To flush or not to flush?

[saemola]

Hello fellas,

I'm about to finish my personal studio construction.
It's a single room mainly for mixing short films and ads and for composing music.
I'm about to build the inside room of a room-within-a-room construction, and the final inside room dimensions (with drywall and Rockwool) will be about 3x4,8m/10x15.7', room height will be 3,5m/11.5' and I'm shooting for an RT60 of 0.2 seconds.

Here are the options I'm considering for my JBL LSR2328p monitors placement:
A) 25°, flush into a trapezoid structure built into the corner of the room (like the left speaker pictured)
B) 30°, non-flush with speakers on stands and the backside of the speakers about 40cm/16" from the back wall (like the right speaker pictured)
C) 25°, non-flush with speakers on stands tucked into the corner (like the left speaker pictured, but without the trapezoid structure)

Questions if the flush route is the way to go:
1) should I build the trapezoid corner the same way I'll be building the inside room (80mm 40kg/m3 Rockwool, 2 layers of 15mm/5/8" drywall with Green Glue) or should I build it with 15cm/6" hollow concrete blocks plastered on both sides like the outside room?
2) can I also use the construction as a bass trap above and below the speaker?
3) how should I account for speaker ventilation?
4) is the fact that my speakers are rear ported an issue?
5) is it ok to place the speakers in a structure that is slightly larger and use a removable front frame? This way I can be prepared for future speaker replacement in case the speakers will be larger.

Extra question:
1) how high would it be advisable to mount the speaker?

Am I oversimplifying here?
I'd love your feedback on this!

sp_pl_v.jpg

[Soundman2020]

H there "Saemola", and Welcome!

will be about 3x4,8m/10x15.7', room height will be 3,5m/11.5' and I'm shooting for an RT60 of 0.2 seconds.

With a ceiling that high, you could probably shoot for a slightly longer decay time. Maybe 230ms, or even a bit more.

Here are the options I'm considering for my JBL LSR2328p monitors placement:

Answer: None of the above!

Option "A" and "C" are both bad, as they would place your speakers in the corners of the room, which is not a good location at all. Option "B" is bad because it places the speaker too far from the front wall: The room is not big enough to be able to move them away from the front wall.. With a 40cm gap, all of the SBIR artifacts and initial comb filtering from that will be in the low frequencies, where it will be very audible. You need to force it up as high as possible, into the low mid range, where it isn't so noticeable. You do that by putting the speaker tight up against the front wall, except for a gap of about 10cm, where you will put a 10cm thick panel of porous absorption, such as OC-703.

What I would suggest is to, indeed, flush-mount your speakers, but do it properly. Flush mounting is sometimes also called "soffit mounting" (which isn't really correct, technically, but a lot of people still call it that!). Soffit mounting involves building a structure to hold the speaker firmly in place, and with a thick, heavy front "baffle" (front panel) with a hole in it, for the speaker to poke through. There are many examples of soffit-mounting here on the forum. Here's one I did for a customer a while back, where you can see the results: http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471

1) should I build the trapezoid corner the same way I'll be building the inside room (80mm 40kg/m3 Rockwool, 2 layers of 15mm/5/8" drywall with Green Glue) or should I build it with 15cm/6" hollow concrete blocks plastered on both sides like the outside room?

It's not really trapezoid, and isn't in the corner, but you can build it either of those two ways. The more mass, the better. I normally use two or three layers of thick wood, often with other methods for increasing the mass of the baffle.

2) can I also use the construction as a bass trap above and below the speaker?

Yes you can! I always do that, when I can. I prefer to use John Sayers method of putting acoustic hangers below the speaker, and I often just use a lot of porous absorption above.

3) how should I account for speaker ventilation?

The normal method is to make a sort of "chimney" out of wire mesh (such as "chicken wire"), starting just above the box that holds your speaker in place, and extends upwards a couple of feet, then out through a large "slot" in the baffle. That wire mesh keeps the insulation away, leaving a path for the air to follow. You also need a large slot in the shelf that the speaker sits on, of course, so it can draw air up from the hanger section, by convection. You must make sure that the "slots" and chimney are large enough to provide sufficient airflow past the rear of the speaker. In some cases, you might need to put a small fan in there somewhere (a very quiet fan!) to move enough air.

4) is the fact that my speakers are rear ported an issue?

Yes and no. Yes, it can be a problem if you don't deal with it correctly, but "no" it is not a problem in most cases, for most speakers, if you design the soffit correctly. The Eve SC-407 speakers that you see soffit mounted in the link I gave you above, are rear-ported. And they work just fine! You can see that in the acoustic graphs: even though they are rear ported, due to the design of the soffit there are no bad effects at all from having them soffit mounted.

The bass reflex port on a speaker only serves to extend the response a little lower, so that the speaker seems to work down to frequencies lower than what it would if the port was not there. But soffit mounting does the same thing, and does it even better! So if you do it right, then there is no problem. Rear-ported speakers can be soffit-mounted successfully, as long as it is done correctly.

5) is it ok to place the speakers in a structure that is slightly larger and use a removable front frame? This way I can be prepared for future speaker replacement in case the speakers will be larger.

Yes. That's exactly what I did in the original soffit design for the room in that link. I designed the soffits to have a large removable "tray" inside that could be pulled out to replace the speakers. A couple of years later, the owner decided to upgrade his old Genelec speakers to the new Eve SC-407 speakers, so he simply pulled out the old tray and slipped in the new tray. I had to design a different tray, of course, since the speakers are very different sizes and need very different mounting, but the actual swap of the old speakers for the new ones went very fast: he just loosened off the mounting nuts for the tray, took out the old tray with the old speaker in it, inserted the new tray with the new speaker in it, tightened the nuts again, and it was done! (Well, OK, so we also did a bit of careful re-aiming and re-tuning, but the actual swap was simple).

1) how high would it be advisable to mount the speaker?

The correct height for speakers in a control room is 1.2m above the floor. That number refers to the height of the acoustic axis! Not the height of the top or bottom of the speaker itself. Not the height of the woofer cone: the height of the acoustic axis. If you don't know where the acoustic axis is on your speaker, then check the manual, or ask the manufacturer. If they don't tell you, then let me know, and I can help you estimate where it is, approximately.

Am I oversimplifying here?

Not at all! In fact, you are UNDER-simplifying! Soffit-mounting is not easy to do right, but it is very, very, VERY recommendable. Soffit mounting your speakers means that you totally eliminate most of the artifacts associated with having the speaker in the room. No more front-wall-related SBIR, power imbalance, edge diffraction, phase-cancellation, comb filtering,or any of the other major problems from having a speaker inside the room.

I'd love your feedback on this!

There's another major problem with your room layout: your client sofa is in front of your mix position, not behind it, where it should be! And your mix position is way too far back in the room: your head should be much closer to the front wall than the back wall. The theoretical optimum point is 38% of the distance between the front wall and the back wall. Your speakers are too far apart as shown in the diagrams, and the angles are wrong. If you fix all of that, and also soffit-mount your speakers, and also install the correct acoustic treatment in the right places, then then you can have a very nice control room.


- Stuart -

[saemola]

Stuart, you are a well of knowledge.
Thank you for also helping me in the construction thread I posted in the other section of the forum (still pending! Shameless plug ).
Your explanation is crystal clear and it gives me a lot to research and think about. I think I understood most of what you said, so I'm only going to address what I'm still confused about.

You do that by putting the speaker tight up against the front wall, except for a gap of about 10cm, where you will put a 10cm thick panel of porous absorption, such as OC-703.

Wouldn't that be exactly like option A plus a 10cm gap between speaker and front wall? Or are you suggesting I move the door? That's really the only place the door can go, and I'd rather not flip my design 180 degrees as I'd like to see through the glass door since there's natural light coming in (a luxury for a studio!). But if that's the only way to do this I guess I'll have to compromise.
Any alternatives to OC-703 you would suggest that can be found in Europe?

I often just use a lot of porous absorption above.

Would 30kg/m³, 85cm glass wool work?

The correct height for speakers in a control room is 1.2m above the floor.

And that's regardless of the room height?

your client sofa is in front of your mix position, not behind it, where it should be! And your mix position is way too far back in the room: your head should be much closer to the front wall than the back wall.

That hurts. I'm really trying to keep my clients away from the editing monitor ("I think the automation should look more like This...") and the idea of my room revolved around this whole concept. Again, I'll have to compromise if necessary, but a different solution would be preferable. Could I maybe use a diffuser behind me to tacke this issue? Or is this a critical distance problem? I calculated that, with an RT60 of 200ms, I was gonna be right at the limit of the critical distance.

The theoretical optimum point is 38% of the distance between the front wall and the back wall.

I considered 38% from the back wall in my design.

Your speakers are too far apart as shown in the diagrams, and the angles are wrong.

How far apart should they be? Is 25-30° not a good angle?

Thanks for everything Stuart, this is priceless advice!

[Soundman2020]

Wouldn't that be exactly like option A plus a 10cm gap between speaker and front wall? Or are you suggesting I move the door? That's really the only place the door can go, and I'd rather not flip my design 180 degrees as I'd like to see through the glass door since there's natural light coming in (a luxury for a studio!). But if that's the only way to do this I guess I'll have to compromise.

Sorry about that! I should have clarified that I was talking about having the room flipped 180°. If the door was centered on that other wall, then that would be fine, but it isn't centered, and happens to be exactly where the speaker needs to go, unfortunately. So you could move the door if you wanted to, or you could flip the room if moving the door is too much of a hassle.

Any alternatives to OC-703 you would suggest that can be found in Europe?

I found this link. Not sure if it is any use: http://www.owenscorning.eu/en/distribution/

Would 30kg/m³, 85cm glass wool work?

That would be fine.

The correct height for speakers in a control room is 1.2m above the floor.

And that's regardless of the room height?

Correct. It's not related to the room at all, but rather to YOU! 1.2m above the floor is the height where your ears are, for most people, when seated...

If you happen to be exceptionally tall or exceptionally short, then you might need to adjust that a bit, but for the majority of people it works out really well. The point of having the speakers set to the same height as your ears is rather simple: So that your ears are on-axis to the speaker! For pretty much any speaker, the cleanest, smoothest, flattest response is along the acoustic axis. As you get away from that axis, the smoothness of the frequency response drops off, and you start running into artifacts. For most speakers, the horizontal direction is better than the vertical, in that you can be maybe 20° or even 30° (very high-quality speakers) off-axis to the left or right and still have reasonable response, but in the vertical plane it is different. Many speakers only give you 10° to 15° or so off-axis before you run into problems. In other words, you ears need to be very close to on-axis vertically, so if your ears are 1.2m above the floor, then your speakers need to be set up the same way: such that the acoustic axis is 1.2m above the floor.

That hurts. I'm really trying to keep my clients away from the editing monitor

Then position and angle the video screens so that the clients cannot see them! And use lighting creatively, so there will always be glare on the screens for anyone sitting at the client couch, but not for you...

and the idea of my room revolved around this whole concept.

Take a look at photos of a few dozen well-regarded pro control rooms from recent magazines, or on the internet: How many do you see that are set up like that? If you come up with any number greater than "zero", I'd be surprised... There's a reason for that...

Could I maybe use a diffuser behind me to tacke this issue?

Nope!

There are multiple issues here. One of them is called the "Haas effect". That has to do with a psych-acoustic issue that was discovered by a smart guy called "Haas". He figured out that our ears and brains are really lousy at dealing with "echoes" or "copies" of the same sound that arrive at our ears with only a very brief delay. If you hear an echo across the grand canyon, it will come back to you many seconds after you made the sound, and your brain is amazingly smart at figuring out that it really is an echo. The same happens for echos coming from much closer: even echos coming back at you from a wall 20m, or 10m way, your brain can figure out. But when the wall is closer than about 3m, your brain quits: It can't process such short delays. Instead of realizing that the "echo" is the same sound repeated, for delays of less than about 20 ms it says that it was not an echo at all: it was just a "smeared" sound that came from a different direction and had a different pitch. It turns out that our ears use those very short time delays to help figure out which direction a sound came from in front of you, so it cannot also use the same information to figure out that the sound was actually an echo from very close by behind your. Our ears/brains can't do that. So for short-delay echos, our brain says it wasn't an echo at all: "rather", says the brain, "that was just one single sound that came from a different direction..."

In other words, for short-delay echoes, our brain screws up! You lose the ability to accurately determine where the REAL sound came from: Did it come from the left speaker? The right one? Some place in between? Maybe it came from the side wall? Or the rear wall? Your brain will end up telling you that the sound came from the wrong direction, because the clues it got from the "bounce off the rear wall time delay" are exactly what it expected for a sound coming from that "false" direction in front of you.

So, if you hear the direct sound from the speaker, and that sound then travel past your ears, hits the back wall, and bounces back to your ears within about 20 ms or less, then it messes up your ability to accurately determine directionality, and it also messes up your ability to accurately identify the tone (frequency). That's not a happy situation for a control room!

So you need to keep as much distance as you can between your head and the rear wall, such that the time delay is as long as possible, and hopefully more than 20 ms.

Putting diffusion on the rear wall won't help, but for a different reason: Numeric-based diffusers (Schroeders, skylines, QRD, PRD, BAD, etc.) all suffer from the same problem: Close up, they create "lobing" patterns, where the phase shift, scattering angle, time shift, intensity, etc. are not smooth: there are noticeable differences as you move your head just a few inches either way. It turns out that you need to be at least 3m away from any numeric-based diffuser in order to have smooth diffusion with non-discernible lodes, and if the diffuser is tuned to a low enough frequency, then you might need even more than 3m distance.

So in both cases, you need to have your head at least 3m from the rear wall, but for very different reasons. It's just coincidence that it turns out to be 3m for both problems.

With your room, you can just barely get your head far enough away from the rear wall. The room is 4.8m long, and by coincidence it turns out that your mix position should be about 1.8m from the front wall (38% of room depth, roughly). You should set up your chair such that your ears are 180cm from the front wall, or maybe a bit closer. Say 170.

Or is this a critical distance problem? I calculated that, with an RT60 of 200ms, I was gonna be right at the limit of the critical distance.

It's not a critical distance problem. In fact, critical distance isn't normally a problem at all, in most control rooms. Only in very large rooms, or very badly treated rooms.

I considered 38% from the back wall in my design.

... which puts your head just 1.8 m from the rear wall!

How far apart should they be? Is 25-30° not a good angle?

For that room, I would set up the speakers 84cm away from the side walls, meaning that they would be 132 cm apart. You would get the angle correct by aiming both of the speakers at a spot about 30cm to 40cm behind your head, perhaps adjusted a bit depending on the Q of the speakers that you plan to use.

Forget the famous "equilateral triangle" and perfect 30 degree angles that you see in diagrams in so many places across the internet (and even in some text books!). That would only work for people who have had their ears surgically transplanted onto their eyeballs! Remember what I said about it being important to have your ears on-axis to the speaker? Well, if the speakers are pointing at your eyes, as those diagrams show, then they are NOT pointing at your ears! Your ears are off-axis. It's that simple. In fact, it turns out that, in order to get a good broad sweet-spot with, clean sound-stage, accurate stereo imaging, and minimal artifacts, it's better to have the speaker axes pointing a bit outside your ears (slightly away from your head), not at any part of your head. Hence, aiming them both for a spot behind your head...

It doesn't matter what the actual angle ends up being, within reason. As long as it's somewhere in the range 20° to 45°, you should be OK. Preferably between 25° and 35°, if possible.

Thanks for everything Stuart, this is priceless advice!

Yup! Speaking of "price", the forum is free, of course, but donations are always welcome! My customers pay good money to get the same type of advice that you are getting for free here... The forum costs John money to run each month, so if you get some value from it, I'm sure he'd appreciate you hitting the "Donate" button at the top of the page...

- Stuart -

[saemola]

If the door was centered on that other wall, then that would be fine, but it isn't centered, and happens to be exactly where the speaker needs to go, unfortunately.

I could move the door (not perfectly centered, but towards the center), but then it'll be completely covered by the TV screen. Yes, it is a mixing room, but I'm also trying hard to not making it look like a mix room. I need this to be a comforting place to spend 8h a day in, and blocking the view of natural light sounds insane to me.
Here's the question that everyone (including me) hates to hear: how much worse would it be to leave the speakers as is?
Could I contrast that by using brute force? Tons of bass traps, Helmoltz resonators, mounting the speakers above the door line and angling them downwards... I really do care about letting natural light in. I work at my best with a relaxed mind and 99% of the studios I've been in make me feel like I'm in a hospital's OR.

Then position and angle the video screens so that the clients cannot see them! And use lighting creatively, so there will always be glare on the screens for anyone sitting at the client couch, but not for you...

I love the evil genius behind this... noted!

Take a look at photos of a few dozen well-regarded pro control rooms from recent magazines, or on the internet: How many do you see that are set up like that?

There's only one I can think of which is the room that inspired the layout of mine. I think it was a room designed by Walter Storyk and, conveniently, I can't find it. I'll look harder, but in the meantime I found this, designed by WSDG and studio A here, designed by Orchard Design NYC. Now of course I have no idea how these rooms sound, so I could be completely mislead. And yes, these facilities probably cost a couple hundred thousands more than mine.

"rather", says the brain, "that was just one single sound that came from a different direction..."

This has got to be the most enthralling explanation of the Haas effect out there. Seriously, you could make an illustrated children's book out of this!

So you need to keep as much distance as you can between your head and the rear wall, such that the time delay is as long as possible, and hopefully more than 20 ms.

Got it. Again, not to oversimplify (and I'm aware of how silly it sounds me suggesting things to you), but isn't that an issue I could solve by absorbing the living hell out of the rear wall? I have so much space behind me I could literally put up a 1 meter thick broadband absorber at the reflection points.

For that room, I would set up the speakers 84cm away from the side walls, meaning that they would be 132 cm apart. You would get the angle correct by aiming both of the speakers at a spot about 30cm to 40cm behind your head [...]
Forget the famous "equilateral triangle" [...] As long as it's somewhere in the range 20° to 45°, you should be OK. Preferably between 25° and 35°, if possible.

By putting the speakers 84cm away from the wall (and, considering that they are a cube with a volume, rather than a piont, they'll end up being about 1m away from each other) and aiming them 30cm behind my ears, they'll make an angle of less than 15°. I understand not following too strict of a guideline, but isn't that insanely narrow?
Would it be a bad idea to rotate the layout by 90 degree and face the large north wall? I'm guessing the couch will then have to go right against the back wall, which I assume isn't really the best place due to room modes. I could even build baffles for the speakers protruding into the room.

Schermata 2016-11-06 alle 12.47.24.png

A little extra question: the switch is not going to happen soon, but one of the monitor pair I'm considering for replacement is the Genelec 8050. I've read multiple times that, due to their shape, they get no benefit from soffit mounting. Is that a myth? Do you have any experience with soffit mounting the Genelec 80xx series?

Speaking of "price", the forum is free, of course, but donations are always welcome! My customers pay good money to get the same type of advice that you are getting for free here... The forum costs John money to run each month, so if you get some value from it, I'm sure he'd appreciate you hitting the "Donate" button at the top of the page...

I have already thought of that and will do for sure!

[Soundman2020]

Yes, it is a mixing room, but I'm also trying hard to not making it look like a mix room. I need this to be a comforting place to spend 8h a day in

That's fine, but it IS a control room, and the PURPOSE is therefore fundamentally acoustic: the entire reason why the room even exists, is so that you can mix accurately, cleanly, clearly, and with your mixes "translating" well to all other locations where they will be played. Making the room comfortable and look nice is secondary. Important, yes, but secondary: not the main purpose. The room does not exist to look good. It does not exist to be comfortable. It exists in order to create the optimum acoustic environment for mixing. Nothing should get in the way of that.

I'm not saying that the room has to be uncomfortable or ugly! Not at all. But those are not the number one priority.

and blocking the view of natural light sounds insane to me.

I'm not talking about blocking that view! It will still be there, any time you want to look at it.

Here's the question that everyone (including me) hates to hear: how much worse would it be to leave the speakers as is?

I'll answer that with a document: ITU BS.1116-2. That's the generally accepted specification for critical listening rooms, how they should be set up, and what the acoustic response of the room should be. If you don't like that one, then trey AES TD-1001. It's pretty much the same. If you don't like either of those, then try EBU Tech-3276. Also pretty much the same. There are others, but those are the "big three", which define what a studio should sound like, and how it should be set up for optimal acoustics, in order to make "critical listening" possible.

You'll find that, with all three of those, putting speakers in the corner is a bad idea. So is not having the listening position in the front third of the room....

So your choice is simple: Do you want a room in which you can mix accurately and that also looks good? Or do you want a room that looks good but where you can't mix well?

Could I contrast that by using brute force? Tons of bass traps,

You will need that anyway! It's a small room, so it willneed a lot of bass trapping. That goes without saying. Adding more than you need won't accomplish much...

Helmoltz resonators,

Why? Are you expecting to have a problematic room mode that needs tightly tuned trapping? If not, then why would you need a Helmholtz resonator? You are also assuming that it is even possible to place that resonator in the correct location where it can deal with the mode, and that you can spare enough room volume to make the device large enough to be effective...

mounting the speakers above the door line and angling them downwards...

Ummm.... Nope! Not for the mix position, anyway. Perhaps for the client couch... if it is at the BACK of the room! But certainly not for the mix position. Bad, bad, bad.

(Yes, you do occasionally see rooms with speakers mounted up high like that, and tilted down... but those are not meant for mixing: they are meant for "checking the mix", and also for the client couch, at the far back of the room, to impress the hell out of the producer, musicians, and WAGs.)

Once again, the reason is very simple: Psycho-acoustics. Your ears and brain are really good at determining direction horizontally, but lousy vertically. Your ears rely on very, very tiny variations in phase, level, timingm and frequency shifts, caused by the way sound waves hit your pinnae and get reflected around inside your ear. Your brain uses those clues to figure out which direction the sound came from. ... provided that it comes from directly in front of you. If it comes from significantly above or below the "horizon", that messes up your perception of direction, because the reflections in your pinnae are at the wrong angles: phase shifts are wrong, timing shifts are wrong, frequency shifts are wrong... and your brain lies to you about direction.

The maximum angle you can have a speaker above the horizon and still expect that your ears will do a reasonable job of figuring out directions, is about 7°. Some speaker manufacturers say "up to 10°". One or two say "up to 15°", but there's no evidence to support such a large angle for accurate acoustic perception. Personally, I have never tilted speakers down by more than 5°.

That's one problem with raising speakers high and tilting them. Another is an even bigger issue: reflections off the desk and/or console. When you raise a speaker up higher and tilt it down, you drastically increase reflections from the console into your ears, and the difference in distance/timing here are very short, well inside the Haas time. And therefore well inside the time where your head get's confused about directionality due to multiple copies of the same sound arriving almost together. The larger the speaker height and tilt angle, the larger the problem becomes.

And a third issue from the "raise/tilt" problem, is comb filtering/frequency response shifts. There's always some "roughness" in the frequency response, somewhere in the mid range, due to the desk / console surface creating comb filtering patterns, and messing up the phase/timing along the way due to the control knobs, buttons and switches sticking up. That's unavoidable. Some manufacturers even provide controls on the backs of their speakers, with instructions on how to use them to minimize the effect. Basically those controls are simple EQ set to certain frequency bands that they know will be an issue with their speaker design in typical room designs. Those controls can help, slightly... but they are only meant to work if the speaker angle is almost flat with respect to the console surface. For higher angles, the problem becomes larger, and the controls become useless.

There are other issues with having speakers above or below the "horizon", but those are the biggies...

I really do care about letting natural light in.

Then let the natural light in! There's no problem at all with that. I'm not saying, in any way, that you would need to block off your window.

but in the meantime I found this ... and this.

Don't look now, but both of those are multi-channel rooms! Yours is not. They are 5.1 rooms or 7.1. And in both cases, there are TWO acoustic zones, with TWO complete speaker setups. One for the clients, and one for the mix engineer. Notice the set of speakers that the engineer actually uses, set immediately in front of the console, in both cases, with the main speakers for the clients set forward of that? Not comparable to your room at all. There's also the issue of size: each of those rooms is probably four or five times the size of yours...

isn't that an issue I could solve by absorbing the living hell out of the rear wall?

That's a good idea for all rooms, and is what I normally do in rooms that I design, whenever possible. But you don't have enough room to do that fully, and it won't do what you are expecting in any case. The wavelength of a 34Hz tone from a bass guitar is about 33 feet (10m). The half wave is about 16.5 feet (5m), the quarter wave is about 8 1/4 feet (2.5m). That's how deep your "living hell bass traps" would need to be to do a good job of hitting the entire quarter wave.... But that would be huge overkill for the mid range, even more so for the highs, and would end up making the room very dead, not neutral.

By putting the speakers 84cm away from the wall (and, considering that they are a cube with a volume, rather than a piont, they'll end up being about 1m away from each other)

Nope! wrong! Check again what I said, carefully.... That entire explanation is about the acoustic AXIS of your speaker. Not the top, bottom or sides of the cabinet. Those are irrelevant for speaker placement. All that matters is the acoustic axis. I even mentioned this in my previous post: "If you don't know where the acoustic axis is on your speaker, then check the manual, or ask the manufacturer. If they don't tell you, then let me know, and I can help you estimate where it is, approximately."

So, if you place your speakers 84 cm from the side walls (location of the acoustic axis), then they WILL be be 132 cm apart. 300 - 84 - 84 = 132. Your ears do not care where the sides of the boxes are located: they only care about where the acoustic axis is located.

and aiming them 30cm behind my ears, they'll make an angle of less than 15°

Nope! Not if you do what I said. Here's how it works out, if you do it correctly:

Speaker-Layout-Template-TOP-01.png

Speaker-Layout-Template-PERSPECTIVE-01.png

Speaker-Layout-Template-PERSPECTIVE-02.png

The speaker toe-in angle is 23.5°, not 15. Not sure how you got to 15 degrees, but something drastic went wrong to get such a major difference....

(The speakers are not shown to scale in the above diagram, but that's irrelevant to the conclusion: the angle would only change very slightly for larger or smaller speakers. The head is to scale, and so is the room, as well as the speaker locations.)

Would it be a really bad idea to rotate the layout by 90 degree and face the large north wall? I'm guessing the couch will then have to go right against the back wall, which I assume isn't really the best place due to room modes.

Yup. And you'd also have your head just 186 cm from that rear wall at the mix position... That's around 12ms delay for the bounce... can you say "Haas effect..."...

Don't get me wrong with all of the above: if you want to set up your room any other way, and you don't care about having an accurate mixing environment, then that's fine! If aesthetics is more important to you than acoustics, then that's fine too! But I'm not an interior decorator, so I can't help you much with that. I'm a studio designer, so that's what I can help you with. And since you came to the studio design forum, I'm assuming that studio design is paramount for you. So that's what I'm telling you about: If you want your room set up optimally, for the best possible acoustics, with a good chance of meeting all those specs that I mentioned above, then what I'm giving you here is the best starting point. You can decide to ignore it completely, of course, since it's your room, not mine! Or you could implement it partially, and get partially good acoustics. The choice is yours, and I'm not trying to tell you that you HAVE to do it this way. But if it really were my room, then that's the way I'd do it.


- Stuart -

[saemola]

The room does not exist to look good. It does not exist to be comfortable. It exists in order to create the optimum acoustic environment for mixing. Nothing should get in the way of that.

And I definitely agree with you. My point was trying to find solutions even if that meant compromising a bit, depending on the degree of the compromise, of course.

Do you want a room in which you can mix accurately and that also looks good? Or do you want a room that looks good but where you can't mix well?

The former definitely sounds better

Are you expecting to have a problematic room mode that needs tightly tuned trapping?

That's what I thought was going to be the big issue with putting speakers in a corner. What I'm trying to understand is what kind of problem the speaker in the corner would create and the magnitude of that problem. I'm clearly trying to create a room that is as good as possible, but I'm also aware that I'm not gonna get a Dolby certification with a 14.5 sqm area. So if getting the speaker away from the corner would give me a 3% improvement, I would be fine in leaving it in the corner considering all the trouble it would create.

Then let the natural light in! There's no problem at all with that. I'm not saying, in any way, that you would need to block off your window.

The problem is there are no windows and the only source of light (the glass door), when put in the middle of the wall, is going to be right behind my desk, my main monitor higher up and the TV screen even higher. It'll be completely blocked. (I know, if there is no solution than what am I whining for? I was just pointing out why keeping the door away from the center was important to me)

And in both cases, there are TWO acoustic zones, with TWO complete speaker setups. [...] There's also the issue of size: each of those rooms is probably four or five times the size of yours...

the quarter wave [of a 34Hz tone] is about 8 1/4 feet (2.5m). That's how deep your "living hell bass traps" would need to be to do a good job of hitting the entire quarter wave.... But that would be huge overkill for the mid range, even more so for the highs, and would end up making the room very dead, not neutral.

Gotcha!

That entire explanation is about the acoustic AXIS of your speaker. [...] Your ears do not care where the sides of the boxes are located: they only care about where the acoustic axis is located.

Yes, I read that. Very interesting by the way. I thought that the distance from the wall was to be considered from the side of the "box" for reflection issues.

Would it be a really bad idea to rotate the layout by 90 degree and face the large north wall? I'm guessing the couch will then have to go right against the back wall, which I assume isn't really the best place due to room modes.

Yup. And you'd also have your head just 186 cm from that rear wall at the mix position... That's around 12ms delay for the bounce... can you say "Haas effect..."...

This one I really don't understand. Facing the long side of the room would give me unsolvable problems related to the Haas effect with the side walls. What changes if that problems is now in the back wall?

But I'm not an interior decorator, so I can't help you much with that.

Damn, I'm in the wrong place!

You can decide to ignore it completely, of course, since it's your room, not mine! Or you could implement it partially, and get partially good acoustics. The choice is yours, and I'm not trying to tell you that you HAVE to do it this way. But if it really were my room, then that's the way I'd do it.

Don't worry Stuart, that was perfectly clear and the reason why I came here, so that I can have the tools to make assessments and make informed decisions about the acoustics of my place!
And thank you for the extra time to post those drawings!

I have two more questions:
1) one of the monitor pairs I'm considering for replacement is the Genelec 8050. I've read multiple times that, due to their shape, they get no benefit from soffit mounting. Is that a myth? Do you have any experience with soffit mounting the Genelec 80xx series?
2) do you think 60m2 of 85cm thick, ~30kg/m3 fiberglass would be enough for the acoustic treatment of the room? I have the chance to grab it for cheap, but it's a long trip and I'd rather take all I need. I could buy up to 110m2.

[Soundman2020]

Are you expecting to have a problematic room mode that needs tightly tuned trapping?

That's what I thought was going to be the big issue with putting speakers in a corner.

Modes are modes, and they are potentially present at all points in the room, not just the corners. If you trigger a specific mode, then it will occur throughout the room. Modes are "standing waves": a resonant effect of the sound wave as it travels around the room, then gets back to the point where it started, in phase with itself, and going in the same direction. That specific modal resonance will be felt at different intensities at various points around the room, as you will be at a different point on the "standing wave": some peaks, some nulls, and some in between's, but the mode will be present everywhere.

So far so good. But here's the thing: ALL modes terminate in the room corners, so if you put your speakers in the corners, you are pretty much guaranteeing that you WILL trigger every single one of them. If you want major modal issues, then the best place to assure that you will get them, is to put the speakers at the point that will trigger all the modes...

On the other hand, If the speakers happen to be located at a point which is a null for some modes, then it won't trigger those. And it probably wont trigger other modes where it is close to a null. It also will probably not trigger modes that are not associated with the wall it is against.

So the first issue is that moving your speakers out of the corners will reduce the probability that you will trigger all the modes.

What I'm trying to understand is what kind of problem the speaker in the corner would create and the magnitude of that problem.

The modal issue is important, but is only one of the reasons for not putting speakers in corners.

Another one is the famous "power imbalance" issue: If you have a speaker out in the open air, not close to any surface (no wall, floor, ceiling) then it will radiate the low frequency energy pretty much evenly in all directions, and it will radiate high frequencies as though it were a torch: focusing them only in the direction it is facing, like a beam of light.

So obviously, if the speaker is putting out 1 watt of acoustic power in the high frequencies, and another watt of acoustic power in the low frequencies, there's a major imbalance! All of that 1 watt of highs is aimed at your head, while the 1 watt of lows is spread around in all directions: there's a "power imbalance" here: half of the low frequency power is heading away behind the speaker, where it will never get to your head, while all of the high frequency power is heading right at you. The frequency where things change over from "all sound going forward" to "half sound going forward, half going back" is called the "baffle step response" frequency, and is governed by one single thing: the smallest dimension of the front panel of your speaker, which is technically refereed to as the "front baffle"

In reality, this should be called "energy imbalance" not "power imbalance", and we'll get to that later.

So what manufacturers do to "fix" this baffle step response problem, or power imbalance problem, or energy imbalance problem, is to double the energy of the lows! They beef things up such that there's twice as much acoustic energy going out in the lows, as compared to the highs, since half of it will be lost. So they carefully craft an equalization circuit that is the mirror image of the "baffle step response curve" for that specific speaker, and that filter ensures that twice the energy comes out for frequencies more than an octave below the baffle step, and ramp that down slowly in a controlled curve until it it is exactly the same energy at one octave above the baffle step.

In other woods, they set up an EQ curve and amplifiers that boosts the low end by exactly 6 dB, with the 3 dB point being at the precise center frequency of the baffle step.

But energy is not power. There's an inverse square relationship, so to get a 6dB increase in sound intensity, you need a 12 dB increase in the signal amplitude. To get twice the intensity, you need four times the power. To get ten times the intensity, you need one hundred times the power. That's the basic reason why you see speakers where the tweeters and its amp area rated at 50W, while the woofer and it's amp are rated at 500 W. It's mostly the "power imbalance" thing. You have to pump a LOT more power into the woofer to get twice as much energy out of it, so that it matches the energy coming out of the tweeter...

So to "fix" this problem, you beef the hell out of the lows, and apply an EQ curve...

Problem solved!

Well, it is solved until you put the speaker inside a room. Now you have ANOTHER problem: If the speaker is close to a wall, then the wall reflects back the energy that would have disappeared, and it gets to your head anyway (delayed, and out of phase, but it still gets there). Depending on how far away from the wall you have the speaker, you might see a boost in low frequency intensity of anywhere between 0 and 6 dB! So the EQ circuit for your speaker is no longer doing the right thing: It is over-boosting the low end, and you need to turn it down. Hence, all good speakers have a control on the back that you can use to "correct the room response". (What a big lie that is! You are not correcting the room at all! You are correcting an acoustic issue with the speaker itself...) But anyway, that control basically adjusts the baffle step filter so that it puts less and less power increase into the lows. If the speaker is right up against the wall, you'll need to "roll off" the full 6 dB, since the wall is now ensuring that all of the "lost" energy is no longer lost: all of it now gets reflected back at you, so there is no more imbalance; effectively, you can switch off the "correction" that is built into the speaker.

Technically, the speaker is now radiating into "half space", instead of "full space", so the power imbalance / energy imbalance / baffle step problem no longer exists, and the circuit is not needed.

But a corner is not a wall! A corner is TWO walls. If you put the speaker into a corner, the speaker is not radiating into "full space", nor is radiating into "half space": rather, it is not is radiating into "quarter space": that second wall cuts takes the low frequency energy that would have radiated out to one side, and also reflects THAT back into the room, where it will get to your head. So now you have the inverse problem of the original power imbalance: That second wall is adding another 6 dB to the lows, but not affecting the highs.

You now have a 12 decibel power problem! In full space, the lows were 6 dB too quiet. In half space, they are just right. But with two walls there, the lows are 6 dB too LOUD: so there's a 12 db difference now.

Ooops!

And if you were to place the speaker at the point where three "walls" meet (in the "tri corner" where two walls meet the ceiling, or two walls meet the floor), then you get a boost of 18 dB, as compared to the original "full space" situation. (Which is why subwoofers sound so darn great when you put them in the corners!)

So putting the speaker in the corner gives you a 12 dB increase in sound output, but only in the low end. You would need to roll off ANOTHER 6 dB in the low end to fix that. Most speaker manufacturers do not put controls for doing that on their speakers, because of other issues. Some do, but usually only on higher-end, more expensive speakers.

That's the second reason why it's a bad idea to put speakers in the corner.

The third reason: The sound that is reflected back by the walls is out of phase with the direct sound! The phase is inverted by the wall to start with, but there's also a delay caused by the round-trip distance, which is the same as a phase shift. And since each frequency has a different wavelength, that implies that each frequency has a different phase shift, by the time it gets to your ears. So you have the direct wave hitting your ears, plus a phase-inverted time-delayed copy of the same wave, arriving well within then Haas time... Not only do you have Haas effects going on, you also have comb filtering, phase cancellation, and other phase-related problems, and they are all in the low end of the spectrum which is the hardest to treat anyway!

And the fourth reason: Impedance mismatch. The room "loads" the speakers, acoustically. If you have ever head a speaker driver when it is not mounted in a speaker cabinet 8especially a tweeter), you'll understand this: It sounds terrible! Tinny, nasal, and ugly. Because the driver impedance is not "matched" to the air impedance. It cannot efficiently transfer the energy from the moving part into the air, because the driver cone itself has one impedance, and the air has a very, very different impedance. So manufactures spend oodles of money on designing wave-guides, to match the impedance. Those are the strangely curved bits that go between the driver and the cabinet. They are not there to make the speaker look cool! They are there to match the impedance of the driver to the impedance of the air, so that energy can be transferred efficiently, and equally at all frequencies. That second part is the kicker: "at all frequencies". If the wave-guide transfers energy much better at some frequencies, and much worse at others, then obviously the speaker response will be lousy, and it will sound terrible: some tones will be louder than others. So designing those wave-guides is a major important part of designing the entire speaker.

The trouble is that when you put a speaker in the corner, you are creating ANOTHER wave-guide! The two sides of the corner at 90° act as an additional wave guide for mids and lows, which upsets the carefully crafted impedance matching of the wave-guides on the speaker itself: it places an additional acoustic load on the speaker, that the designer never accounted for (and in fact, could NOT account for, no matter what he did...). So now the speaker is not matched to the air. It does not transfer energy smoothly and evenly at all frequencies, and there is nothing you can do about it...

Need more reasons why it's a bad idea to put speakers in a corner?

I'm clearly trying to create a room that is as good as possible,

Yup. BS.1116-2 et. al. specify exactly that. In order to have a critical listening setup, the room response (including speaker response) must be smooth and flat to within +/- 3 dB. That's a high standard indeed, and hard to achieve: most home studios are doing really well if they can get within +/- 6 dB.

So if getting the speaker away from the corner would give me a 3% improvement, I would be fine in leaving it in the corner considering all the trouble it would create.

Well, lets do the math! Since there's a difference of between 12 and 18 dB in the power imbalance, that works out to a difference of between 400% and 1600%... Not sure if that's a big enough number to be worthwhile...

the only source of light (the glass door), when put in the middle of the wall, is going to be right behind my desk,

Not if you turn the room around, 180°, as I suggested. In that case, the entire glass door will be free and uncovered... It will be behind your back, yes, but it will still be providing 100% natural light into the room, with no restrictions or blockages...

This one I really don't understand. Facing the long side of the room would give me unsolvable problems related to the Haas effect with the side walls.

Not it would not. The Haas effect is related to the REAR wall, not the side walls. The rear wall is the one behind you, not the one next to you! If you set up the room such that you are facing one of the long walls, then the other long wall is the "rear", and it is only 186 cm behind your head.

so that I can have the tools to make assessments and make informed decisions about the acoustics of my place!

Here's an idea: Set up the room the way YOU want to do it, facing the door, with the speakers in the corners, the mix position at 72%, the couch in front of that, and run a test using REW. Then set it up exactly the way I said, carefully measuring the distances and angles, and do another REW test. Post the resulting MDAT file, and I'll analyze it for you, so you can see the differences. (For each layout, run three REW tests: one with just the Left speaker turned on, one with just the right speaker turned on, and one with both speakers turned on. Do not adjust anything between tests! Calibrate your system and REW correctly using a hand.held sound level meter first, then run the tests without touching any controls).

That would be the best possible tool for helping to make your decision!



- Stuart -

[saemola]

[death and devastation...] Need more reasons why it's a bad idea to put speakers in a corner?

I would say those sound like pretty good (bad?) reasons!
The speaker waveguide explanation was super cool and enlightening.

In that case, the entire glass door will be free and uncovered... It will be behind your back

Something about not being able to see the enemy sneaking behind my back makes me very uncomfortable...

The Haas effect is related to the REAR wall, not the side walls.

I am even more confused (and intrigued). I thought a reflection was a reflection and neither it or my ears knew which wall it was bouncing off. But I'll take your word for it, I don't want you to spend more time explaining this to me (I actually do, but it doesn't feel right )

Here's an idea [...]

As inviting as your suggestion is, I have no doubt that you ARE right. This whole mess is here because I'm trying to understand whether I should move the door or not since it needs to be done no later than in 3 days. Also because I wan't to be able to look outside, even if that means having the door on my side.
But I understand now: facing the east wall is not an option.
It is now a metter of getting the most out of my room and face the west wall or feeling more comfortable and face the north wall with Mr Haas breathing down my neck.
If I face the west wall, I think I should move the door in the north east corner because right now it is right where the first reflection point between me and the speaker would be, preventing me from applying acoustic treatment in that spot.
If however I face the north wall, it looks like the door should be fine there.

Stuart, again, I can't believe you took the time to explain all of this to this donkey.
If you feel like answering the other two questions in my last post that would be amazing. And if you feel like replying in my other topic on studio construction... I think I'm gonna have to make a statue after you.
But this is really great.
Thanks so much man!

[Soundman2020]

If I face the west wall,...

Your diagram isn't marked with north, south, east or west, so I referenced all of my comments to the diagram itself: You should be facing the left of your diagram, towards the wall that is marked " 3.0M / 10' ". The one opposite the door. That's the only orientation that makes sense. Do not orient the room either "up" or "down" (door on your left or right). A distant second best would be to face right, towards the wall with the door in it, but moving the door to the middle of that wall (or as close as you can get to the middle).

In both cases (facing left or facing right) it would be an excellent idea to flush-mount your speakers in properly designed and built "soffits". That alone eliminates the power imbalance problem, as well as a number of others that I didn't go into yet...

I think I should move the door in the north east corner

Huh???? That would be about the worst possible place you could put it! That's where you would need to put either the speaker soffit (if you face the studio "right") or the bass traps (if you face it "left").

I am even more confused (and intrigued). I thought a reflection was a reflection and neither it or my ears knew which wall it was bouncing off.

.... and you'd be wrong! The reflections off the side walls at the first reflection points are a problem, yes, but not as big a problem as the ones that eventually get back to your ears after hitting the rear wall: Those are getting close to the edge of the Haas time. Also, that "Haas time" isn't fixed and written in stone. It's not that at 20.1ms everything is all rosy and wonderful, but at 19.9 ms the world is screwed up: It's a transition area between roughly 20ms and roughly 30 ms, where the problem is increasingly noticeable. at 40 ms, the world really is wonderful, and at 10 ms it really is totally screwed up, but in between there's a "gray" area, and even then the boundaries of that are different for different people. So reflections off the side wall are almost certainly in the "bad" zone for everyone (unless your room is huge!), and reflections off the rear wall are probably fine for most people, if the room is long enough, or otherwise they are a mix of "terrible", and "lousy" and "not so good", and "resonably OK" for most people.

There's also the issue of frequency: reflections off the side walls are usually more in the low-frequency range, since they are coming from the speaker fairly far off-axis, while reflections off the rear wall are "everything": those are on-axis direct reflections from the entire spectrum, plus the "reflections-of-the-reflections" from the wall bounces, floor bounces, and ceiling bounces, with a mixed bag of frequency spectra, and a mixed bag of timing delays... some come directly from the speaker and straight back to your ears, while others also bounced of one more surface along the way, taking a longer (and slower) path, and yet others bounced off two (or more) surfaces, with an even slower path. Plus the first order modal problems on the length axis...

That's why you'll often see comments on the forum about the rear wall being the most problematic of all! It catches all the garbage from the rest of the room, and happily sends it back to your ears.... which is why it needs the most treatment.

So I guess you could say that "all reflections are not equal, and some are way more unequal than others"... And your ear can tell the difference, especially with the ones that came back to you after a longish delay, outside the Haas time...

I don't want you to spend more time explaining this to me (I actually do, but it doesn't feel right)

As inviting as your suggestion is, I have no doubt that you ARE right.

Even so, it would be still be a good idea to do that! For your own benefit, as well as for the benefit of the forum: members who happen to be following your thread right now, and those that might find it in the future. So if you can spare a couple of hours to shove furniture and speakers around, and click your mouse a few times, it would be very much worthwhile. You'd be helping yourself, and also helping many others. That's what the forum is about too: members helping out other members. Giving back some of what you got...

Stuart, again, I can't believe you took the time to explain all of this to this donkey.

I certainly hope that your health status is somewhat better than that of the donkey!

- Stuart -

[saemola]

Your diagram isn't marked with north, south, east or west

Right. My reference is: Up=North; Down=South; Left=West; Right=East.

it would be an excellent idea to flush-mount your speakers in properly designed and built "soffits".

You definitely convinced me on that one. I just need to see if I feel up to the task of designing such soffit! Wouldn't wanna make a mess.
I'm gonna play devil's advocate for a second. Well, not really, but I wanna pick your brain about something I've always wondered about, both regarding flush mounting speakers and about mounting them on isolation pads: clearly a mixing room needs to be as neutral as possible, but isn't flush mounting an unrealistic advantage over what 99.9% of the people who will hear the material are gonna have? I've never seen a home with flush mounted speakers. Isn't this gonna give us a better but unrealistic representation of what the mix is going to sound like in the real world?

I think I should move the door in the north east corner

Huh???? That would be about the worst possible place you could put it!

I'm with you when it comes to facing right. However, if I face left I understand that I would lose the ability to put a bass trap in that corner, but what about not being able to absorb the first reflection point that goes from the speaker, to the back(right) wall and to my ear? It would fall precisely where the door is.

.... and you'd be wrong!

More cool stuff! Thanks!

it would be still be a good idea to do that!

I didn't want to bother you further, but now you are preaching to the choir. I will post my results for sure as soon as the room is ready.

Andreas

[Soundman2020]

clearly a mixing room needs to be as neutral as possible, but isn't flush mounting an unrealistic advantage over what 99.9% of the people who will hear the material are gonna have? I've never seen a home with flush mounted speakers. Isn't this gonna give us a better but unrealistic representation of what the mix is going to sound like in the real world?

Welll... yes no sort of maybe not quite absolutely and never!

OK, here's the thing: The purpose of your speakers in your control room is NOT to sound good! They are not supposed to sound good at all. They are not supposed to sound like typical speakers you'd find at home, or a club, church, office, shop, or anywhere else. Those are supposed to sound "good", but the ones in your control room should NEVER sound good. They are supposed to sound "flat". They should do nothing at all to the signal coming in, except reproduce that as faithfully as possible, without changing it in any way.

The same for your room: it should be totally neutral, and do nothing at all to the sound that comes out of the speakers. It should not add to it in any way, nor should it subtract from it in any way. It should not "color it": The combination of speaker and room should be perfectly "flat".

But "flat" is boring! Most people don't like flat response and flat acoustics. It sounds a bit "lifeless". There's no booming bass, no sizzling crispy highs, no warmth in the mids... it is all just exactly the same, flat, and boring.... which is exactly the way you want it to be! You, as a mix engineer, need that. You NEED to hear totally flat response, so that you can make the mix sound good in your room. If it sounds good in a room with flat response, then it will sound GREAT in any other room. That's the point. If you do the mix so that it is well balanced, nicely even, clean, equally strong throughout, etc., then your mix will sound EVEN BETTER when played on systems that are designed to have their own "sound". If you play it on a a "warm" system, it will sound warmer. If you play it on a "booming" system, it will sound "boomier". If you play it in a crispy zingy system, it will sound crisper and zingier. Wherever you play it, it will sound good, and will seem to adapt to that system perfectly... because you made it sound good on a neutral system!

On the other hand, if you put a couple of cheap old hi-fi speakers on your meter bridge, in a room that is treated badly, you can indeed still make your mix sound good in that room. It can sound GREAT in your room... but it will sound lousy everywhere else!

Let's assume that your hypothetical "lousy" room is asymmetric, has modal problems around 40 Hz and 80 Hz, and it has the typical 120 Hz "dip" seen in most small rooms, there's comb filtering from the console surface in the mid range, and you have thick pile carpet on the floor which is sucking out the highs. To make it sound good in that room, you'd skew the panning a little to even out the asymmetry, turn down the bass guitar and kick drum (because the modal problem overemphasize them), you'd boost the floor tom and low end of the keyboard and electric guitar, you'd scoop out some mid EQ and balance the vocals and rhythm instruments a bit on the low side to compensate for the comb filtering, and you'd boost the hi-hat, ride, crash, high end of the electric guitar, and maybe female vocals too, because the pile carpet is killing those. Then because your speakers are cheap little things, you'll roll off a bit of the low-mid rumble, add something to the missing high-middle around the bad cross-over, and dial in a bottom end boost as well. Then maybe you'll add some reverb here and there to make it sound warmer, nicer, and WOW!

Your mix will sound wonderful! You'll be amazed at what a genius you are, and how good your cheap nasty speakers and untreated room sound! And you'll think "Gee. I'm so glad I didn't blow two grand on studio monitors, and another ten on doing my room right! Who needs that? Just listen to how great this sounds!". Then you'd send out copies of your masterpiece mix to all your friends, to impress them, ... and they'd either stay silent, or timidly ask: "How come there's no bass guitar in this song? Why didn't you use a kick drum? Why does it sound so dreadfully shrill and shrieky? Is that a new genre you invented? Did the vocalist have a bad cold that day? I though you had an amazing Stromberg Master acoustic guitar, so why does it sound like you use a five dollar nylon-string schoolboy guitar? What happened to the keyboard? It sounds like a toy Casio... And how come it is all lopsided?"

Shocked by the comments, you'll wonder about that, so you'll go play your amazing mix in your car... and it will sound like crap! (Excuse my French). Then you'll plug in your iPhone and ear buds, and it will sound like even worse crap! (Excuse my even worse French).

And you'll wonder what the hell happened...

What happened is that your mix did not "translate". It sounded fine on your system in your room, because you compensated for all the defects, in the mix. But it sounds lousy in all other places, because none of them need those "compensations". The only place on the planet that needed that, was your room. In every other location, it sounds bad, in one way or another. In boomy places, there will be no boom. In sizzling places, the sizzle will be deafening. In warm places, it will be either "sludge-ishly" hot, or icily cool... etc. It will sound lousy.

So that's the reason why you need your place to sound neutral, flat, boring, and unlike what "99.9% of the people who will hear the material are gonna have". Not because they will hear it the same way you heard it, but because they will hear it the exact way they think it SHOULD sound on their system, because it was totally neutral on YOUR system. It will sound great everywhere, because it is mixed on a neutral system, and therefore does not have any unneeded coloration or compensation in it. So it sounds neutral on all systems. Each system will do what it normally does to music, so yours will sound "right" on whatever system it is played on.

I've never seen a home with flush mounted speakers. Isn't this gonna give us a better but unrealistic representation of what the mix is going to sound like in the real world?

That's why you need soffits and a perfectly treated room: Not because anyone will have that in their own home, but because they DON'T have them in their home! You need it, because they don't.

Your system must tell you the exact, horrible, ugly truth about every part of your mix, so that you can fix it. If you can't hear an ugly detail because the speaker didn't produce it well, or the room asked it, then you won't be able to fix it, and it will still be heard on all systems that CAN produce it, and in all rooms that DON'T mask it. You need to hear the truth so that they can't hear it! You need to kill the "ugly" so it never gets through to them, and the only way you can do that is on a flat, neutral system in a flat, neutral room.

If it sounds good on that system in that room, it will sound "right" on ANY system, in ANY room.

It's also a good idea to have a pair of typical cheap speakers set up badly in the room, so that you can check that your mix really does sound good on those too, but it's not a good idea to mix on those: that's just the final check. Mix on the big, neutral, clean boxes, in the soffits, with the room treatment set up for those, in a neutral environment.

but what about not being able to absorb the first reflection point that goes from the speaker, to the back(right) wall and to my ear? It would fall precisely where the door is.

It's an issue, yes, but the door is only a relatively small area of the rear wall. I'm not sure if you looked at the Studio Three thread I linked you to a few posts back (previously called "Monstertrax"). Here's a view towards the rear of the room:

RDMOUS-2014-Jul-29--ROOM-REAR-SML-ENH.jpg

What do you see on the rear wall? Looks like large glass windows and doors to me!

Now take a look at the preliminary acoustic response curves for that room, in the thread, or even better, the final curves on the Studio Three website, which are even cleaner. The effect of that glass is not evident at all. It was before we treated for it! But in the final finished room, it is gone...

So the point is that it can be done. Your door is a problem, but fixable. It's not easy, but there are ways of compensating for issues like that. In the case of Studio Three I was hired too late in the build to modify those rear walls issues (the room was already built), so I had to live with them and work around them. It's not what I would have preferred, but it worked out fine in the end. It might not work out so perfectly in your room, but the effect can be minimized, with good acoustic design.

You definitely convinced me on that one. I just need to see if I feel up to the task of designing such soffit! Wouldn't wanna make a mess.

If you don't feel up to the task yourself, then you could hire someone to do that for you.... That's actually what Rod did (the owner of Studio Three). He originally hired me to design "just the front six feet of my control room, with the soffits mainly"... Then he ended up wanting me to do all the rest of the studio as well! If you want, call him to see how that all came about. He's a great guy. His web page link is in his signature, and he'd be happy to hear from you! Tell him I suggested that you should call.

I didn't want to bother you further...

No problem!


- Stuart -

[saemola]

The purpose of your speakers in your control room is NOT to sound good! [...] They are supposed to sound "flat". They should do nothing at all to the signal coming in, except reproduce that as faithfully as possible, without changing it in any way.
The same for your room: it should be totally neutral, and do nothing at all to the sound that comes out of the speakers.

Ah yes, I am aware. I'm not TOTALLY oblivious to how a mixing environment should work. I still work as a sound designer/mixing engineer daily.
My thought process was more like: I'm aware that the end listener's room could end up adding or subtracting bass, so I can't account for that, on the other hand I also know that the end listener for sure isn't gonna have soffit mounted speakers.
However, your...

If you can't hear an ugly detail because the speaker didn't produce it well, or the room asked it, then you won't be able to fix it, and it will still be heard on all systems that CAN produce it, and in all rooms that DON'T mask it.

... makes perfect sense.
The first thing that came to mind were all the famous rooms without soffit mounted speakers (Real World's Big Room, Blackbird Studio C, ...) which then led me to realize that soffit mounting is probably more important in small rooms than in big ones...

It's an issue, yes, but the door is only a relatively small area of the rear wall.

Ok, now this does shock me a little bit. It is a small area, but it is exactly where the first reflection takes place. Wasn't that first reflection supposed to be the main cause of death and destruction in my studio and the main reason why I couldn't keep my desk in the back of the room facing right or simply facing up?
I guess I'll have to make all these measurements after the fact. In the meantime I have moved the door. New floor plan attached!

I'm not sure if you looked at the Studio Three thread I linked you to a few posts back (previously called "Monstertrax").

I did, but I focused on the flush speakers and the fact that that the back was glass totally escaped me.
It makes me wonder though: what if I faced up and put a reflective surface on the back wall to deflect the first reflection from the speaker off to the side walls were the absorption is going to be?
I'm almost scared of asking but... how do you feel about room correction software?

If you don't feel up to the task yourself, then you could hire someone to do that for you....

Oh, trust me, if I had the budget that would have been the first I would have done: let studio designers be studio designers and me be... the clown behind the faders.
Unfortunately I know that hiring a person to take care of this is out of question (and my studio will suffer the consequences of that).
I embarked into this thing thinking it would have been a fun thing to do in a moment when work wasn't too crazy.
Work ended up being INSANE and this turned up to be... yes, fun, but pretty much a part-time job!

Stuart, if I one day decided to turn this into a small 5.1 editing room, do you think that could be achievable by looking at one of the short walls or am I forced to look at the long wall due to the narrow width of the room and the inability to place the Ls and Rs speakers at the same distance as the front ones?
I have another question: it seems to me that acoustic hangers are more cost/effective (in terms of the price of the material) thank "superchunk" bass traps. Do you agree? Do hangers need thin but very dense (~70kg) mineral wool, or can they be achieved with thicker, lighter (30kg) glass wool?

studio 4.jpg

[Soundman2020]

Ok, now this does shock me a little bit. It is a small area, but it is exactly where the first reflection takes place. Wasn't that first reflection supposed to be the main cause of death and destruction in my studio and the main reason why I couldn't keep my desk in the back of the room facing right or simply facing up?

The rear wall is "sort of" a first reflection point, but not in the same sense as the side walls and ceiling. The side walls and ceiling are going to cause you problems in the mids and highs if you don't deal with them. The rear wall is going to cause you issues in the lows. Long wavelengths. Many meters long. It is the entire rear wall that is involved in doing that, not just a small part of it.

I'm almost scared of asking but... how do you feel about room correction software?

I almost don't want to answer that!

OK, here goes: room correction software does not correct rooms! So in very first place, the name itself is a lie.

When used the way most people use it (from ignorance, not from understanding), it is a useless and dangerous piece of junk. When used correctly in the hands of someone who truly understands what it does and how to use it, it's a fantastically useful tool. When done automatically by a software algorithm that was written by some guy who never even saw your room, it is only slightly above "useless trash".

I don't use stand-alone room correction software, no. However, I do sometimes apply equalization filters to the signal chain, intelligently, but I do it in dedicated hardware, not software. And even when I do it, I will ONLY do it if the room has already been suitably treated with acoustically treatment, as much as possible, because it would be stupid to try doing it in an untreated room.

I would not recommend that it should be used by everyone, either in hardware or software. If the person using it does not understand what the Q of a mode is, has no idea of what "minimum phase" means, and would not be able to identify an acoustic pole from an acoustic zero even if his life depended on it, them that person has no business at all trying to use it. If you look at a frequency response graph for a room and the associated waterfall plot, and you cannot deduce from that where the SBIR problems are in the room, then you have no business trying to use it. And if you think that boosting is better than cutting, narrow is better than broad, and fixing the high end is a piece of cake and a good idea, then you definitely have no business using it!

That's the problem. The manufacturers promote it as a magical solution that will fix any room: just press the button and "abracadabra!" all your acoustic issues are gone! Not even remotely close to being true. Basically, it's a marketing lie.

At the very best, room correction software or EQ hardware can correct for a limited number of issue, but ONLY for one location in the room, and ONLY for frequency domain issues, UNLESS the room is truly minimum phase, AND you can place both a pole and a zero at the correct location, in which case it can also help with time-domain issues for the entire room. That can only happen in a well-treated room.

Mostly, it's just an expensive toy that fools you into complacency, making you think that your room is great, acoustically, when it actually is not.

Oh, trust me, if I had the budget that would have been the first I would have done: let studio designers be studio designers and me be... the clown behind the faders.
Unfortunately I know that hiring a person to take care of this is out of question (and my studio will suffer the consequences of that).

Did you ask a designer? It might not be as expensive as you expect. Most designers offer a few different services, at different rates, depending on what you need.

Stuart, if I one day decided to turn this into a small 5.1 editing room, do you think that could be achievable by looking at one of the short walls or am I forced to look at the long wall due to the narrow width of the room and the inability to place the Ls and Rs speakers at the same distance as the front ones?

In a room that small, I would never orient the room to face the short wall. Never.

I don't see why you would have a problem with placing the rear surround speakers: it's simple to figure out. Measure the distance from the center of your head to the acoustic center of one of your speakers, and draw a circle on the floor with that exact diameter. Now place your rear surround speakers on that circle, at whichever of the "standard" angles you'd like to choose. Done!

If you do think you might want to go 5.1 in the future, then the studio needs to be designed for that NOW. Trying to modify the acoustics of a dedicated 2.0 studio to make it 5.1 is a major issue. But mixing in 2.0 on a studio that was designed for 5.1 is no problem at all....

I have another question: it seems to me that acoustic hangers are more cost/effective (in terms of the price of the material) thank "superchunk" bass traps. Do you agree? Do hangers need thin but very dense (~70kg) mineral wool, or can they be achieved with thicker, lighter (30kg) glass wool?

Never use high insulation that has too high a density for bass traps. Low density is better than high for bass traps (contrary to popular belief...) For hangers, use an inch or two inches of the correct density product. 1" is minimum, 2" is better.

- Stuart -

[saemola]

I almost don't want to answer that!

Hahahaha I laughed hard at this one

I don't use stand-alone room correction software, no.

So I assume you have no interest or experience with things like Sonarworks Reference and the likes. Your explanation makes perfect sense, and I'm sure it can only be a subtle thing. For the record, I was wondering about integrating room correction software after I had done everything possible with proper acoustic treatment, not as a replacement.

Did you ask a designer?

No, and it's mostly because I have no idea who to ask. There is very little market for studio building over here. Not only don't I know people who do this... I'd also want them to be reliable!

In a room that small, I would never orient the room to face the short wall.

Yes, you convinced me with that. I'll take the long wall route for sure (though I'm gonna make some acoustic tests in both positions just for personal knowledge to see what the difference would be).

I don't wee why you would have a problem with placing the rear surround speakers: it's simple to figure out. Measure the distance from the center of your head to the acoustic center of one of your speakers, and draw a circle on the floor with that exact diameter.

That's where I think lies my problem: the way you suggested I place the speakers would place my head about 188cm from the front of the speakers, but then I don't have the enough room behind me to place the Ls and Rs speakers. At 110° I'd have about 135cm between me and the speakers (and that's without space for 10cm of absorption behind them), and at 125° I'd have ~160cm (still, without absorption).
Could I get away with it by simply delaying the signal feeding the rear speakers (I'm not gonna ask about EQ correction here )? I'm assuming the biggest issue with having them closer to me than my front speakers is that the signal comes from the rear would get to my ears way too early.

If you do think you might want to go 5.1 in the future, then the studio needs to be designed for that NOW. Trying to modify the acoustics of a dedicated 2.0 studio to make it 5.1 is a major issue.

That's very interesting. Would you mind sharing what kind of details I should take into consideration when designing the acoustic treatment of the studio if I wanted to turn it into a 5.1 room? Or are you referring to construction details (which is now too late for me I guess...)

Low density is better than high for bass traps (contrary to popular belief...) For hangers, use an inch or two inches of the correct density product. 1" is minimum, 2" is better.

I found a good deal on some Knauf material and purchased an extra 75m2 of 85mm, 30kg/m3 glass wool assuming it was going to be low density enough for bass absorption. Is that low density/thick enough? Or would you suggest other specifications?

If you feel like giving some HVAC baffling suggestions, these are my baffling questions on the subject.
As always, thank you SO much Stuart!

P.S. I'm going to build some thick, concrete blocks or bricks speakers stands following the suggestions on the forum. What an incredible resource!