John Sayers' Recording Studio Design Forum

Hi All. I'm a newbie and I've started planning the rip out and redesign of my studio. This forum is superb and I'm hoping you guys can help me with some questions as I go.

Firstly, its quite a small room and I've had bottom end issues so to give you a quick run down, there is a solid wall (non structural) between the control room and the live room at the moment. I'm planning on taking that down and building a double timber frame wall to make the wall about 30-40cm thick. This will be packed with rockwool slabs and double skinned plasterboard. I'm hoping this in itself should help to sort out bottom end issues and flatten the response of the room somewhat. What do you think?

I'm thinking of 'soffit' mounting my speakers. The room is not that big (I'll post dimensions later) so the monitors are close to the corners. I was either gonna go for soffit mounted or build 'superchunk' (I've been on the forum all day and getting familiar with the lingo ) traps and put the speakers in front of them on isolated stands.

They are active Mackie HR824s and I use a HRS120 Sub as well. Is it ok to soffit mount these and is it beneficial?

I'll post more details of the room later with some pics. Cheers guys

Ian

Hi Ian, and welcome!

There is an announcement at the top of the forum about what to do to assure getting as many responses as possible. The announcement leads to this post (click here). Actually, several people, who are experts on this forum, will not reply if you don't do what is written in that post. Many others who are very helpful, will not reply out of respect for the moderators' wishes.

But having said that, I noticed this comment tat you made:


If you already have a solid wall there (brick? concrete? cinder block?) then you probably don't need to knock it down, unless it is in the wrong place. A solid, massive wall is a good thing! It can form one leaf of your two-leaf wall, and if it is solid (as in brick, concrete, etc.) then it is already giving you a good head-start on isolation. Don't get rid of it unless it is in totally the wrong place. Just add another leaf next to it. If you need to put in a window, then just cut out the hole for that, (with a lintel over the top if necessary!).


You seem to be confusing "isolation" with "treatment". It's a common misconception, so don't worry! Isolation stops sound getting in and out of your room. Treatment makes it sound good inside. They are two entirely different, independent and even incompatible things. To isolate a room, you need hard, stiff, solid, massive, dense surfaces, sealed absolutely airtight. Building hard, massive, etc. surfaces all around it, is about the worst possible thing you can do to a room, in terms of treatment. It makes it sound like a boomy, clangy, ringing resonant cave. But it is the best possible thing you can do for isolation!

So first you have to isolate your room by putting those surfaces around it, but that makes it sound terrible, so then you have to treat it.

Once your room is correctly isolated, then you can think about how to it, acoustically, so that it does NOT sound like that cave. Most acoustic treatment is based on soft, fluffy, floppy, light, airy, fibrous volumes, such as thick layers of mineral wool and fiberglass insulation, which are terrible for isolating a room. There are some types of treatment that are based on hard surfaces too, but most of what you need is based on the soft fluffy stuff.

Isolation and treatment: two different things. the stuff you use for isolation generally makes lousy treatment, and the stuff you use for treatment generally makes lousy isolation.


Probably a good idea in a small room, since you can't get the speakers far enough away from the wall if you don't have a lot of space. I'm trying to find the paper where I discovered the numbers, but as far as I recall, you need at least 2 meters between your walls and your speakers to avoid low-end comb filtering and other unpleasant artifacts, which is really hard to do in a small room. So you can either put copious absorption behind the speakers to help deal with that a bit, or you can soffit mount them and avoid the problem entirely, while also tightening up your bass and improving your stereo imaging. Mackie HR824s seem to be designed for the possibility of soffit mounting. (At least, the Mk2 version is: not sure about the earlier version). There is a switch on the back that is specifically designed to adjust the response curve for radiating into quarter space (in a corner) or half space) up against a wall, or soffit mounted. Curiously, the manual says that that half-space switch only rolls off 2 db for the bass, whereas it should roll of 6 db (theoretically), but the quarter space switch rolls of 4 dB (which should be 12 dB, theoretically) which is much closer to what you need for soffit mounting. Try both and measure, to see which works best. My guess would be "quarter space", even thou a soffit gives you half-space. There is also an additional bass roll-off switch on the speaker, so you could try that too.



Beneficial? Absolutely! Especially in a small room, but good in any room. See above. A soffit is basically an "infinite baffle", which prevents low frequency sound from "wrapping around" behind the speaker, crashing into itself, and bouncing back from the walls all muddied up and confused, with comb-filtering and strange interference patterns coming back at you, mixed with the direct sound coming out the front of the speaker. If you can do it, then great! It's more work, of course, but it has many benefits. If you search for "soffit mount" and "flush mount" on this forum, you'll find numerous references and examples of how to do it right (and a few of how to do it wrong!).

The HRS120 sub does not need to be soffit mounted. Just put it on the floor at the base of the soffit wall, half way between the two mains. Setting up the system might be a bit trick in terms of getting the EQ right, since the soffits are already enhancing the bass response of the mains, but Mackies gives you plenty of controls to play with on those speakers, so if you measure carefully and play around a bit, you'll get it right: Worst case, you might need to add a good parametric equalizer right before the speakers, to give you absolute control, but most likely that won't be necessary.


Great! And do a SketchUp model too! That's kind of the standard around here for 3D modeling of studios and things. It's free: download it from google, then spend several hours bashing your head against the wall as you try to figure out its idiosyncrasies and strange concepts, until suddenly the "eureka" moment arrives and it all starts making sense. It's great tool, but has a steep initial learning curve.

- Stuart -

edited to add:
(PS. I'm just taking another look at the specs of the HR824, and it seems they have some kind of "rear-firing mass-loaded passive radiator". Not sure what that does in practice, or if it will hinder soffit mounting or not. You better contact Mackie to find out for sure!)

_________________
I want this studio to amaze people. "That'll do" doesn't amaze people.

Hi Stuart,

Thanks very much for getting back to me. I'll call Mackie tomorrow and ask them if they are suitable for soffit mounting.

Forgive me for not following the rules straight away, this is my first post on here. I'll read thru the guide carefully tomorrow and do some rough drawings but to address a couple of points for now, I am in the located in the UK, in England.

The rooms are set up like this:

It is an extension to the side of the house with a flat roof. The walls of the rooms are of solid wall construction (no cavity). It runs the full length of the house and split in to 2 with the dividing wall I mentioned. The dimensions of the front room (control room) are Length: 5.81m, width: 2.35m, height: 2.22m. The back room which will be used as a live room is length: 4.23m, width: 2.35m and height: 2.22m.

The dividing wall has a door off to one side which needs to be moved to the middle to aid monitor placement and room treatment. By the time its been moved, it may as well be knocked down and a deep double timber frame (as described) built instead. The current wall is 1 breeze block (i think this is what you mean by cinder block) in thickness with a layer of plaster either sideI know what you mean by the difference between isolation and treatment, sorry if it appeared I didnt, I prob didnt post enough detail in my first post, it was mainly started as a question about the monitors you see.

I want to use the dividing wall for isolation yes but I'm told from a very knowledgeable engineer that having such a wide double wall filled with rockwool slabs and double / triple skinned will also help a lot with the 'treatment' of the control room. Getting as flat a response as possible in the control room is my primary concern. I am a dance music producer mainly but I do do live work as well so this is why the control room is the main concern.

I know the solid wall will prob give better isolation but very little in the way of treatment so weighing up the options it seems better to get rid of it do you think?

Heres some pics of the room. In its current state the ceilings have been taken down and the wall and floor are bare so its almost ready to start working on!!

I'll let you know what mackie say about the soffit mounting and the rear-firing mass-loaded passive radiator -----Sounds like something off Star Trek!!

Spoke to a French guy at Loud Technologies (Mackie distributor for the UK). He struggled to grasp what I meant but went away to check and said acoustically it should be fine but because of the rear-firing mass-loaded passive radiator, heat build up may be a problem so not recommended. From what I've seen on the forum here, the soffits can be built to maintain airflow behind the monitors which should in theory keep them cool. They do get quite warm during use but I really like the idea of an "infinite baffle" as you described Stuart. I think it could help a lot in this room.

Sorry for my ignorance but does anyone have a link to John Sayers soffit design? I've searched but cant seem to find it. Cheers

Saying that, I've just been on the Mackie forums and there was a discussion regarding soffit mounting the 824s. Here is one of the replies:


Icon 1 posted May 31, 2005 01:05 PM Remember that monitors that are specifically designed as nearfield monitors are intended to be used in a free space without the benefit of an infinite baffle. Generally speaker cabinets loose low end because the low frequency waveform wraps back around the cabinet. An infinite baffle is the equivelant of a big flat wall (like soffit mounting speakers) which provents the low end from wrapping around anything. It just bounces off of the "wall" or baffle instead of falling away behind the speaker..

I once had some RCF 3 way passive studio monitors that sounded good, but had little or no low end in the bottom octave. They were about the same size as a SRM450, but were three way and had a soft dome mid and high driver. Once I soffit mounted them the low end improved dramatically. They actually sounded really nice!

Interestingly enough if you stand behind an SRM450 you can hear a substantial amount of low end that is not propogated very far in front of the speaker box. Although not very practical, if you put an SRM450 in a soffit (infinite baffle) you would hear that low end extend out front.

So.... nope... don't soffit mount the 824s or any cabinet designed with rear firing components. They were designed to have decent low end without the infinite baffle. You would benefit from the baffle, but loose the rear firing component's contribution. In short it would be pointless.

Truthfully, the rear firing stuff is a bit of a compromise and it might actually have a flatter response with a baffled wall, but it would most likley be a washout.

Danny Brown

Not sounding too promising for the 824s if this guy is correct

but he didn't mention the HRS120 Sub.

when you add a sub you roll off the extreme low end to allow the sub to take over. The frequencies enhanced by the soffit mount are the frequencies handled by the sub.

The speaker has -3db @80hz and -4@50hz roll offs.

Cheers John, so you think it should be ok then, as Stuart says? Just spotted a post from Windmill agency on here as well from last year saying he soffit mounted 824s so I've messaged them on myspace to ask how it turned out and if they've had any problems.

Hi,

No one seems to be posting anything on my thread . I hope I havent offended anyone .

I decided to demolish the wall so heres a pic of the work in progress so far.

I'm working on sketchup - I see what you mean Stuart about the learning curve!! I'm gonna try to start with a basic sketch of the control room with accurate dimensions.

If you guys (and Mark) agree, I'm gonna go for the soffit solution with the 824s. Eric from the Windmill Agency has kindly come back to me and said he likes the 824s in the soffits and is getting good results.

If I do the sketchup, would you guys be able to help me out with the optimal monitoring position and speaker angles etc?

thanx for filling in your profile, I wondered where you came from. Altho your name kinda gave it away, perhaps.

Get familair with SKUP and you'll ask yourself "why the heck didn't I found out about this GREAT proggy before?". Yes, it's that great. Post your plan and we'll love to check it, sure!

Thanks Ro,

This is my first extremely feeble attempt at my control room with sketchup. I'm posting it now rather than wait until I can do a better job of the sketch in the hope someone will take pity on me!!

I cant quite get the dimensions perfect but I'm still working on it! The monitors will be on the right hand side of the sketch as you look at it. There is a window on the left wall. The piece jutting out in to the room at the bottom is a chimney breast. The door at the bottom is the entry door from the house. The door on the right is in to the live room (on the new partition wall that isnt built yet). I'm sorry its a poor sketch but I'll keep improving it as I learn sketchup.

I'd really like to identify the best monitoring position and the angles and height for the monitors in the soffits which will be in the corners on the right hand side wall either side of the door in to the live room. I also want to angle the walls going back to where the door by the chimney breast is (ie forward from the monitoring position - facing right). The angling wall I'm talking about is similar to the ones coming from the soffits in the first image from clicktracks superb van (although theirs is facing the opposite way around):

http://www.johnlsayers.com/Studio/Pages/Clicktrack.htm

If I can get the angles & positions sorted I can get the joiner to build the structure. He is coming this weekend hence the time pressure and lack of time to properly learn sketchup before posting, sorry it's a bit vague guys.......clarity will prevail........

Hi Ian. That part is relatively easy: Standard height for speakers is the height YOUR ears are at when YOU are seated in YOUR chair at YOUR console . In general, for most people this works out to roughly 1.2m above the floor, so you can use that as a starting point. That's the height you want your speakers at.

But Careful! That height does NOT refer to the bottom of the speaker box, nor the top, nor even the center! It refers to the height of the "acoustic center" of the speaker. That might be hard to find with many manufacturers: call them and ask, but you might not get a reply. So you can "guesstimate" it as roughly halfway between the centers of the woofer and tweeter, or maybe a bit closer to the tweeter than that. Ballpark. The acoustic axes is an imaginary line that pokes out of the speaker at the acoustic center, and projects forwards, perpendicular to the front face of the speaker.

So, you want the acoustic axes of the speakers to be at the same height as your ears. That's your starting point.

Next, you want your speakers somewhere around 1 to 2m apart, for most home studios. A bit more or less is fine too, but not so close or so far apart that the sound stage is squashed up or spread very wide. In a bigger room they will probably need to be further apart (or closer together in a smaller room), due to the geometry that you are aiming for (see below).

Next, you want the acoustic axes of the two speakers to intersect at an angle of 60 degrees, at a point about 15 - 20 cm behind your head. If you do that right, then those imaginary acoustic axes should just graze your ears. With this laoyut, the two speakers and the intersection point behind your head, are at corners of an equilateral triangle, so the distance between the speakers will be the same as the distance from either speaker to the intersection point.

Bingo! You have your speaker/head geometry in place! Now you just need to fit it to the room.

That intersection point should be at roughly 38% of the room depth (distance from front wall to back wall) for the reason of keeping your ears out of undesirable nulls and peaks caused by the standing waves in the room. But don't get too hung up on that "38%" number! It's just a theoretical guideline. Many engineers prefer to be a bit closer than that, some prefer to be a bit further away, and the finished room will dictate some of that too. 38% is a starting point, a rule of thumb, not some kind of absolute law. So if your head ends up at 41% or 35%, it isn't the end of the world. However, one point you should avoid is 50%: Half way between front and back wall is the worst possible position, theoretically, as ALL the first order modes have huge nulls at exactly that point, and all the second order modes have huge peaks there.

In a very short room (not much distance between front and rear walls) you might have to increase the intersection angle to as much as 90° in order to keep the speakers far enough apart to give you a good image and sound stage, while still keeping your ears close to the 38% mark.

And if you can't put the speakers at 1.2 m above the floor, due to whatever reason (intervening furniture, computer monitors, console, strange shape head, whatever), then you can put them higher up in the soffit, and tilt the entire soffit down a bit (not just the speakers: the whole soffit panel must be tilted) so that the axes of the speakers still point at your ears (or rather, at a point just below that "20 cm behind your ears" point). But you do not want to tilt them down more than 15° down, or you will get comb filtering and reflections off your work desk, console, keyboard, or whatever else you have in front of you. 15° is already a lot, in fact, and you probably don't want to go more than 10° of tilt, if you can avoid it. Some experts (hi André!) recommend no more than 7 degrees, as anything beyond that can mess up your frequency perception, do to the angle that the waves strike your ears, which use minor phase and timing differences to locate sounds and determine tones, etc. So 7° max, unless you really have no choice, then try to shoot for 10° max.

So that's the basic geometry that you need to figure out for your speakers and ears. It's easy to do in SkethchUp!


Whoa!!!!! Hang a on a sec! Hold your horses!!!!

You really, really should re-think that! You don't yet have even a basic design, and you already have a carpenter coming in to build stuff?????? Maybe you'll think that I'm being presumptuous in telling you this, but:

STOP!!!!

You really, really do not want to start building ANYTHING in your studio, until you have a detailed, accurate, well thought out plan in place, with every possible contingency already thought of and dealt with. I can't emphasize this enough! Building a studio is 90% design, and only 10% construction. If you build something now without a plan, then either it means that you will have to tear it apart later and re-build it when you discover why it wont work, or you end up locked in to an inferior, mediocre design, and you'll spend a lot of time, money and effort trying to work around a problem that should not have been there in the first place. And when you are finished, you won't have a good studio anyway, despite all the effort.

You need to plan carefully, everything, and think it through to the last detail.

For example, I bet you don't even have a clear idea what you are going to do with the bottom of your soffits: All the way to the floor? Hangers inside? Absorption? Resonators? Something else? And what about the soffit panels themselves? Do you have any idea how dense / thick to make them? What material? What kind of support structure do you need for that? Should you seal them to the wall, or not? What about ventilation for the speakers? Cabling? Power? What about the center panel between them? Reflective or absorptive? Tight surrounding boxes, or loose? Neoprene or not? Suspended mountings, or massive stands, or decoupled foam? How high do you need to make the soffits? That depends on your ceiling angle. How wide? That depends on your side wall design. How deep? That depends on your speaker dimensions plus the box, plus ventilation, plus mountings, and also determines the width of each soffit, from wall to center panel....

And about a million other questions that must be asked and answered. And that is JUST for your soffits, without considering anything else about the rest of the room: Are your side walls splayed or not? That will affect the soffits too...

You can't just knock something together on the fly, and hope it will work. Chances are about a million kazillion to one that it WON'T work, if you do that.

I'd really suggest that you cancel the joiner's visit this weekend, and postpone it for a while, until you at least have your plan clear!


- Stuart -

_________________
I want this studio to amaze people. "That'll do" doesn't amaze people.

Hi Stuart,

You are right about the careful planning!! Joiner was coming to build the studwork for the double partition wall you see so I was thinking if I could get it planned out in time he could do the rest of the studwork while he was here.

Cancelled his visit for now

I'm going to start a new thread now in the studio design forum. I've been working on sketchup. It is very frustrating but I'm getting there. Done a better plan of the control room so I'll start a new thread with this plan. Thanks for your help

Ian

Good thinking, Ian.

Have you checked the online video tutorials @ sketchup.google.com yet?
They will guide you through and have you sketching up like a pro in no-time!

Remember: groups and/or components are your friend(s)