John Sayers' Recording Studio Design Forum Archive

Well it's more of a "converted garage into a rec room/laundry room thing" in the house I'm renting. I will not be recording in this room, only mixing, and my main goal is to even it out as much as possible to make mixing easier and translate better (especially in the low end).

I am as loud as I want to be. I am pretty far away from my neighbors and I don't really do this late at night so they can take a little noise if I crank my monitors (which I don't do often).

Not exactly sure what the garage is made out of. The ceiling seems to be thin ceiling tile with studs running along it (which is where I hung the cloud from). Walls are wood. Floor is linoleum and I think it might just be cement below it. House was built in the 50's. I have a floor rug 8 feet by 6 feet under my desk and back towards my listening position right now.

The closet to my has sliding doors and is fully mirrored from top to bottom.

I currently have 4 6" traps of 703 made, 2 4" traps to be hung as a cloud, and 703 left for another 3 6" traps to be made.

I borrowed an ECM8000 and did measurements with FuzzMeasure, L then R (5 sweeps averaged each measure). I placed the mic at ear level and pointed it at the speaker I was doing the sweep from.

I have attached an image of my room. The scale of the room/closet is to scale, but the desk/speakers/washer/drier is not. There are also pictures attached of my layout (chair was not there when I did the sweeps).

The pink places are where I currently have the traps set up. The bottom has a washer and drier, so I cannot set up on that side. Not sure how badly having the closet will change my listening. Currently I notice the stereo image skews to the left. When I was getting my traps out of there last night to begin measuring tonight, I noticed it skewed a LOT more when I didn't have something blocking off the mirrored closet door. I did sweeps both with the door open and closed to see how much that would change things.


Right now I have ADAM A7's, and will be upgrading to some Focal Solo6's when the opportunity arises.



In the measurements I'm noting a huge hole at 55hz, and a large peak at 160hz-ish. I'm hoping to get those smoothed out as much as I can. I can't do construction or anything since this is a rental, but the owner is very accommodating (he helped me drill the holes to hang the cloud) so hopefully I can get some traps placed around and fix stuff up.

Budget is pretty decent sized since I will do whatever I need. I can't buy everything all at once, but if I need to spend $1000 more on OC703 then I will. Superchunks may sound like a good idea but there really is only one corner I could put them in (2 corners have washer and drier, another corner has the closet door as one wall, and the corner by the door has a heat vent on the bottom so nothing can go there).

I'm also going to buy some monitor stands and try taking them off of my desk and moving them between there and the corners to see what kind of results I'll get.

Closed door measurements.

With closet door open.

Updated the charts again. I added a second cloud (so now it's total 4 feet by 4 feet). It brought the waterfall graphs down even more. Also opening the closet door helps shorten the delay time of 30hz and 80hz, but brings up 150 just a bit.

So it looks like what I need help on is the big dip at 55hz, the huge bump at 160hz, and then there's also a big hole around 450hz.

Any advice would be great!

Hi Kita, and Welcome!

A couple of comments in general:

I borrowed an ECM8000 and did measurements with FuzzMeasure, L then R (5 sweeps averaged each measure). I placed the mic at ear level and pointed it at the speaker I was doing the sweep from.

That would probably account for the difference between the modal responses you are seeing for the left and right speakers. You should really keep the measurement mic in the exact same place for all your measurements, regardless of which speaker you are using. The mic should be in the same position as your head will be while mixing, facing straight ahead at the front wall, and angled slightly up, maybe 30° to 45°. Once you have that location, measure it very, very carefully, as you'll need to get the mic back to that exact position, every time, with an accuracy of a few mm (half an inch or so). Otherwise, comparing graphs taken with the mic in slightly different locations is not possible, as you are looking at two different things.

(chair was not there when I did the sweeps)

It should have been! Set up the room as close as possible to the way it will be when you are mixing, and change ONLY the treatment. Everything matters, to a greater or lesser extent.

However, the graphs clearly do show some pretty large modal issues! Your treatment is taming them a bit, but they are still there.

Right now I have ADAM A7's,

Excellent choice! (OK, so I'm a little biased, as I own a pair myself). However: they should not be laying on their sides! You should have them upright. Your geometry is too squashed up to be able to use them on their sides. Also, get them off those support thingies, and of the desk completely. Get them onto heavy, massive stands just beyond the desk. You did mention that later in your post, but I wanted to comment on just how important that is. You could be getting all kinds of resonant issues and other artifacts like you have them now.

But clearly the issues you are seeing are not only due to your speakers.

From your dimensions:

Length=19.5 ft, Width=11.5 ft, Height=7.17 ft
Room Ratio: 1 : 1.6 : 2.71

That's not a great ratio at all. The modal spread is not even, and the Bonello graph doesn't look promising. And the source of that large peak also seems to be in there:

157.6 hz 0,0,2 Axial
158.4 hz 2,3,0 Tangential
160.2 hz 1,0,2 Tangential
164.9 hz 5,0,1 Tangential
165.1 hz 0,1,2 Tangential
167.1 hz 0,3,1 Tangential
167.6 hz 1,1,2 Oblique
167.9 hz 2,0,2 Tangential


You have a whole bunch of modes all lined up on top of each other. 8 modes covering 10 Hz! But I'm suspecting the first one there: 157.6 is your second order vertical mode, involving the floor and ceiling. Curiously enough, the first-order mode for the same surfaces, is at 78.8 Hz. Take a look at your graphs, and see if you notice something around 78 Hz...



Question:

1) Are your clouds angled, or flat? In other words, is one side of the cloud closer to the ceiling than the other?

2) Are your clouds hard backed or not?

From the photos, it looks like the answer to both those questions is "no". If so, then I'd put a thick, hard, massive back on the clouds (plywood, MDF, etc.), but another layer of 703 on top, and angle the clouds so that the front edge (nearer the speakers) is lower and the rear edge (nearer to you) is higher. That might help to break up that mode a bit, or at least shift it. The effect won't be huge, since those are low frequencies and the wavelengths are long compared to the size of the clouds, but it should have some effect.

However, I'd also put more absorption on the ceiling, since your clouds are only covering a small part of the total area. I'd also think about turning your two front traps into superchunks.

Superchunks may sound like a good idea but there really is only one corner I could put them in (2 corners have washer and drier, another corner has the closet door as one wall, and the corner by the door has a heat vent on the bottom so nothing can go there).

There are twelve corners in a room: You only mentioned 4. What about the other 8? ...


But there's a bigger issue here: Symmetry. You don't have any! You MUST have excellent room symmetry at least for the front half of the room, but yours doesn't even cover a third, and is pretty poor anyway.

You say: "Currently I notice the stereo image skews to the left. When I was getting my traps out of there last night to begin measuring tonight, I noticed it skewed a LOT more when I didn't have something blocking off the mirrored closet door.". Yup Not surprising. The close is your problem. If it weren't for the washer/dryer, I'd say flip your room around 180°, but clearly that isn't an option. So here is the other option, and it's one that you don't want to hear: lose the closet. Take it out. Get rid of it. Talk reaaaaaaallly nice to your landlord, and promise him you'll put it back in if/when you leave. You really can't do much with the closet there. With the closet gone, you'd have a much better shaped room at the front: wider, and with no more symmetry issues.

A third option is to build a temporary wall just in front of the closet, extending half way back into the room. Just a stud frame with drywall on one side of it. That will close of the closet completely, and leave a little nook next to it.

By the way, the dip at 50 Hz is probably nothing to worry about. It could be many things, including the roll-off of the A7's, or the sensitivity of the measuring system. It's really hard to get accurate data for very low frequencies, so unless you actually perceive a 30 dB hole there, with your own ears, then there might not even be one.

Having said that, you do have your first-order 0,1,0 mode at 49.1 Hz, so it could be related to the room width! Do if you really are hearing something there, then large heavy hard-backed gobos angled along the side walls might help. (Kind of like your hard-backed cloud, but turned vertically.)

My $0.02...

- Stuart -

Soundman2020 wrote:

I borrowed an ECM8000 and did measurements with FuzzMeasure, L then R (5 sweeps averaged each measure). I placed the mic at ear level and pointed it at the speaker I was doing the sweep from.

That would probably account for the difference between the modal responses you are seeing for the left and right speakers. You should really keep the measurement mic in the exact same place for all your measurements, regardless of which speaker you are using. The mic should be in the same position as your head will be while mixing, facing straight ahead at the front wall, and angled slightly up, maybe 30° to 45°. Once you have that location, measure it very, very carefully, as you'll need to get the mic back to that exact position, every time, with an accuracy of a few mm (half an inch or so). Otherwise, comparing graphs taken with the mic in slightly different locations is not possible, as you are looking at two different things.

(chair was not there when I did the sweeps)

It should have been! Set up the room as close as possible to the way it will be when you are mixing, and change ONLY the treatment. Everything matters, to a greater or lesser extent.

Of course the usual "everybody says different things on the internet." From what I read I had things set up "as I should." Haha. I am buying an ECM8000 (borrowed the last one) and will redo the tests when I get it. I also have a pair of Focals here to test. I also bought some monitor stands so I can place them off of the desk and further away to see what that does, as well. I will make sure to have the mic positioned the same the next time I do them.

Soundman2020 wrote: 157.6 hz 0,0,2 Axial
158.4 hz 2,3,0 Tangential
160.2 hz 1,0,2 Tangential
164.9 hz 5,0,1 Tangential
165.1 hz 0,1,2 Tangential
167.1 hz 0,3,1 Tangential
167.6 hz 1,1,2 Oblique
167.9 hz 2,0,2 Tangential

Of course. I have been hearing that forever. Whenever I would eq bass or kick I'd think "Man that 170 ish is TUUUUBBBYYY." Then I'd cut it. Then wonder why my bass or kick sounded thin.

Soundman2020 wrote: 1) Are your clouds angled, or flat? In other words, is one side of the cloud closer to the ceiling than the other?

2) Are your clouds hard backed or not?

You're right on both accounts. They are angled flat along with the ceiling. I am re positioning them because they more centered towards my sitting area when if I scoot them a little more forward they will cover the future area of my monitors (on stands) as well as where I'm sitting. I was figuring I would drop the front one down to an angle but I can easily do both of them (they are on chains, so I can just add 2-4 inches more on one end to drop them).

They made just like my other traps, a frame around them and fabric on the front. 4 inches of 703 in them. What does adding a hard back do to them? I understand there will be a difference, but what will it be?

Soundman2020 wrote: lose the closet. Take it out. Get rid of it. Talk reaaaaaaallly nice to your landlord, and promise him you'll put it back in if/when you leave. You really can't do much with the closet there. With the closet gone, you'd have a much better shaped room at the front: wider, and with no more symmetry issues.

As much as my landlord is a cool guy and lets me hang random crap from the ceiling, he definitely wouldn't let me do this. Haha. The water heater for the house is in there, as well.



Thanks for the response. A lot of stuff I had guessed at, pretty much. When I get another ECM8000 I will try dropping the cloud ends and see what that changes.

Also, any suggestions on how far away to have my monitors? I always read that closer to the wall is bad, but I think I read some conflicting information on this site.

What does adding a hard back do to them? I understand there will be a difference, but what will it be?

Adding a back to the cloud creates a hard, massive angled surface that will help to break up the standing wave that is causing your vertical modal issue. Any time you put a sufficiently rigid, massive barrier in the path of a sound wave, you force it to take a different path: it has to deflect (reflect at a different angle, instead of the same angle), if the barrier is physically larger than the wavelength in question, or it could diffract around the barrier if the wave is somewhat similar in size. But if the wavelength is considerably larger, then it basically just ignores the barrier, as though it wasn't even there. Fortunately, the dimensions of your clouds are in the ball park to have some effect on those wavelengths (quarter waves and half waves). The hard back also shortens the distance from floor to ceiling, thus shifting the frequency of the mode, hopefully.

The hard-backed cloud won't break up the standing wave completely, of course, but anything you do to deflect the wave motion will help to shift it, partially. Try to get at least a 12° angle on that cloud, more if you can.

Of course the usual "everybody says different things on the internet." From what I read I had things set up "as I should." Haha.

Yup, it happens! But sometimes simple logic wins out over internet hype about acoustics (and there's more than plenty of that to go around!). Anything you put in a room or take out of it will have some effect on the acoustics, at some frequency or other. The larger the object, the greater the effect. That's just plain intuitive (unlike many things in acoustics, it actually makes sense! . So, since you plan to use this room with you sitting in a chair, and all your gear around you, well, it's also obvious that it is under THOSE conditions that you want toe room to sound its best. Once again, intuitive. So, since you are measuring things right now to see how the room is reacting to your treatment, once again it makes sense to have the room set up just as close as you possibly can to the way it will be used, eventually. Which includes things like chairs, desk, etc. So you DO want the chair, desk and everything else in there, just as it will be when you use the room. About the only thing that won't be in its final position, is you. But since your head and the mic cannot occupy the same space at the same time, you can't be there!

That's the logic behind the room being set up the way you'll use it. And the logic behind keeping the mic in the same spot every time is so that you can compare readings. If you move the mic, it is in a different sound field, experiencing different room effects, differ modes, different reflections, different comb filtering, etc. So you are comparing apples to bananas. Or maybe its more like comparing watermelons to golf balls! Or some such. If the mic is in the same place always, then you can validly compare graphs and draw conclusions. If not, you can't.

Simple Logic Team: 2 Internet Myth Team: 0!

The reason why you might want to point a mic at a speaker, is to measure the response of the SPEAKER, but that's not what you are doing: you are measuring the response of the ROOM, and such a room isn't useful for measuring speakers anyway. That's the problem: someone somewhere probably saw a video of speakers being tested in an anechoic chamber, and saw the mic was always pointed directly at the speaker, so they assumed that was the correct way to measure rooms! That's just the correct way to measure on-axis speaker response, and has nothing at all to do with rooms. But that's often how myths are born! "I saw it on YouTube, so it MUST be right!"...

I also bought some monitor stands so I can place them off of the desk and further away to see what that does,

Are they large and massive, as in very heavy? If not, are the hollow? Fill them with sand. If they are light and not hollow, then don't use them. Speaker stands need to be really heavy, massive, solid. some folks here have even been known to stack up concrete bricks and then wrap pretty fabric around them. Others have been known to take a PVC sewer pipe, stand it on end, and fill it with sand. Some buy/build hollow metal stands, and pour in sand of concrete.... You get the picture! The reason is that you do not want the stand to be transferring speaker vibrations into the floor. Sound travels faster through solid materials than it does through air, so you can even get weird and wonderful effects of sound arriving at your ears via the stands/floor/walls before it arrives from the speakers! Massive stands resist vibration. Then decouple the speaker from the stand with some type of soft rubber or foam pads. Some acoustic companies make pads specifically for this purpose, matched to the weight of your speaker.

Also, any suggestions on how far away to have my monitors? I always read that closer to the wall is bad, but I think I read some conflicting information on this site.

Well, there's a very clear, precise, answer to that question: "It depends!". Don't you just love acoustics? Everything is so clear-cut and easy!!!!

OK, the ideal for a small room is to have the speakers about 1.2 m above the floor, spread apart by about 1.5 to 2 meters, and the same distance from your ears. So if your speakers are, for example, 1.8 m apart, then each speaker should also be 1.8 m from your ears (and your ears should be at 38% of the room depth, 1.2m above the floor). That, of course, creates an equilateral triangle, with a speaker at each of two corners and your head at the third corner, with all the angles being 60°.

But that's not written in stone: It's an excellent starting point, but you can vary the angles, distances, and percentages as needed by your room geometry, within a reasonable range, provided that you always maintain symmetry! So whatever you change on the left, you must change the exact same thing on the right.

OK, I didn't say anything yet about your actual question: Distance to walls. The rule here is:

1) Best possible location is IN the wall, such that the front panel of the speaker is flush with the wall: This is usually called "flush mounting" or "soffit mounting" (which isn't technically correct, but the term has kind of stuck).

2) If you cannot flush mount, then get them as far away from the wall as possible, at least 2 m away from all walls. The reason here is that the direct sound from the speaker bounces off the walls and interferes with itself in different ways, creating artifacts. But if you get the speakers more than 2m away from the walls, then the artifacts are at such low frequencies and reduced levels that it doesn't matter much.

3) Next choice, if your room isn't big enough to get the speakers 2m away from all walls while also getting the room geometry correct, then put the speakers right hard up against the front wall. It's sort of the poor man's way of kind of simulating a flush mount.

4) Last and final choice: anywhere else.

Note that for options 1 and 3 to work, your speaker needs to have some for of bass roll-off applied, since placing a speaker in the wall or up against the wall forces the speaker to radiate into half-space across the entire spectrum, instead of just the mids and highs, thus correcting the power response, and negating the need for the compensation that the designer built in to the speaker. So the roll-off control is an absolute necessity for successfully setting up speakers in solution 1 and 3. In other words, mounting speakers like this gives you a bass boost of 6dB (theoretically), and you need to be able to roll that off to get flat response again.


So the conflicting information yo might have seen on that was probably for different situations. It's only a conflict if you take one of the above solutions out of context, without considering the others.

In any event, the number 1, absolute, unarguably, undeniably best place to put your speakers, is in "soffits", also called "flush mounting". A "soffit" in this context is just a large, flat, massive surface with a hole cut in it, to poke the speaker through. Soffit mounting your speakers will give you amazing benefits. But not all speakers are suitable for soffit mounting.

When I get another ECM8000 I will try dropping the cloud ends and see what that changes.

What other mics do you happen to have on hand? If you just want to do before and after COMPARISONS to see what changed, then pretty much any half-decent omni will do. It might not have accurate flat response, but if you only want to compare some graphs taken by the same mic in the same location, then that doesn't matter. You can't use that for accurate measurement of frequency response, of course, but just for comparison, it's fine.


- Stuart -