John Sayers' Recording Studio Design Forum Archive

We recently had to move and give up my studio at the University of Rio Grande.

The good news- The house we bought has a room that is much better dimensions acoustically! Since I paid for everything at the old studio, I was able to bring much of the studio constructions with me, but of course, they don't quite fit, so I am having to figure out what I can use, and what it will be easier to just start over with. It is also pretty wonderful to get a second chance to take what I learned from this site the last time, and try to improve upon it.

The new room's dimensions are

(L) 13' 2" x (W) 10' 11 1/2" x (H) 7' 1 1/2"
In addition there are closets along the back wall that are 31" deep x 10' 11 1/2". These are divided into three sections with shelves on either side, and an area for hanging things in the middle.

There is one door, but no windows.

The room is in the basement, and I do not need to worry much about sound isolation, I prefer to listen at moderate levels, and the house itself is very well built, and the level of isolation from the outside is acceptable.

I primarily compose Classical music, as well as theater, though at URG I taught songwriting, which I hope to do here as well. In that role, I worked in just about every genre imaginable, (and invented some new ones!)

I am already fairly familiar with John's techniques, and intend to follow his typical design ideas with locating the monitors (Alesis M1 passives) in angled front walls, with acoustic clouds over the listening area , Mineral wool and or rigid fiberglass at the primary reflection points, bass traps made with wood slats, and hangers behind the monitors, as well as in the center of the closet at the back of the room. I will also place mineral wool spaced from the back of the closets with the shelves, though, I would like to use the shelves for storage as well. The Closet doors will remain, but I can open them anytime I need to do any critical listening.

Questions that I have:

Help with adjusting the optimum angles and dimensions of the front, angled walls.

Should I remove the drywall on the ceiling and fill the spaces between the joists with mineral wool? This would give me an additional 10" of height, but when I ran the room node calculations, I was very surprised that it appears the room should be better with the lower ceiling!

I will post pictures of the room, and the salvaged contents of the old studio that I could use.

I also have started a google sketch up of the room, which I will finish up shortly.

Thank You!

Scott Michal

Composer, Songwriter, Cellist and Pianist, Teacher

Medina, Ohio

The left side wall, with 2 of 6 4x4 acoustic panels made from 4" mineral wool. These were hanging as a cloud in the ceiling of the URG tracking room.
The right side wall. my DAW desk, an old rack, and one of the monitors have been moved to the center of the room when we painted yesterday. The wall mounted lights have got to go! I will turn one of them into a wall socket and cap the other.
The rear wall with closet doors. I hate to get rid of the doors but can if I have too. I am not sure what the angled wall above the doors was originally for but behind it is another large area that could be filled with insulation for a 31" deep bass trap.
The rest of the rear wall with doors closed
Here we have the doors open. The center I will put in hangers. The side sections have shelves that are 31" deep. I will install 4" of mineral wool with a front of burlap, and with several inches of air space behind it to serve as rear wall absorption.
A closer look at 3 of the acoustic panels. I will probably start with hanging a few of them on the walls, and knock down the rest for raw materials of the rear absorption and side walls.
The 6" thick, 6' x 4' cloud, filled with rigid fiberglass. There is a secondary cloud, 4" thick, 6' x 3" as well. on the left side of the picture is one of 2 2x4 panels filled with 3" of rigid fiberglass.
1 of 2 angled walls for the monitors. I have several more pieces of bamboo that attach on the other side of the opening. The bottom is mineral wool, (I removed the burlap panel to show the construction) I will extend the wall to the ceiling and add mineral wool there as well. In the center, I had another section of similar construction, but this room is much wider! 11' compared to 8" so I will need to rebuild that part. Also, I gave up on trying to remove the slat wall sections from the old studio, they were too big and heavy, so I will need to rebuild those.



The floor is concrete.

Next- google sketchup

Here are the room nodes as calculated with Bob Gold's calculator

Freq % Wavelength, 1/2, 1/4 p,q,r Mode Group Weighting
42.4 hz 26'8", 13'4", 6'8" (1,0,0 Axial) Start iso, End iso
47.4 hz 10.5% 23'10", 11'11", 5'12" (0,1,0 Axial) Start iso, End iso
63.7 hz 25.5% 17'9", 8'10", 4'5" (1,1,0 Tangential) Start iso, End iso
74.4 hz 14.3% 15'2", 7'7", 3'10" (0,0,1 Axial) Start iso, End iso
84.9 hz 12.3% 13'4", 6'8", 3'4" (2,0,0 Axial)
85.7 hz 0.9% 13'2", 6'7", 3'4" (1,0,1 Tangential)
88.3 hz 2.9% 12'10", 6'5", 3'2" (0,1,1 Tangential) Start iso, Near
94.9 hz 6.9% 11'11", 5'11", 2'12" (0,2,0 Axial)
97.3 hz 2.4% 11'7", 5'10", 2'11" (2,1,0 Tangential)
97.9 hz 0.6% 11'7", 5'9", 2'11" (1,1,1 Oblique) Near
103.9 hz 5.7% 10'11", 5'5", 2'9" (1,2,0 Tangential)
112.9 hz 7.9% 10'0", 5'0", 2'6" (2,0,1 Tangential)
120.6 hz 6.3% 9'4", 4'8", 2'4" (0,2,1 Tangential)
122.5 hz 1.5% 9'3", 4'7", 2'4" (2,1,1 Oblique)
127.3 hz 3.7% 8'11", 4'5", 2'3" (2,2,0 Tangential)
127.3 hz 0% 8'11", 4'5", 2'3" (3,0,0 Axial)
127.8 hz 0.3% 8'10", 4'5", 2'3" (1,2,1 Oblique) Same Axial, Near
135.9 hz 5.9% 8'4", 4'2", 2'1" (3,1,0 Tangential)
142.3 hz 4.4% 7'11", 3'12", 1'12" (0,3,0 Axial)
147.5 hz 3.5% 7'8", 3'10", 1'11" (2,2,1 Oblique)
147.5 hz 0% 7'8", 3'10", 1'11" (3,0,1 Tangential)
148.5 hz 0.6% 7'7", 3'10", 1'11" (1,3,0 Tangential)
148.9 hz 0.2% 7'7", 3'10", 1'11" (0,0,2 Axial)
154.8 hz 3.8% 7'4", 3'8", 1'10" (1,0,2 Tangential)
154.9 hz 0% 7'4", 3'8", 1'10" (3,1,1 Oblique)
156.3 hz 0.8% 7'3", 3'7", 1'10" (0,1,2 Tangential)
158.8 hz 1.5% 7'1", 3'7", 1'9" (3,2,0 Tangential)
160.6 hz 1.1% 7'0", 3'6", 1'9" (0,3,1 Tangential)
161.9 hz 0.8% 6'12", 3'6", 1'9" (1,1,2 Oblique)
165.7 hz 2.2% 6'10", 3'5", 1'8" (2,3,0 Tangential)
166.1 hz 0.2% 6'10", 3'5", 1'8" (1,3,1 Oblique)
169.8 hz 2.1% 6'8", 3'4", 1'8" (4,0,0 Axial)
171.4 hz 0.9% 6'7", 3'4", 1'8" (2,0,2 Tangential)
175.4 hz 2.2% 6'5", 3'3", 1'7" (3,2,1 Oblique)
176.3 hz 0.5% 6'5", 3'2", 1'7" (4,1,0 Tangential)
176.5 hz 0.1% 6'5", 3'2", 1'7" (0,2,2 Tangential)
177.8 hz 0.7% 6'4", 3'2", 1'7" (2,1,2 Oblique)
181.6 hz 2% 6'3", 3'1", 1'7" (1,2,2 Oblique)
181.7 hz 0% 6'3", 3'1", 1'7" (2,3,1 Oblique)
185.4 hz 1.9% 6'1", 3'1", 1'6" (4,0,1 Tangential)
189.8 hz 2.3% 5'11", 2'12", 1'6" (0,4,0 Axial)
191.0 hz 0.6% 5'11", 2'11", 1'6" (3,3,0 Tangential)
191.4 hz 0.2% 5'11", 2'11", 1'6" (4,1,1 Oblique)
194.4 hz 1.5% 5'10", 2'11", 1'5" (1,4,0 Tangential)
194.5 hz 0% 5'10", 2'11", 1'5" (4,2,0 Tangential)
195.9 hz 0.7% 5'9", 2'11", 1'5" (2,2,2 Oblique)
195.9 hz 0% 5'9", 2'11", 1'5" (3,0,2 Tangential)
201.6 hz 2.8% 5'7", 2'10", 1'5" (3,1,2 Oblique)
203.8 hz 1% 5'7", 2'9", 1'5" (0,4,1 Tangential)
205.0 hz 0.5% 5'6", 2'9", 1'5" (3,3,1 Oblique)
206.0 hz 0.4% 5'6", 2'9", 1'4" (0,3,2 Tangential)
207.9 hz 0.9% 5'5", 2'9", 1'4" (2,4,0 Tangential)
208.2 hz 0.1% 5'5", 2'9", 1'4" (1,4,1 Oblique)
208.3 hz 0% 5'5", 2'9", 1'4" (4,2,1 Oblique)
210.3 hz 0.9% 5'4", 2'8", 1'4" (1,3,2 Oblique)
212.2 hz 0.8% 5'4", 2'8", 1'4" (5,0,0 Axial)
217.5 hz 2.4% 5'2", 2'7", 1'4" (5,1,0 Tangential)
217.7 hz 0% 5'2", 2'7", 1'4" (3,2,2 Oblique)
220.8 hz 1.4% 5'1", 2'7", 1'3" (2,4,1 Oblique)
221.6 hz 0.3% 5'1", 2'7", 1'3" (4,3,0 Tangential)
222.8 hz 0.5% 5'1", 2'6", 1'3" (2,3,2 Oblique)
223.3 hz 0.2% 5'1", 2'6", 1'3" (0,0,3 Axial)
224.9 hz 0.7% 5'0", 2'6", 1'3" (5,0,1 Tangential)
225.8 hz 0.3% 5'0", 2'6", 1'3" (4,0,2 Tangential)
227.3 hz 0.6% 4'12", 2'6", 1'3" (1,0,3 Tangential)
228.3 hz 0.4% 4'11", 2'6", 1'3" (0,1,3 Tangential)
228.5 hz 0% 4'11", 2'6", 1'3" (3,4,0 Tangential)
229.9 hz 0.6% 4'11", 2'5", 1'3" (5,1,1 Oblique)
230.8 hz 0.3% 4'11", 2'5", 1'3" (4,1,2 Oblique)
232.2 hz 0.6% 4'10", 2'5", 1'3" (1,1,3 Oblique)
232.5 hz 0.1% 4'10", 2'5", 1'3" (5,2,0 Tangential)
233.7 hz 0.5% 4'10", 2'5", 1'3" (4,3,1 Oblique)
237.2 hz 1.4% 4'9", 2'5", 1'2" (0,5,0 Axial)
238.9 hz 0.7% 4'9", 2'4", 1'2" (2,0,3 Tangential)


Computed Information:
Room Dimensions: Length=13.31 ft, Width=11.91 ft, Height=7.59 ft
Room Ratio: 1 : 1.56 : 1.75
R. Walker BBC 1996:
- 1.1w / h < l / h < ((4.5w / h) - 4): Pass
- l < 3h & w < 3h: Pass
- no integer multiple within 5%: Pass
Nearest Known Ratio:
- "21) Origin unknown: meant for small room" 1 : 1.5 : 1.6
RT60 (IEC/AEC N 12-A standard): 218 ms
- ±50ms from 200Hz to 3.5kHz = 168 to 268ms
- ±100ms above 3.5kHz = 118 to 318ms
- <+300ms at 63hz = 518ms
- 300<RT60<600ms
RT60 (ITU/EBU Control Room Recommended): 174 ms
- ±50ms from 200Hz to 4kHz = 124 to 224ms
- <+300ms at 63hz = 474ms
- 200<RT60<400ms
Absorbtion to achieve ITU RT60: 337 sabins
Volume: 1203 ft^3
Surface Area Total: 698 ft^2
Surface Area Floor: 158 ft^2
Surface Area Ceiling+Floor: 316 ft^2
Surface Area Front Wall: 90 ft^2
Surface Area Front and Rear Wall: 180 ft^2
Surface Area Left Wall: 101 ft^2
Surface Area Left and Right Wall: 202 ft^2
Surface Area 4 Walls: 382 ft^2
Surface Area 4 Walls + floor: 540 ft^2
(sabins - front wall - carpet) / Left+Right+Rear wall: 30 %
(sabins - front wall) / Left+Right+Rear wall: 84 %
Schroeder Fc: 135hz
Frequency Regions:
- No modal boost: 1hz to 42hz
- Room Modes dominate: 42hz to 135hz
- Diffraction and Diffusion dominate: 135hz to 540hz
- Specular reflections and ray accoustics prevail: 540hz to 20000hz
Count (42.4-240hz) : Axials=13, Tangentials=55, Obliques=75
Count (42.4-100hz) : Axials=5, Tangentials=4, Obliques=1
Critical Distance (direct = reverberant field): 11.80ft

Sketchup file.

COMMENTS

1) I have used 2 of my existing 4x4 absorbers at the first reflections point. Ideally I would rather use a floor to ceiling broadband helmholtz slat resonators, 4" wide, and sloping from 12" deep at the intersection with the angled walls for the flush mounted monitors, to flush against the walls on the other end, but........ money is an issue right now, and I have the absorbers! I do plan on adding the helmholtz walls at a later date.

2) The area behind the monitors will have hangers, and an angled panel of compressed fiberglass in the corner

3) The closets will be utilized as

Center Lower section- short hangers, about 5 feet high, 31" deep

side lower sections- these have shelves in them currently- I plan on putting 4" of mineral wool vertically at the back side of each shelf, with an air space behind. I would like to use the area in front of the absorption for storage, but if it adversely affects the acoustics, I could empty them out when I need to do critical mixing.

the top section is currently closed off to the room, but open to the utility room on the other side. it contains an air duct at the top along the from edge, but the area behind it is empty. I have some loose, unfazed fiberglass insulation that I could stuff into the space giving me a 31" deep area of insulation. I can close off the area from the utility room, and put in vents in the angled wall going up to the flat area with the HVAC vent.


GOALS

My primary use will be composing classical, theater and music for media works. For classical music, I use Kontakt to help me mock up demos of orchestral and chamber music, but the goal is a live performance with breathing musicians! (This is however, much more fun to do in a great sounding room.)

Having well done TRAX helps tremendously with getting more performances for my theater work. I use MIDI for creating these and sometimes add in recorded musicians to make it sound more "real". After the TRAX are finished, I bring in singers to do a demo of the entire score. This also helps with sales, as well as giving singers in various productions help in learning their parts.

I am thinking of seeking out some music for media work. Classical composing is not terribly lucrative. This would be primarily MIDI productions in a similar being to my theater work.

I probably will not be doing much actual recording here, except for demos. I have other places in town that I can go to do location recording.

you can hear examples of my work that I did at the URG Studio at scottmichal.com



QUESTIONS

1) What would be the best angle for the flush mounted monitor walls with this width of room, and are my narrow (34") walls wide enough for the monitors, or should i make them wider?

2) Should I tear out the ceiling drywall to give me another foot of height in the room? I could then install mineral wool in the spaces between the joists covered with poly and burlap to serve as a built in cloud.

3) Should I dig into my precious savings and go ahead and build the helmholtz resonators? Or will the absorbers be enough to get started?

4) Are my ideas for using the rear closets reasonable, or should I tear out the closets and turn the whole area into hangers and bass traps?

5) I welcome any other suggestions!



Thank You!

bump

The Closet doors will remain, but I can open them anytime I need to do any critical listening.

I doubt if that would work: The open closet doors would massively change the room acoustics, as compared to closed doors, since they are very large, flat, reflective surfaces: Having them open would create a whole bunch of strange reflections at the rear of the room that probably would not be very useful at all, acoustically!

Questions that I have:
Help with adjusting the optimum angles and dimensions of the front, angled walls.

Designing a speaker soffit is not just a matter of putting up a piece of wood with a hole in the middle at a nice angle! It is far more complex than that. The soffit needs to be built massively enough (thick, heavy materials for the front baffle) and rigidly enough (large, solid, closely spaced framing), in order that the front panel actually can act as an infinite baffle: The speaker has to be carefully positioned in the room and also in the baffle such that it is aimed at the mix position correctly, and it has to be supported solidly and held in place rigidly. There also has to be a ventilation system built in to the soffit, to ensure that the speaker itself does not overheat, and the section below the actual speaker shelf should be designed as a bass trap, to make the most effective use of space.

It's a fairly complex process to get right! It takes a lot of time, and careful design.

(L) 13' 2" x (W) 10' 11 1/2" x (H) 7' 1 1/2" Should I remove the drywall on the ceiling and fill the spaces between the joists with mineral wool? This would give me an additional 10" of height, but when I ran the room node calculations, I was very surprised that it appears the room should be better with the lower ceiling!

I'd go for the increased room volume with the higher ceiling, to be honest! Choosing between basically a 7' ceiling and an nearly 8' ceiling is pretty much of a huge bonus. Low ceilings are bad. Yes, the ratio for the lower ceiling is a bit better, but both are still well inside the Bolt area, and the extra ceiling height and volume are good.

However, do be aware that you will probably lose some of the isolation that you have at present. Probably not much, but noticeable.

The wall mounted lights have got to go! I will turn one of them into a wall socket and cap the other.

Ummmm... you can't do that! Light circuit wiring is NOT meant to carry the loads of an electrical outlet. That can be a light, or it can be nothing, but you can't convert a lighting circuit into a power circuit, unless you re-wire completely.

1 of 2 angled walls for the monitors.

That structure is nowhere near massive enough and rigid enough to be usable as a speaker soffit. Sorry. It will need to be rebuilt completely.

QUESTIONS
1) What would be the best angle for the flush mounted monitor walls with this width of room, and are my narrow (34") walls wide enough for the monitors, or should i make them wider?

That's really hard to say. There's a lot of calculation involved in correctly designing speaker soffits, in terms of the positions, angles and dimensions. Every room is different, and each one needs to be done on its own.

2) Should I tear out the ceiling drywall to give me another foot of height in the room? I could then install mineral wool in the spaces between the joists covered with poly and burlap to serve as a built in cloud.

Definitely.

3) Should I dig into my precious savings and go ahead and build the helmholtz resonators? Or will the absorbers be enough to get started?

Why do you need slot walls? What problems do you foresee that you expect will need treatment, and what frequencies would you need to tune the walls for?

4) Are my ideas for using the rear closets reasonable, or should I tear out the closets and turn the whole area into hangers and bass traps?

I would take off the doors, but the rest of what you have in mind is reasonable. It could be better: you could build proper bass traps in the corners and just leave the center section for shelving...

- Stuart -

Thanks Stuart,

I will go ahead and take the closet doors off and remove the drywall from the ceiling.
The lighting circuit will be converted to new lighting, just moving the lights up to be on the ceiling.

The wall panels that I have for the front soffit mounted speakers are actually built to John's specifications, with 3/4" plywood as a backing, fire code drywall glued to the plywood, and then 3/4" bamboo glued to the drywall. What is missing is the joists that it was mounted too. When I moved, I just brought the expensive part! I will be building new joists to support the corners with the panels mounted to the joists. Under the bamboo is a section with 3/4 particle board mounted behind the supports, and 3 and 1/2" of mineral wool to save as absorbtion overhead with burlap, at the bottom is an opening for the bass ports. The top was low in the old study because we had another set of speakers set on top of the unit, but for the new studio I will continue the wall up to the ceiling. What I need help with is the calculations for optimum speaker placement and angles of the soffit walls. ( the speakers are on stands that are completely isolated from the wall, and are enclosed in a 2x8 box to help dampen resonances of the speaker. The old studio worked very well!

The old studio design had helmholtz resonators nest to the speakers, so I was just copying that design.

Thanks again,

Scott

scottmichal.com

I worked on trying to figure out the angles myself.

This will all be done according to johns typical studio design. The angled sections could be either slat walls or absorption. I turned the back closet into a bass trap, but added corner absorbers in front of the closet wall as well, since the speakers will basically be aimed right at that corner.

Your angles don't seem to be working. You have reflections getting to your ears...


- Stuart -

Thanks,

Is this better?

Yup! That looks pretty good now.

- Stuart -