in sympathy at its own resonant frequencies: If the shelf is attached to the wall, it will also transmit those vibrations to the wall, and he wall will also vibrate in sympathy. The more dense/massive you make the speaker support, the lower those frequencies will be, and the intensity will also be reduved. If you look around, there are several designs on this forum for decoupled massive speaker stands. Maybe you can figure out how to adapt those to your room. You could even consider cutting holes or slots in your desk, so that the speaker stands can pass right through the desk, without touching it.

- in researching superchunks for corners, it seems like they are usually made so that the front face of the triangle is either 24" or 36" wide. i might be able to do 24", but obviously my room is really small, so is it wrong to consider making slightly smaller superchunks?

With a small room, you have to live with what you've got, so if 24" is all you can fit in, then that's what it will have to be. But if you can figure out how to make it wider / deeper, then go for it!

- if anyone has insight into whether rigid fiberglass is significantly more effective than ultratouch cotton, i'd love to hear it.

"Pink fluffy" fiberglass, 703 semi-rigid compressed fiberglass, mineral wool (rock wool), etc. All will work. Go for whatever is cheaper in your area. Look around on this forum for ideas on how to build your treatment, but I'd suggest that you start by only doing the bass traps and first reflection points, then measure and see how it is going before you decide on how to proceed from there.

- Stuart -

[cadesignr]

Hello guys. Just a quick reminder. "TWO HUNDRED DOLLARS"...COMPROMISE COMPROMISE COMPROMISE

I could go on and on with this design. I already had 12 hours and my wife was PISSED!!

Yea, I know EVERY BIT of the compromises..AND solutions. This is what I came up with in the time I had. But I WILL change some things. It was already 10 on New Years and my wife was really pissed at me.

Anyway, I'll be back. And one other thing. Thanks for the civility and compliment. I know I haven't been too civil myself...but what do you expect from an Irishman I'll do better from here out. Just understand...I'll be the first to admit..I AIN'T NO STINKIN EXPERT!!

But I DO try to help.

fitZ (sigh)

[Matt C.]

i can probably push the budget a bit past $200 if needed. i feel a lot better about spending money on fun DIY projects rather than expensive pre-made stuff.

from a practical/workflow standpoint (not an acoustical standpoint), it would work better to leave the gear in the same general position as it is now (obviously with a different desk, decent monitor stands etc.). do you think if i construct that huge bass trap across the front ceiling and cover that big irregular ceiling section with absorber panels, it would create a workable symmetry in that front section of the room, allowing me to leave the monitors roughly where they are? or am i dreaming? i'm not totally opposed to rearranging things, mainly i'm concerned about people bashing their heads on that section of really low ceiling if i move things.

for speaker stands, i like the design that's a section of sand-filled PVC pipe connected to squares of wood on top and bottom using toilet flanges. although if i get lazy, the stack of concrete blocks is cool too.

[Soundman2020]

from a practical/workflow standpoint (not an acoustical standpoint), it would work better to leave the gear in the same general position as it is now (obviously with a different desk, decent monitor stands etc.).

I'm not sure why you think it is better to stay as you are now. What I'm suggesting is to rotate your layout by 90 degrees, with the mixer and speakers against the wall on the right side of your diagram, marked "window". That would gain you several things:

1) Your speakers would be firing down the length of the room, instead of across the width, which is always a good idea.

2) It would be easy to get the front half of the room symmetrical, since you would not have that ugly cube-thing (HVAC?) causing all kinds of unacceptable issues. You'd only have a wall with a window in it. If you can't afford to cover the window now, you can do it later, but at least you'd have room symmetry.

3) It would free up the area under the "ugly cube-thing" for a bass trap. That would make a great area for a superchunk! Since you can't use that area for anything else anyway (as you say, people will bang their heads on it), then use it for acoustic treatment. Stack up as much insulation as you can underneath it.

4) It would put the door more or less right behind you, roughly in the middle of the rear wall. That's a good place for a door: it frees up the space on either side for bass traps. You have a closet on one side of that door, but you could easily build a "rolling superchunk" bass trap to go in front of it. Triangular base on wheels, OSB or MDF on two sides, fill it with rockwool, and bingo! Just wheel it out the way when you need access to the closet.

5) You'd be able to get better geometry for your speaker / mix position layout while keeping your head and the monitor out of bad locations.

6) Etc.

do you think if i construct that huge bass trap across the front ceiling and cover that big irregular ceiling section with absorber panels, it would create a workable symmetry in that front section of the room,

Aesthetic symmetry, but not acoustic symmetry. Just because you hide the "ugly cube-thing" behind cloth and make it invisible to your eyes, does not make it invisible to sound waves. In order to get symmetry without rotating your room, you'd have to build an exact replica of that "ugly cube-thing" and place it in the mirror image position, above your other speaker, so that they will both sound equally bad. Whatever the existing "ugly cube-thing" is made of, you'd have to try to duplicate that as close as possible for the other side. THEN you could fill in the gap between and use that as a bass trap, I guess, but I'm not sure how that would work out either! It would be pretty small, and right between the speakers.

mainly i'm concerned about people bashing their heads on that section of really low ceiling if i move things.

That wont be a problem if you build the superchunk underneath it, all the way down to the floor. If people can't get underneath it, then the can't bang their heads on it. Remember, we are talking about rotating your room only 90 degrees to the right, here! Not 180 degrees. That "ugly cube-thing" would then be at the BACK of the room, behind you.

for speaker stands, i like the design that's a section of sand-filled PVC pipe connected to squares of wood on top and bottom using toilet flanges. although if i get lazy, the stack of concrete blocks is cool too.

Both of those would work, and they are both cheap! You might even be able to pick up all the pieces to make them for free or real cheap at a construction site, or something. Over-orders, slightly damaged, off cuts, etc.

I like Fritz's idea of using a door for the work surface, but I think he made a mistake when he labeled it: that should be "solid core door", of course, not "hollow core". A hollow core would resonate badly, and probably not be able to take the weight of your console, but a solid core door won't resonate anywhere near as much, and would easily handle the weight. Once again, cheap and easy to find second-hand. Mount it far enough away from the wall that you can get your speaker stands behind it, or maybe cut slots in it for the stands to pass through.

Regarding your acoustic treatment, ultratouch might well do the trick, but depending on pricing in your area you might find that plain old ordinary fiberglass or mineral wool is cheaper, and that will work great too. You did say you can get the ultratouch cheap and easy, but look around: you might be able to get off-cuts or overstocks ore something of fiberglass or rockwool. There's a thread on here somewhere, currently in progress, where someone is getting a lot free and very cheap stuff, just by looking around. I don't recall what thread it was, but he's spent something like US$ 500 to do what he originally estimated would cost US$ 7,000! Look for that thread, and read through how he did it!

But I'd really, really start by rotating your room 90 degrees. I just don't see it as being acoustically workable right now, due the huge symmetry problem. I'd also suggest that you download SketchUp and start playing around with it, so you can play some "what if" games with the layout.

For the front wall, the basic treatment layout shown by Fritz should work fine. (It just needs adapting to the shorter wall, instead of the long wall). Hopefully your budget should extend to what he shows there: ceiling cloud and first reflection points, plus the corner superchunks, and something directly behind the speakers. You should really plug that window, too, if you can. (It could be a removable plug.)

Anyway, that's what I think I'd do.


- Stuart -

[Matt C.]

thanks for all the advice. i will plan on rotating the layout 90 degrees like you suggest. putting a huge bass trap under the ugly-cube-thing (yes, hvac) is a good idea. my (probably delusional) hope was that covering the ugly cube thing with absorber panels would help make it disappear acoustically. but i'm sure you're right that that wouldn't solve the problem. i'm really tempted to see if there's any way i can get rid of that cube thing all together by rerouting the hvac and redoing that corner of drywall, but that is, again, a delusional hope (and a huge project)

i like the idea of the rolling superchunk to put in the corner with the closer, that would definitely be workable.

i think for the new mixer support, i will just make it exactly the size of the mixer, put the computer monitor on a shelf directly above it (like the monitor shelf in the designs above) and place the speakers on stands on each side. it might be a little wider than an equilateral triangle but it should work fine, and will be more simple.

i think i just have to come to terms with the fact that i'm going to lose a lot of space in order to treat the room properly (not as much seating space for band members), but i can deal with that. i can always try to consolidate the gear layout to make more space.

thanks again, i really appreciate you guys talking me through my options here. i'm excited to get this figured out and start the project!