Rehearsal Room/Tracking Room in Massachusetts

[soldtoscience]

Hello all you wonderful studio designers! This forum is amazing and I finally worked up the courage to post my project.

My name is Phil and I’m building a rehearsal room/recording room in my house.

My house has been rebuilt and Frankensteined many times since 1947. A single car garage was added to the property at some point, which was then attached to the house. Some time later the single car garage was expanded to a double car garage. Then some time after that it was converted into a 2nd living room area with library, and on the 2nd story the master bedroom was extended over it and a bathroom and closet were added.

I moved in 2 years ago, and it was tough to dig up the plans to even learn that much. The house was a residence, then a dentist office, and then a residence again. Pretty wild!

Anyway, I’m converting the garage area into a rehearsal room/tracking room. I went to school for music, and did a thesis in acoustics, but I’m always ready to learn more, and also to dispel fact from fiction in this confusing world of acoustical materials and misinformation. I’m also nearly clueless when it comes to practical construction techniques, I feel much better building hanging diaphragmatic panels and diffusors than a framed wall.

Demolition has begun, and a new frame has been built sectioning off the room from the rest of the house. I didn’t have much choice, the new frame had to go where it went because of the outside door. However… now…. I am free to go as acoustically wild as needed.

I would like to isolate the room as much as possible. I would love to be able to practice and record with an 8 piece band while the kids are sleeping. Neighbors are less of an issue, and we are a block away from the train tracks, but my biggest concern is not disturbing the family while I play to my heart’s content.

Budget is not as important to me as doing it right. I would rather spend more, take longer and do it right. I expect about $50,000 if I hired people to do all the work. I would be really embarrassed if I had my Sound Recording degree hanging up on the wall inside a faulty room I designed!


Design so far:

I’ve decided to go double walls, room inside a room, green glue. I was debating using clips as they claim to have higher STC ratings than double walls, but this quote got me, “Phil, those tests are done in perfect environments, what do you think will work better? Something that simulates decoupling or actual decoupling?” And that was that. Though the walls aren’t up yet….

A local company keeps trying to sell me Mass Loaded Vinyl, but never fear… I was finally sworn off the stuff a few weeks ago after I saw a study showing that if you put it in the walls it either creates a triple leaf, or doesn’t work, or adds less mass and more expensive mass than sheetrock. So none of that!

We are looking at getting an isolated HVAC system for the room. Probably a split system that does heat and AC. We already have 4 split units in the rest of the house, and they are awesome. 4 is the max you can put on the system we have, so it’s full, and it costs as much to move one as it does to buy a new one. So I kind of lucked out there. I have to get an isolated system! Yay! I have questions about what I should do here. If we get a wall mounted remote controlled unit like we have, how and where do I build the isolation muffler box? How should I send it around the room?

The walls are mostly concrete blocks. I think I’m going to be fine building a 2x4 frame around the room and filling it with fiberglass. It was a surprise tearing off the existing wall and finding the old garage doors still inside! I’m debating on converting the alcove on the south wall into a vocal booth/amp closet/storage closet/bad drummer cage… what do you think? I could decouple a little room there. Could be fun!

I’m not sure what to do about the floor. It’s a poured concrete floor, and I think it’s technically isolated from the rest of the house. I want a hardwood floor, but what goes under that? I was thinking of some kind of mat that goes on the concrete, then plywood, then hardwood floor. I don’t think I need to go much crazier than that but I’ll know more when I do my tests.

The ceiling is my weakest point. There’s a hole where I can actually see the bathtub! On top of that I can’t add anything to the hardwood floor above. Not allowed. I’m all for suggestions here too. Any success gluing sheetrock to the bottom of the floor to add mass? My loose plan was to caulk and fill all gaps and holes, and fill it with fiberglass. Also there is an I-Beam running though the middle of the room… .what to do with that?!

Here’s a rough outline of construction:

Phase 1: build the new wall – DONE!, Add new outer door (coming next week)
Phase 2: build the outer frame around the room, fill gaps, caulk, and add fiberglass
Phase 3: Test! I’ll start my baseline tests here. Figure out how my room is doing. And how to proceed. I’ll be able to take out or add more fiberglass, try different materials
Phase 4: New Floor and HVAC, convert one of the outside sets of doors to a window.
Phase 5: Inside walls and ceiling, inside doors, power ect… finish the isolation portion.
Phase 6: Variable Room acoustics – this is when I get to have fun building contraptions that will absorb the drums If I want, spin around, and diffuse the violin if I want… There will be some permanent installations for sure but I’d love to be able to play with different acoustics.


Let me know if there’s anything else you want to know. And thank you in advance!!!

Pictures, Diagrams, ect to follow:

[soldtoscience]

Here are a few pictures of the current conditions.

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Sketch up attempts, go easy on me, I just started using Sketchup

[soldtoscience]

Sketchup animation of Current Conditions

http://youtu.be/f7YIb-eqhMY

Animation of proposed phase 2:

http://youtu.be/-yWMo2JsMgQ

[Soundman2020]

Phil, I have no idea how your thread ended up with no replies at all! If you are still around, I'm really sorry about that, and hope we can still be of some use to you.

Great first post, by the way.

I just took a look at your videos, and you are obviousness putting a lot of thought and design into this. Since you already know acoustics, that's a major benefit!

“Phil, those tests are done in perfect environments, what do you think will work better? Something that simulates decoupling or actual decoupling?”

Yup! That pretty much covers it. With clips on a single frame, your maximum MSM cavity depth is limited by the width of the studs. But with fully decoupled double-frame construction, you can make that gap just as big as you want. As you already know, the bigger the air cavity, the lower the MSM resonant frequency is, and therefore the better the isolation. Can't do that with clips! Clips are fine for medium isolation, but not for "8-man band downstairs, family sleeping upstairs. That takes just a bit more than clips can handle.

A local company keeps trying to sell me Mass Loaded Vinyl, but never fear… I was finally sworn off the stuff a few weeks ago after I saw a study showing that if you put it in the walls it either creates a triple leaf, or doesn’t work, or adds less mass and more expensive mass than sheetrock. So none of that!

Well, there's one more effect that you didn't mention: it takes a lot of money out of your pocket, and puts it in their pocket! That's the number one reason why most places promote it heavily. But as you certainly know, sound waves can't read price tags, and only react to the amount of mass in the wall, not the amount of greenbacks that were used to buy out. There's no place you can fit a dollar sign into the equations of resonance!

That said, MLV does have some uses in acoustics, but they are few and far between. I've only used it a couple of times on places I designed, and even then only rather small pieces.

We are looking at getting an isolated HVAC system for the room. Probably a split system that does heat and AC.

Yup. That generally is the best choice for home studios, if the existing house HVAC doesn't have any extra capacity on it, or if you just don't want to connect the two systems.

If we get a wall mounted remote controlled unit like we have, how and where do I build the isolation muffler box? How should I send it around the room?

Here's the thing: with a typical low-cost mini-split (what you seem to be talking about), there is no ducting or fresh air! The box just sits on the wall, sucking in warm air at the top, pushing it though the heat exchanger and out the front several degrees cooler. That's it. It does not bring in any fresh air from the outside world (which you need, if you happen to like breathing), and it does not pump any stale air out (which you also need). So in addition to your mini-split, you also need a ventilation system that does that part. Usually a simple duct system with a fan on one end and silencer boxes wherever a duct goes through a wall.

The walls are mostly concrete blocks. I think I’m going to be fine building a 2x4 frame around the room and filling it with fiberglass.

OK, but how are you going to make up the mass in the spaces where the garage doors were? as you know, one of the keys to getting good acoustic isolation is to ensure that each of the leaves has roughly the same amount of mass on it (same surface density), and that the surface density is also fairly consistent throughout each leaf. If your outer leaf is mostly concrete block (hundreds of kg/m2) and then in some places you switch to drywall on studs (tens of kg/m2), then you have a pretty major change there! An entire order of magnitude... If you want high isolation, then you'll likely need to beef up the mass in those gaps.

It was a surprise tearing off the existing wall and finding the old garage doors still inside!

Can you remove them, and just brick up the gaps? That would be your best bet, for sure.

I’m not sure what to do about the floor. It’s a poured concrete floor,

Then its perfect! Hard to beat that for a studio floor. Unless, of course, you don't like the look of it. But acoustically, bare concrete is great (assuming that the rest of the room is treated accordingly).

I want a hardwood floor, but what goes under that? I was thinking of some kind of mat that goes on the concrete, then plywood, then hardwood floor.

The general recommendation here is to use laminate flooring. It isn't true hardwood, but there are some really, really convincing imitations that look fantastic. Normally there's a thin foam pad that goes down on the concrete, then the flooring just clicks together, edge to edge. Fast, not too expensive, and very good, both aesthetically and acoustically.

The ceiling is my weakest point. There’s a hole where I can actually see the bathtub!

hhoooo boy! Yup, I'd say that's just a little bit of a problem! As in HUGE!

I’m all for suggestions here too. Any success gluing sheetrock to the bottom of the floor to add mass?

Not gluing no: that would be a mistake. But the basic idea is right. That's often called "beefing up the mass", and the way to do it is to cut strips of drywall to fit in between the joists, then hold that in place with cleats around the edge, and seal the edges with caulk. You might need two ore more layers to get enough mass up there. You know the equations to figure it out, so I don't need to repeat them here, but you will need some serious mass to get good isolation.

Which brings up the next point: structural integrity. You can't just go hanging tons of mass from your joists without first checking with a structural engineer! The fact that there's a bathtub up there indicates that there's already some serious live loading going on, as well as the dead loading, so there might not be that much extra capacity. You may need additional joists, beams, pillars, etc. Only a qualified structural engineer can tell you about that. Hire one.

My loose plan was to caulk and fill all gaps and holes, and fill it with fiberglass.

That's a good start, but it will need more than just that.

Also there is an I-Beam running though the middle of the room… .what to do with that?!

Work around it!

I really hope this is useful for you, but I suspect you may be way advanced already, after all this time. But even so, it might help others who find your thread in the future...

Do let us know how the build is going, either way.

- Stuart -

[soldtoscience]

Hello!

Thank you for the detailed replies Stuart! I’m glad I checked back here and found your response!

I have made quite a bit of progress, and this forum has been instrumental in every step in my design. You guys are wonderful!

One controversial decision is I decided to build an A-Frame shape on either side of the I-beam. The angles are at about 10 degrees to take care of the flutter echo. I plan to put a lot of absorption in the front of the room on the ceiling. And build custom diffusors for the back of the room on the ceiling.

I was hoping to use the dreaded concave shape combined with skyline diffusors to get a “focused diffuse field” (I just made that term up) that might be good for recording classical instruments. I’ll have more information on this soon!

I plan to put diffusors on hinges all around the room, which can be open and closed, revealing absorption or diffusion. I plan to put diaphragmatic panels (1” 703, hardboard, 1” 703 hanging from wire) behind cloth for broadband absorption.

Then you can “open” the diffusors around the room, closing off absorption channels, creating an almost entirely reflective environment. I’ve been looking at plans on http://arqen.com/sound-diffusers/ for DIY “low profile” diffusor design.

I’m really proud of the ventilation system. Entirely inspired from this forum. Here we made muffler boxes, put them in the crawlspace above the south side of the room and vent out through the roof. I used a “Greentek PH 7.15 Heat Recovery Ventilator” which pulls fresh air in, warms it as it passes by the stale air, and pulls stale air out. This unit is completely separate from the AC unit which is exactly as you described. No fresh air! The only surprise here is when I saw the 4 foot smoke stacks coming out of the roof. OOPS! I think I’ll be painting those black and the historic district may have a thing or two to say to me….

I’m glad I checked because I’m making the final call on the flooring in the next few days. Reading up on hardwood vs. other surfaces. I always loved hardwood, and I used to think it “sounded better” but if the laminate flooring is really no different looks and reflection wise, and it’s even easier to install and quieter than hardwood? Then I’m excited to check that out. Any detailed information on flooring options would be greatly appreciated!

I already had a session in the room. DVD commentary! I setup a “Masterpiece Theatre” vibe, which worked great! We had an ISDN line live to Los Angeles. The inner sheetrock wasn’t even up. I threw up insulation for the session and had to tear it back out for the framing inspection the next day. Uff Da!

The window has been installed, next step is insulation and inspection, and we are almost done! It’s diffusor designing time!

Sorry for the long post, but I guess if I’m going to post once every 6 months, this is what you get! Thank you so much for all the help and inspiration.

Cheers!

Phil

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