John Sayers' Recording Studio Design Forum Archive

I had a previous thread, but I have come to the realization that I have gotten way ahead of myself in terms of design, and I want to do this right, so I'm starting over. I have a very modest budget of $5-10K for my build so I need to make every penny count, and I would greatly appreciate any input or guidance you can offer. Also, I will be doing the majority of the work myself.

I plan on closing off part of my homes attached two car garage and using it as a control room. I do not record very often and my main goal will be to design a room with a good frequency response so that my mixes will translate well. I generally monitor at around 70-75db in my current room which is located inside my home and shares a wall with the garage. I have not received a noise complaint in the past 8 years so I don't believe isolation is critical, but if budget allows I would like to have something in place.

For now, let just start with dimensions..

The current space is 20' L x 20' W x 8' 2" H


Now, assuming height is fixed at 8'2", mostly due to budget, I then use the height to come up with an appropriate ratio. Ideal control room ratios I've come across are 1H:1.14W:1.39L, 1H:1.28W1.54L, and 1H:1.60W:2.33L. Now since I need as much volume as I can get, I choose the largest ratio.. 1H : 1.60W : 2.33L.

This gets me a control room of 8.16' H x 13.05' W x 19.01' L

When I put those dimensions into a room mode calculator things look pretty good. However, when I played around with different dimensions and diverted from ideal control room ratios, I was suprised. Using the dimensions 8.16' H x 13' W x 20'L displays better results and a smoother bonello curve. In my case it seems that diverting from ideal ratios would provide better results. If I do choose to go with a 13' width the main problem I will have is functionality of my existing garage door. I will have to either make allowance for the garage door in my control rooms ceiling (which is far from ideal), or change my garage door's mounting to a "one piece garage door" style hardware. Since budget is a huge consideration in my case, I chose to play with dimensions a little bit more. If plug in the dimensions of 8.16' H x 11' W x 20' L I still see better results than the previous two control room ratios and only a slight decrease in the smoothness of the bonello curve vs a 13' width, and I spare the expense of altering the current garage door. However I'm losing more overall volume.

My questions to you are, given my budget and obstacles, which dimensions will afford me the best chances of getting good results? And are there other ratios that could help me get even better results?

8.16' H x 13.05' W x 19.01' L
8.16' H x 13' W x 20' L
8.16' H x 11' W x 20' L

I also checked 8.16' H x 11' W x 17' L, and that would eliminate issues with the garage door and water heater, but would that be too small?

You using Bob Gold's calculator for that, which is great, but are you also using Andymel's "Amroc" calculator? The latter shows you the Bolt diagram as well as simple distribution graphs and tables, and marks your location on it. It also gives you arrow buttons to nudge the dimensions up and down and shows you the results in real time. Very useful. I use both calculators, as each has its strengths.

which dimensions will afford me the best chances of getting good results?

ITU, EBU, AES and other specs for critical listening rooms all call for a range of floor area, and a room volume referenced to a room "standard" of 100 m3: The actual numbers are slightly different for each spec, but basically for a 2.0 or 2.1 room, you need a floor area of between 20m2 and 60m2, while for a 5.1, 7.1 etc. room it should be 30-70 m2. In Imperial units, that would be roughly 200 ft2 to 650 ft for stereo, or 300 to 750 ft for multi-channel, and in both cases referenced to the hypothetical standard of 3500 ft3. In reality, many acousticians suggest a room volume of greater than 40m3, which is roughly 1400 ft3.

All three of your options meet the "minimum" floor area, no problem. And all three meet the "minimum" room volume, no problem.

So you could go with any of those without needing to be concerned about overall size and volume. Go with the one that is least expensive to build, due to your very, very tight budget.

You do not need to go crazy about room ratios anyway: As long as you are far away from the bad ones, and reasonably close to one of the good ones (hopefully inside the Bolt area, or close to the edge if you are a bit outside, then you will be fine.

Having said all of the above, it is still possible to get really good acoustics in much smaller spaces: John has built an entire studio inside a shipping container, for example, with excellent results.

One more thing: You say your ceiling height is limited to 8'2": But is that the height of the final finished inner-leaf ceiling, or the total available height up to the joists right now, before you build anything?

- Stuart -

Soundman2020 wrote: are you also using Andymel's "Amroc" calculator?

I had not, but it is certainly a nifty tool!

Soundman2020 wrote:ITU, EBU, AES and other specs for critical listening rooms all call for a range of floor area, and a room volume referenced to a room "standard" of 100 m3: The actual numbers are slightly different for each spec, but basically for a 2.0 or 2.1 room, you need a floor area of between 20m2 and 60m2, while for a 5.1, 7.1 etc. room it should be 30-70 m2. In Imperial units, that would be roughly 200 ft2 to 650 ft for stereo,

Ok, I monitor in 2.1 so I can definitely hit 200sqft. Based upon that the most cost effective/best results would be..

8.16' H x 12' W x 17' L

Those dimensions fall right in the middle of the bolt area and look good on gold's calculator as well. Those dimensions would also save me the expense of moving a water heater and changing out garage doors, although I may be changing my mind once I get your reply to you final question..

Soundman2020 wrote: You say your ceiling height is limited to 8'2": But is that the height of the final finished inner-leaf ceiling, or the total available height up to the joists right now, before you build anything?

From concrete floor to finished drywall is 8'2''. Drywall is attached to a 2"x4" frame, there is no insulation, then there is a 8' air gap before hitting a radiant barrier, plywood roof, and asphalt shingles.

And last but not least, thank you again for all of your help, Stuart.

Those dimensions fall right in the middle of the bolt area and look good on gold's calculator as well. Those dimensions would also save me the expense of moving a water heater and changing out garage doors,

Then it sounds like a good possibility!

tying back in to my previous question: Are you sure you can get 8.16' for your final finished inner-leaf ceiling? If so, then it looks like you have your basic plan. If not, then you might need to adjust the dimensions to to fit.

From concrete floor to finished drywall is 8'2''. Drywall is attached to a 2"x4" frame, there is no insulation, then there is a 8' air gap before hitting a radiant barrier, plywood roof, and asphalt shingles.

A photo of the actual situation would help to understand that.


- Stuart -

Soundman2020 wrote:Then it sounds like a good possibility!

please excuse the mess and the orientation of the photos, forgot to turn my phone sideways. Perhaps you could just lay sideways on your desk..

floor to ceiling is 8.16'


finished inner leaf of ceiling to roof looks like this...


Also, what would be the best way to build the walls in my situation? I was planning on applying green glue and a sheet of 5/8" sheetrock over the existing walls, and then copying the same design to the new walls, but I'm not sure what sort of TL I could expect below 125hz. Would designing a wall like the following image provide enough isolation to justify the cost, or should I look into a different construction method?

and the orientation of the photos, forgot to turn my phone sideways. Perhaps you could just lay sideways on your desk..

I tried that, but then I fell asleep!

Also, what would be the best way to build the walls in my situation? I was planning on applying green glue and a sheet of 5/8" sheetrock over the existing walls, and then copying the same design to the new walls,

that would be a 4-leaf wall! terrible isolation in low frequencies. Study this diagram carefully:
That's why you do not want to ever have a 4-leaf wall: the exact same amount of materials in the exact same total wall thickness, but placed correctly, gives you 100 times better isolation (increase from 40 to 60: 100 times lower intensity, or 1/4" the level, subjectively).

Use only 2-leaf.

MSM resonance can be your enemy, or your friend. Use it wisely...

- Stuart -

Hi Stuart, thanks for your reply! I noticed you'd been away for a while, and I'm glad to have you back. Hope all is well, my friend.

Soundman2020 wrote:I tried that, but then I fell asleep!

haha, nothing wrong with a little nap!

Soundman2020 wrote: that would be a 4-leaf wall! terrible isolation in low frequencies. Study this diagram carefully:

I am very familiar with that diagram, and I do understand that a 4 leaf wall will never provide as good of isolation as a two leaf wall, but having a 2 leaf system doesn't seem practical in my situation in regards to the new walls. Using the existing left and bottom walls of my existing garage would be a 2 leaf system. In order to improve isolation on those walls I propose using green glue and adding a layer of 5/8" drywall to increase TL. This should give me a STC of around 52 according to Green Glue's testing Data http://www.greengluecompany.com/test-data. Adding green glue and a layer of 5/8" drywall to the ceiling and adding insulation would be a 2 leaf system as well, but I'm not clear on what kind of isolation I will achieve here given that the attic space is ventilated. The two new walls confuse me a bit. I know that if I remove the inner layer of drywall from the remaining two existing garage walls and then build a single leaf as my new control room walls, I would then have a 2 leaf system, but wouldn't the existing 15'x7' garage door being lightweight steel and the fact that it is unsealed be a big problem in terms of isolation? Closing off and sealing this existing 15' x 7' garage door is not an option I am willing to entertain. I still want access to the remaining garage space from the outside. I have read that as long as the air gap between leafs is quite large, (2' 7 3/8" and 8' in my situation, both are completely open to eachother) that the detrimental effects of having a 4 leaf system is greatly reduced.
http://johnlsayers.com/phpBB2/viewtopic.php?f=2&t=8395
https://www.gearslutz.com/board/studio- ... table.html
https://www.gearslutz.com/board/studio- ... ystem.html

For the above reasons I felt that a 4 leaf system was the most practical choice in my situation. I would also like to reiterate the fact that I am not trying to achieve huge levels of isolation within my space. I generally monitor at around 75 -80db, and this space is only for my personal use. Outside noise is very rarely a nuisance and I have never received a complaint from my neighbors. If I achieve around -30db to -40db of TL I would be a happy guy. I did a test with my RadioShack db meter and with my current wall construction I am achieving about -20db of TL on the low end. These results are from playing music at 80db in my current control room which shares the left wall of my garage, and standing inside my garage. When I go outside and stand next to the 15' x 7' garage door, (3 leaves away) I have -80db of TL. The music is completely inaudible.

Am I missing the plot all together or can I reasonably expect my desired TL using a 4 leaf system? If I'm way off in my thinking, could you please help point me in the right direction as far as a way to achieve my goals?

Thanks again for your help!

I noticed you'd been away for a while, and I'm glad to have you back. Hope all is well, my friend

Thanks for noticing! Yup, just got a lot going on right now...

but having a 2 leaf system doesn't seem practical in my situation in regards to the new walls.

Well you CAN go 4-leaf if you want, but the extra mass and large loss of space seem to be things that you could avoid. Higher expense, greater complexity, and a smaller room to show for it, doesn't make a lot of sense in my book. But I guess if you have a big enough budget, a long enough time, and lots of extra space to play with then that could be an option. Personally, I try to minimize expense and maximize space, but I do realize that not everyone is a perfectionist, like me.

Using the existing left and bottom walls of my existing garage would be a 2 leaf system. In order to improve isolation on those walls I propose using green glue and adding a layer of 5/8" drywall to increase TL.

The way I would improve the isolation of those walls is to take the drywall off! Not put more on. Take the drywall off to expose the studs, and if necessary use the stuff you took off to "beef up" the wall from within, between the studs. That's a very common method for improving isolation. That leaves you with a single.leaf wall. Then all you need to do is to put up your new framing about an inch away from that, and put drywall on only ONE side of that. Then you'd have a classic two-leaf wall: high isolation, low cost.

This should give me a STC of around 52

Forget STC. It is useless as a measure of isolation for a studio. STC does not take into account the bottom two and a half octaves of the musical scale, and it does not take into account the bottom two and a half octaves of the musical scale. It only takes into account a narrow section in the middle, which is basically the area where normal speech occurs. If you only plan to isolate talking voices, then by all means use STC, but if you need to isolate full-spectrum music, forget it. Just look at the full TL data. I can build you two walls, one rated at STC-50 that is really lousy at isolating rock music, and one rated at STC-40 that is much, much better at isolating rock music...

Adding green glue and a layer of 5/8" drywall to the ceiling and adding insulation would be a 2 leaf system as well, but I'm not clear on what kind of isolation I will achieve here given that the attic space is ventilated.

With a ventilated attic, normally the easiest thing to do is to just go with a 3-leaf ceiling. However, if the joists are already very low, and you have a decent budget, then it's much better to modify the trusses to collar-tie first, so you can gain some height inside, and also get better isolation. I've done that on a few projects, and it works rather well.

but wouldn't the existing 15'x7' garage door being lightweight steel and the fact that it is unsealed be a big problem in terms of isolation?

Yep. There too the common solution is to build a wall across the room in front of that, to create your actual leaf. Yes, technically the garage door is a third-leaf like that, but in practice it is not an issue for the very reasons you mentioned.

Closing off and sealing this existing 15' x 7' garage door is not an option I am willing to entertain. I still want access to the remaining garage space from the outside.

Then you have a problem. You can't eat your cake and have it too! If you want the garage door to open, the you'll have to sacrifice several feet of space above the studio for it to open into.... you'll end up with a studio that has a very, very low ceiling.

Go out and open your garage door right now, so that it is fully open and horizontal to the floor. Now measure the distance from the under surface of that door down to the slab. Subtract one foot. That's the maximum ceiling height you could expect for your studio, realistically.

If I achieve around -30db to -40db of TL I would be a happy guy

30 dB is about what a typical house wall gets you, which is not very much at all...

I have read that ...

as Rod says on one of the threads you mentioned: "From my perspective it's a no brainer if all I have to do is lose the drywall face on the inside of an existing wall." Yup. Agreed.... And another highly regarded acoustician (Andre) responded to Rod with: "+1". In fact, that entire thread says the opposite of what you think it says. The experts there (Rod, Andre and John) all agree that the 2-leaf wall is a much better option than the 4-leaf.

On the other thread, where someone mentions doing a three-leaf window, Rod replies: "Not the approach I would take. Why not simply 2 glass panels with enough mass to get the job done at each wall face?" Yup!

Your third link doesn't seem to work at all!

Am I missing the plot all together or can I reasonably expect my desired TL using a 4 leaf system?

With large air gaps and plenty of mass, yes, you can get there. But the very low ceiling height, the smaller room, and the higher costs and complexity don't seem to be justifiable to me. Of course, like I said before, if you have plenty of money and don't mind the small room with the low ceiling and poor acoustics, then it probably is an option.


- Stuart -

Hi Stuart, Thanks for your continued generosity with your time and expertise. It is truly appreciated!

I am not and will never debate the fact that physics and all experts in acoustics agree that having a 2 leaf MSM system will provide the best isolation given the same type of materials, and overall dimensions.

The main goal of my project is to create a mixing room with an adequate frequency response so that my mixes will translate. I would like to have -30db to -40db of TL to the outside. As this is a personal space, and I do not record, I am not trying to achieve higher levels of isolation. I have only $5-10K to achieve my goal.

The first step in achieving my goal was to pick suitable dimensions. 17' x 12' x 8.2' is the logical choice as it is within the bolt area, shows good modal distribution, spares the expense of moving the water heater, and spares the expense of changing or modifying the garage door (provided the new walls are no more than 6" thick). If the overall width of my new space is wider than 12' 6", then I no longer spare the expense of modifying the garage door. Luckily a standard residential wall at 4" thick provides around -25 to -30db of TL, which is extremely close to my goal of -30db - -40db of TL. With the very limited space available in order to achieve -10db more of TL than a standard 4" thick wall, I propose to add a layer of green glue and 5/8" sheet rock to the entire inner leaf of the mixing room. Given the size of my budget, and all other fixed parameters I see no cheaper method of achieving my goal TL.

Layout would be as follows:

Would my soffit design be acceptable? I borrowed from both John's and Thomas's designs. The front baffle is 1/2" mdf with a wood veneer. The yellow bits are rigid backed 4" OC 703. The monitors are positioned at 2/5ths from the height and width of the baffle. Monitors acoustical access is at listening height. Monitors are attached to their wall mount bracket on a 2"x6" post. Monitors will not come in contact with the baffle. The holes above and below the monitor will be used for ventilation. I plan on filling the entire rear cavity with fluffy pink fiberglass insulation except for a chicken wire pathway around the monitors to allow proper ventilation. I would then cover the unfinished areas of the front with fabric. One concern I have is that the 2"x6" the monitor is mounted to won't be rigid enough and will resonate. Should I use thicker wood for those, or will that not be a problem? Any other pointers or thoughts would be greatly appreciated. Thanks for your help!

The front baffle is 1/2" mdf with a wood veneer.

It will need to be MUCH thicker than that! I normally use at least two layers of 5/8", and preferably two or more layers of 3/4". the key to a good soffit is mass and rigidity. That front baffle has to be built such that it cannot move or vibrate at all.

The monitors are positioned at 2/5ths from the height and width of the baffle.

Try to vary that a bit, if you can, so that it is not 2/5 in both directions. Keep it at 2/5 width, and make the baffle taller, or have the bottom edge start a bit higher up.

Monitors are attached to their wall mount bracket on a 2"x6" post.

That won't be rigid enough. The mounting needs to be very, very solid, absolutely rigid, and non-resonant in the entire audible range.

The holes above and below the monitor will be used for ventilation. I plan on filling the entire rear cavity with fluffy pink fiberglass insulation except for a chicken wire pathway around the monitors to allow proper ventilation.

One concern I have is that the 2"x6" the monitor is mounted to won't be rigid enough and will resonate.

Yep!

Should I use thicker wood for those, or will that not be a problem?

Many pieces of thick wood, built as a solid, rigid, tough, heavy framework.

Any other pointers or thoughts would be greatly appreciated.

I don't see the enclosure box around the speaker....

I don't see the hangers below the speaker shelf... in fact, I don't see the speaker shelf either!

I don't see the absorption area to deal with reflections from the rear of the desk/console...





- Stuart -

Hi Stuart, thanks for the feedback!! I'll beef up the baffle and and lower it a bit so that height and width aren't both 2/5ths. I'll also triple the 2x6 so it'll be 6"x6". Would that be sufficient? Or is there anywhere I can go to help figure out how to calculate the resonant frequency of a wood beam?

In regards to your statements..

I wasn't going to enclose the monitor in a box. I was borrowing from Thomas's design and using the OEM wall mount to attach the monitors to a wood post that will be decoupled from the front baffle. At no point will the monitor come in contact with the front baffle. Am I not understanding Thomas's design?

As for the hangers, I hadn't planned on putting hangers. The entire cavity behind the baffle will be filled with +\- 2-3' of fluffy insulation. I thought that's how Thomas had done it.

And in regards to the reflections from the desk, the entire area below the baffle will be rigid backed 4" oc703 with exception to the cold air inlet. That's the yellow bits in the drawings I posted.

ok, after more reading and research i've decided to make quite a few changes to EVERYTHING.

new room dimensions 15' 1 3/8" x 12' x 8' 1 3/8" its under 200sqft, but modal distribution is much better, its in the middle of the bolt area, and the bonello curve is much improved.

Monitors flush mounted at 35 degrees
36" of fluffy fiberglass along back wall
12" of fluffy fiberglass along wall/ceiling corners
6" thick OC 703 broadband absorbers on first reflection points
6" thick OC 703 Cloud angled 6 degrees

Does the basic plan/layout look ok? Do you have any suggestions?



Download sketchup file here
http://s000.tinyupload.com/?file_id=698 ... 6611971542

Thanks for your help!

its under 200sqft, but modal distribution is much better, its in the middle of the bolt area, and the bonello curve is much improved.

Don't go too crazy on finessing your ratio, especially if it means that you have to make the room a lot smaller. Ratios are one thing, but room volume is another. You need to find a good trade-off between them, If I have to chose between a fantastic ratio but low volume, vs. a not.so.great ration with a much higher volume, I'd take the higher volume (unless the volume is already very good).

Monitors flush mounted at 35 degrees
36" of fluffy fiberglass along back wall
12" of fluffy fiberglass along wall/ceiling corners
6" thick OC 703 broadband absorbers on first reflection points
6" thick OC 703 Cloud angled 6 degrees

Sounds about right, but you might be over-doing the absorption? What is the total area that will be covered with absorption, vs. the total area of of the room?


- Stuart -

Soundman2020 wrote:Don't go too crazy on finessing your ratio, especially if it means that you have to make the room a lot smaller. Ratios are one thing, but room volume is another. You need to find a good trade-off between them, If I have to chose between a fantastic ratio but low volume, vs. a not.so.great ration with a much higher volume, I'd take the higher volume (unless the volume is already very good).

No more going crazy, I promise. I agree with you, I just realized I couldn't fit the 17' length with my tiny budget, and anything else caused lots of problems modaly. This is also why I went thicker with all absorption..

Sounds about right, but you might be over-doing the absorption? What is the total area that will be covered with absorption, vs. the total area of of the room?


- Stuart -

About 45%