John Sayers' Recording Studio Design Forum Archive

I'm planning to build the inner-leaf walls "inside-out", since I have such a tiny space to work with, and I'm trying to squeeze out every last centimeter that I can. So basically ALL of the sheetrock on the inner leaf will have outside corners. I also found out that (from reading all over this forum) that "inside-out" walls give you more space for acoustic trapping, and I'm going to need PLENTY of that!

I know that inside-out construction is much more complicated, but I'm prepared to live with that in order to get a better room.

My next task is to figure out a construction sequence that will actually allow me to do that, since two of those walls are going to be facing existing brick walls, with only a few inches in between. No space to work in. I think I have a workable sequence, but I need to sit down and work through it carefully on paper, to make sure I'm not going to paint myself into a corner at some point.

If you are interested, here is a link to the the actual SketchUp file, which you can download and examine more closely:

Version with no drums

It's now way too big to post here (over 4 MB), and I'm still not happy with the design, so it will definitely change. And of course, all suggestions would be VERY welcome!

For example: I already spotted one glaring error that I'm working on fixing: the main electrical distribution panel is on a wall that I had planned to cover up with acoustic treatment. Oops! I also went overboard with the splaying of my control room walls (due to my speaker angle being at 90 degrees, not 60 degrees, because of the tight space), but John said that this is not a biggie, so I'm going to reduce those angles slightly to gain space in the live room.


- Stuart -

Just checking.

This is the home of the inside out wall, so I'm getting used to knowing when I am seeing it.


Have you done any testing for noise/sound levels of your place?
This information might be more helpful to you then you know.

Have you done any testing for noise/sound levels of your place?
This information might be more helpful to you then you know.

You just asked me more or less the same question in another thread! And yes, I know that is my fault, of course, for asking too many questions in other forums! Guilty as charged.... I'll try to keep it all here, from now on I think, to avoid fragmenting the discussion about my studio.

Here's a link to the other thread, just to keep things kind of tied together....

http://www.johnlsayers.com/phpBB2/viewt ... highlight=

So, to answer your question: I have not tested yet, as I think I would not get valid readings, since the garage is full of accumulated "junk", and there is a row of small "closets" (cupboards) along the brick wall that I need to rip off I suspect all of this will distort the measurements. I think I need to clear out the junk and get down to bare walls first, then I'll do the test. Is that necessary?

However, if you think it would be worthwhile to do the measurements now, just like it is, then I could do that tomorrow or Sunday, and post the results. Is it worth doing that already?

I was curious about your exterior noise / levels.

OK, Ill measure some levels for you over the weekend. Anything in particular you'd like me to measure?

If you are thinking about ambient noise: This is a residential neighborhood, but we are just a block away from two major streets (one to the south, the other to the East), with trucks and buses all day, heavy traffic around rush hour, etc. However, I'm not too worried about that getting in to the rooms, since the existing isolation seems to be quite good. What I am most concerned about is the "noise" inside my rooms getting out and annoying the neighbors, especially if I feel like recording drums at 3:00 AM! (OK, so that might be a bit too ambitious, but you get the picture.... )

I'll measure ambient noise inside and outside at rush hour, and post those here. I'll also do a "quick and dirty" test with a full-range speaker pumping out various things, and measure how that sounds outside, at a quiet time during the evening.

Some ambient sound level measurements, as requested: (all levels are C-weighted, slow response, taken with an Extech 407750 digital sound level meter.)


Outside at rush hour: Average 68 dB, Peak 79 dB
Inside the future studio at rush hour: Average 57 dB, peak 68 dB.


Outside at a quite time (early Sunday morning): Average 56 dB, Peak 65 dB
Inside at quite time: Average 49 dB, Peak 64 dB.


“Outside” means standing out in the front yard, about 5 meters away from the main garage doors. “Inside” means standing next to the washing machine, roughly in the center (side to side) of the garage.

"Average" and "Peak" were both measured over a period of 5 minutes. “Peak” is the direct reading give by the meter’s “Max Hold” function. “Average” is a subjective “guesstimate” from observing the level for five minutes, as this meter does not have any Leq function.

While I was taking the "Peak" reading for the quite time, a helicopter flew over, which is the reason for the high reading. If it had not been for that chopper, the reading would have been around 55 dB. That is one of the issues that I need to keep in mind with the design: There is a hospital three blocks away, and occasionally choppers bring in patients. Also, there are ambulances going in and out several times per day with their sirens screaming. I’ll try to measure the level next time one comes by.

These are important points that I had not considered until now! Thanks for asking me to take the readings, since the chopper is what got me thinking about other noise sources.

Anyway, the readings inside the room are not really a good indication of the acoustic isolation, since there are a few noisy items in the garage still, but that won’t be inside the studio: There is an electric chest freezer, a couple of old Internet servers that I have running full time, and some water and gas pipes in the "laundry" end of the garage, which were "hissing" gently both times I measured. (These are outside of the area that will become the studio, but they still affected the SPL measurements by a few dB.) . There is also a washing machine, but it was not running at the time I took the measurements.

Is this info any use to you? Too much / too little / totally wrong? Do you need other measurements? I

could do another set of measurements the other way around later in the week, generating pink noise inside the garage and measuring the level outside, if that would help. But I can't do that before Thursday, as I'll be out of the country.

- Stuart -

I just stole your "head" from your sketchup file, as a nice addition to my soon-to-be-updated design (you can find my current one HERE), hope you don't mind...

Btw, nice design...

I just stole your "head" from your sketchup file, as a nice addition to my soon-to-be-updated design (you can find my current one HERE),

No problem! You are entirely welcome. It's not actually "mine" anyway: I downloaded it from the Google library. All I did to it was clean up the geometry a bit, especially around the eyes. So go ahead and use it all you want!

Thanks for your comment! If you have any suggestions on how I might improve it, then I sure would appreciate it.

OK, now I get to display my ignorance again: I'm starting to quote materials in order to refine my design, and I'm running into problems in some places, and dumb questions in others.

HELP!

Don't forget that I live in Chile, way down there at the bottom end of the world. Santiago is a big modern city, but construction techniques are different here, and I simply can't get some of the stuff that is recommended by you guys. In other cases, I can get stuff that looks similar, but I'm not sure if it will work.

I'd REALLY appreciate comments!


First dumb question: Sheetrock / drywall / gypsum board / plasterboard / wallboard / etc. Is this all the same stuff? I've seen folks refer to it by several different names, and I've always assumed that it is just called different things in different countries, but is really the same thing: Basically, this stuff:

http://www.volcan.cl/productos_y_soluci ... ita_st.htm

It's generally called "volcanita" here, although I've also seen it called "yeso carton" (roughly translates as "plaster cardboard"). Basically, it's just planks of "plaster-of-paris" in various thicknesses, backed with a layer of thin cardboard, and with the front and sides covered with a thick "paper" finish? That is the stuff we are talking about, right? Are there differences that I should be aware of (apart from the fire rating, which I already know about)? Any advice on special characteristics to look for or avoid? Or will any old stuff like this work fine?


Second dumb question: Backer rod. I can't seem to find it anywhere here in Chile. Nobody has heard of it. Any suggestions on what I could substitute? From what I've found by googling the term, it seems to just basically be a thin round extrusion of some type of foam, that comes in various diameters and can be either open-cell or closed-cell. What can I use to replace that? Could I run a bead of some type of caulk / sealant ( foam instead? Maybe cut strips off of pipe lagging foam? Rubber? Thin nylon rope?


Third dumb question: Caulk. No problem getting it here, but there are so many different brands to choose from, each with half a dozen different special-purpose caulks, that I'm really confused! What exactly should I be looking for? Anything special? Or will any old caulk do?


Fourth dumb question: Nails or screws? For the drywall, I mean. Normal construction here in Chile calls for nailing drywall tp the studs, but I've seen that practically everyone here talks about screwing it, and using different length screws for for each layer. Should I nail or should I screw? I'm inclined to screw, as I'm happier with the idea of hundreds of kilograms of drywall hanging over my head on screws, rather than nails...

I can get drywall screws here, but I'd appreciate any suggestions on what to look for specifically for best performance.



Fifth dumb question: Green Glue. I've decided to bite the bullet and import it, since you just cannot get it here in Chile. It's gonna be expensive, but I'm taking Rod's high opinion of GG into account. So how much should I use per sheet, given my design? I've seen on their web site different dosages, but I'm really not sure if going for the lower dosage (I think they call it "50% coverage" or something like that) is a good idea. Will I lose a lot? I'd really like to use as little as possible, since it is going to be so dam expensive to ship it here, but at the same time I don't want to sacrifice isolation.



Sixth dumb question: 703: I think I found something resembling 703!!! Is this a reasonable substitute?

http://www.volcan.cl/productos_y_soluci ... neral.html

It's mineral wool, and they sell it in rolls, batts and rigid panels. I kind of like the idea of using rigid mineral wool, instead of rigid fiberglass, due to the higher density, and the fact that I hate fiberglass itch!

They also have the same thing in fiberglass:

http://www.volcan.cl/productos_y_soluci ... libre.html

And even this one:
http://www.volcan.cl/productos_y_soluci ... idrio.html

which comes with some kind of fabric that is "thermo-cured" to the fiberglass itself, to keep it from shedding, and is supposed to be ideal for use in "movie theaters and event venues".

They advertise both the glass panels and the mineral wool panels these as being "acoustic" but I can't find any technical specs about that on their web site. I'm going to call them and see if they have real laboratory test specs available.

But does this look like basically the right stuff, as a substitute for 703?

More dumb questions to come, but these will suffice for now!



- Stuart -

dumb answers:

Soundman2020 wrote:First dumb question: Sheetrock / drywall / gypsum board / plasterboard / wallboard / etc. Is this all the same stuff? I've seen folks refer to it by several different names, and I've always assumed that it is just called different things in different countries, but is really the same thing: Basically, this stuff:

http://www.volcan.cl/productos_y_soluci ... ita_st.htm

It's generally called "volcanita" here, although I've also seen it called "yeso carton" (roughly translates as "plaster cardboard"). Basically, it's just planks of "plaster-of-paris" in various thicknesses, backed with a layer of thin cardboard, and with the front and sides covered with a thick "paper" finish? That is the stuff we are talking about, right? Are there differences that I should be aware of (apart from the fire rating, which I already know about)? Any advice on special characteristics to look for or avoid? Or will any old stuff like this work fine?

Yup, looks like the same stuff. GB/Drywall/etc is GYPSUM with a paper layer on both sides to keep it together

Second dumb question: Backer rod. I can't seem to find it anywhere here in Chile. Nobody has heard of it. Any suggestions on what I could substitute? From what I've found by googling the term, it seems to just basically be a thin round extrusion of some type of foam, that comes in various diameters and can be either open-cell or closed-cell. What can I use to replace that? Could I run a bead of some type of caulk / sealant ( foam instead? Maybe cut strips off of pipe lagging foam? Rubber? Thin nylon rope?

Funny, I don't know many people here in Holland too who ever heard of such stuff. (it's known as "vulrug" here )
It's just a wire of foam, nothing special. It's only purpose is to keep the kit/sealant from spilling too much and to make a nice seal. Ask you local dealer or call a constructor (who builds GB walls) if they know how to get it in your country.

Third dumb question: Caulk. No problem getting it here, but there are so many different brands to choose from, each with half a dozen different special-purpose caulks, that I'm really confused! What exactly should I be looking for? Anything special? Or will any old caulk do?

Ah
Caulk/sealant/kit (same stuff) is to seal boundaries between wall panels (vulcan, gheh) and floor, for example. So it needs MASS (else it'll be your weakspot). And it needs to be flexible (and need to STAY flexible, not harden). And it should not SHRINK too much.
Well most acrylic and especially silicon sealant will do. Transparent acrylic iis about 1200 kg/m3 while a coloured sealant has a mass of about 1400 kg/m3. So get the coloured one (gray, white, black, pink etc) to match the weight of the gypsum panel.
(GB is about 700 kg/m3 and you will use half the width of the GB for sealant when using backerod so the mass will equal in the end)
Silicon has better props but is usually twice as expensive.
You might look for a sealant with great properties as I mentioned (mass, flex, shrink etc) But you're prolly save with generic sealant. no worries.

Fourth dumb question: Nails or screws? For the drywall, I mean. Normal construction here in Chile calls for nailing drywall tp the studs, but I've seen that practically everyone here talks about screwing it, and using different length screws for for each layer. Should I nail or should I screw? I'm inclined to screw, as I'm happier with the idea of hundreds of kilograms of drywall hanging over my head on screws, rather than nails...

Another good question. I use screws, others use nails. There's great posts on that on this board, granted they're old posts (I remember some about this topic a few years ago). Can't help you with that... ask your local builder what's needed (up to code)

I think I can get drywall screws here, but I'd appreciate any suggestions on what to look for specifically for best performance.

Drywall screws will do, have a "fine" (or "medium") threaded screw (so called "fast" screws)

Fifth dumb question: Green Glue. I've decided to bite the bullet and import it, since you just cannot get it here in Chile. It's gonna be expensive, but I'm taking Rod's high opinion of GG into account. So how much should I use per sheet, given my design? I've seen on their web site different dosages, but I'm really not sure if going for the lower dosage (I think they call it "50% coverage" or something like that) is a good idea. Will I lose a lot? I'd really like to use as little as possible, since it is going to be so dam expensive to ship it here, but at the same time I don't want to sacrifice isolation.

Check the GG website, you'll find the answer there. Do it good, or leave it alone.

Sixth dumb question: 703: I think I found something resembling 703!!! Is this a reasonable substitute?

http://www.volcan.cl/productos_y_soluci ... neral.html

It's mineral wool, and they sell it in rolls, batts and rigid panels. I kind of like the idea of using rigid mineral wool, instead of rigid fiberglass, due to the higher density, and the fact that I hate fiberglass itch!

looks like the Colchoneta Libre is the one. The specs don't tell anything about acoustics and weigth tho... ou don't need higher density. look for 48kg/m3 more or less. Then you'll be save. No paper back, just plane wool. y

Thanks Ro! Very much appreciated.

Soffit Sanity Check:

Below is the current stage of evolution in the design for my soffits. Before I go any further, I'd like to get a sanity check from the experts: Am I on the right track? Doing anything wrong? Doing anything right at all?

I'm not concerned about the actual construction details yet: Just the general concept.

All suggestions welcome! Especially constructive criticism on how to fix it / improve it.

Image below, link to SKP file here:

Soffit sanity check

Soundman2020 wrote:Soffit Sanity Check:

Below is the current stage of evolution in the design for my soffits. Before I go any further, I'd like to get a sanity check from the experts: Am I on the right track? Doing anything wrong? Doing anything right at all?

Overall you are going in the right direction.

The speaker height is around 170 cm. Standard is 120 cm. Going with the standard height removes the need for angling the monitor walls. If you choose to still do that, the maximum recommended angle is 7°.

In the skp you are not with the top/front/side planes. The short cut keys for front/back etc do not work as labeled. Rotate the drawing so that they are correct for future versions that you share with people.

Thanks, André. Your input is always valued!

Let me explain my reasoning, and then you can shoot me down and correct my poor understanding of soffits:

I actually started out with the speakers at 120 cm, but that put them very low to the desk, behind the LCD screens.

Also, at 120 cm there isn't much space for soffit panel below the speaker, and I've read on the forum that you want the soffit surface around your speaker to be as large and flat as possible.

Finally, since the ceiling height at the front of the room is going to end up at around 235 cm, a speaker height of 120 cm would put them almost exactly at 50% of the room height, firing straight down the 50% axis, which I assume is not a good idea as it puts them in a huge acoustic null. (Am I right there? Truth or myth?).

That's why I moved them up to 160, which is more like 68% of room height. I was aiming for 62%, but ran into problems with depth behind the soffits to fit the speakers in. The reason why I was aiming for 62% (reciprocal of 38%) is because I'm assuming that if 38% of a room dimension (front to back) is the ideal listening position, clear of most nulls, then 38% of another dimension (height) should be a good spot for the speakers. Am I wrong in that assumption?

Anyway, let me see if I can bring the angle down to 7 degrees (it's around 14 right now).

Also, I understand what you are saying about the model being rotated, but I'm not sure which way I need to rotate it to align it with the general convention. Is it 90 degrees clockwise as seen from above that I need to go?

Thanks again!


- Stuart -

Soundman2020 wrote: I actually started out with the speakers at 120 cm, but that put them very low to the desk, behind the LCD screens.

Loking at the drawing is no blocking by the screens at that (120 cm) height. I may be wrong.

Also, at 120 cm there isn't much space for soffit panel below the speaker, and I've read on the forum that you want the soffit surface around your speaker to be as large and flat as possible.[

That is a general guideline. Extend the surface down more if you wish.

Finally, since the ceiling height at the front of the room is going to end up at around 235 cm, a speaker height of 120 cm would put them almost exactly at 50% of the room height, firing straight down the 50% axis, which I assume is not a good idea as it puts them in a huge acoustic null. (Am I right there? Truth or myth?).

The nominal speaker height is from the acoustic centre of the speaker, which is near the tweeter. With the woofer below it, it gets out of the 50% zone. The 38% guideline is for low frequencies. The speaker height affects perception of frequencies above 160 Hz. Over 6 octaves. The low frequency range for your height is ~ 70-280 Hz or 2 octaves.

Assuming your speakers have 10 cm between the woofer centre and acoustic centre, this would place the woofers at ~110 cm or 46% of the height. Well off the 50% where room mode nulls would be strongest.

You are going to have a drop in that range regardless because your ears are at that height! So many people, including "experts" forget the ear position when looking at frequency charts.

Also, I understand what you are saying about the model being rotated, but I'm not sure which way I need to rotate it to align it with the general convention. Is it 90 degrees clockwise as seen from above that I need to go?

Check how your drawing matches with the directions indicated when using the short cut keys CTRL 1-6.

It is greta to see that you are doing it the right way. 90%...

Keep it going. It is looking great.

Andre