very small room - mixes translate a loss in high frequencies

[axemanchris]

I'm in Hamilton, Ontario, Canada (near Toronto).

I just finished building my room - well, nearly done. You'll see from the pics that I still have to attach the bifold doors on the closets, and the actual swing door to enter the room. Other than that... I'm just looking for room treatment options.

I mixed something today (Yorkville YSM-1 monitors) and the mix sounded good in the room. Put it on in the car and a good deal of my high end disappeared - it was a generally muddy mix lacking in presence.

My room is 8' by 9'6" by 6'10".

My monitors are placed pretty symmetrical in the room. My mix position generally follows the 38% rule.

photo.JPG

You can see here the doorway entering the room (NE corner) and the side of the one closet. The wall that the door and the closets are along are 2x4 construction with 1/2" drywall, with Roxul Safe and Sound in between. I make no pretense towards "soundproofing" but wanted to deaden it somewhat to noise passing through the walls. You can also see in the picture that the ceiling drops down (about a 45 degree angle) towards the door to allow for the support beam.

photo (1).JPG

^ Here are the two closets that go along the North wall, which is 9'6". Also 2x4 construction with 1/2" drywall. No Roxul between the studio and the closets but Roxul around and behind the closets.

photo (2).JPG

^ This is the West wall. It shows the contour of the ceiling a bit better, and a bulkhead hiding some duct work. The corner build hides the water meter and there is a built-in shelf (IKEA wood) to better utilize some of the space. The corner sticks out into the room 18 inches, and is 25" across the front. This means that the brick wall there (South wall) is actually 8' in that direction too, but it is only about 1/4 of the 8' width of the room, so I am counting the length as 9'6".

photo (3).JPG

^ Here you can see the rest of the South wall on the right. It is partly brick from the corner by the built-in shelf (which you can see in the picture above this one, but not in this one), but is made of wood, behind which is the fruit cellar. The East wall (directly behind the monitors) is concrete block with Owens Corning rigid foam insulation, furring strips, a vapour barrier, and 1/2" drywall.

The ceiling is also 1/2" drywall attached to 2x8" ceiling joists. I put Roxul Safe and Sound up there too, between the joists, and put it up against the floor of the upstairs. I did not let it hang so as to make contact with the drywall, so there would be a cavity there of... maybe3 inches or so.

FWIW, the room dimensions are almost exactly the ratio of 1.00:1.14:1.39 as indicated in this site here: http://www.acoustic.ua/forms/rr.en.html - the very first L. W. Sepmeyer, 1965 one.

In fact, they are 1.00:1.17:1.39 (not counting the angled ceiling where it drops, and not counting the shelf/water meter build-out in the corner.

I should add, too, that I have an area rug covering the concrete floor that is about 5x6, and the concrete floor itself slopes downwards towards the door slightly (about 3" over the 9.5' length of the room). The 6'10" measurement I took for the height was at the midway point in the room.

I know I need to look into some absorption diffusers (is that the right term?) to control reflections on either side of the monitors, and quite probably behind me as well.

My reading says that any very small room will have a significant need for bass traps (broadband). (but wouldn't that suggest that there is too much bass in the room, causing my mixes to lack bass, and therefore have the opposite problem??). A concern I have is that, in the interest of the little space I have, I don't have much room in my corners. There is the door, the shelf/water-meter, and the closet door in three of the four vertical corners. Horizontal corners are mostly okay, except I only have about 4" above that one closet along the North wall.

Any help would be very appreciated! Thanks!

Chris

Edit: I did notice this while I was mixing... I was mixing quite loud (I could get a rough SPL on this if need be). When I turned the volume down, I noticed less high end. I have not experienced that before with these monitors, so would that be a function of the room also? Or just the whole Fletcher Munson thing (right terminology?) where the louder something is, the more bass and treble you tend to hear?

[Eric Best]

You do need bass traps. Bass traps even out the bass. If you don't have rooms in the corners, the corners between the walls and ceiling are the way to go.

For reflections in a room that small you want absorption to deal with your reflections. Use some of the Roxul in frames covered by fabric and hang them at reflection points on the wall and ceiling.

Don't mix so loud. There is this thing called the "Fletcher, Munson Effect." The louder you listen to music, the better you hear the highs and the lows. Typically if you mix to loud, you tend to roll off the high end.

[axemanchris]

Thanks, Eric!

As I continue to read, your words here fit exactly with what I have been gathering.

For bass traps: a common design is the superchunk using triangular corners stacked up and glued together, but they seem to be 24" or so across.

Or would I be better off building panels and hanging them at roughly 45 degrees in front of the corners?

Whichever design I go with, can they be narrower... like... 18, or even 12" across? I'm guessing "the bigger the better", but once they're small enough, there is surely not much point. I imagine one 6" across wouldn't do anything.

I'll really need to figure out how big to make them and where to put them. (and from there, that would dictate how many....) I've been reading that vertical traps are more effective than horizontal.

Is it safe to say that more will generally be better, and that I should put them anywhere I can - whether they be horizontal or vertical in whatever combination?

If I have more traps on one side of the room, will it affect the stereo image? (thinking, I have lots of horizontal room along the south wall, but hardly any along the north wall)

And what about any corners where wall-meets-wall-meets-ceiling (triaxis, I guess you'd call it?)

Onto diffusers to control reflections between the monitors and the listening position. I'm thinking I'll need one on each wall on either side of the monitors and one on the ceiling. Probably one or two at the back of the room wouldn't go amiss either, I guess.

Same kinds of questions, though.... the DIY panels are 2' x 4'. What if I made one 18" x 4'? What if I made one 12" x 3'? Auralex has the "wedgies" that are only 1' x 1'. Are they big enough? At what point do they become pointless? Would my own DIY panels made 1' x 1' perform similarly?

Sorry for all my questions!

In other news... I think I've figured out why my mixes are bottom heavy. I must have low frequency nodes that are not quite a "null" but are somehow weakening themselves as they come back from the back wall, causing me to exaggerate the amount of bass in the mix without it sounding exaggerated in the room. Sound about right?

Thanks!
Chris

[axemanchris]

Don't mix so loud. There is this thing called the "Fletcher, Munson Effect." The louder you listen to music, the better you hear the highs and the lows. Typically if you mix to loud, you tend to roll off the high end.

Dang.... I had a feeling that might be part of the equation.



Chris

[axemanchris]

Sorry - couple more thoughts here:

My mix position is a little less than the "equilateral triangle" recommended for monitor placement. I have the large desk, and from cone to cone on the monitors, they are about 4' across. From cone to ear is more like 32". If I move my chair back another foot, that puts me almost in the middle of the room, which causes more problems.

I can't move my monitors any closer together than they are now, because of the two computer screens. Would it be ridiculous to suggest that I build a platform of some sort to allow me to view my one computer screen above the other one, so as to allow me to move my monitors closer together?

A couple of other things I have thought about:
-putting them on stands so they are not on top of the wooden desk... but where would I put the stands with those computer screens still in the way??
-putting the monitors sideways and basically using them as 'boxes' on which I could place my computer screens. This just seems to be asking for more trouble than I'm in now.
-just finding some way to decouple them from the top of the computer desk... was it a few layers of mouse pads or something that I read about somewhere?

Thanks!
Chris

[Soundman2020]

For bass traps: a common design is the superchunk using triangular corners stacked up and glued together, but they seem to be 24" or so across.

Yes and no: Stacked up, yes. Glued together? NO! Just stack them, but do not glue them. And 24" is the usual minimum size. 32" or more is great. Bigger is better, but anything is better than nothing, within reason.

Or would I be better off building panels and hanging them at roughly 45 degrees in front of the corners?

That will work too, but not quite as effectively.

Whichever design I go with, can they be narrower... like... 18, or even 12" across? I'm guessing "the bigger the better", but once they're small enough, there is surely not much point. I imagine one 6" across wouldn't do anything.

18" is reasonable, but I would not go less than that.

I'll really need to figure out how big to make them and where to put them. (and from there, that would dictate how many....) I've been reading that vertical traps are more effective than horizontal

Really? Where did you read that???? Not here on the forum, I hope!!! sound waves don't even know which way is "up" or "down", and low frequencies are not directional: they don't care. Bass trapping is mostly about smoothing out room modes a little. All modes meet in the room corners, so that's the best place to put the bass traps. The "tri-corners" are the absolute best spot. (A tri-corner is where 3 surfaces meet, such as 2 walls and the ceiling, or 2 walls and the floor). But all corners are good for bass traps. You need them, and lots of them, because that is a small room. But in order to not suck out too much of the high end, one option is to put plastic sheeting in front of the absorption.

Is it safe to say that more will generally be better, and that I should put them anywhere I can - whether they be horizontal or vertical in whatever combination?

Yup! Absolutely!

If I have more traps on one side of the room, will it affect the stereo image? (thinking, I have lots of horizontal room along the south wall, but hardly any along the north wall)

To a certain extent, but mainly because they affect the mids and highs too. try to keep the front half of the room symmetrical: that is critical. The rear half is not so important here.

Onto diffusers to control reflections between the monitors and the listening position. I'm thinking I'll need one on each wall on either side of the monitors and one on the ceiling. Probably one or two at the back of the room wouldn't go amiss either, I guess.

Nope! Bad idea. In a room that small, most kinds of diffusers don't stand a chance. Things like skylines and other QRD based designs cause lobing, which takes a long distance to even out. As in many, many meters. It is a common misconception that you need diffusion in small rooms (of, course, the manufacturers of diffusers don't exactly do a lot to dispell this myth!!! I wonder why? ). So forget diffusers in a small room, except maybe for something like a very mild poly, or a good slot wall.

Same kinds of questions, though.... the DIY panels are 2' x 4'. What if I made one 18" x 4'? What if I made one 12" x 3'? Auralex has the "wedgies" that are only 1' x 1'. Are they big enough? At what point do they become pointless? Would my own DIY panels made 1' x 1' perform similarly?

See above! "Bigger is better". You also do not need to buy commercial treatment: plain old mineral wool and fiberglass in a simple wooden frame with cloth stretched across the front is MUCH cheaper, and just as effective.

In other news... I think I've figured out why my mixes are bottom heavy. I must have low frequency nodes that are not quite a "null" but are somehow weakening themselves as they come back from the back wall, causing me to exaggerate the amount of bass in the mix without it sounding exaggerated in the room. Sound about right?

Yup! "Small room syndrome". You have modal issues in that room, undoubtedly, since it is a very small room. Your room does not support modes below 60 Hz, and you have modal issues at 60Hz, 70 Hz, 83 Hz, 94 Hz, 102 Hz. etc. The first three are all axials, as well. The spread is about as good as you could hope for, in such a small room, but still lots of gaps in there. Your room ratio actually isn't that bad (close to Sepmeyer's best ratio, actually), but the room volume is very small: about 520 ft2, where the minimum recommended size for critical listening is 1500 ft2.

That doesn't mean that you can't use the room: it is what it is, so you have to understand the limitations, treat it the the hilt, and learn it. Still usable, just not ideal.

My mix position is a little less than the "equilateral triangle" recommended for monitor placement. I have the large desk, and from cone to cone on the monitors, they are about 4' across. From cone to ear is more like 32". If I move my chair back another foot, that puts me almost in the middle of the room, which causes more problems.

Exactyl! So don't move the chair back! Put the chair in the place that sounds best, starting at 38% of the room length as a guideline, but moving forwards and backwards till you get the best sound, then adjust the speaker angles so that they are firing at your EARS, and the apex of that triangle is a few inches BEHIND your head. Speakers should be 1.2 m above the floor. That is, the acoustic axis must be at 1.2m, not the top or bottom of the speaker. If your speaker documentation does not specify where that "acoustic axis" is located, then pick a spot about 2/3 of the way between woofer and tweeter, and you won't be far wrong. That's the spot that needs to be at your ear height, which is normally 1.2m above the floor for most people. If your triangle is no longer equilateral, don't sweat it. If the angles are no longer 60°, don't commit suicide: it's not the end of the world. Those angles and triangles are just good starting points, not written in stone. You will not be arrested by the speaker triangle police and jailed for life if your speaker intersect angle is more like 90° than 60°! The important thing here is to keep it symmetrical: both speakers spaced the same distance from the side walls and the front wall, and your head exactly in between them, at the same distance from each speaker, woith your nose on the room centerline.

I can't move my monitors any closer together than they are now, because of the two computer screens. Would it be ridiculous to suggest that I build a platform of some sort to allow me to view my one computer screen above the other one, so as to allow me to move my monitors closer together?

do not put the closer together! They are already too close. Move them further apart if you cane, and just ANGLE them more, so they are facing your ears, as above.

But don't go overboard: You don't want them in the corners, or right up against the walls, either. Just try to get them a bit further apart, pointing at your ears, and be religiously zealous about the symmetry thing: that is KEY.

Also, get them off the desk! They are most likely causing all sorts of ugly interactions and vibrations like that. Put them on some heavy, massive, decoupled stands, just next to the desk, or even move your desk away from the wall a bit, and put them on stands just behind the desk.

You also need treatment on the front wall, directly behind your speakers. Large panels of 4" 703 would be great.

-putting the monitors sideways and basically using them as 'boxes' on which I could place my computer screens. This just seems to be asking for more trouble than I'm in now.

Exactly: that would be a bad idea, for many reasons. Keep them vertically, and get them on stands next to the desk. The stands must be MASSIVE, as in VERY HEAVY. Some people get large hollow stands and fill them with sand. Others just buy a few cheap concrete blocks (large bricks) and stack them up. You need MASS. (Did I mention they need to be HEAVY?). Then put a piece of 703 between the top of the stand and the speaker, to help with decoupling. This alone (speakers on massive decoupled stands) will undoubtedly improve your sound a lot.

It seems like you realize what the issues and solutions are, intuitively, and in most cases you are right! So the key things here are: symmetry for the front half of the room, get your speaker geometry fixed, mount them on massive decoupled stands, and install huge volume of bass trapping.

I'm betting your mixes will improve greatly!

- Stuart -

[axemanchris]

Wow! Soundman, thank you! I'm starting to feel better about this all, and am really grateful for your time to respond to my myriad of questions.

For bass traps: a common design is the superchunk using triangular corners stacked up and glued together, but they seem to be 24" or so across.

Yes and no: Stacked up, yes. Glued together? NO! Just stack them, but do not glue them.

Noted. Thank you.

And 24" is the usual minimum size. 32" or more is great. Bigger is better, but anything is better than nothing, within reason....

18" is reasonable, but I would not go less than that.

Errrrmmmmm..... shoot.

Looking at that pic, this will be difficult. (no, I'm not shooting the messenger here... really....)

There are a number of places where I can go 12" across - where the corner is about 8-9 inches deep before hitting some obstacle (the edge of a bulkhead, the edge of the "water meter" insert shelf, the top of the fruit cellar door, etc.) There aren't many places where I can go more than that.

How is this for theory... in an ideal situation, you would have a room with only obtuse angles - hence the popularity of pentagonal/hexagonal rooms and such. By filling a corner with a bass trap, you effectively eliminate a 90 degree corner and replace it with two 135 degree corners. Hence, the "anything is better than nothing, within reason" way of thinking.

So, by filling a corner with a trap that is, say, 9x9x12.73, there's not really "much" of a square corner for those bass frequencies to hang out in, right? Maybe not as good as a trap that is 22.6 x 22.6 x 32, but should make a noticeable difference?

*sigh*

I'll really need to figure out how big to make them and where to put them. (and from there, that would dictate how many....) I've been reading that vertical traps are more effective than horizontal

Really? Where did you read that???? Not here on the forum, I hope!!!

Meh... probably just me just getting confused with the wealth of information I've flooded my brain with over the last few days. Never mind. I stand corrected in any case.

sound waves don't even know which way is "up" or "down", and low frequencies are not directional: they don't care. Bass trapping is mostly about smoothing out room modes a little. All modes meet in the room corners, so that's the best place to put the bass traps.

Ah, yes... this rings true with the reading I have done here. Noted. Thank you.

The "tri-corners" are the absolute best spot. (A tri-corner is where 3 surfaces meet, such as 2 walls and the ceiling, or 2 walls and the floor). But all corners are good for bass traps. You need them, and lots of them, because that is a small room. But in order to not suck out too much of the high end, one option is to put plastic sheeting in front of the absorption.

Have I missed it or is there a good model or design for a "tri-corner trap" here?

For aesthetics purposes, could I put the plastic sheeting underneath the fabric, or does that sort of defeat the whole point? I'm guessing the purpose is to make the traps "non-breathable". But I don't want them to be reflective, do I?

If I have more traps on one side of the room, will it affect the stereo image? (thinking, I have lots of horizontal room along the south wall, but hardly any along the north wall)

To a certain extent, but mainly because they affect the mids and highs too. try to keep the front half of the room symmetrical: that is critical. The rear half is not so important here.

Uh-oh...

I can stack some traps in the corner between the desk and the fruit cellar (to the left of the monitors) from floor to ceiling. To the right of the monitors, between the desk and the closet, I can only go up to about 5.5 feet, as I hit the window there.

To the left of the listening area, I can run about a 12" trap along the ceiling from the corner of the room to the bulkhead behind the listening area. (needs to clear the fruit-cellar door) But to the right of the listening area, I can only put one 18" across, between the air vent and the doorway of the large closet. The good news is that that one can be deeper than 12" across.

Behind the listening area, to the left (where the "water meter" shelf meets the brick wall), I can put one from the bulkhead down to where the air return vent is (actually not an air return, but an access panel to the water meter / water shutoff). This would be about 4' and could be about 12-14" across. But behind the listening area to the right, where the closets are.... I have *nothing* to put a trap in. I guess the good news there is that that means there is nowhere for the bass to be trapped, no?

(keeping in mind that the characteristics of the room will change when I get closet doors put on, and when I get the entry door to the studio on - and will change further whether the door is open or closed... The door will open into the studio and open against the closets) With the door closed, I will actually have a corner for bass frequencies to bounce around in, but nowhere to put a trap.

Onto diffusers to control reflections between the monitors and the listening position. I'm thinking I'll need one on each wall on either side of the monitors and one on the ceiling. Probably one or two at the back of the room wouldn't go amiss either, I guess.

Nope! Bad idea. In a room that small, most kinds of diffusers don't stand a chance. Things like skylines and other QRD based designs cause lobing, which takes a long distance to even out. As in many, many meters. It is a common misconception that you need diffusion in small rooms (of, course, the manufacturers of diffusers don't exactly do a lot to dispell this myth!!! I wonder why? ). So forget diffusers in a small room, except maybe for something like a very mild poly, or a good slot wall.

Well that makes my life a little easier. I was fretting about diffusers and the placement being not very friendly. (using a mirror, they seem to belong part way straddling the closet door to the right of the listening station, for instance, and if I make them 18" wide, they would also straddle the edge of the fruit cellar door to the left.) Good thing I don't need to fret about that so much anymore!

Same kinds of questions, though.... the DIY panels are 2' x 4'. What if I made one 18" x 4'? What if I made one 12" x 3'? Auralex has the "wedgies" that are only 1' x 1'. Are they big enough? At what point do they become pointless? Would my own DIY panels made 1' x 1' perform similarly?

See above! "Bigger is better". You also do not need to buy commercial treatment: plain old mineral wool and fiberglass in a simple wooden frame with cloth stretched across the front is MUCH cheaper, and just as effective.

More good news. A pair of those 1'x1'x2" Wedgies costs something like $115! To my chagrin, this basement project has made me a bit of a pro with lumber and Roxul....

Mind you, if I only have to worry about a diffuser behind the desk (from your comment below), then I really have a ton of space there. Bigger. Got it!

In other news... I think I've figured out why my mixes are bottom heavy. I must have low frequency nodes that are not quite a "null" but are somehow weakening themselves as they come back from the back wall, causing me to exaggerate the amount of bass in the mix without it sounding exaggerated in the room. Sound about right?

Yup! "Small room syndrome". You have modal issues in that room, undoubtedly, since it is a very small room...but the room volume is very small: about 520 ft2, where the minimum recommended size for critical listening is 1500 ft2.

Yer not kiddin'!!

Your room does not support modes below 60 Hz, and you have modal issues at 60Hz, 70 Hz, 83 Hz, 94 Hz, 102 Hz. etc. The first three are all axials, as well. The spread is about as good as you could hope for, in such a small room, but still lots of gaps in there. Your room ratio actually isn't that bad (close to Sepmeyer's best ratio, actually),

Believe it or not, that was on purpose. I knew the room was going to be very small, and I spent a good deal of time trying to optimize the room for dimensions in just this way when I was planning it. I could have made the room slightly wider (maybe a foot?), at the expense of shallower closets, but the ratios were all screwed up. (say, 9 x 9.5 x 6'10")

That doesn't mean that you can't use the room: it is what it is, so you have to understand the limitations, treat it the the hilt, and learn it. Still usable, just not ideal.

I can live with that.

My mix position is a little less than the "equilateral triangle" recommended for monitor placement. I have the large desk, and from cone to cone on the monitors, they are about 4' across. From cone to ear is more like 32". If I move my chair back another foot, that puts me almost in the middle of the room, which causes more problems.

Exactyl! So don't move the chair back! Put the chair in the place that sounds best, starting at 38% of the room length as a guideline, but moving forwards and backwards till you get the best sound, then adjust the speaker angles so that they are firing at your EARS, and the apex of that triangle is a few inches BEHIND your head. Speakers should be 1.2 m above the floor. That is, the acoustic axis must be at 1.2m, not the top or bottom of the speaker. If your speaker documentation does not specify where that "acoustic axis" is located, then pick a spot about 2/3 of the way between woofer and tweeter, and you won't be far wrong. That's the spot that needs to be at your ear height, which is normally 1.2m above the floor for most people.

Noted. Thank you!

If your triangle is no longer equilateral, don't sweat it. If the angles are no longer 60°, don't commit suicide: it's not the end of the world. Those angles and triangles are just good starting points, not written in stone. You will not be arrested by the speaker triangle police and jailed for life if your speaker intersect angle is more like 90° than 60°!

The important thing here is to keep it symmetrical: both speakers spaced the same distance from the side walls and the front wall, and your head exactly in between them, at the same distance from each speaker, woith your nose on the room centerline.

I can't move my monitors any closer together than they are now, because of the two computer screens. Would it be ridiculous to suggest that I build a platform of some sort to allow me to view my one computer screen above the other one, so as to allow me to move my monitors closer together?

do not put the closer together! They are already too close. Move them further apart if you cane, and just ANGLE them more, so they are facing your ears, as above.

Really?! Already too close?! Okay... I can change the angle easy enough... widening the distance might be a trick to not interfere with the closet to the right - even with stands - especially if I have a trap in the corner. (see below)

But don't go overboard: You don't want them in the corners, or right up against the walls, either. Just try to get them a bit further apart, pointing at your ears, and be religiously zealous about the symmetry thing: that is KEY.

Done. Er... well... will do.

... cont'd for purposes of organization.

Chris

[axemanchris]

Also, get them off the desk! They are most likely causing all sorts of ugly interactions and vibrations like that.

Yeah, I was worried about this - reflections, resonance from the wood, etc.

Put them on some heavy, massive, decoupled stands, just next to the desk, or even move your desk away from the wall a bit, and put them on stands just behind the desk.

Hmmm... *squirms*

I was under the impression that mass was important with the stands so as not to transfer vibrations from the speakers to the floor. A wood floor would clearly be problematic. A concrete floor, though? Do I still need the mass?

This is probably possible, but will be dicey. If I put traps in those corners, I have a little less right-left room. If I put a diffuser behind the desk and then add space for a couple of stands, that will put my listening area probably almost right smack dab in the center of the room. Argh@@@!!!

I have a couple of thoughts...

1. I'm guessing the panels should be not only between, but behind the speakers, yes? I could make a panel, then, 2' high (basically from the top of the desk to the bottom of the window frame) and upwards to 6' wide. Is there any point in having that panel extending below the edge of the desk?

I guess with some care in design and measuring I could cobble together some sort of stand that will get up close to the wall behind the desk, and then extend outwards over the top of the desk (but under the diffuser panel.... might have to make the diffuser panel 22" high or something...), placing the speakers basically where they are now, but completely decoupled from the desk.

2. I'm guessing that mounting the speakers on shelves mounted on the wall and over the desk (and under the diffuser) would be less than ideal with vibrations carrying through to the wall? (wall is 1/2" drywall screwed to furring strips, which are screwed to concrete block, though with rigid foam insulation between the block and the furring strips) Come to think of it, with no wood framing to speak of, it might not be so bad, would it?

You also need treatment on the front wall, directly behind your speakers. Large panels of 4" 703 would be great.

I haven't seen 703 around here, but honestly I have not looked specifically for it. Is Roxul basically the same product?

It seems like you realize what the issues and solutions are, intuitively, and in most cases you are right! So the key things here are: symmetry for the front half of the room, get your speaker geometry fixed, mount them on massive decoupled stands, and install huge volume of bass trapping.

I'm betting your mixes will improve greatly!

- Stuart -

I'm getting there, Stuart, with much thanks to you and Eric so far, along with a ton of posts here on this forum, and the Gervais book, which I do own. It was a great purchase!

Thanks so much!
Chris

[BriHar]

Hi axemanchris,

How is this for theory... in an ideal situation, you would have a room with only obtuse angles - hence the popularity of pentagonal/hexagonal rooms and such. By filling a corner with a bass trap, you effectively eliminate a 90 degree corner and replace it with two 135 degree corners. Hence, the "anything is better than nothing, within reason" way of thinking.

The trap is just an absorber the 90° corner is defined by the hard boundaries so it remains 90° and not 2 135° corners as you suppose.

You may be able to use a wider triangle of insulation at the ceiling and or floor in a super chunk configuration. By this I mean use the 12" face if that's all you can, but if you can increase this surface near the floor or ceiling, then do so. Another possibility might be to use your 12" directly in the corner, and then panels on the adjacent walls to either side.

I knew the room was going to be very small, and I spent a good deal of time trying to optimize the room for dimensions in just this way when I was planning it

In a room this small, unless the ratio is very bad (i.e. near cubic), maximum real-estate usually trumps the ratios.

Regarding Monitor angles, anything between 60° and 90° is good. Less than 60 and you begin eating into your image (too narrow), more than 90 and the image starts becoming too undefined. (Just for clarity: The angle refers to that formed at the apex behind the listeners head. These comments are made in reference to a near- to midfield configuration.

As for the stands - as massive as possible. Even if on a concrete floor (or perhaps moreso - remember concrete propagates the vibrations better than wood!)). The more the stand can vibrate in sympathy with the speakers, the more energy the stands are stealing from your speakers, and even worse they will blur the imaging.

[axemanchris]

Hi axemanchris,

How is this for theory... in an ideal situation, you would have a room with only obtuse angles - hence the popularity of pentagonal/hexagonal rooms and such. By filling a corner with a bass trap, you effectively eliminate a 90 degree corner and replace it with two 135 degree corners. Hence, the "anything is better than nothing, within reason" way of thinking.

The trap is just an absorber the 90° corner is defined by the hard boundaries so it remains 90° and not 2 135° corners as you suppose.

Hmmm... got it. Makes sense, I suppose.

You may be able to use a wider triangle of insulation at the ceiling and or floor in a super chunk configuration. By this I mean use the 12" face if that's all you can, but if you can increase this surface near the floor or ceiling, then do so. Another possibility might be to use your 12" directly in the corner, and then panels on the adjacent walls to either side.

Of course! Funny how I keep reading that there are twelve corners in a room, but still I kept neglecting to consider the floor. Duh! Mind you, not a lot of room there either....

I guess I'll mostly be stuck with 12" wide bass traps in a mish-mash of places wherever I can fit them in the room. I could throw up a couple of panels to support that in a couple places - small ones.

I knew the room was going to be very small, and I spent a good deal of time trying to optimize the room for dimensions in just this way when I was planning it

In a room this small, unless the ratio is very bad (i.e. near cubic), maximum real-estate usually trumps the ratios.

Damn.... oh, well. It's not like I don't need the storage. Grrr....

Regarding Monitor angles, anything between 60° and 90° is good. Less than 60 and you begin eating into your image (too narrow), more than 90 and the image starts becoming too undefined. (Just for clarity: The angle refers to that formed at the apex behind the listeners head. These comments are made in reference to a near- to midfield configuration.

Gotcha. Thanks!

As for the stands - as massive as possible. Even if on a concrete floor (or perhaps moreso - remember concrete propagates the vibrations better than wood!)). The more the stand can vibrate in sympathy with the speakers, the more energy the stands are stealing from your speakers, and even worse they will blur the imaging.

Hmmm... okay. I think I'm going to investigate getting a smaller desk. There seems to be a LOT of advantages to that. The big desk was great in the bigger room (though bigger, it was an acoustic nightmare.... wood paneling, low ceiling, 10x20.... the lot....), but the big desk is just consuming this room.

If I get a smaller desk I can put the speakers on stands on either side of it. I think I'll look into getting some concrete blocks and covering them in some sort of cloth wrap or something.

Thanks for your input, Brian! It has been helpful!

Chris

[axemanchris]

Here is my plan so far. First picture below:

I'm trying to keep the front of the mix area as symmetrical as possible. I can build two 4' superchunk absorbers and place them in the two corners. Unfortunately, the best I can do is for them to be 12" (maybe 13") across. At least they will extend in height beyond the top of the monitors. I'm guessing this is significant?

I can also place a large-ish absorber along the west wall behind the monitors that would be about 2' x 6', which would extend from the top of the computer desk to almost the bottom of the window frame (as shown) and will span nearly the entire width of the room, including the area behind the monitors.

Should that large flat one be 2" or 4" deep?

Looking at the upper corners, is there a DIY tri-corner trap that I can make, or should I buy a pair... were they from Primacoustic? Blocking off a portion of the window is not a big deal for me.

WestWall.jpg

Second picture below:

I can place two more 4' superchunk absorbers in those two corners. They are the only other significant corners (vertical, anyways) where I can place anything in the room. They, too, will only be 12-13" across.

SEcorner.jpg

I could place some bits and pieces along the horizontal corners where the wall meets the ceiling, but with the obstacles leaving only very narrow stretches of corner, I don't have a lot in the way of options. I mean, I have a few options, but they are all on the south side of the room. Should I bother with them, or proceed, even though the absorption in the room is really becoming decidedly asymmetrical?

Does this seem like I'm on the right track?

Multi-posting, but only for clarity to separate out ideas...

Chris

[axemanchris]

I've got another desk that is identical, only instead of being double-wide (63"), it is half that. (32")

This will allow me to place my speakers on stands on either side of the desk, and will mean less real-estate lost in the room to a desk that is bigger than it needs to be.

Here's my predicament...

The room at the front is 82" high. From my reading, I know that 41" would be the worst-possible height, and ideally, the speakers would be placed at 31" or below, or 51" or above. As I sit in my chair and measure from the floor to my ears, the distance is 44". The desk is 31" high. The "acoustic axis", as measured by figuring 2/3 of the way between the woofer and the tweeter is 12" from the bottom of the speaker - at the moment, as they sit on the desk, in line with my ears at 44".

I'm completely perplexed as to how to place my speakers for height. Can I place them higher and angle them downwards slightly? That just seems to be asking for trouble.

I'm going to be using concrete blocks as the basis for my stands using this kind of design:
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=10021

Thanks!
Chris

[axemanchris]

I'm wondering what the best kind of covering treatment would be best for my superchunk traps.

I plan on using Roxul safe and sound to fill them. Soundman suggested that I use plastic in front of the absorption. I have some 6 mil vapour barrier left over from my construction. Is this too heavy?

Am I correct that I want "breathable" fabric? If so, what is the point of breathable if there is plastic under it?

Could I pre-build a frame, and cover the whole thing around with burlap or whatever (fire retardant) all the way around, or should I plan it so that I only cover the front of the absorber?

Thanks for all the help so far!!

Chris

[BriHar]

I think you should forget about the corners as the possible width of 12" will not bring enough to be effective.

On the right side of the desk I see a door. Judging from the guitar cases I assume this is a cupboard. Regardless, it seem to have no door.
Here's what I would do in that room.

I'd add a door - this would hang on a track i.e. a sliding door as I think you don't have enough room for the swing of a hinged door. So the door could slide across in front of the shelving unit. You might also want to thiink about a similar door on your rear wall.

Next I would build a series of absorber panels (what some refer to as bass traps). These are the rigid fiberglass panels mounted on a frame and covered in fabric, as has already been mentioned. I would however suggest you not make the cradle type of panel, that is where the insulation sits in a wooden frame. What you need is the open type where only a wooden support frame or skeleton is used for structure, and the insulation panels sit on this. The reason is you get maximum absorption including the sides of the traps which is important in this case as you will be forgoing corner traps, and if the relative proximity of these panels to one another is good then you will have similar absorption as if you used corner trapping (You can check this out on Ethan Winers RealTraps site). For maximum effect, these panels have to stand off from their respective wall a few inches ( I used sections of foam pipe insulation as standoffs).

I'd mount one of these panels on either side making sure you cover the first reflection points. On the right side this would be affixed to the sliding door.
On the front wall I'd mount either one long panel or two or three smaller ones.

Id hang another one or two panels from the ceiling as clouds. Finally I'd mount a large panel on the wall behind you (hence the sliding door here as well). Another alternative for the rear wall would be a panel on a stand (so called Gobo) which you could move into position behind your chair when required.

Burlap should be fine (treat with Borax or buy it pretreated for fire retardation) breathable is the key. As for plastic, I'd leave that out at first and only add it if you feel that the highs are suffering, and then only perhap on the panels to the sides.

Here is a pic of a room I used a couple of years back just to give you an idea. While not perfect its acoustics were quite good, and the imaging excellent.

IMG_1062r.jpg

[axemanchris]

I think you should forget about the corners as the possible width of 12" will not bring enough to be effective.

Okay. I think hanging absorbers on the walls wherever I can will actually be easier anyways. Not that I was averse to building superchunk traps.

On the right side of the desk I see a door. Judging from the guitar cases I assume this is a cupboard. Regardless, it seem to have no door.
Here's what I would do in that room.

I'd add a door - this would hang on a track i.e. a sliding door as I think you don't have enough room for the swing of a hinged door. So the door could slide across in front of the shelving unit.

Yes, it is a small closet. The door itself is 24" wide and is ready for a bifold - exactly as you described. I have the door. I just need to put it up.

You might also want to thiink about a similar door on your rear wall.

I already have a swing door for the entrance to the studio, and another bifold for the other larger closet door. (48" wide to be covered by a pair of 24" bifolds)

I'm hoping that this could be advantageous over a bifold in that I can more easily mount a larger absorbent panel / trap on the back of the door.

Next I would build a series of absorber panels (what some refer to as bass traps). These are the rigid fiberglass panels mounted on a frame and covered in fabric, as has already been mentioned. I would however suggest you not make the cradle type of panel, that is where the insulation sits in a wooden frame. What you need is the open type where only a wooden support frame or skeleton is used for structure, and the insulation panels sit on this. The reason is you get maximum absorption including the sides of the traps which is important in this case as you will be forgoing corner traps, and if the relative proximity of these panels to one another is good then you will have similar absorption as if you used corner trapping (You can check this out on Ethan Winers RealTraps site). For maximum effect, these panels have to stand off from their respective wall a few inches ( I used sections of foam pipe insulation as standoffs).

I'm a little unclear about what you mean in the difference in design between "not making it where the panel sits in a wooden frame" but where I would use "a wooden support frame or skeleton for structure." The latter doesn't have any framing on the sides, meaning the sides are absorptive as well? But if that's the case, how do I "attach" the top part of the frame to the bottom?

I'd mount one of these panels on either side making sure you cover the first reflection points. On the right side this would be affixed to the sliding door.

I just got my wife to help me with the mirror test, and I was surprised at how narrow the area was between where the speaker came into vision and then left the visual field of the mirror. It was about 12", and seemed to coincide exactly with the right side of where that bifold is going to be. Now, given that each half of the bifold is going to be about 11.75", to avoid straddling the two halves of the bifold or having the panel straddle the door and the wall, would it be okay to build a panel 11.5" and mount it on the one half of the bifold?

Otherwise, I would have to remove the panel every time I want to get into the closet. I'll do that if that's what will be necessary, but if it isn't necessary, then I'd rather not.

The other panel on the other side would mount nicely on the fruit cellar door.

On the front wall I'd mount either one long panel or two or three smaller ones.

I think I'll go with one longer one, just because there seems to be no obvious advantage to make two or three smaller ones, and building one will be easier than three.

Now, all of these panels so far... would they be 2" deep or 4" deep?

Id hang another one or two panels from the ceiling as clouds.

I was thinking about this. Might it be better to make a panel that would be, say 3/4" plywood covered with a thin layer of insulation and fabric? The reason I ask is that by effectively using a hard surface, the sound waves would act as if the ceiling was, say, 4-6" lower than it is, meaning I solve my problem of my speakers being almost exactly at the half way point between the ceiling and the floor.

Finally I'd mount a large panel on the wall behind you (hence the sliding door here as well). Another alternative for the rear wall would be a panel on a stand (so called Gobo) which you could move into position behind your chair when required.

The mid point of the wall is where the light switch is. Given that I have a swing door for the entrance way into the room, could I mount, say, one panel 2' x 18" below the light switch (mounted horizontally), and another similar one on the door vertically?

Burlap should be fine (treat with Borax or buy it pretreated for fire retardation) breathable is the key. As for plastic, I'd leave that out at first and only add it if you feel that the highs are suffering, and then only perhap on the panels to the sides.

Here is a pic of a room I used a couple of years back just to give you an idea. While not perfect its acoustics were quite good, and the imaging excellent.

IMG_1062r.jpg

Got it! Thanks again for your continued help!
Chris