Vocal and Dialogue-Interview room

[Warwick]

Hi,

This forum is great.

I like the booth design offered here by John Sayer, so I started playing with that.

I am wanting to build a vocal and interview booth in one end of our down-stairs rumpus room. That is a big room about 4.5m wide and 12m long and the vocal booth would go at one end, but not up to the side where there is an outside window. The ceiling is open rafters to the floorboards of our lounge above, the height from floor to those ceiling floor boards being 2.63m. [Being in Australia I've used metric measurements. Let me know if you want me to edit them to imperial.] The floor is concrete house foundation. The booth is for vocal, also for singing, and dialogue of two people voice acting. The room is downstairs of a house on the downside of a not very busy road. If you are in the existing room and listen, you do get outside noises like cars, lawnmowers, dogs - none of it is insulated, The walls I will situate the booth against join other internal rooms, and I will insulate those walls. The windows of the big room are old sliding ones (presently with old inefficient rubber lining). The purpose is initially for voice acting to make an audio book, which is why sometimes I want to record dialogue between two people. The budget is, what it has to be, but not to burn a whole in my pocket - probably 2K. I'll do all the work myself.

I referenced the Vocal Booth design by John Sayer, thinking I would make it bigger, then I thought longer. I measured it with a tape measure in SketchUp, then averaged the splayed walls to get a workable rectangle of ~2.20m, a width ~2.10m, and height ~ 2.59m.

Then I played with these measurement at http://amroc.andymel.eu/ in relation to my room space options, and arrived at a longer Room Length from the original shape: 3.25m, Room Width: 2.20m, Room Height: 2.59m (only 4 cm to the ceiling) to just fit within the Bolt area. It's 17m3.

And, then at http://www.bobgolds.com/Mode/RoomModes.htm I played some more for a good Bonello line and got: Length 3.17m Width 2.267m Height 2.59m (18m3) To get L. W. Sepmeyer: 1965 - 1:1.14:1.39. Then I re-splayed the walls to look a bit like the original reference.

Q1 I think I have enough space to splay the walls, because if I went any wider, the Bolt area and Bonello curve deteriorated, also it suits me to get around the big concrete support. But I don't think I can splay them by 16 degrees (which I just read in "How to Build a Small Budget Recording Studio from scratch, by Mike Shea & F. Alton Everest). Is less that 16 degrees worth it? If 16 degrees is essential, I'll see what I can do.

This measurement takes me close to the ceiling. I figure I can do something like the pictures in http://johnlsayers.com/Recmanual/Titles/Acoustics3.htm in the section on CEILINGS, but I'll have to work around the existing ceiling rafters, that hold the floor boards of our upstairs lounge.

Q2. Also to get the height, the large room floor is concrete, so that can be covered simply with carpet or matting, correct?

Q3 Is this Plan A workable? Higher is better, I realize, but it's all I've got. I suppose a plan B would be to just use the big room, and maybe build a bunch of TubeTraps, for a put up and pull down booth. In that case I would work on soundproofing the whole room, but in that case It wouldn't be able to completely soundproof it (It also has stairs to the upper level of the house). I could insulate and re-line it using furring channel, and putting in double sliding windows. Shame though if we moved, which we might do in 5 years. But if it's a better option, I'd go with plan B.

Thank you so much for any response.
The project begins
Warwick

[Soundman2020]

Hi Warwick, and Welcome!

The ceiling is open rafters to the floorboards of our lounge above, the height from floor to those ceiling floor boards being 2.63m.

It's not clear how you are planning to build your booth. Is this going to be a stand-alone unit, built entirely within the rumpus room, without touching the existing structure at all? Or are you going to build it as an integral part of the house, with the outer-leaf directly joining the existing walls and ceiling at some points?

Being in Australia I've used metric measurements.

Not a problem. Most of us are "bilingual" here...

If you are in the existing room and listen, you do get outside noises like cars, lawnmowers, dogs -

How loud is that, at the location where the booth will be? How quiet do you need it to be inside the booth? Both of those measured in dBC (decibels, "C" weighted).

The walls I will situate the booth against join other internal rooms, and I will insulate those walls.

Be careful that you don't create a 3-leaf system! Or even worse, a 4-leaf system...

then averaged the splayed walls to get a workable rectangle of

Are you saying that you want to make your booth rectangular? OR do you want to leave it with angled walls, as with John's design?

to just fit within the Bolt area. ... To get L. W. Sepmeyer: 1965 - 1:1.14:1.39.

This is a vocal booth, not a control room, so it's not that important to have a good room ratio. You won't be tracking loud acoustic instruments in there, so modes are likely not a big issue.

Then I re-splayed the walls to look a bit like the original reference.

Acoustic response does not scale, not even "to look a bit like" some other acoustic response. A room that measures 2m x 3m x 4m will have very, very different acoustics than a room that measures 4m x 6m x 8m, even though the latter is just the former scaled up to double in each dimension. Scaling a room will produce very different "sound" inside it. So your booth that "scaled up and looking a bit like John's" will not sound anything like Johns.

Treatment does not scale either. Since the treatment in John's booth was specifically designed to deal with the acoustic issues in that room, using the same treatment in a scaled up version that also isn't the same shape, will not work. Not even if you scaled up the treatment by the same factors. The frequency ranges that needed treating in John's booth are different than those that need treating in a "scaled up but different shape" version, so you will likely need to re-rune the treatment to be more suitable for the scaled-up room.

I think I have enough space to splay the walls, because if I went any wider, the Bolt area and Bonello curve deteriorated,

Why do you want to splay them (apart from "getting around the pillar")?

And here too, you can pretty much ignore Bolt and Bonello, since this is not a control room.

But I don't think I can splay them by 16 degrees

Take a close look: John's are not splayed by 16° either...

splay them by 16 degrees (which I just read in "How to Build a Small Budget Recording Studio from scratch, by Mike Shea & F. Alton Everest)

Are you SURE they were talking about walls in a vocal booth? Are you sure they were talking about a booth like John's?

the large room floor is concrete, so that can be covered simply with carpet or matting, correct?

No. Carpet does the exact opposite of what a small room or booth needs. Carpet absorbs highs very well, absorbs mids randomly and poorly, decreasing as frequency goes down, and absorbs absolutely no lows at all. What you actually need for a small room, is just a little absorption in the high end, smooth, warm absorption in the mid range increasing as frequency goes down, and tons of low frequency absorption. The exact opposite. Forget carpet, and just leave the floor as bare concrete: that's the best possible surface, acoustically, provided that you treat your ceiling correctly. If you don't like the looks of bare cojcrete, or if yours is in bad shape, then lay some ordinary laminate flooring over it, after the booth is finished.

and maybe build a bunch of TubeTraps,

Why? In what way do you think Tube Traps would make for a good vocal acoustic environment? How would they change the room acoustics, favorably? What frequency ranges would they absorb / diffuse / reflect?

In that case I would work on soundproofing the whole room, but in that case It wouldn't be able to completely soundproof it (It also has stairs to the upper level of the house)

The you'd be wasting a lot of time, money and effort! You cannot "soundproof" a room if it has huge holes in it. That would be exactly the same as trying to build an aquarium that has a large hole cut in the glass on one side... Your room would "hold sound" just as well as that aquarium would "hold water"....

I could insulate and re-line it using furring channel, and putting in double sliding windows.

That would be sort of like taking the following approach to the holed aquarium: "I'll put a second layer of much thicker glass on three other sides, and more sand and rocks in the bottom, but there will still be a huge hole in one side..."

Isolation is "all or nothing". In order to isolate, your booth must be completely sealed, air-tight. If there is even a small gap, then isolation won't be very good. If air can get in or out, then so can sound.

And taking into account that your booth will actually be two "leaves", each of which is sealed hermetically, I'm sure you can see why you will need a suitably designed ventilation system that can feed you enough fresh air to keep you alive, and also remove the same amount of stale air. You will need to design a pair of "silencer boxes" to do that: They allow air to move through wile blocking the sound.

I would also suggest that you do your design in 3D, preferably in SketchUp. You'll find it a lot easier to visualize how it will work out.


- Stuart -

[Warwick]

Thanks so much for the feedback, Stuart

I would also suggest that you do your design in 3D, preferably in SketchUp. You'll find it a lot easier to visualize how it will work out.

See attached Sketchup files. One shows using the man cave to extend the booth space, the other showing the man cave separate.

...Is this going to be a stand-alone unit, built entirely within the rumpus room, without touching the existing structure at all? Or are you going to build it as an integral part of the house, with the outer-leaf directly joining the existing walls and ceiling at some points?

Integral part of the house, with me utilizing the two walls into the corner as two of my outer leaf walls, and the same with the ceiling. Then I will build the other two needed outer walls/laeves - to join to the ceiling. I know that comes with an issues of foot banging on the ceiling/floor above, so a) I can add mass to the pesently floor board ceiling e.g. adding gypsum and OSB, and b) place carpet on the hardwood floor upstairs, over area, to reduce foot scraping noise.

How loud is that (the big room), at the location where the booth will be? (decibels, "C" weighted)

The big room, when as quite as it can be: 34.5dBC. Other measurements:
- dog toe nails walking upstairs: 40dBC
- common noises (walking upstairs, car coming into garage, dog barking outside of the house): 60dBC
- son noisily coming roughly down stairs: 73dBC
- my voice loud: 85dBC
- son playing/banging with dog above - 60-90dBC). Banging upstairs is effectively banging on the outer leaf, because the floor boards are the outer leaf, before any acoustic treatment. At the moment the floor boards are exposed to the large room below.

How quiet do you need it to be inside the booth?

50dBC. From reading it sound like a reasonable goal for quietness in the booth would be 30dBC. And if I want to isolate from, say 80dBC of any outside soud, then that means I want to acheive 50dBC of isolation. I can ask for no loud banging upstairs when the sound booth is in use. If I want to isolate a bit more from that goal, I could add extra layers of gypsum to inner leaf.

I started wondering how much insulation I need to achieve that? At http://johnlsayers.com/Recmanual/index.htm in the Walls and Ceiling section? So, outer wall: Gyprock 16mmx2, ~100mm insulation, air 50-100 mm, insulation 50mm, Gyprock 16mmx2, inner stud open for the internal treatment. Double doors and windows. Will that acheive 50dBC?

Be careful that you don't create a 3-leaf system (when insulating the outer walls)! Or even worse, a 4-leaf system...

So if I am utilizing those two existing walls for two of my outer walls, I believe I need to remove the existing facing-inwards-side gypsum, so there is exposed insulation, correct?

Are you saying that you want to make your booth rectangular? OR do you want to leave it with angled walls, as with John's design?

I got it in my head it was better, but if not, no, I have changed the design to parrallel walls.

(I said: to just fit within the Bolt area. ... To get L. W. Sepmeyer: 1965 - 1:1.14:1.39.) This is a vocal booth, not a control room, so it's not that important to have a good room ratio. You won't be tracking loud acoustic instruments in there, so modes are likely not a big issue.

Good to get that in perspective. I'll still want to do the best I can with internal treatment, because althoughb I say the purpose is for voice acting and dialogue, in the fututre may family may like to try accousting instruments in there.

Acoustic response does not scale, not even "to look a bit like" some other acoustic response....

What, no short-cuts

Treatment does not scale either.

...Why do you want to splay them (apart from "getting around the pillar")?

I thought to reduce 'flutter echoes'. I just read, somewhere else on the forum, the splay would need to be 12% to acheive that (from you I think), which would not be worth the space, so I'm going parallel.

Are you SURE they ("How to Build a Small Budget Recording Studio from scratch, by Mike Shea & F. Alton Everest) were talking about walls in a vocal booth?

Checked. I was wrong, sort of. It's written generally, "We all know that parallel walls can cause nasty flutter echoes". Then they go on to discuss various 'flutter-free diffusers' to resolve the issues.

Carpet does the exact opposite ... Forget carpet, and just leave the floor as bare concrete

I can glue some carpet on my feet Oh, no, I know. Socks

In what way do you think Tube Traps would make for a good vocal acoustic environment? How would they change the (big) room acoustics, favorably? What frequency ranges would they absorb / diffuse / reflect?

I'm out of my depth, you could say I'm talking out of a hole in my head, but if that hole is treated, there could be some value in it, right? When I read about them, it seems like they are built half to absorb base and half to disperse, and they are movable, so you can experiment with placement - other than that, I do not know any specific frequencies, or how they 'stack up' with other methods.

... wasting a lot of time, money and effort(trying to soundproof the bigger room)! You cannot "soundproof" a room if it has huge holes in it.

Yeah, that's what I figured.

Isolation is "all or nothing". In order to isolate, your booth must be completely sealed, air-tight. ... And taking into account that your booth will actually be two "leaves", each of which is sealed hermetically, I'm sure you can see why you will need a suitably designed ventilation system that can feed you enough fresh air to keep you alive, and also remove the same amount of stale air. You will need to design a pair of "silencer boxes" to do that: They allow air to move through while blocking the sound.

Yes, I see.
Okay, so on to Ventilation:

I referenced an AC company diagram in this forum forum link and other discussion threads on the subject.

I the sketchup file you can see i am utilising the man cave, which joins the booth area, and the cupboard, which is already seperate from the booth area.

Change air for a recording studio at 10 -12 times per hour:
http://www.fantronix.com/acatalog/Recom ... Rates.html
So 18m3 room x 10 = 180m3. I can get a 6" fan to pump much more than that (so can run on slow speed, by getting fans with speed adjustment).

In the SketchUp file, I've shown a portable air-conditioning (AC) unit in a largely surrounded area (sound bafled) within the big cupboard, which also has a draw of fresh air from the outside world. So the big cupboard air is a mix of what is drawn from outside and cool air when AC is on in summer.

Air movement:
This air is fanned into the sound booth (by a 6" fan with full speed controller), through a plenum, through duct in the man cave, through a silencer, through into the sound booth ---------------- Sound booth air is then extacted out through a silencer, out through a duct in the man cave, out through a plenum in the cupboard, out through a 2nd fan (6" fan with full speed controller), and on, out through a duct, out of the cupboard, and out through the house wall to the outside world. In addition, the portable AC has its own extraction hot air directly to the outside world.

It is possible a third fan is needed for the short double-open-ended duct between the outside world and the cupboiard. Effectively the outside world air is being sucked in by the intake fan in the cupboard and the AC when on, but that may not be enough. I can measure the pressure in the cupboard when it's up and running and if the pressure drops too much when AC is on or off, I can add a third fan to specifically pull in air from the outside world.

Positioning of duct intake and extraction points:
Cold air intake from outside below exhaust hot air vents (because hot air/thinner mass rises, so hot exhaust vents won't get sucked in).
Cold air intake from cupboard and to sound room, on low side, (because cold air/thicker mass, natuarally sinks low).
Hot air extraction from sound room, from high position (where hot air is, because it naturally rises in the room).
Booth registers reasably away from centre area of room where mic will approximately be.

Insulating sound in this HVAC system:
The portable AC unit we have, at the moment, puts out 61dBC when the fan kicks in. If the noise still gets to the booth (past the plenum, ducts and silencers), I'll have to plan on a split system budget. I know that would be better, but I'm trying to avoid the cost at the momenty. I have added some baffles between the portable AC and the intake fan (to try and reduce the AC noise in the cupboard). For other things I put in the cupboard, I can make sure I leave free air space for the fresh from outside the AC and the air intake at the plenum. Even without an AC, the system would still move air (with fresh air) in and out of the sound booth. A temporary plan B in the case of the portable AC being too loud could be in summer to have an open chilli bin with ice, in the booth, near the air intake register.

Insulation over silencers, plenum and ducts:
In one Sketchup, I can use the double leaf idea over the HVAC pieces in the man cave, by walling off the silencers and ducts in the man cave, using framing and gypsumx2, and fill the gap with Earth Wool. In that case, that framing and gypsumx2 leaf would be the outer leaf of that wall, with the existing wall framing being filled with insullation batts only. That makes those two silencers inside the outer leaf wall and the outer leaf wall about 1m thick.

In the other Sketchup I use the man cave as an extention to the sound room, as an accoustic space that can probably hold alot of insulation to make a big base trap.

Which idea would be best?

What do you think?

Thank you for any advice.
Warwick