The Drum Bubble - construction details

Ekimtoor1

Member
The Drum Bubble

The room’s only purpose is to contain my drum kit and allow me to play with some privacy and not intrude on my family or the neighborhood.

Here’s what I built: a 7’x9’x8’ room in a room, 2”x4” framing with rockwool in the bays, on the concrete slab of my garage. The entire house is built on the same slab. The walls are 24” on center and the ceiling is 16” on center. The first layer of 5/8” drywall is screwed with 1-5/8” drywall screws about every 16”. The second layer of 5/8” drywall received two tubes of green glue per 4’x8’ sheet and was secured with 2” #8 drywall screws about every 12” on the ceiling and 16” or more on the walls. The drywall construction is the same for all surfaces inside and out. Acoustic sealant was applied to seams and gaps at both layers.

The room is in a corner of my garage. One wall faces a concrete block exterior wall, and one wall faces an interior BR wall of the house. There is a two inch air gap between the room and these walls. The garage ceiling is 9.5’ so there is an 18” air gap between the room’s roof and the garage ceiling.

For the door, I built what is essentially a wall section on wheels. It is a sliding door like affair that is guided into place by a set of rollers top and bottom. The rollers are adjustable to press the door into a rubber seal as it is closed. The seal is a double row of 1/2” diameter hollow neoprene weather stripping.

A hinged door was not practical as the door weighs 300 pounds. The garage floor has a slope which would make any other configuration of door difficult. The door works well due to it’s mass and the seal is light tight. Friction is a bit of a problem, it takes a good tug to open.

The walls were finished with mud, tape and paint, inside and out.

When the construction was complete I installed thin carpet tiles to the floor and moved my drum kit into the room. It is a medium large kit, three up, two down with an array of cymbals.

I bolted two 6.5” speakers in the upper corners to the corner framing and hung a small rack on drywall anchors next to the drum kit. It holds a Soundcraft Ui24R digital mixer. A 32” tv is mounted with drywall anchors directly in front of the drum kit.

Now that you know the details of the room build so far, here is the first test result:

Pink noise
57-69db inside
Inaudible 4’ outside the door
78-80db inside
Inaudible in BR
90db inside
57-63db 4’ outside the door
Barely audible ear to BR wall
All above inaudible outside house

Dream Theatre - At Wits End
92-96db inside
55-58db 4’ from door
42-48db 4’ from BR wall, all low end
Slightly audible 4’ from garage door
Inaudible from sidewalk
Slight low end ear to garage wall
Inaudible 4’ from garage wall

I was going to do more tests but it seems obvious that my problem at hand is low end leaking into the BR. Everything else is quite acceptable.

It appears that I have created a quadruple leaf between the bubble and the BR wall. Reading the below info, it seems I might be able to improve the leak by increasing the gap between the bubble and the BR wall.

Please comment and thank you.

https://www.soundproofingcompany.com/soundproofing_101/triple-leaf-effect
 
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mjbphotos

What?!?
I bet when you are playing drums in the room, its a lot louder than 96dB. AS has been discussed in your other thread, the sound gets transmitted through any hard materials, including the slab and the drywall screws into the studs.
 

mixsit

Well-known member
Wow. I wouldn't even try offering comment acoustically useful. I was wondering about the peak levels -vs steady state in play as well.
But been 'round long enough to recognize a hell of a lot of work represented when it's there. Hoping here maybe this won't be one of these '90% to get 'close, but another 90 getting the last 10' for you. :)
 

Ekimtoor1

Member
I bet when you are playing drums in the room, its a lot louder than 96dB. AS has been discussed in your other thread, the sound gets transmitted through any hard materials, including the slab and the drywall screws into the studs.
All I’ve done is measure some hard kicks and snare hits inside. Those are just over 100db.

I can’t find any data that sound travels through the slab. Most of what I’ve read says a concrete slab absorbs. If I could be sure it would help, I would put some neoprene or some other material under the plate.

I don’t see how I could build a drywall system without screws. It is feasible to remove the screws at the second layer walls and roof but not the ceiling. I can’t get at the first layer screws and even if I could, what then would hold the drywall up? The room is completely isolated except for the plate on the slab. Are screws really a substantial problem?

Not knowing how much I’m going to get from either of those changes, I’m hoping for input on other things I could do to make it better, if there is anything. All I need is some way of reducing low end into the BR. Everything else is good.

Here’s my current question: I have about a foot more I could take to move the structure another foot away from the BR wall. Do you think that would reduce the low end problem?
 

Ekimtoor1

Member
Wow. I wouldn't even try offering comment acoustically useful. I was wondering about the peak levels -vs steady state in play as well.
But been 'round long enough to recognize a hell of a lot of work represented when it's there. Hoping here maybe this won't be one of these '90% to get 'close, but another 90 getting the last 10' for you. :)
Yeah, not only was it a hell of a lot of work, it was all done in the 97 degree summer heat of south central Florida. I started it on July 22 and the construction was complete about a week ago. It was a full time job seven days a week. Of course the work continues now chasing whatever improvements I can make.

Im very satisfied with the result except for the low end leak into the BR.
 

mjbphotos

What?!?
All I’ve done is measure some hard kicks and snare hits inside. Those are just over 100db.

I can’t find any data that sound travels through the slab. Most of what I’ve read says a concrete slab absorbs. If I could be sure it would help, I would put some neoprene or some other material under the plate.

I don’t see how I could build a drywall system without screws. It is feasible to remove the screws at the second layer walls and roof but not the ceiling. I can’t get at the first layer screws and even if I could, what then would hold the drywall up? The room is completely isolated except for the plate on the slab. Are screws really a substantial problem?

Not knowing how much I’m going to get from either of those changes, I’m hoping for input on other things I could do to make it better, if there is anything. All I need is some way of reducing low end into the BR. Everything else is good.

Here’s my current question: I have about a foot more I could take to move the structure another foot away from the BR wall. Do you think that would reduce the low end problem?
I agree regarding the need for the drywall screws.
Lots of internet info on sound transmission through concrete. https://www.soundproofingcompany.com/soundproofing_101/flooring-protecting-a-concrete-slab

My point was that you are never going to get 100% isolation,
 

Ekimtoor1

Member
I’ve moved inside and started sorting the many issues I’m going to face there in a 9’x7’ space.

I started with the bass drum. There is so much reflection and resonance going on I had to take all the drums out except the bass drum to be able to hear it at all.

I’m trying to use a Behringer BA19a boundary mic and not liking it very much. Everyone raves about it but it’s not sounding good at all. It’s mostly the rooms fault, I think it’s just too small for a mic like this. I’m going to replace it with something like an Audix D6, a mic I played live for many years. I just thought I’d try something new with the Behringer.

As far as traps, my first priority is to make some corner traps and see where things are after those are up.
 

jamesperrett

Active member
Having only just had a look at this thread, I would say that you've missed out on some kind of compliant layer between the walls and the concrete slab. You could use neoprene strips but I found rubber crumb carpet underlay to work well. I would also build a false plywood floor over some carpet underlay to stop some of the drum vibrations from coupling into the concrete slab.
 

Ekimtoor1

Member
Having only just had a look at this thread, I would say that you've missed out on some kind of compliant layer between the walls and the concrete slab. You could use neoprene strips but I found rubber crumb carpet underlay to work well. I would also build a false plywood floor over some carpet underlay to stop some of the drum vibrations from coupling into the concrete slab.
Thanks for your input.

The floor and the plate is on my list, although from what I’ve read there is little to be gained from neoprene under the plate. But I may do it anyway as I have access to the plate’s underside because the structure is not bolted down. I do plan on some sort of floating floor.

I’m a little weary of chasing leaks right now so I’m playing with my toys on the inside for a while. Gotta keep the fun going!

Thanks!
Mike
 

Ekimtoor1

Member
Wow. I wouldn't even try offering comment acoustically useful. I was wondering about the peak levels -vs steady state in play as well.
But been 'round long enough to recognize a hell of a lot of work represented when it's there. Hoping here maybe this won't be one of these '90% to get 'close, but another 90 getting the last 10' for you. :)
I’m afraid it’s exactly that. I am chasing that last 10% which of course is at the top of the db scale making it super challenging.

But I have a number of relatively simple things to try and maybe I’ll get something for it.
 

Ekimtoor1

Member
I live in a brand new neighborhood here in south central Florida, which is still under construction. There are dumpsters everywhere and the builders throw out an unbelievable amount of perfectly good building materials and other items. I scavenged a lot of framing for the Drum Bubble.

Today, I was looking for a piece of 1/2” material and I came upon these perfectly useable moving blankets. (See above post). About 40 of them. I don’t expect to block anything with them, but they will provide a quick and dirty inside treatment for reflections and such. Or will they?

Anybody ever use these ?

Thanks
Mike
 
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Ekimtoor1

Member
I’ve moved inside and started sorting the many issues I’m going to face there in a 9’x7’ space.

I started with the bass drum. There is so much reflection and resonance going on I had to take all the drums out except the bass drum to be able to hear it at all.

I’m trying to use a Behringer BA19a boundary mic and not liking it very much. Everyone raves about it but it’s not sounding good at all. It’s mostly the rooms fault, I think it’s just too small for a mic like this. I’m going to replace it with something like an Audix D6, a mic I played live for many years. I just thought I’d try something new with the Behringer.

As far as traps, my first priority is to make some corner traps and see where things are after those are up.
I figured out my problem with the Behringer BA19a boundary mic. It is excellent. Really good. The recorded tracks are accurate and able to be processed into pretty much whatever kick sound you’re going for. Very happy with it and only $70!
 
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