John Sayers' Recording Studio Design Forum Archive

My understanding is that I need a total of 4 boxes; one for each leaf that I pass through.

I am planning on using the space between the outer and inner leaves to place the baffle boxes in.

Would this be the correct plan for using the baffle boxes on the intake side (Pulling air from control room, into vocal booth)

My main question is where should the long stretch of space after the baffles be oriented on each leaf? should this always occur at the register?

Please note, the length of the wooden sleeve was exaggerated and will be much shorter (probably closer to 6" long)

Am I grasping this correctly?

Soundman2020 wrote:

Ok, so I would need a total of 4 baffle boxes then?

If you want high isolation for your room, yes. You COULD do it with just one box on each, provided that you have a massive sleeve through the leaf on either end, and a method for decoupling the box from both leaves, but it won't be as good as using two boxes. That's only acceptable if you only need moderate isolation. Another method, even lower on the scale, is to just have one box on the outside of one of the leaves, with a single sleeve that extends through both leaves, once again decoupled form both. That's only good for "medium to low" isolation needs.
I am only looking to be able to record vocals in the booth without having vocals (chatter) from control room bleeding into the recording. Also, I want to be able to run the ventilation exhaust fan while recording without introducing noise from the registers. Would the "medium to low" isolation method you described meet my need?

Also, could i have the inline fan directly on the outside of the outer leaf or do i need to distance it a certain distance away from the outer leaf?

Assuming that your outer-leaf is the external wall of the building, then you could do that. But it would not be an in-line fan for that application! It would be an exhaust fan. Inline fans go... well... IN LINE .... they have duct on either side of them. Exhaust fans (also sometimes called "extractor fans") only have duct attachment on ONE side, and a register on the other side.
I was thinking of using an inline fan as an extractor fan... duct > inline fan > duct > muffler , but perhaps it would make more sense to have the extractor fan with grill on the outer leaf?

to fix holes, they either weld up the little holes or cut out and replace larger squares of metal (again by welding new patches on).

It can also be done with a pair of large rubber washers (one on each side of the sheet metal), with large galvanized steel washers behind them, threaded on a small bolt to keep them in place. Drill the hole out to the right size for the bolt, thread the bolt through with the washers on each side, and tighten up the nut. As long s there's a large enough flat area of clean metal in good condition around the hole, that can work. But the rubber will need replacing eventually, so the methods that Greg mentioned are better for a more permanent repair.

I ran the plan by the landlord and he said it shouldnt be a problem since themajority of that roomis drop ceiling, only the vocal booth section is drywall ceiling and the area was small enough to be ok.

Unless you have a signed and notarized waiver from the landlord, absolving you of all responsibility, with him fully accepting all responsibility, that would be a bad idea. And even then, you'd be on shaky legal ground. As Greg said, if you modify a structure or safety feature or electrical system or anything else that is regulated by law, then something bad happens, YOU are responsible for all the consequences, including both civil and criminal. Let's say there was a fire in your studio, and the sprinklers didn't put it out because you covered them up. And somebody died. You would be responsible criminally for the death of that person, as well as for the repairs to the landlord's property, as well as any "wrongful death" civil damage suit brought y the family, as well as fines for having disabled the sprinklers, as well a whole bunch of other things. It does not matter at all of the landlord says "Yeah, I think that's OK.", because he is not the regulating authority, and cannot allow you to do something that breaks the law. It would be the same as if he told you "Yeah, it's OK to kill the tenant downstairs". He cannot give you that authority because he does not have it!

In other words, do NOT do anything that your landlord says is OK unless your contract already says that it is OK, AND ALSO it does not violate local, city, state, and national regulations.

Check your building code to find out what is REQUIRED by law, and do not build anything that violates that, even if the landlord says it is OK.

And do make sure you get all the necessary permits and inspections to do this!


- Stuart -

Gregwor wrote:

My understanding is that I need a total of 4 boxes; one for each leaf that I pass through.

I am planning on using the space between the outer and inner leaves to place the baffle boxes in.

Would this be the correct plan for using the baffle boxes on the intake side (Pulling air from control room, into vocal booth)

I don't know the math you used or dimensions you have there, but the idea is right. The only things I really see that could be problematic so far with your design are:

1. The sleeve lengths may be too short to deal with the turbulence (remember, the exit from the silencer box is a sharp 90 degree turn.
2. Again, I'd need to know your logic here, but ensure that your register size allows for an air velocity of less than 300 feet per minute.

My main question is where should the long stretch of space after the baffles be oriented on each leaf? should this always occur at the register?

The long stretch needs to be after the last sharp corner or major cross sectional area change. That means your sleeve has to be long.
I was hoping that the flow would have been slowed down by the time it reached the last turn before the register and would not cause any significant turbulent noise issues. If I would need to have an additional 18" length in the sleeve itself, that wouild require a total distance of 29" between my inner and outer sleeve just to fit the box and sleeve! (18" for sleeve, 11" for box width)
Im really hoping that this is not the case. Can anyone else chime in? Would the air flow be slow enough by the time it reached the last 90 degree turn for my register sleeve? or do I have to modify my design so that the 18" run occurs after the last turn (my sleeve for the register) and not after the last baffle inside the box, as I have it now?

Please note, the length of the wooden sleeve was exaggerated and will be much shorter (probably closer to 6" long)

Taking note of what I wrote above, they actually may need to be longer.

Am I grasping this correctly?

Other than the things I pointed out that may need to be addressed, it seems you're doing great. Stuart is the wizard with this stuff, but from everything I've learned, it seems you're doing a great job so far. I like your use of cross sectional area changes in your boxes. Clever design --> only having one baffle area super large. It prevents the entire box from having to be so damned big.

Greg

Is this plan acceptable?

I was hoping that the flow would have been slowed down by the time it reached the last turn before the register and would not cause any significant turbulent noise issues. Will the 90 degree turn before the sleeve cause too much noise or will the flow be slow enough not to worry about the bend created by the sleeve?

Also, am I grasping the concept of using a box for each wall that I penetrate?

The intake from the box on the control room side is 6 x 10, the outlet of that box is 6" rd duct. there will be a short piece of insulate flex duct between the two boxes, the inlet of the box conected to the vocal booth side will be 6" round duct, and the outlet of that baffle box will be 6 x 10 rectangular grille.

Is this correct?

Please advise so that I can begin building the boxes.

Gregwor wrote:

Is this plan acceptable?

Almost, I think.

I was hoping that the flow would have been slowed down by the time it reached the last turn before the register and would not cause any significant turbulent noise issues. Will the 90 degree turn before the sleeve cause too much noise or will the flow be slow enough not to worry about the bend created by the sleeve?

The sharp 90 degree turn is where turbulent noise will be. Not only do you have to worry about the air velocity change, you also need to worry about the sharp corner. THAT is why you need the extra sleeve length.
Hmmm, I am struggling to see how I am going to fit that additional length into my space without eating up space in my vocal booth. Can the boxes be mounted directly to the studs of each wall or do they need to be not touching the walls other than the sleeve that passes through?

Also, am I grasping the concept of using a box for each wall that I penetrate?

Yep!
Ok cool!

The intake from the box on the control room side is 6 x 10, the outlet of that box is 6" rd duct. there will be a short piece of insulate flex duct between the two boxes, the inlet of the box conected to the vocal booth side will be 6" round duct, and the outlet of that baffle box will be 6 x 10 rectangular grille.

If your math tells you that your CFM and air velocity will be correct with 6x10 rect for each room, then cool.

Is this correct?

Your math is the only thing that can tell you if this is correct.

Please advise so that I can begin building the boxes.

The only things that concern me thus far are:
- where and what inline fan are you using?
I was planning on having the fan placed on some 6" round duct on the exterior of the outer shell (behind the rear wall) I wanted to make sure I am understanding the concept before I waste time trying to draw new boxes and reconfigure the space in sketchup
- have you calculated the static pressure of your path?
I haven't calculated the static pressure. I am not sure how to do that, but the length of duct is going to be minimal so I don't think this will have a huge effect on my plan. I was thinking of getting a fan similar to fan tech 6" fan , I think it was capable of 240cfm or more, which is more than what I need.
- how will you control that fan?
I am going to have an electrical switch for on/off. i could order a controller to reduce/increase speed if you think it is necessary. For this small/mid size booth I am not sure if that level of control is really necessary though. I think I would be ok with smile on/off control
- will the fan you've picked out provide the correct CFM you require with your calculated static pressure?
Based on the math I did, it will be more than enough, I have not calculated static pressure, but Im assuming with very short duct length that the effect of static pressure will be minimal
- you still haven't really told us where you're getting your fresh air from.
The control room is not air tight. The walls do not extend all the way up to the ceiling, I'd say there is about 2 feet of free space between the drop ceiling and true ceiling. I am trying to convert an office type space into a project/type studio. Only concern is isolating vocal recordings. Therefore, I was assuming I could just pull cold air from the control room into the booth, and then exhaust that air out into the unused warehouse space behind the rear wall. My logic here is that prior to me doing any modifications to the room there wasn't a separate source for supplying fresh air, or exhausting stale air, all the air just floats in and out of the room through the gaps between the drywall and real ceiling. There is probably a fresh air and exhaust vent elsewhere on the floor in one of the connecting rooms or main hall/atrium type space? If that were acceptable before, why would it not be acceptable now just because I am constructing a small vocal booth? Also, would that mean that these designs are illegal? I've seen other booths you can buy or plans to build that basically do the same thing for ventilation. I am not trying to be smart, or question your knowledge, I am really just trying to get a better understanding of what is actually acceptable.

Here are some examples of other booth's that I was originally looking to model after in the very beginning plan I had...

http://www.dawbox.com/acoustic%20produc ... lation.htm Looks like they mount this on the outside of their booth and pull and exhaust air from the room the booth sits in.

http://johnlsayers.com/phpBB2/viewtopic.php?f=1&t=14147 When I originally saw John's vocal booth design on this forum, I assumed that the vents were also pulling and exhausting from the room that it is staged in.

http://www.vocalbooth.com/images/includ ... lation.jpg Similar concept as What I am thinking of doing except with more baffle boxes than they use (4 instead of 2), and also I would be pulling air from one room, and exhausting into a large, abandoned, uninhabited, unused space.

- you still haven't really told us where you're exhausting your stale air to? I just see one of your silencers going into your control room which means you're either pulling stale air from your control room and dumping it into your booth (pretty sure this is illegal). OR, you're dumping stale air from your booth and dumping it into your control room (pretty sure this is illegal).


In other news, it seems that you're getting pretty handy with SketchUp so that's awesome. You still have a zillion guide lines in your renders which drives me nuts though! AND, I don't know how you are able to draw up such detailed plans using the online SketchUp Free version without signing yourself into a psych ward! I will make the suggestion once again for you to use SketchUp Make as it runs about 5000 times faster and is also free of charge.

I will definitely look into Sketchup Make, didn't realize that was an option. Sketchup is a PITA! Still takes me longer than it should to make these drawings, and it is quirky as hell, but It helps for planning purposes, and the fact that is free probably means I shouldn't be complaining!
Greg

Hmmm, I am struggling to see how I am going to fit that additional length into my space without eating up space in my vocal booth. Can the boxes be mounted directly to the studs of each wall or do they need to be not touching the walls other than the sleeve that passes through?

I was planning on having the fan placed on some 6" round duct on the exterior of the outer shell (behind the rear wall)

I haven't calculated the static pressure. I am not sure how to do that, but the length of duct is going to be minimal so I don't think this will have a huge effect on my plan. I was thinking of getting a fan similar to fan tech 6" fan , I think it was capable of 240cfm or more, which is more than what I need.

I am going to have an electrical switch for on/off. i could order a controller to reduce/increase speed if you think it is necessary. For this small/mid size booth I am not sure if that level of control is really necessary though. I think I would be ok with smile on/off control

Based on the math I did, it will be more than enough, I have not calculated static pressure, but Im assuming with very short duct length that the effect of static pressure will be minimal

I was assuming I could just pull cold air from the control room into the booth, and then exhaust that air out into the unused warehouse space behind the rear wall. My logic here is that prior to me doing any modifications to the room there wasn't a separate source for supplying fresh air, or exhausting stale air, all the air just floats in and out of the room through the gaps between the drywall and real ceiling. There is probably a fresh air and exhaust vent elsewhere on the floor in one of the connecting rooms or main hall/atrium type space? If that were acceptable before, why would it not be acceptable now just because I am constructing a small vocal booth? Also, would that mean that these designs are illegal? I've seen other booths you can buy or plans to build that basically do the same thing for ventilation. I am not trying to be smart, or question your knowledge, I am really just trying to get a better understanding of what is actually acceptable.

I will definitely look into Sketchup Make, didn't realize that was an option. Sketchup is a PITA!

Thanks for the feedback, I am getting antsy, and ready to just start building already but I know there are still some things I need to get a better grasp on

Gregwor wrote:

Hmmm, I am struggling to see how I am going to fit that additional length into my space without eating up space in my vocal booth. Can the boxes be mounted directly to the studs of each wall or do they need to be not touching the walls other than the sleeve that passes through?

It looks like your booth sleeve penetrates near the floor in the corner. You could try turning your silencers on their sides so that your booth sleeve is coming out near the ceiling and more in the middle of the wall. This would prevent a longer sleeve from impeding on your floor space. Another option is to build it into sound treatment. A corner super chunk bass trap needs to be nice and deep so your sleeve could live within it and not visually appear to stick out super far.

Either way, it would stick out like a sore thumb... On the intake side (pulling air from control room) could i compromise and deal with turbulent air at the register on the control room side? As long as I have the extra length on the vocal booth side I should be able to have no noise at the vocal booth register correct?

I was planning on having the fan placed on some 6" round duct on the exterior of the outer shell (behind the rear wall)

Cool.

I haven't calculated the static pressure. I am not sure how to do that, but the length of duct is going to be minimal so I don't think this will have a huge effect on my plan. I was thinking of getting a fan similar to fan tech 6" fan , I think it was capable of 240cfm or more, which is more than what I need.

There are calculators online as well as spreadsheets you can download Don't guess here. It doesn't take too long to enter your info and figure out your static pressure. Your silencers are introducing a ton more static pressure than an average system. You have to make sure your fan will put out 240 CFM under that static pressure load! Also, you don't want one that is more than what you calculated otherwise it will be putting out more CFM than your design accounts for which could mean too much air velocity!

I am going to have an electrical switch for on/off. i could order a controller to reduce/increase speed if you think it is necessary. For this small/mid size booth I am not sure if that level of control is really necessary though. I think I would be ok with smile on/off control

A variable fan is always ideal when possible. On/off obviously still works.
If i use a variable fan, do they allow for the control of the cfm from 0cfm to the max cfm?

Based on the math I did, it will be more than enough, I have not calculated static pressure, but Im assuming with very short duct length that the effect of static pressure will be minimal

Static pressure won't be minimal due to all of the baffles in your silencers. Also, see my comment above regarding the CFM and air velocity relationship. In the technical document for your selected fan, they should have a CFM vs static pressure chart. You can match your static pressure up to it and see what setting it will put out the correct CFM.
How do I interpret the CFM vs static pressure chart and ensure that the fan is sufficient? Do you have an example? I found a chart for fantech fg6 but I have no clue how to interpret it.

I was assuming I could just pull cold air from the control room into the booth, and then exhaust that air out into the unused warehouse space behind the rear wall. My logic here is that prior to me doing any modifications to the room there wasn't a separate source for supplying fresh air, or exhausting stale air, all the air just floats in and out of the room through the gaps between the drywall and real ceiling. There is probably a fresh air and exhaust vent elsewhere on the floor in one of the connecting rooms or main hall/atrium type space? If that were acceptable before, why would it not be acceptable now just because I am constructing a small vocal booth? Also, would that mean that these designs are illegal? I've seen other booths you can buy or plans to build that basically do the same thing for ventilation. I am not trying to be smart, or question your knowledge, I am really just trying to get a better understanding of what is actually acceptable.

You could call an HVAC company in your area and ask them if that would pass an inspection. I can't say for certain what's legal where you live. Make that 2 minute phone call and let us know what they say. Hopefully it would be fine so that your build is easier.
I contacted someone from the building code department and they said that as long as the room I am intaking and exhausting air from has its own mechanical capable of replacing the amount of fresh air Im pulling and exhausting then it is ok to intake and exhaust from an adjoining room (Only because the room I am pulling from has a drop ceiling and there is mechanical in place for ventilation already. If i were to make the control room an air tight room it would have to have its own mechanical that would bring in fresh air and vent to the outside.

I will definitely look into Sketchup Make, didn't realize that was an option. Sketchup is a PITA!

Make is a different beast. It runs lightning fast compared to Free. Plus Free cannot yet do a fraction of what Make can. Basically, upload your model to 3D warehouse from Free. When you open Make, go to 3D warehouse WITHIN Make. Download your model (downloading your model into Make will convert the .skp file to work in your Make version automatically). When I download an .skp file I never load in into my model. I just save it on my computer then open it up as a fresh model. From there, you'll be off to the races!
I tried to find sketchup make, but it looks like it is no longer available for download

Thanks for the feedback, I am getting antsy, and ready to just start building already but I know there are still some things I need to get a better grasp on

I'm glad you realize the importance of the planning stage before you start building. It will be worth the wait.
As far as construction of the walls. What should be the proper order that I build these walls in? Vocal booth first and then outer room walls? Or should I build outer room first, and then build vocal booth. My main dilemma is that the height of the vocal booth framing is longer than the width of the outer shell framing and therefore would not allow me to build flat on the ground and then raise into place if I had already installed the outer shell walls. What order of construction do you suggest?
The vocal booth will be inside out wall, the front and rear walls of the outer shell will have drywall on the side of the framing not facing the vocal booth in order to allow for a large air gap between the outer shell wall and vocal booth drywall.
Greg

Either way, it would stick out like a sore thumb... On the intake side (pulling air from control room) could i compromise and deal with turbulent air at the register on the control room side? As long as I have the extra length on the vocal booth side I should be able to have no noise at the vocal booth register correct?

If i use a variable fan, do they allow for the control of the cfm from 0cfm to the max cfm?

How do I interpret the CFM vs static pressure chart and ensure that the fan is sufficient? Do you have an example? I found a chart for fantech fg6 but I have no clue how to interpret it.

I contacted someone from the building code department and they said that as long as the room I am intaking and exhausting air from has its own mechanical capable of replacing the amount of fresh air Im pulling and exhausting then it is ok to intake and exhaust from an adjoining room (Only because the room I am pulling from has a drop ceiling and there is mechanical in place for ventilation already. If i were to make the control room an air tight room it would have to have its own mechanical that would bring in fresh air and vent to the outside.

I tried to find sketchup make, but it looks like it is no longer available for download

As far as construction of the walls. What should be the proper order that I build these walls in? Vocal booth first and then outer room walls? Or should I build outer room first, and then build vocal booth. My main dilemma is that the height of the vocal booth framing is longer than the width of the outer shell framing and therefore would not allow me to build flat on the ground and then raise into place if I had already installed the outer shell walls. What order of construction do you suggest?
The vocal booth will be inside out wall, the front and rear walls of the outer shell will have drywall on the side of the framing not facing the vocal booth in order to allow for a large air gap between the outer shell wall and vocal booth drywall.

Gregwor wrote:

Either way, it would stick out like a sore thumb... On the intake side (pulling air from control room) could i compromise and deal with turbulent air at the register on the control room side? As long as I have the extra length on the vocal booth side I should be able to have no noise at the vocal booth register correct?

It's up to you to decide whether or not you're okay with a constant wind blowing type sound or not. The booth side shouldn't be neglected though. Make sure it's quiet there.

If i use a variable fan, do they allow for the control of the cfm from 0cfm to the max cfm?

Some have high and low settings, some have high, medium and low settings, some are 100% variable. And yes, speed determines CFM. So yes, 0 CFM to max CFM. Typically for ones with 2 or 3 speeds, it will tell you how much CFM they put out.

How do I interpret the CFM vs static pressure chart and ensure that the fan is sufficient? Do you have an example? I found a chart for fantech fg6 but I have no clue how to interpret it.

The charts show how much CFM it will put out under x amount of static pressure. I just looked up your chart. It's quite simple. Basically it's stating that with a static pressure value of 1.2, it will put out 100 CFM. Static pressure at 0.4 it will put out 225 CFM. I hope that makes sense after you look at the chart again and see how I referenced it. Just like playing the game Battleship.
So if my static pressure was 0.4 then the MAX I could put out is 225CFM, and I could achieve lower, lets say 100 CFM, by reducing the speed of the fan, correct?

I contacted someone from the building code department and they said that as long as the room I am intaking and exhausting air from has its own mechanical capable of replacing the amount of fresh air Im pulling and exhausting then it is ok to intake and exhaust from an adjoining room (Only because the room I am pulling from has a drop ceiling and there is mechanical in place for ventilation already. If i were to make the control room an air tight room it would have to have its own mechanical that would bring in fresh air and vent to the outside.

Awesome!

I tried to find sketchup make, but it looks like it is no longer available for download

Here are all of the Make downloads:
https://help.sketchup.com/en/article/60107

As far as construction of the walls. What should be the proper order that I build these walls in? Vocal booth first and then outer room walls? Or should I build outer room first, and then build vocal booth. My main dilemma is that the height of the vocal booth framing is longer than the width of the outer shell framing and therefore would not allow me to build flat on the ground and then raise into place if I had already installed the outer shell walls. What order of construction do you suggest?
The vocal booth will be inside out wall, the front and rear walls of the outer shell will have drywall on the side of the framing not facing the vocal booth in order to allow for a large air gap between the outer shell wall and vocal booth drywall.

Basically, prep and beef up any outer leaf walls. In your case, after that, you could build your inner leaf and then build your final outer leaf wall that separates your control room and booth. Just go through it in your head and picture where you will run into problems and try to solve for that. It would be wise to maybe write out the order of the build on paper or a computer document and follow it that way. Also, building it in SketchUp will really let you see where problems will occur.
This makes sense. Thanks
Greg

Can I use the same stuff for my bass traps and wall panels? Or should I use different material for the bass traps and/or wall panel?

So if my static pressure was 0.4 then the MAX I could put out is 225CFM, and I could achieve lower, lets say 100 CFM, by reducing the speed of the fan, correct?

Gregwor wrote:

Can I use the same stuff for my bass traps and wall panels? Or should I use different material for the bass traps and/or wall panel?

You certainly can. Check out https://www.bobgolds.com/AbsorptionCoefficients.htm to get an idea of how your material is stacking up (pun intended) against other products.

So if my static pressure was 0.4 then the MAX I could put out is 225CFM, and I could achieve lower, lets say 100 CFM, by reducing the speed of the fan, correct?

Correct.

Greg