Sketchup for my new control room

Hi, Following on from my post on the acoustics forum, I thought I'd start a new thread on the design forum (as it seems more appropriate) with my still basic but much improved sketchup. I'm planning on building soffits either side of the right hand side door and angling the walls on the right to improve acoustics. I'm currently working out the measurements and angles to the monitoring position based on soundmans excellent advice. 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 sketchup is the control room only. I've tried to indicate the soffits and angles from the soffits to by the door. As per Soundmans suggestion, aiming for monitoring position @ 38% in to the room with a 60 degree angle between the speakers intersecting 15-20cm behind monitoring position. I'm struggling with the angles etc in sketchup :-( Any help you can offer me will be greatly appreciated :-)

Just to mention, I've pinched a couple of bits from Johns small studio setup sketchup to put in the room. Heres the link to my other post which has pics of how the room looks now with the old dividing wall taken down ready to build the timber frames for the new double wall to the live room: viewtopic.php?f=3&t=13063&p=89733#p89733 cheers

Hi, I've finally worked out the basics of sketchup. The room dimensions are now 100% accurate with the doors and window in place. I've measured 60 degree angles from 15cm behind the 38% monitoring position and, if I'm reading this correctly, this means the room is too narrow and the monitoring position needs to move closer to the monitors. I've tried and tried but I cant build representations of the soffits or splayed walls I want to put in going from the right hand wall to the door on the bottom edge (entry door) I'm hoping now that the dimensions are all correct and it is a proper drawing, that one of you experts will take pity on me and help me with the design. I'll gladly contribute to the site..... Thanks in advance.... --Ian--

I'm sorry I dont have any advice as I'm pretty new to this as well, but how did you save your files small enough to attach. My files are over 500kb and thus cant be attached on the forum.

IanKaravas wrote:

I'm sorry I dont have any advice as I'm pretty new to this as well, but how did you save your files small enough to attach. My files are over 500kb and thus cant be attached on the forum.

Ian - goto model info and purge the unused - it could reduce the size of your file.

I've measured 60 degree angles from 15cm behind the 38% monitoring position and, if I'm reading this correctly, this means the room is too narrow and the monitoring position needs to move closer to the monitors.

If that's the case, then increase the angle of your speaker axis intersection from 60 degrees up to as much as 90 degrees if you need. That sometimes is necessary in a small room where the geometry just doesn't work out the normal way. It will squash your sweet spot a bit, and give you a slightly wider sound stage, but other than that it will work fine. That will allow you to place your speakers far enough apart to still get your head at a decent location in the room. If you have splayed walls, then you will also need to increase the splay angle from 6° up to 9° or so. One other point: the "38% rule" is not carved in stone! It's just a starting point. If you have to move a bit forward or backwards to get the best sound, then nobody is going to arrest you! Many engineers prefer sitting a little closer than that anyway, according to one paper I read on the subject a while back. So don't feel guilty if you end up at 35%, or 41% or whatever. As long as you are close to 38%, and far away from 50% and 25% then you should be OK. - Stuart -

Thanks Soundman, I was up at 4.30 am this morning trying to amend the sketch before I went to work, to show the way I am going to build the wall on the right in to the live room!! Trying to add the proper construction with the batonned wall etc!! I'm not gonna sleep properly till I get this design ironed out!! When you say increase the angle to 90 degrees, wouldnt that mean that the monitoring position would be brought even further forward given that the speakers will be soffit mounted in the corners and the room is really quite narrow -- or am I getting this mixed up? I thought the 60 degrees related to the angle where a straight line drawn out from the centre of each speaker intersect....I'm probably wrong!!!!

wouldnt that mean that the monitoring position would be brought even further forward

Yes. that is, after all, what you said you need to do! Originally you said:

.... the room is too narrow and the monitoring position needs to move closer to the monitors.

. In other words, you originally said that the monitor position needs to go further forward. That's what you get by increasing the intersection angle: the mix position moves forward, and the speakers can be set further apart. In order to move the listening position closer to the monitors, you need to increase the intersection angle. That's what you seemed to be saying! In other words, you need to turn the speakers so that the face more towards each other (making the the axes less parallel). If you increase the angle to the absurd extreme of 180 degrees, then the speakers would be pointing directly at each other, and your head would be directly between them. If you turn them the other way until they both face the back wall and are perpendicular to it, then the angle would be zero and your had would be infinitely far away. (Actually there would be no angle at all, since the axes would be parallel). So right now, you have an angle of 30 degrees between your room center-line and the speaker axes. 30+30 = 60. If you increase that angle to 45 degrees between the center-line and the speaker axes then you have 45+45 = 90.

I thought the 60 degrees related to the angle where a straight line drawn out from the centre of each speaker intersect

That's correct. But first you said that you wanted to get the mix position closer to the front, and now it seems like you don't want that, so I think I'm the one that is confused! Where exactly is your intersection point now (in terms of percentage of room depth), and which way does it need to move in order to get it 38% away from the front wall? Do you need to get your mix position closer to the front wall, ot further away from it? Increasing the speaker angle will bring it closer to the front wall, thus allowing you to move your speakers further apart, where they belong. Decreasing your angle will move the intersection point towards the rear wall. - Stuart -

I think it is me who is causing the confusion. Apologies. What I'm trying to say is that, looking at the current sketchup, the intersect is set at 60 degrees. The lines indicate the direction of the straight lines coming out from that point at 60 degrees. These lines do not hit the corners, they are somewhat further up the side walls. So, this is where I am confusing things I think, in order to maintain the 60 degree angle AND get the speakers in to the corners (I know they wont be properly in the corners, they will be in the soffits, but this is all I have to go off for now), the monitoring position would have to come forward. Looking at it like this, increasing the angle to 90 degrees would only make it worse because the room is not wide enough to move the speakers further apart. I think my point is that I hope the monitoring position doesnt have to come forward too far (towards 25%) in order to maintain the angle, given the narrow dimension of the room.... I hope that makes sense!! Things will probably become a lot clearer to me once I can get the splayed walls in to the design and the soffits. I think the confusion may be a result of lack of sleep and too much thinking about it!! :shock: I'm going to work on the sketch later today and see how far I can get. Cheers Ian

Ok, heres the sketchup with the 2 leaf wall in to the live room (front boards not added control room side). I've had a go at the splayed walls@6 degrees. Cant seem to narrow the timber frames though as these will only be 2x1 timber whereas the 2 leaf wall will be 4x2. I'm getting there but if anyone would be so kind as to fix the splays and help out with the soffits I'll be eternally grateful.......Sketchup 7 is soooo much better than 6 when you are new to it!!! :shock: :lol: ps, just corrected the angle to 60degrees to properly indicate what I said in my last post

I think my point is that I hope the monitoring position doesnt have to come forward too far (towards 25%) in order to maintain the angle, given the narrow dimension of the room....

OK, I see what you are saying, from that SketchUp model. Once you draw the speakers at their correct locations and correct separation, then you'll need to move the listening point BACKWARDS, not forwards, to put your mix position at the right location too, or it will be too close to the front wall. Your control room is very long and thin. What ratio is that based on? Since your limiting factor is width, maybe one idea would be to use a different ratio and make the room shorter. Either move your dividing wall towards the rear (chimney) end of the room, or maybe build another wall across the back, to create a small storage area, or even a vocal booth. That would make the room shorter, which automatically moves the 38% mark closer to the front wall. Another comment: Your speakers should not be in the corners. They need to be in the middle of the soffit panels, and those need to be as large as you can possibly make them, given the limitations of room geometry. That will probably place them roughly one quarter of the room with away from the walls, meaning roughly half of the room width between them, meaning they will be about 1.3 m apart, and about 50 cm from the walls. Somewhere around there. That isn't much to work with, but it is what it is! --------- EDITED TO ADD: I have since learned that the speakers should NOT be in the middle of the soffits, but rather offset to one side or the other, in order to avoid creating peaks and nulls in the frequency response. It seems that a position about 2/5 of the width is good. They should also not be centered vertically, for the same reason. - Stuart - ---------- So if your speakers are 1.3 m apart, then your head needs to be about 1.3 m from each speaker. That would place your listening position around 1.3 m from the front wall, meaning that your room needs to be about 3.4 m long, instead of the 5.8 that you have right now. Those are very rough figures, of course. Rule of thumb and "guesstimates". But it should give you an idea of the geometry and dimensions that you need to play around with, to make things fit. - Stuart -

Thanks Stuart, I havent worked any room ratios, to be honest this is the first I've heard of ratios. I'm just limited by the actual physical size of the space. Maybe I need to do some reading on room ratios before building the new dividing wall to define the length. I cant physically alter the length from the other end of the room as there is a window there. I really want to keep the room as long as possible but obviously acoustics are top priority. Am I right to accurately draw the splayed walls first before placing the soffits? Do you think splaying the walls like that is the right thing to do in this room? The soffits can be bigger if the walls are not splayed but I could do with some direction on this. Cheers Ian

I'm getting there but if anyone would be so kind as to fix the splays and help out with the soffits I'll be eternally grateful.......Sketchup 7 is soooo much better than 6 when you are new to it!!!

Ok, here is a series of jpgs showing the progression, for those who can't download the file. However, i have no idea of your ear height when sitting at the engineering position. Therefore, these are generic HEIGHT expressions. As soon as you post that dimension, I'll fix the monitor height. Plus, these are just to give you an idea. I'll post the whole file once I'm done. :) fitZ ps, this is the first ten of...? :mrgreen:

Heres the rest so far. and then you may like this... :mrgreen:

btw, the soffit construction works. I know because I built mine. :) ps..if you are interested, I'll share the construction photos with you so you can see how to do it. in the meantime, here is a model of the soffets and superchunk treatment, and the frame for supporting the fabric.

Ok, here is a series of jpgs showing the progression...

Ummmm.... So what happened to the DOOR from Ian's CR into his LR? You seem to have eliminated it...

Am I right to accurately draw the splayed walls first before placing the soffits? Do you think splaying the walls like that is the right thing to do in this room?

I'd suggest that you figure out your soffits first, then add the splayed walls from there. They should be 6° to help control first reflections and flutter echo, but if you can only get 5°, that you have to live with what you have. And if you absolutely cannot get both splayed and soffits to work, I think I'd dump the splayed walls, keep the soffits, and go with inside-out side walls that are parallel to the existing walls with as big an air gap as you can afford. Splayed walls would help for isolation too, but you have concrete in your first leaf, so you probably already have reasonably good isolation there, and you might be able to skimp a bit on your air gap. That will increase the resonant frequency of the MSM system, but once again, if those are thick concrete walls, then it might not be that important. What is on the other side of those side walls? How thick are they? And how loud are you? Key points. - Stuart -

:D Wow. Thanks a lot guys, you are so helpful. Here are the answers to the questions: Monitoring height of my ears @ the monitoring position sitting in my chair is 120cm. The walls are brick & plaster cavity walls. Solid. I have the rest of the house to the right when seated @ monitor position facing speakers and to the left is the garage which runs the full length of both the CR and LR. I am loud but I dont really have a prob disturbing the neighbours from the control room, the only thing I may do is fit secondary glazing across the windows. Isolation to the sides is not really a concern so I dont need to worry about it. Not planning on building a second leaf on the side walls due to the narrow dimensions of the room, except for the splayed bits which I want to taper down to the existing walls if this is possible. Gonna use timber & soundbloc for this if it turns out once this is all worked out that the splays are possible. I agree with you that the soffts should be take precedent over the splays but it would be great to have both. Those jpegs look amazing (once the door is in :wink: ). For the rest of the walls, I was going to build frames for rockwool batts and use superchunk in the corners under the window. Still checking on the correct way to do the dividing wall (CR into LR) and correct way to fit the new ceiling. Then I was going to use an acoustic cloud over the monitoring position. Quick point about the speakers. They are mackie hr824s - active powered so for the soffits I'm gonna need to get airflow round the back of them and possibly encorporate a fan in there. They get quite warm but not excessively so. Also I've got the hrs120 sub to use with them which I was thinking would be placed forward of the monitoring position in front of the door in to the LR. I am going to call mackie tomorrow to get the position of the acoustic centre of the 824s as I was told in a previous post that they should be mounted in the soffits such that this centre is at the same height as my ears at the monitoring position. I'll post the info on this as soon as I've spoken to them. I cant thank you guys enough for your ongoing help and invaluable expertise. This forum is absolutely fantastic and as my knowledge of acoustics & techniques improve as they no doubt will during this project, I will contribute to the site in any way I can. I cant thank you enough. --Ian--

Hello ian. I'm limited on time today, but I have a few quick questions.

Quick point about the speakers. They are mackie hr824s - active powered

First, what are the EXACT dimensions of your hr824's?

The walls are brick & plaster cavity walls.

:? Second, what is this opening for? And why do you have two walls there. It looks like those are embedded in what I thought was a solid wall in your first file.

Ummmm.... So what happened to the DOOR from Ian's CR into his LR? You seem to have eliminated it...

Ummmmm...looks like a door to me. :roll: :mrgreen:

Hi, The opening is the door in to the live room. There are 2 doors. The one youve drawn already is the entry in to the control room from the house. The door thats missing is the one to the live room. The opening youve mentioned is this door to the live room. Currently, the wall you are asking about isnt there. I'm going to build a 2 leaf system between the control room and the live room with the door in the middle of it into the live room. This is what i've tried to represent in the sketchup i did. I'll post the pic of the rooms as they are now so you can see. It is currently one long room that is going to be split in to two once I know the correct size for the control room I can decide where to build the 2 leaf wall. The mackies are: height - 40cm, width - 26cm, depth - 27cms with a 4cm passive radiator on the back so the actual depth is 31cms Cheers --Ian--

The opening is the door in to the live room. There are 2 doors. The one youve drawn already is the entry in to the control room from the house. The door thats missing is the one to the live room. The opening youve mentioned is this door to the live room.

You mean to tell me that you are planning a door...in front of your console, between soffits???????? :shock: :shock: :shock: ummmm, where did I miss that? What a dunce I can be. Well........that changes everything. Good luck with that one. Considering the centerline planes required for centering monitors on a Soffit baffle plane...it leaves about a foot between the door and the back of a console...approx. ??????? How are you goint to do that? :shock: :shock: :shock: :shock: I mean...sheeezus..what about cables, and traffic AROUND your console??? Well, I don't know if this helps now. I did 20 more jpegs..but no time to post them now nor any reason to. For what its worth, here is the end result. The monitor was sized from your hr824 face and depth Gotta go now.... :oops: :( :shock: :shock: btw, the baffle size requirement was defined here... viewtopic.php?f=1&t=5457&p=89832#p89832

Just extend the baffle 2 times the original baffle on EACH SIDE and you'll be save

fitZ

Just a quick question. Have you considered other axis and boundary locations? Like in front of the window, or using the short axis? It might be worth looking at. btw...

The opening is the door in to the live room. There are 2 doors. The one youve drawn already is the entry in to the control room from the house.

I didn't draw any doors. You did. I only assumed that was the door to the live room.

cadesignr wrote:

You mean to tell me that you are planning a door...in front of your console, between soffits???????? :shock: :shock: :shock: ummmm,

Yes, I have to . I've got to work with what I've got I'm afraid. Its not ideal but it is surely workable?? There is another entry in to the live room from the back garden so the door wont be in constant use and my desk / console setup is not massive so there should be some room either side to get past. The space in front of the desk / console is yet to be determined because I still dont have a definate decision on room ratio and where to put the new dividing wall so dont know the exact length of the room yet. If anyone can offer a suggestion on this I'd be grateful. Once The dividing wall position (hence room length, speaker, soffit and monitoring position) is decided, everything else should hopefully slot in to place........ Cheers --Ian--

Other axis and in front of the window really arent feasable unfortunately. I'm slowly becoming depressed....... :( :cry:

Second, what is this opening for?

That's the DOOR that I mentioned you had left out. The one from the CR to the LR.

And why do you have two walls there.

Well, gee, that kind of is the normal way to build an MSM wall! Two leaves of mass, with an air gap between, on two separate stud frames. How else would you go about building a high isolation wall between CR and an LR, on a reasonable budget?

Ummmmm...looks like a door to me.

Yeah, but it looks like the WRONG door, too! :) I asked you about the door between the CR and LR, not the door from the CR to the house....

You mean to tell me that you are planning a door...in front of your console, between soffits????????

And there is a problem with that? Is there a good acoustical reason why doors should not be placed in front of consoles and between soffits? Sure, in this case it doesn't leave much size for the soffits, but you make it sound like in general it is a bad idea to put a door behind a console and between soffits....

it leaves about a foot between the door and the back of a console...approx. ??????? How are you goint to do that?

Well, gee, how about changing the geometry of the mix position and speakers? As was discussed earlier in the thread. I guess you missed that part....

I mean...sheeezus..what about cables,

The normal way is to duct them all through conduit, which could be chased into the floor, or run off to one side of the console, leaving the other side free for traffic.

or using the short axis?

Huh? Use the short axis? As in: "have the speakers firing across the room, instead of down it"? Is that what you mean? If so, I assume that was meant to be some kind of sick joke. Not funny. - Stuart -