Home Mix/Edit Room in NYC Residence

Hi Everyone – My previous post was about a space for a friend. This one is for myself. I'm working on a room treatment design for my home. The purpose of the room is a home mixing/editing environment for working when I'm not in the studio. My goal is for the room to be a decent sonic environment for doing editing and mix work in prep for returning to the studio, where final critical work will be done. It may also be a place to get together with clients to discuss mixes, experiment a little, etc. when my partner has a project previously booked in the studio. It will also be a place to work on pet projects. Lastly, it will be a place to practice piano on the MIDI keyboard. Isolation from the neighbors is not a goal of mine. We have decent isolation as it is, and I do not plan to do any tracking or or even mixing at high levels. I want to set up my DAW on a tiny desk with my 88-key MIDI keyboard in front of it. Keyboard and trackball sit nicely atop the e-piano. There will be no console. I have about 7-10 rack mount pieces that trade off between the studio and home, depending on what I'm working on. Permanent setup is Digi 002, two Apogee Rosettas, API 2500, Dangerous 2-Bus, 1U stereo Manley preamp. My monitors are Dynaudio BM15a's on Sound Anchor monitor stands made of large-section rectangular steel tubing. They each weigh well over 100 lbs. I also have two 2'x4' RPG Diffractal diffusors that can be used anywhere we see fit. My current plan is to set up the monitors towards the southern (window) wall, hopefully somewhere around 33% of the way from the wall, firing length-wise down towards the north (entry door & closet). Room construction: Drywall on studs. Ceiling is drywall, but I do not know what's behind that. However, we are the top floor, so it is the last stop before the roof. Floor is hardwood, which is harder than hell (nothing will scratch it -- believe me, I've put it to the test!). Feels quite massy -- no give, jumping doesn't make it bounce much, etc. Factors I Must Work Around: •This is a rental apartment, where we may stay for less than 3 years, so my build-out cannot alter the drywall, floor, ceiling, doors in any way that would require landlord permission/ire. I feel comfortable attaching structures to the drywall with anchors, but need to demolish the treatment and restore drywall to it's original state when we vacate. •The room is asymmetrical on the northeast corner. As you'll see in the floor plan, the entry door is on a splayed wall, which cannot be complimented by any similar construction to create symmetry (access is required to closet door and to window). •I must have room for storage as well. Right now I have two Ikea bookshelves that go floor-to-ceiling, and need to put them SOMEWHERE. Cables, books, DI's, junk I collect -- my wife has the usual rule of my-stuff-my-room, so I have to have shelving to accommodate. •I want the window and air conditioner sleeve on the southern wall to remain exposed and accessible. •There is a radiator on the eastern wall that must remain in-tact and available for heating in the winter. •This IS a 4th-floor NYC rental apt, so I do not want to create any weights that would require permitting or violate common-sense residential limits. If it becomes critical, I'll find the certificate of occupancy and see what the live-load-limit is. •I don't think budget will be a huge issue on this one. If it's a good idea, I'll do it. I'm a happy woodworker and DIY-er, and can't imagine cost will become significant. If it does, and it's worth it, I'll do it. Below you'll see a floor plan, an isometric view of the room's inner walls and openings, and my first idea for front-wall treatment. My thought in this design was to make 703-based superchunk traps for the corners, the right one having a cutout for the window and AC unit, and then have the remaining front wall be a 703 surface with an air gap of 5.5" (I chose that depth arbitrarily). I figure that the frames for the traps will be 1x lumber, but am open to suggestions. Then – something for first reflection points on sidewalls (RPG Diffractals? Or room too small?), standard 703 stand-off bass traps on back wall & closet door, a cloud or other ceiling treatment. Membrane traps if recommended – have built them with success before. Slat resonators? Questions: •Where else/what type of treatment do you see as possibilities for this space? The intrusion of the closet door, the window, the AC sleeve and the radiator limit many of the usual options I can think of. •Does my superchunk with recesses for the window and AC make sense, or will it fail to absorb sufficiently? And will it be terribly unbalanced with the southeast corner's superchunk, which would be uninterrupted? •How do I compensate for the room's asymmetrical design? •What is the lowest profile way of hanging a cloud, and what is the lightest design I could use for a cloud? I love Kendale's clouds, and would love to do something like that -- but I need to be respectful of the existent ceiling and do this in such a way that it can be restored when we vacate. Thanks for your thoughts, everyone! Reed

Have I provided enough info?

Hey Reed.. "My previous post was about a space for a friend. This one is for myself." Cool! Your own place! :) :) It's about time! OK; so from your explanation I guess you could best describe this as basically a multi-purpose control room / office / rehearsal room / listening room / production room, but mainly a control room for mixing?

My current plan is to set up the monitors towards the southern (window) wall, hopefully somewhere around 33% of the way from the wall, firing length-wise down towards the north (entry door & closet).

I guess you mean "around 33% of the way from the SIDE walls"? As in positioning the speakers one third of the room width apart? I think you might want them a bit further apart than that, since the room is only 7'3" wide. If you have them too close together, you won't be able to get your head far enough back in the room and still have a good stereo image.

•The room is asymmetrical on the northeast corner. As you'll see in the floor plan, the entry door is on a splayed wall, which cannot be complimented by any similar construction to create symmetry (access is required to closet door and to window).

I don't think that will be much of a problem: It will be a long way behind your head.

•I must have room for storage as well. Right now I have two Ikea bookshelves that go floor-to-ceiling, and need to put them SOMEWHERE. Cables, books, DI's, junk I collect -- my wife has the usual rule of my-stuff-my-room, so I have to have shelving to accommodate.

How about symmetrically opposite each other on the side walls, just in front of the door, with suitable treatment on the front faces?

•This IS a 4th-floor NYC rental apt, so I do not want to create any weights that would require permitting or violate common-sense residential limits. If it becomes critical, I'll find the certificate of occupancy and see what the live-load-limit is.

It' is ALWAYS a good idea to know how much weight you can put in, but since you only need treatment, no isolation, weight probably wont be to much of an issue. But still good to check.

I also have two 2'x4' RPG Diffractal diffusors that can be used anywhere we see fit.

Do you know what the lowest frequency they are tuned to is? Take that down one octave lower (the still scatter down to an octave below cutoff), figure the wavelength for that frequency, multiply by three: It has to be at least that far away from your head. If the number you come up with is less than ten feet, then take ten feet as the minimum distance. So only place them further away from you than that.

•Where else/what type of treatment do you see as possibilities for this space?

Your basic plan sounds fine, but probably not enough total bass trapping. However, I'd suggest that you use REW to measure the empty room, then measure it again after you put in that first round of treatment, so you can see what changed and what still needs to be done, then add your second round based on that.

•Does my superchunk with recesses for the window and AC make sense, or will it fail to absorb sufficiently?

As a superchunk, it will probably work fine since most of the action is going on at the top and bottom, in the tri-corners, which are well covered in your design. However, there is a symmetry issue there with your speakers: you will be getting asymmetrical reflections off that glass, different for left and right sides. I would try to make that front wall plan more symmetrical.

•What is the lowest profile way of hanging a cloud,

Hooks and eyes. Screw the "eyes" into the ceiling joists, screw the hooks into the cloud frame, and Bingo! Or hook and hook: use hooks on both sides: That way, if you do need to adjust the angle you can add in one link from a piece of chain between the hooks, to drop down one side of the cloud a bit.

and what is the lightest design I could use for a cloud?

Maybe use aluminium extrusions for the framing, lay chicken mesh across that, lay the plastic then the insulation on the chicken mesh, then wrap the whole thing in cloth, and attach the hooks.

but I need to be respectful of the existent ceiling and do this in such a way that it can be restored when we vacate.

Unscrew the hooks, force some drywall filler into the holes, sand and paint. Voila! - Stuart -

Awesome, awesome, awesome! Thanks Stuart! :yahoo: So let's see:

OK; so from your explanation I guess you could best describe this as basically a multi-purpose control room / office / rehearsal room / listening room / production room, but mainly a control room for mixing?

Absolutely, mainly, a control room for mixing and editing. Rehearsal won't happen because it's too small, and I can just "rent a room" elsewhere where a band can spread out and be comfy. The only other uses will be a listening room for work with clients, and every once in a while, an overdub room for a bass player (going in DI) who couldn't make it to the main studio tracking session, etc. etc.

I guess you mean "around 33% of the way from the SIDE walls"?

No, I meant 33% from the rear (southern, windowed) wall. But I've also heard 38% is better, since at that point it isn't a subdivision of the length, either. But from side walls I just figured I'd setup whatever the largest equilateral triangle (2 speakers, back of my head) I could comfortably do without the speakers getting too much blow-back from the sidewalls. Regarding your assessment of the splayed wall, that's very instructive to me. I guess my main worry was that the splayed wall would create SOME sort of weird dispersion that would affect the response everywhere in the room -- but that was based on a wild guess, not science. If it's as simple as "that rear wall is in the far field, your monitors are in the nearfield," then I am pleased as pie. Regarding weights: I'll look it up. The DOB website is a little hairy to wade through, so stay tuned.

Do you know what the lowest frequency they are tuned to is? Take that down one octave lower (the still scatter down to an octave below cutoff), figure the wavelength for that frequency, multiply by three: It has to be at least that far away from your head. If the number you come up with is less than ten feet, then take ten feet as the minimum distance. So only place them further away from you than that.

Here is the explanation of diffusors and minimum room size that no one has ever been able to explain to me. And of course, RPG wants to sell as many units as they can, so they're not going to tell you anything that will discourage you from trying to use them in small rooms. The lowest the Diffractals claim to go down to is 500 Hz (amazing, I know). They're high-freq QR diffusors nested in mid-freq diffusors nested in low-mid freq diffusors, so they are definitely quite advanced... at any rate: 500 Hz /2=250 Hz 250 Hz wavelength ≈ 4' 7", which is < 10', so we go with 10' Conclusion: they can ONLY be used on the back wall, if at all. But that could be interesting: mount the diffusors on the back wall, one hung on the closet door, for a Live End-Dead End design? Or will the lobing be jammed by the room width only being 7' 3" wide? (<10')

Your basic plan sounds fine, but probably not enough total bass trapping. However, I'd suggest that you use REW to measure the empty room, then measure it again after you put in that first round of treatment, so you can see what changed and what still needs to be done, then add your second round based on that.

Ah, an empiricist, eh? But what about well-argued imaginary philosphical armchair science??? :lol: I use Metric Halo's Spectrafoo, which I will dutifully employ for this task. I shall report back on this.

However, there is a symmetry issue there with your speakers: you will be getting asymmetrical reflections off that glass, different for left and right sides. I would try to make that front wall plan more symmetrical.

I wonder how... maybe a second piece of glass in front of the current window at the same angle as the bass trap? At least that would get it moving instead of just shooting right back. I'd introduce a three-leaf design, but I don't think I care. Thoughts? Thanks Stuart! ¡ Que tenga buen día ! R.

No, I meant 33% from the rear (southern, windowed) wall. But I've also heard 38% is better, since at that point it isn't a subdivision of the length, either.

I think you might be confusing your ears with your speakers! The 38% location is where your ears should be, not where your speakers should be. That's the theoretical location where the modal nulls and peaks are least offensive, but it's also just a guideline, a starting point, not a carved-in-stone rule. Your speakers should be at least 2 meters (roughly 6 feet) from the front wall if you want separation, but your room isn't big enough to do that. So the next best option is to have them right up against the front wall, with fat absorption between them and the wall. Of course, better than either of the above is to have them in soffits, but that doesn't seem to be an option in your case, due to the "temporary" nature of the studio, as a rental. So it seems your best option is up against the front wall, on stands.

But from side walls I just figured I'd setup whatever the largest equilateral triangle (2 speakers, back of my head) I could comfortably do without the speakers getting too much blow-back from the sidewalls.

The apex of the equilateral triangle should actually end up a few inches behind your head, if the geometry is set up correctly. When figuring this out, lots of people tend to forget that their ears poke out the side of their head, not the front, so if the speakers are properly aimed at the ears, then the axes will intersect behind your head, not inside it. So start by setting up your chair such that your ears will be at roughly 38% of room depth (front to back), set your speakers on stands up against the front wall at roughly the 30% and 70% positions (maybe even 25/75), and point the speakers at your ears. In your case, the angles of he speakers in that triangle will be a bit less than 30°, and the angle of intersection will be a bit less than 60°, because you have a long, thin room. So play around with that a bit, to get your speakers as far apart as you can, and the angles as close to 30° as you can, and your ears as close to 38% as you can. Do you juggle at all??? :) It ain't gonna work out perfect, so just trade things off against each other, until you find something that makes sense. In general, keep the speakers out of the room corners as much as possible, since corners don't do nice things to speakers. But also don't bring them so close to each other that the toe-in angle, and therefore the stereo image, suffers, and also so that your head is not at the dreaded 25% or 50% positions.

If it's as simple as "that rear wall is in the far field, your monitors are in the nearfield," then I am pleased as pie.

Something like that! But not quite as clear-cut... :)

500 Hz /2=250 Hz 250 Hz wavelength ≈ 4' 7", which is < 10', so we go with 10'

You forgot one step in the process: "multiply by three". So the answer is more like 13 and a half feet, minimum. The reason for the "multiply by three" thing is simply that you need at least three full wavelengths of the lowest frequency in order for the lobing issues caused by the diffuser to start smoothing over. Some experts say it should be more like SEVEN full wavelengths... Diffusers mess with both the direction and the timing / phasing of sound waves, and up close there are "lobes" of higher level energy in some directions, lower in others. As you get further away, that smooths out. The distance where it is "good" (whatever that means! :) ) varies depending on which expert you listen to, but "at least ten feet" seems to be the general consensus, while 3 x lowest wavelength and 7 x lowest wavelength are both derived from the mathematics, apparently. Some folks point to a test that Ethan Winer did (check his web site for the video), and claim that he "proved" that you can get close to numeric sequence diffusers without problems, but that isn't true: what Ethan proved is that you can play instruments close to diffusers and get nice warm sounds from them, that record well, but he did not claim to be proving that you can use diffusers close to your head in a control room! Very different thing.

wants to sell as many units as they can, so they're not going to tell you anything that will discourage you from trying to use them in small rooms.

Ya think? :) Yup, that is, unfortunately, the case with many manufacturers of acoustic products: They tell you the truth about what their products do, but maybe not all of it... And of course, some of them even dispense with the "truth" part. (Not RPG: they are among the good guys, and do sell good products). But as you say, the issue with lobing and usable distances is not exactly listed in large glowing neon signs... Diffusers are great for large rooms, not so great for small rooms.

for a Live End-Dead End design?

LEDE design fell out of favor many years ago: Engineers found that it wasn't pleasant to be stuck in a room like that all day, every day. Acoustically fatiguing. That concept was developed further, the "unpleasantness" fixed, and today the more popular design concepts are RFZ and CID, with a touch of "Non-Environment" thrown in for good measure.

Ah, an empiricist, eh? But what about well-argued imaginary philosphical armchair science??? I use Metric Halo's Spectrafoo, which I will dutifully employ for this task. I shall report back on this.

Naah, no armchair science philosophy here! What you REALLY need is a Rockwell Turbo Encabulator: Does the job better than any other... It's the unilateral phase detractor that makes the difference, in my opinion. http://www.youtube.com/watch?v=oIS5n9Oyzsc :) - Stuart -

http://www.youtube.com/watch?v=oIS5n9Oyzsc

Oh my God, dying of laughter. And how many times have I heard such thing said with a serious face... http://www.youtube.com/watch?v=bjmYee2ZfSk And thankfully corrected -- I had thought it was SPEAKERS at 33%, not ears... now it makes sense. EARS at 33%, speakers in a location determined by different criteria. Also, duh, thanks for the clarification of the "x3" part and lobing. I do also respect RPG, and have read many of D'Antonio's articles (through to the math I can't understand -- what the hell is a modulo???), so they're not the baddies. But you're right, they don't scream through a bullhorn that their best pieces have no place in a small room. Q: Did you like my slanted glass idea to eliminate direct first reflections? Or am I barking up the wrong tree here? As Always, R.

now it makes sense. EARS at 33%,

38%. Not 33, but 38. :)

Q: Did you like my slanted glass idea to eliminate direct first reflections? Or am I barking up the wrong tree here?

Ahh, sorry! I missed that one. I think the encabulator dingle arm must have spindled it...

I wonder how... maybe a second piece of glass in front of the current window at the same angle as the bass trap?

Maybe just better to cut the insulation on the other side in the same way as on the glass side. The drywall between reflects roughly the same as the glass, at the frequencies we are talking about. So you could just make the left side insulation a mirror image of the right side. - Stuart -

Maybe just better to cut the insulation on the other side in the same way as on the glass side. The drywall between reflects roughly the same as the glass, at the frequencies we are talking about. So you could just make the left side insulation a mirror image of the right side.

THAT's interesting. That reminds me of a recording I did of a marimba part where one mic's output was a bit hissier than the other. They were two Telefunken ELA M 251's, so I wasn't about to swap them out with a pair of 57s. Their response was similar, but the hiss on one side made you go cock-eyed when you listened to it. I tried noise reduction tools and none of them did the trick. Finally, I just added a little his from another high-quality preamp on top of the cleaner track and -- voila! You didn't hear the hiss anymore, it just sounded like a gorgeous, detailed, stereo marimba! Here's my question, though: for symmetry, do we only care about highs reflecting and comb-filtering, etc., or is asymmetrical bass trapping also apparent to the ear? Since those waves are so huge, part of me intuits that bass trapping itself (at least in a room this small) affects bass everywhere in the room (as long as it includes the tricorner). Is that true? Or is it "true, but still you'll notice?" Or is it false and the left speaker in my old design would just have much tidier bass response than the right? Inquiring minds want to know. Back to the encabulator... R.

Here's my question, though: for symmetry, do we only care about highs reflecting and comb-filtering, etc., or is asymmetrical bass trapping also apparent to the ear? Since those waves are so huge, part of me intuits that bass trapping itself (at least in a room this small) affects bass everywhere in the room (as long as it includes the tricorner). Is that true? Or is it "true, but still you'll notice?" Or is it false and the left speaker in my old design would just have much tidier bass response than the right?

Interesting question! The answer is "yes" :) But since you asked both sides of the issue, then you'll have to guess which side the "yes" is for!!! :shock: :lol: :!: :roll: OK, let's put it this way: There is no specific cut-off point where you can say the room boundaries and treatment just plain stop affecting waves of longer wavelength, and affect them totally above that. Rather, it is a gradual transition across the entire spectrum, but even then it isn't linear. So some parts of the spectrum will be more affected, and others less affected. Also, it isn't just about comb-filtering: that's just one of several possible issues, and some studies show that comb filtering isn't even hugely important, as long as the pattern doesn't change. So it's a complex issue. And finally, bass trapping isn't just about evening out the bass in the entire room: it is also very much about room modes. So even though putting a large, thick bass trap on the rear wall will certainly have an effect on the way 78.3 Hz sounds in the entire room, it won't necessarily have any effect at all on a room mode that happens to be tuned to 78.3 Hz, if that mode happens to be associated only with the side walls, or only with the ceiling and floor. It would only have an effect if the mode happened to be associated with the rear wall. And one more thing: it's hard to separate out just "the bass" when we are talking about real-world music. Even a bass guitar puts out substantial energy in higher frequencies (especially for "slap"), so even though the bass absorption in the entire room might be fine, if it is not symmetrical at higher frequencies the entire bass line sounds "skewed", not just the lower frequencies. That's probably more of a psycho-acoustical effect than a real measurable effect, but it is there, nonetheless... So the answer is a qualified "yes": it does matter, and symmetry is important at all frequencies, to differing degrees. If you want to convince yourself, find an empty room in your house (no furniture), set up your system properly (speaker / listening position geometry) and symmetrically in that room, and listen carefully to good commercial music for a while, paying great attention to the lows. Now put one single large roll of fiberglass insulation, standing up in the front left corner of the room only: nothing else. Listen again to the same music, once again paying special attention to the bass. Sound skewed? You bet it does! Now add another identical roll to the front right corner. Sound symmetrical and even again? Yup. :) - Stuart -

That's very interesting. In that mental experiment, I can "hear" exactly what you mean! But aren't lower frequencies so large in comparison to your head (no longer "casting a shadow" as a barrier) and to the room (therefore non-directional within the space) that it SHOULDN'T skew the image? Or does this have to do more with the feedback characteristics I've read about, where the each monitor's response changes according to it's proximity to the room's six (or in my case seven) boundaries? Well anyway, here are 2 screenshots of my room in Sketchup (file has become too large to post), integrating your suggestions: Note the new additions: 1) Implemented Stuart's idea of making a symmetrical cutout to mirror the window on the back wall. :yahoo: 2) I have added a slot resonator on the back left wall, taking up the extra space in the corner. It will have to be shallow--9 ¾" shell at the deepest section. Will this do good things in terms of absorbing bass in a way that doesn't mess with my symmetry? Just trying to think of good ways to trap as much bass as possible. :?: 3) I have placed the two bookshelves symmetrically as far back in the room as the splayed wall will allow, putting them well behind the listening position. I also put corner superchunk trap on the closer side of the bookshelf to the listener and speakers-- 1' x 1'. I know that the bookshelves hardly constitute a boundary: Will this absorb bass the way I want? Or just mess things up? 4) Mores superchunk on the left and right wall-ceiling junctions, measuring 1' 3" x 1' 3", making a hypotenuse of 10 ⅝" -- by my calculations, assuming the trap works down to the quarter-wavelength, that means it will absorb efficiently down to 330 Hz. That's still not getting into the real deep-bass trouble areas, I suppose. Remaining Q's: 1) What other kind of trapping should I add? 2) Am I finished dealing with the window opening? Or keep going? I thought of putting something removable in the symmetrical window gap--either a light-weight frameless 703 plug that holds in by friction, or even curtains that can be retracted to the drywall side when critical listening is not the objective, so I can have light, & then when I need to do real mixing, slide them back over to cover all reflective surfaces. Are either of those a good idea? :idea: OTHER, BRIGHTER THOUGHTS? :D Thanks all, Reed

But aren't lower frequencies so large in comparison to your head (no longer "casting a shadow" as a barrier) and to the room (therefore non-directional within the space) that it SHOULDN'T skew the image?

True, but your brain does not just relay on shadowing to determine direction: it also uses the slight difference in level, and also the difference in timing: Even though the wave passes by your head as though your head was not there, (curiously, I often do have the feeling that my head is "not there at all" when I'm mixing some types of music! :) ), the wave still arrives at one ear just a little bit before it gets to the other ear, and your brain is really good at using those timing difference to figure out which direction the wave came from. And while it's true that we speak of low frequency sound as being "non-directional", that is more about the way it propagates, not the way we perceive it. The waves expand out roughly equally in all directions from the source of the sound, but we still can figure out in which direction that source is located, relative to us. Subtle difference. The wave is not directional as it propagates in the sense that it goes out in all directions evenly, at the same level, but we can still tell where it came from. So the wavefront is not directional, but our hearing system is. Another thought experiment (or a real one too, if you want to try it!). Set up a kick drum way out to the left side of the stage in a real room, and then stand in the middle of the room with your eyes closed while someone thumps the drum: Can you tell where the drum is, roughly, just by listening? Yup. Move the drum to the right side of the room, and repeat. Can you tell that the sound is now coming from the other side of the room? Yup. Perhaps not as accurately as for higher frequency sounds, but still well enough to know the direction. One more: In your next mixing session, pan the kick and bass hard left, but leave the rest of the mix in tact: can you hear that they are now way off center? Yup. So why do we always pan the lows centered, then? Ahh, well, that's another story entirely: more to do with the vinyl recording process for stereo LPs, and tradition, and convention, and what we have come to expect, rather than any real acoustic reasons. Put it this way: it just sounds "better" with the bass panned center. - Stuart -

Well explained, Stuart! It makes so much sense to me now. Thanks! What do you think of my new treatment plan? :D -Reed