John Sayers' Recording Studio Design Forum Archive

Hi Stuart,

I did try doing a corner CR design a while ago inspired by the one in Rod's book, but I really struggled to get one to work with a door out of the CR in a sensible location, and I was also concerned about the soffit and not being able to calculate room modes or use ratios. At least with rectangles or trapezoid shaped rooms I can do some type of predictions.

As for positioning the CR between the two live rooms - this is not something I had yet considered. Mainly because I saw the middle part of the basement as being the preferred location for the noisiest area - the drum room; due to it's lack of external windows (or fireplace ash box I the case of the south wall). A second factor is my desire to have the two live rooms feel like one room to the performers, with the ability (if possible) to open up the two rooms into one large room. Or at the very least I had hoped to have good site lines between the two live rooms. I realize at some point I have to start making compromises though.

I will definitely give your comments great reflection and see if it stimulates any new solutions. I'm all ears btw if you had something specific that sprung to mind. What comes naturally for you in 2 minutes takes me weeks of going back and forth following lots of research and deliberation

Many thanks as always for your valuable time and kindness,

Andy.

So I spent all day yesterday playing with various different room shapes and sizes. I attempted the middle control room and the corner room with a number of sizes (using known good ratios as a starting point) but just couldn't get any to work - something always seemed to make it fail - a window location, the support pillar, wasted space, lack of sight lines. I'll post some pics below of some of the best failed attempts. I'm kind of at a loss

One other thing based on Kevin's feedback. I recall watching a video on Mitch Gallagher's home studio where he talked about using a "leaky wall" as a bass trap at the back of the room. This leaky wall was basically framed and insulated and then used pegboard on the front face. I was wondering if that might provide a possible solution to the door / bass trapping issue that Kevin raised. Attaching a quick pic of what I mean if that helps....

Andy,

Thats funny, i just watched that a couple weeks ago.. from sweetwater right? Anyways, I think thats a good idea, and definitely worth considering... I'd be even tempted to not make it reflective at all... and just keep the entirety of the back wall absorbent... or if you need to keep some of the highs, use a pvc / plastic sheeting on top of the rockwool and cover with a cloth... the lows will still be absorbed...

slightly related to your post...
I was wondering what would happen if you keep the CR at the end, and just rotate the design to face outward to the tracking rooms... so where the window is now, install a larger sliding glass door... yes, you'd have to walk around your desk everytime you get in and out... but, you could treat the walls however you like, and open up the middle room for a kit... plus, facing the musician while recording is always nice... like your last posted picture suggests... (i just saw that)...

as for stuarts suggestion, i'd be hesitant to put the CR in the middle... (no offense!!!) it's just that lugging amps or drums through the CR seems like a pain, if not a danger. I think it would be different if it was just a vocal booth or for acoustic stuff...

kevin

Yes that's the one Kevin - here's the video in question for anyone else that is interested:
http://youtu.be/FuRiqoNRDmc
The discussion about the leaky wall starts around 36m40s

I've continued trying additional approaches, shapes, orientations and ratios over the last 48 hours but have still yet to find anything that works any better. I have been keen to find an approach as you suggest where the CR looks into the drum room by way of the window although I've yet to find a way to do that while still be able to use a sound-lock approach, hence I suspect your suggestion to use the sliders. While I'm not oppose to using SG doors per se, I'm really not sure that I could get used to me (or worse still others) navigating their way around the console to get to the door. I think I'd be very nervous! I should also point out that I have a vested interest in using doors and a window if at all possible, as I was able to salvage the four doors (including the closers and adjustable seals), and window from my last studio when I moved. I will say also that from my last studio, and given how much I tend to run back and forth between the CR and live room during a session; that I love the pull / push doors with automatic closers.

I've also been keen to find a solution where I can splay the walls to help with the flutter echo, but given the other design constraints I'm really struggling to find a working design. I wish that support column weren't there, and that the mechanical room didn't notch out into the space - but it is what it is and I have to find a solution that works around them and the other constraints (exterior windows, duct soffit etc.)

In other news the Structural Engineer finally came back to me with the numbers for under the kitchen. They were all hand-written (take a look here)and this time he e-mailed them to me with no seal / stamp so I asked if he could mail me the final signed and sealed report (since this is what I'm paying money for) and he said "sure - it'll be another $200 for the extra calculations". I don't mean to split hairs, but I was very clear from the get go that the under-kitchen area was the area of greatest concern (given the dead load in there and the wider joist spacing) so I'm not sure why he failed to provide them in the initial calculations nor if I should have to pay for him to do "additional calculations".

Anyone have any thoughts on the matter? Am I being overly sensitive? Perhaps the frustration from weeks of not getting my studio design to work is causing me to act irrationally.

And here's my latest sketch (.skp file is here). As you can see it's a variation on the previous design using the "leaky wall" at the back of the CR, but splays the front half walls by 6 degrees. I have also opened up the live room and gotten rid of the lounge. The door in that room would go into a closet area that would eventually serve as an air-lock if and when I add a walk-out exit there.

Let me know what you think...

Andy

I've created a slightly improved sketchup file here that took care of a couple of issues:

1. Created access to the Fireplace Ashbox on the south wall by starting the splay after the Ashbox
2. Adjusted the average room width to better match the Sepmeyer 3 room ratio based on a rectangle with the same volume.

What do you guys think? Would you go with something like this? See any "gotcha's"?

Many thanks and wishing all a wonderful weekend,

Andy

So I've been doing further tweaking to the plan (not to be confused with twerking of course) and you can see the latest Sketchup File here...

However, having lived with this plan for a number of days now and having gone down into the space and tried to imagine working down there I find myself questioning whether or not I can live with it.

The biggest issue that I see is the lack of space in the Control Room. There's just no room for a Sofa and people to sit at the back of the room due to the "leaky wall" bass trap idea. In my last space the Control Room became the hang out spot between takes or for my own band after Jamming - and I don't know that it's doable with this configuration. That's kind of a deal breaker.

There were other concerns regarding where to place bass trapping in the Booth etc., but the above is perhaps my biggest concern right now.

So I think it may be back to the drawing board again.

Please please please - if you have ANY ideas - please let me know. I'm starting to get desperate!!!

Okay I think I may finally have something here. I have rotated the CR 90 degrees counter clockwise which allows me to add the door away from the bass trapping area. Sketchup file is here for anyone that wants to see in detail. Stuart I am attaching JPG's for you in case you still are unable to upgrade.

As you can see I would still need to add treatment to the CR. The large sound lock to the side of the CR would also serve as storage space and could perhaps double as a booth / isolation space if needed.

Would love to get some feedback from any of you

Okay I think I may finally have something here. I have rotated the CR 90 degrees counter clockwise which allows me to add the door away from the bass trapping area

Now THAT I like! that makes a lot more sense, Andy!
If you slide the entrance door a bit further back, and put in a window to that "hallway", it would make a great emergency vocal booth...

However, you do still need inner-leaf walls for that hallway/booth: right now, it is in the air cavity of your MSM system. That will make it narrower, of course, and will create an issue with the door to the drum booth, but if you splay your CR walls a bit more (aiming for a true RFZ design... ), then the door should still fit in just fine.

But I really do like this a lot more: the CR is much bigger, can have a better ratio, and has good sight-lines to everything else. I think you are on the right track with that!



- Stuart -

You have no idea how happy your reply made me Stuart! Seeing your thumbs up means the world to me!

So naturally I have a few questions and comments...

If you slide the entrance door a bit further back, and put in a window to that "hallway", it would make a great emergency vocal booth...

Yes I was thinking about using it for something like that but hadn't considered adding a window and making it a legit booth - interesting idea

However, you do still need inner-leaf walls for that hallway/booth: right now, it is in the air cavity of your MSM system.

Yes, this was actually my intent. Kind of like an oversized air lock that could perhaps double as a booth / isolation space if needed. I figured that I could add fabric over the framing and insulation and it would be kinda like one of John's inside out rooms. Would you advise against that or is there perhaps an issue that the building inspector might have? As you can see I was planning to do something similar, albeit much smaller, for the sound lock going to the future walk-out door from the live room (the room furthest from the CR). Is that wrong also - I figured there was some benefit to having this be a large spring. Ahhhhhh (lightbuuuulb) - is that why perhaps your saying I would need to finish the other area to use it as a booth? Since if it's a spring and someone is jamming on the drums in the adjacent room - this area would be picking up a lot of residual sound energy from that room. I guess then it's only an issue if I plan to record in that small hallway rather than use it for storage. For storage it would be fine to leave it without Sheetrock?

if you splay your CR walls a bit more (aiming for a true RFZ design... ), then the door should still fit in just fine

I may need a few pointers here. I've been doing some research over the past few days on Ray tracing and how to predict reflections (MHOA, Newell, and online threads - including your very own discussion here that I found very useful). I tried drawing a line directly from the midpoint of my HR824mkI's in Sketchup to see where the first reflection would be point would be and it seemed to be back to the corners where the bass traps are - so I know I'm doing something wrong here. If I use a cone rather than a straight line - what should be the angle inside the cone? Also is it only truly an RFZ if i soffit mount my speakers? I am leaning towards leaving them as near fields - would that then affect the need to increase the splay angle?

Many thanks again Stuart for making my day - it's great to know I'm finally getting close to having a working design, and thanks as always in advance for your time and insight with my endless questions

Kind regards,

Andy.

Ahhhhhh (lightbuuuulb) - is that why perhaps your saying I would need to finish the other area to use it as a booth? Since if it's a spring and someone is jamming on the drums in the adjacent room - this area would be picking up a lot of residual sound energy from that room.

Yup! You got it. If you are standing inside the "spring" of the MSM system, then you are in the acoustic war zone! Don't forget that that's a two-way street in there: It's two different MSM systems at once: one with respect to the CR, and the other with respect to the LR. So there's two different wars going on at once. If you are in there, then you only have one leaf between you and each of those noisy things, but also you are part of the dueling MSM battle zones. That's probably not a place you'd want to set up a mic to record vocals!

I guess then it's only an issue if I plan to record in that small hallway rather than use it for storage. For storage it would be fine to leave it without Sheetrock?

I would drywall it regardless: If you don't, then anyone walking through that space is only one leaf away from either room: a cough, a sneeze, a cell phone ringing, a chat with the guy walking next to him, things getting dumped on shelves, dragged off shelves and dropped on the floor... I think you get the picture!

I may need a few pointers here. I've been doing some research over the past few days on Ray tracing

OK, it's easy and hard! Easy in concept, hard in the sense of boring, repetitive, figuring angles, drawing lines, figuring more angles, drawing more lines, rinse, repeat....

The basic idea is this: Start from the acoustic center of your speaker, then looking directly down from above, draw a line at 90° to represent the acoustic axis. Then draw some more lines angled at 10°, 20°, 30°, 40°, 50° and 60°, going BOTH ways: to the left and to the right of the axis. Now follow each line in turn across the room, to see what it hits: wall, window, door, another speaker, etc. At the point where it hits that surface, figure out the angle of incidence, then draw another line bouncing off that surface starting from the very spot that the first lie touched it, but at the exact opposite angle. For example, if the incoming line hit the surface at 27.3°, then the reflected line must bounce off at 27.3° going the other way. You measure all of these angles with respect to the "surface normal", which is just a fancy way of saying "a line poking out of the surface perpendicular to it, at the point where the incoming line hit it". You always measure all your incoming and outgoing angles with respect to the "normal".

So, then you follow this new reflected ray across the room again, to see where it goes: Hopefully it heads off to the back wall, where you will absorb it. It might also head off towards another surface in the front half of the room, in which case: "rinse, repeat".... same procedure for another bounce.

As you follow each line, you want to make sure that it does NOT get close to your ears at he mix position! That's the entire point of the exercise. So draw a circle at the mix position to represent the size of your head, then draw a couple of bigger circles, about 1 foot radius and about 2 feet radius. Ideally, you want no rays at all passing through the 2-foot circle, and definitely none in the 1-foot circle. If a ray gets into the 1-foot circle, then you need to change the angle of the surface that the ray bounced off and rinse-repeat until the ray no longer gets into the circle. It might not be possible to keep all rays out of the 2-foot circle, but do your best to minimize them, and keep them just passing through the edges, as far away from the 1-foot circle as possible.

OK, have you done all that, and gotten all your rays out of the circles by carefully angling the walls, doors and windows? Great! Now it's time to do it all again, but this time starting with a SIDE view of your room, instead of the top view. This time you'll be making rays that spread out upwards and downwards from the acoustic center of your speaker, towards the ceiling... and towards the desk, console, video monitors, etc.

When you are done, you'll have dozens of lines running all over the room in all directions, both vertically and horizontally, but hopefully there will be a clear area around your head at least 12" to 18" on each side of your head, and with a bit of luck, as much as 24" each way. But 24" is really hard to do in a small room.

OK, adding to the above: If you do find lines that are getting into your 2-foot circle (actually, it's a 2-foot sphere, really, since it goes out in all directions...) then you can also do a bit of "devil's advocate" prioritizing, by seeing which ray it actually is, and deciding if you will allow it to live or not... If it is a ray that started out with an angle of 10° or 20° from the speaker, then you really cannot allow it, since that is practically on-axis for most studio monitors. If it started out as 60°, on the other hand, then it's probably not too much of a problem, since that is pretty far off-axis, so it is going to be a mostly lower frequencies on that path, which are probably not too directional anyway.

Don't forget that each time you change the angle of a surface, you need to go back to Square One with this whole procedure, and start again, since you might have also moved some part of the surface into a position where a different ray now also hits it, at a different point....

rinse... repeat ... rinse ... repeat....

Did I mention that this is boring?


- Stuart -

Sorry, I missed a part in my answer above:

Also is it only truly an RFZ if i soffit mount my speakers? I am leaning towards leaving them as near fields - would that then affect the need to increase the splay angle?

Well, you can do an RFZ that is pretty decent without soffit mounting, but you'd still be left with all the usual artifacts of speakers that are NOT soffit mounted: SBIR, edge diffraction, phase shifts, comb filtering, and all the other nasties that mess up your speaker response, in both the frequency and time domains (and phase domain too, but that's sort of time domain anyway... ). If you soffit-mount, then all of those go away...

If you do soffit mount, then half of your ray-tracing is taken care of anyway, since a large piece of your front wall is already angled correctly: Your soffits are angled at about 30° (give or take) since they match the speaker angles, which is almost always more than plenty for RFZ, in the majority of rooms. So the only part that you still need to ray-trace is the surfaces that blend your soffits into the side walls.


- Stuart -

my brain hurts too much reading this now... let alone trying to make an intelligent comment... I'd blame my current sinus cold, but i'm not so sure thats it so i did want to cheer you a bit, keep up the good work andy, stuart, again, this is really helpful!

kevin

On no - feel better soon Kevin!

Ok Stuart - so I took a quick stab at following your superb instructions (many thanks for the explanation) and am pasting a shot below so that I can ask a few follow-up questions. I did this really as a trial to see what would happen with the existing room shape (12 degree splay) if I added soffit mounts for my HR824's (it seems quite a few folks have done this successfully even if Mackie don't advise it). So on to the questions:

• Since I don't have the space to angle my ceiling and planned to just add a hard-backed cloud above the mix position - is it worth conducting the exercise again for the vertical axis?
• Since my room is symmetrical - do I only need to conduct this for one of the speakers? Won't the other be a mirror image? (assuming there is no furniture or other items to interfere with the wave)
• Even with just the 12 degree splay and soffit mounting it would appear that none of the 1st reflections travel through the 1ft radius circle, and the only ones entering the 2ft circle are first reflections from further off axis (50 and 40 degrees). So is it worth angling the walls further or should I just treat that first reflection point? I'm guessing it would take some significant splay to angle that 50 degree reflection back behind the mix position.
• Am I right in thinking that as well as having the bass traps in the rear corners I would want to make the rest of the rear wall absorptive, and / or diffuse to help dissipate or randomize those reflections?
• Is there value to me adding absorption around the front wall window (between the two soffits)? It would appear that none of the primary on-axis rays appear to hit back there.

Many thanks again for your detailed and very helpful explanation. I'm sure I'm making some errors here but I'm also sure that if you're able to get me to understand this then anyone will be able to!

All the best,

Andy