John Sayers' Recording Studio Design Forum Archive

Hi guys!!

Looooong time site-follower, first time poster. My name's Colin, and I'm a freelance audio engineer working out of Boston, MA. I am currently working out of my apartment, and have a very DIY set-up. I run ProTools and have a solid recording rig with some outboard processing (Apollo Twin interface, API Lunchbox with Hairball Pre's and some DIY compressors). I primarily work out of a local recording studio on which I am a staff engineer with a wonderfully treated room. However, as I've just upgraded to a set of my own Adam A7X monitors, I very much want to get my own room treated as well as it can be to work from home!

I plan on using my room primarily for mixing, basic tracking (mostly vocals) and production, and critical listening. I do have neighbors, however living in a very college-city, noise is not usually a problem in terms of neighbor-friendliness! The walls and ceiling are gypsum, while the flooring is hardwood about 75% covered with a throw rug. I also have 24 pieces of 12x12" room treatment bought with my speakers to start with (having briefly worked at GC I knew how to finagle a deal ). I also have two ~25 lb speaker stands with rubber isolation on top and bottom. My mixing desk is entirely made of wood (pine with rosewood), for whatever that knowledge is worth. I have a large bookshelf on the rear wall, and also have lots of canvas paintings covering the walls with several hanging acoustic guitars.

Room Dimensions:
L (outward wall): 11'7" (with three 60"x26" windows in a 9" deep window well)
(inward wall): 11'8" (7'3.5" of which is recessed by 14")
W (front wall): 10'7"
(back wall): 9'8"
H: 8'8"

Here is my (very rough) sketch using SketchUp. Here also are some quick JPEG's My primary concerns/questions are:
- The room is fairly boxy - will it be possible to control this room?
- How can I address a wall almost entirely of windows?
- Is my basic speaker/mixing desk orientation a good starting place for monitor placement, especially considering the recession/doorway situation on the inward wall?
- I plan on doing the basic/general treatment (diffusors directly behind speakers, on the rear wall behind my head, diffusors on the adjacent walls to my ears, diffusors in all of the corners). Given my specific room, where should my attention go?

Basically (if it's not completely obvious by now), I am very much so a newbie, acoustically speaking , so really any sort of advice or points in the right direction would be phenomenal. Thank you so so much guys, can't wait to start to be a part of this wonderful forum!

Hi there Colin, and Welcome!

That's a strange shaped room, with the "kink" in the right wall. That's going to cause some issues, but unless you can move that wall (! !) You'll just have to live with the symmetry issue. It's behind your head, so it won't be too disgusting, but it will still be there.

OK, layout: The room is too small to be able to have the speakers away from the front wall, so they will have to go tight up against it, with only enough gap for the treatment between them and the wall. The A7X doesn't have any cooling issues, so the rear corner of each speaker can be pressed against the panel, to minimize the SBIR and comb filtering artifacts.

So your speakers go up against the front wall, and each of them should be 35" from the side wall, and 48" above the floor. That will place the speakers 57" apart. HOWEVER! All of that refers to the location of the acoustic axis of the speaker, not the top, bottom or side of the cabinet. Adam can tell you where that is, or if not, then we can estimate it.

Mix position: On the center line of the room, with your head (ears) positioned about 54" from the front wall. With all that in place, set up a mic stand about 16" behind your head, also on the room center-line, and angle the speakers so they are both aimed at that stand. Once again, it's the acoustic axis that needs to be aimed at that point. One easy way to do that is with a couple of cheap laser levels taped carefully to the top of the speaker, directly above the acoustic center, so that the beam is aligned with the acoustic axis. Then just fiddle around with the speakers so that both beams hit the mic stand at the same point, while the speakers remain correctly positioned, 35" from the side walls.

That's the roughly correct layout. We'll adjust it later, to see if it can be improved, but after you get the basic treatment in...

while the flooring is hardwood about 75% covered with a throw rug.

Get rid of that, at least for the initial testing. Carpets are not good, acoustically. Ever wonder why you seldom see carpet on the floors of world-class control rooms? There's a reason.... (We might need to put some type of carpet or smaller rug on the floor for the final tweaking, but not that big).

I also have two ~25 lb speaker stands with rubber isolation on top and bottom.

Is there any way you can make them heavier? Are they hollow? If so, fill them with dry sand. More mass would be good.

Treatment:
First, bass traps. Big ones (it's a small room, so you need BIG bass traps. Nope, not the size you are thinking of... I mean BBBIIIGGG!)

I would put 24" superchunks in each front corner, a 36" superchunk in the left rear corner, and another superchunk in the wall/ceiling corner of the rear wall. Cover all of those with 4mil plastic, before you put the fabric on them.

You will also need to make a "mini superchunk" for that "kink" in the right wall: Make it at least 18" long (along the side wall) and as deep as the kink goes (14"?).

All of that can be done with 4" OC-703.

You'll also need 4" of OC-703 for those panels I mentioned that go between the speakers and the front wall. That needs to extend at last a couple of feet above and below the speaker, and at least a foot out to each side.

Do the same for the first reflection points on the side walls, and a cloud on the ceiling, above the desk.

Finally, the rear wall: Lose the bookcase, and cover the entire rear wall with 6" of OC-703

That's your basic treatment. With all that in place, try moving the speakers left and right just a bit, maybe an inch or two, to see of there might be a better spot, and also try moving the listening position a few inches forward/backwards.

If you really want precision tuning, then before you put any treatment in the room, do a full test with the REW acoustic software package (free!), and post the results here for us to analyze. Then do another test after you put each part of the acoustic treatment in.

The room is fairly boxy - will it be possible to control this room?

Well, it won't be Abbey Road, but it can still give you pretty good results.

- How can I address a wall almost entirely of windows?

You'll have to cover up part of that with the front and rear superchunks, so you'll need to come up with some type of self-supporting frame that stands on the floor and does not need to be screwed into the window behind it. You'll also need to put your first-reflection-point treatment for that side on a stand that goes up against the glass. You might also need other treatment there: REW will help to determine that.

especially considering the recession/doorway situation on the inward wall?

It's certainly not ideal as it prevents you from getting a truly symmetric room, which is very important, but there doesn't seem to be any other way of orienting the room, as far as I can see. So you'll just have to live with the skewed sound-stage and offset stereo imaging, unfortunately.

- I plan on doing the basic/general treatment (diffusors directly behind speakers, on the rear wall behind my head, diffusors on the adjacent walls to my ears, diffusors in all of the corners).

Nope. Not possible. The room is too small to be able to use diffusers. For a room that size, your only real option is absorption. So I'd suggest that you sell the diffusers, and use the money to buy lots of OC-703.

Thank you so so much guys, can't wait to start to be a part of this wonderful forum!

Excellent! And please do keep us updated on your progress! Post some photos of the room at each stage, and also post the REW file. That way, if we notice that something isn't right, we can correct it before it's too late.

- Stuart -

Stuart! Thank you so so much! This is why I love this forum... Anyway, I don't have much by way of a response just yet, but I at least wanted you to know I've seen (and hugely appreciated) your post and I'm on it!

Next I shall clear the room of the rug and the bookcase, set up the monitors as to your specs, and get to REW testing! I'll be back shortly with some results

Thanks so much again! I'm a huge fan of DIY so I'm all giddy at the idea of having at all this!

Okay so I couldn't sleep/stop fidgeting till I did something!

I've rid the room of both the rug, and the bookcase. I've also revamped the computer desk and everything along the front wall. I've placed the speakers, with acoustic axes 35" from the side wall (perfectly framing the artwork, I knew one I was gonna reap the benefits of putting that in the exact middle of the room ) and the mix position to be 54" away from front wall along the center line. How are we lookin' so far, before I go testing? Also apologies for the slight unkemptness of the room
Questions:
- I'm assuming the center line would be based on the total width of longest wall, i.e. not accounting for the recession/"kink" in the right wall?
- I can't find any info in the manual/Adam website about the acoustic axis of the A7X. Based on some stuff I've read online, I've estimated it to be the point between the center's of both the tweeter and the woofer. Halp?
- Horizontal vs. vertical speaker placement? The stands' platforms are ~45" off the ground, and are unfortunately not adjustable. Placing the speakers horizontally puts the acoustic axis just about exactly 48" off the ground. Placing them vertically puts it to about 52" off the ground. Thoughts?? Am I just gonna hafta get new stands...
- Also, my greenhorns were showing - I bought acoustic foam, and not diffusors. Specifically, I bought the Ultimate Acoustic pack of both wedges and bevels. Will these help me at all in addition to the OC-703, or should I just totally ditch and go 100% OC-703?
- Will a load of bagged drums/hardware along the lower half of the back wall be disastrous? Or should I get them out of the room when testing.

Either way - hooray insomnia!! As always thanks so much! This is so exciting

Okay so I couldn't sleep/stop fidgeting till I did something!

Gotta love enthusiasm!

How are we lookin' so far, before I go testing?

Fine!... except that your speakers are laying down on their sides... So "not so fine". More about that below...

- I'm assuming the center line would be based on the total width of longest wall, i.e. not accounting for the recession/"kink" in the right wall?

Exactly. It is in relation to the front wall, then one where the speakers are. The one we see in your photo.

- I can't find any info in the manual/Adam website about the acoustic axis of the A7X. Based on some stuff I've read online, I've estimated it to be the point between the center's of both the tweeter and the woofer. Halp?

It's actually a bit higher than that, closer to the tweeter. With the A7X, I'd go for a spot almost on the edge of the ART module. And yes, the axis will be at some point on the imaginary line that joins the center of the woofer to the center of the tweeter.

- Horizontal vs. vertical speaker placement?

Yup. That's a problem. Here's why: You do sometimes see that arrangement in photos, and even in some speaker manuals, but for the exact reason shown above, it's a bad idea if you want high precision in your room... or if you ever happen to want to move your head!

The stands' platforms are ~45" off the ground, and are unfortunately not adjustable. Placing the speakers horizontally puts the acoustic axis just about exactly 48" off the ground. Placing them vertically puts it to about 52" off the ground. Thoughts?? Am I just gonna hafta get new stands...

Try it with the speakers standing vertically and the axis at 52". The Adam ART drivers have pretty good dispersion characteristics in vertical, and your head should be far enough away that you'll still be reasonably close to on-axis. It's worth doing a test like that, to see what REW shows, and also a listening test with music you know well, to see how it sounds.

Specifically, I bought the Ultimate Acoustic pack

Which manufacturer? There's good foam, and not-so-good foam. And there's also "foam-by-mail-order", which I would only use as a mattress for my dog to lie on... (except that I don't have a dog right now, so I guess I'd just use it to line the trash bin... )

If it is good foam from a reputable manufacturer, then you cold probably use some of that. Better still if you have a link to the exact make/model of the pack you bought, so we can check out the acoustic properties.

- Will a load of bagged drums/hardware along the lower half of the back wall be disastrous? Or should I get them out of the room when testing.

It would be better to get them out for the testing. And any other acoustic instruments, or in fact anything at all that might vibrate, rattle, or resonate. You want to be sure that you are measuring what the room is doing, not how long your floor tom can sustain a note!


- Stuart -