Building a new Drum Room

[Jason Morris]

There is an extreme weak link on the drawing, with the new modules fitting in between the new studs

Well, according to the John Sayers folks, those sections where there is no continuous sheathing are not really a weak point, because you have 5 1/2" of timber. I'm not sure what the density of 5 1/2" of pine is vs 5/8 OSB and 1 1/4" of drywall.

In any case, my inside-out ceiling should be done soon and I can provide some insight into whether it was a success or not.

 

[kmetal]

Well, according to the John Sayers folks, those sections where there is no continuous sheathing are not really a weak point, because you have 5 1/2" of timber. I'm not sure what the density of 5 1/2" of pine is vs 5/8 OSB and 1 1/4" of drywall.

The reason i ask is because in Rods book, in the section about massing up the existing ceiling, where drywall is placed in between the bays, he cites the weak point of the assembly's isolation as the studs themselves.

I presume it has to do with density, a continuous seal, as well as the properties of wood which make it a good conductor of sound, drums, guitars, ect are all made of wood.

Ive never seem test data for an inside out assembly, where i have seen plenty for standard iso walls, many of which are freely available in the USG handbook.

Im not claiming the inside out method isnt effective, i am curious as to how effective it is relative to a standard assembly. I also submit that wrapping the framing with drywall wouldn't make the assembly worse based on what i understand. How much improvement or if its necessary or not, i dont have a conjecture on until i can see some test data on the performance of the inside out ceiling. Maybe someone over at JS has some? Totally not being an A$$, im just not super well versed in this method, and i know Stuart and John, are bright minded individuals.

 

[Jason Morris]

I AM still plugging away at this.
I am almost done with the "isolation" portion of the build.

I am not at a point where I need to make final decisions about how I want to build the doors.
I am planning on a solid core door, with two layers of MDF green glued and screwed to it.

What I am NOT sure about are seals.
What are good seals to use around the jambs and what is a good seal to use at the floor?

I have looked at these door sweeps:
https://www.amazon.com/dp/B00TXGLLX2/?tag=r06fa-20

and these seal kits:
https://www.amazon.com/dp/B07H4PY1XN/?tag=r06fa-20

Im wondering if those (expensive) seal kits for the bottom of the door are really the best way to go? or maybe i need to just build a threshold at the floor with good seals on it?
I know there would be a "trip hazard" there, but I wont be bringing a lot of equipment in and out, as it's just for my own use.
And I dont mind stepping over a threshold.
I really just want it to work well.

Any thoughts?

 

[Jason Morris]

Or maybe I should just go with a "seal kit" like this?

https://acousticalsolutions.com/product/acoustic-door-seal-kit/

 

[pcrecord]

Or maybe I should just go with a "seal kit" like this?

https://acousticalsolutions.com/product/acoustic-door-seal-kit/

I've installed some of those on my doors and they work nicely.
https://www.amazon.com/dp/B00TXGLLX2/?tag=r06fa-20

Althought I regret buying doors that the mecanism is already embedded in the door. For the look and the effectiveness, if I had to redo it, I'd buy them all premade with the door cases.

 

[kmetal]

Theres no doubt the pre-fab seal kits will work as perscribed. They are pretty pricey, so it really depends on your budget, and needs. Ive used them (door sweeps) at Normandy sound, but i can say with age (35+ years) they dont exactly work smoothly. The drop seal isnt perfect. Im sure lubrication would have help even more, but just working them loose got them moving "ok" when i was working on the doors during the re-build.

For the door seals, on the triad wave cave, i built them as described in rods book. I did however use a single seal, rather than wonderful triple seal in rods book. This was because we didnt add mass to the solid core doors.

For the weatherstrip we used GM type K, trunk rubber. It was available from "facca fasteners" supply company, and possibly elsewhere now. At one point it was tough to aquire. Its extremely durable, and looked brand new 5 years later, standing up well in the commercial studio.

For the threshold i just continued the door jamb style using 1x4 (ripped to width) jamb and stops.

I was concerned about tripping, and knicks and dents, but it proved not to be a problem on any of the 5 doors in the studio.

Had i used a double or triple seal, then i would have used a gasketed threshold, a drop seal routed into the door bottom, and door sweep, since a triple seal on a threshold would be quite tall.

Ive seen rod reccomend regular ribbed weatherstrip as an alternative to the magnetic weatherstrip in the book, for the third seal.

If you end up going rods method, i can write out how to install the jambs and weatherstrip, as rod told me on RO many years back. He doesn't describe the process in the book.

At the end of the day you just need something that creates and airtight seal, and is durable. The durability is im guessing one of the main reasons behind using trunk rubber, vs standard dept store exterior weatherstrip for the primary seal(s).

 

[kmetal]

My concern about MDF would be its durability over time. It might be worth the slight increase in cost to use a sheets of A/C cabinet grade plywood. They go for about 35$ per sheet around here, and can look nice when stained.

 

[pcrecord]

Theres no doubt the pre-fab seal kits will work as perscribed. They are pretty pricey, so it really depends on your budget, and needs

In Canada they can be found around 300$CAD .. pricey but one less thing to doubt when looking for the max isolation
Depends on budget for sure !

 

[Jason Morris]

So, things are progressing.
The room is "enclosed" now. Just need to finish up the seals on the doors and then start the acoustic treatment and flooring.
As one might expect from a room that small the sound is .. chaotic. Everything is just bouncing all over.

I think in a room this small Im going to be looking at just absorbing as much as possible.
Planning to line the walls and ceiling with Rockwool, corner superchunk traps, then add 1x slats to make liven the room up a little.
Not sure how much as room that small can really be "livened up" though.

You guys think Im on the right track with this thinking?

 

[kmetal]

So, things are progressing.
The room is "enclosed" now. Just need to finish up the seals on the doors and then start the acoustic treatment and flooring.
As one might expect from a room that small the sound is .. chaotic. Everything is just bouncing all over.

I think in a room this small Im going to be looking at just absorbing as much as possible.
Planning to line the walls and ceiling with Rockwool, corner superchunk traps, then add 1x slats to make liven the room up a little.
Not sure how much as room that small can really be "livened up" though.

You guys think Im on the right track with this thinking?

Yeah thats pretty much what id start with. I think of the slats more as EQ than reverb. It will help balance back in some of the highs.

Even in small rooms a little life is just fine.

What are the internal dimensions.?

Great work btw.

 

[pcrecord]

I think in a room this small Im going to be looking at just absorbing as much as possible.
Planning to line the walls and ceiling with Rockwool, corner superchunk traps, then add 1x slats to make liven the room up a little.

That's what I did in my 10x11 small room.. I made triangle shape bass traps in 2 corners (rockwool covered in draps and holded with pine wood in the corners.. it makes them decorative and very fonctionnal. Sorry I don't have a better picture..

 

[Jason Morris]

Yeah thats pretty much what id start with. I think of the slats more as EQ than reverb. It will help balance back in some of the highs.

Even in small rooms a little life is just fine.

What are the internal dimensions.?

Great work btw.

The walls and ceiling are all inside out, so from stud to stud is 12'7" x 9' 10 1/2" and 7'10 to the bottom of the ceiling frame.
The sheathing is obviously 3 1/2" farther on each side so, I guess the room is "acoustically" a little over 13 x 10, with ceilings that are like 8' 1"

Thats the "main" section of the room. There room is a little "L" shaped, so there are a few more feet by the doors.

 

[kmetal]

Thats a pretty decent size booth, ive gotten good drums sounds in smaller booths than that. The booth im thinking of was more like 8x11, with splayed walls and ceiling, and just some 2" rigid fiberglass panels, spaced along the wall, with a 1.5" space behind the panel. The ceiling was untreated, and 7.5' on one side 8.5' on the other.

You could conserve some floor space by putting bass traps at the wall/ceiling corner junctions. These can be rectangular or strandled.

I would also consider putting slats on the front wall, instead of behind the kit. This will keep the (out of phase) reflections in the null spot of the mics. This opposed to the direction the mics are facing. Other locations id consider is on the wall/ceiling bass traps if you have them there, and especially if their rectangular so they dont spit back at the kit. Also the ceiling, beyond the kit could be an unobtrusive place to add them.

Another place to build a bass trap could be the L shape alcove itself.

You can use a Helmholtz calculator to get the board spacing right. You'll likely have fundemental room modes between 75-100hz if my memory is correct.

You can experiment with their location before you nail them in, to see what you like.

I would also without a doubt, test the isolation of the room before adding treatments. Just to verify its isolation level is satisfactory.

 

[Jason Morris]

You could conserve some floor space by putting bass traps at the wall/ceiling corner junctions. These can be rectangular or strandled.

Yep, that was my plan. Pretty much every corner was going to have corner traps. I was thinking superchunk style traps made of Owens Corning Fire and Sound mineral wool batts.

I would also consider putting slats on the front wall, instead of behind the kit

Also was the plan. Although I am thinking of making the wall across from the kit (which is, incidentally . the . longest wall in the room) a wiggly wall, with mineral wool of different depths (3" - 8") behind it.

You'll likely have fundemental room modes between 75-100hz if my memory is correct.

I havent measured the room, but I did play my kit a little bit in there, an d based in what I was hearing, you are correct.

 

[Jason Morris]

I would also without a doubt, test the isolation of the room before adding treatments. Just to verify its isolation level is satisfactory.

Oh yes. I will. I still have a couple things I need to nail down before I can call the . isolation "done".
Pretty much just seals and . the hatch/door . to that water main. Right now the isolation is kinda blown due to . a 3'x3' hole in the inner leaf. Once it . is framed and a door installed I expect things will be better

 

[kmetal]

Heres some useful acoustic calculators.

https://amcoustics.com/

Theres plenty of free stuff here too.

https://www.jhbrandt.net/resources/

 

[Jason Morris]

You can use a Helmholtz calculator to get the board spacing right. You'll likely have fundemental room modes between 75-100hz if my memory is correct.

Been playing around with a hemholtz calculator... Doesnt look like it's particularly useful for frequencies between 75 and 100.
Any ideas what I can use for those frequencies?


edit: Ahh. from what I am reading, the corner super-chunk traps should deal with those frequencies.

 

[kmetal]

Been playing around with a hemholtz calculator... Doesnt look like it's particularly useful for frequencies between 75 and 100.
Any ideas what I can use for those frequencies?

A slat resonator with an 8" depth, 2
1x8 slats, and 1/8" spacing, gives you 103hz, and 1/16" spacing gives you 73hz.

You can also consider usung 5/4" thick slats to lower the resonant frequency. This is available anywhere that sells lumber and is a true 1" thick 1x board instead of the usual true 3/4" thick "1x" trim board we are used to.

Its a pita that the calcs i found are metric.
http://www.acoustic.ua/forms/calculator5.en.html

You may want to space/size your slats to a much higher harmonic or otherwise useless frequency like 700-800hz like we did in the normandy booths to liven up the otherwise completely dead rooms.

Also with regaurd to the super chunks, you may want to consider the straddled panel variation, wich is a rigid fiberglass panel on the surface, with standard unfaced fluffy R- value insulation behind that.

This design is cheaper, and more efficient in the lows, because r value insulation is better at lows than rigid, due to a more optimized GFR, gas flow resistivity.

If it were my place, id consider rectangular soffit traps around the ceiling perimeter about 1.5 feet deep, x 1x1.5 feet tall. Faced on the front and bottom with rigid fiberglass, filled with fluffy, covered with fabric.

This gives you quite a bit of cubic footage, stays out of the way. It gives you double the cubic footage than a straddled type design would if spaced the same 1.5ft off the wall. Its also easier to build.

 

[Jason Morris]

Well, last night didn't go great. Tried doing seals on the doors, and it turned out to be more challenging than we expected. We finally figured out a method that worked well, but not before ripping the seals off two or three times. In the end we got one set of seals out of the 50ft roll of trunk rubber. Well, thats not entirely fair, we do have 10 feet or so left over for the next set of seals.

I will have to order another box of this type-K trunk rubber. probably two more boxes. :/

 

[pcrecord]

Well, last night didn't go great. Tried doing seals on the doors, and it turned out to be more challenging than we expected. We finally figured out a method that worked well, but not before ripping the seals off two or three times. In the end we got one set of seals out of the 50ft roll of trunk rubber. Well, thats not entirely fair, we do have 10 feet or so left over for the next set of seals.

I will have to order another box of this type-K trunk rubber. probably two more boxes. :/

Sad you got a hard time there..
I had a bit of trouble with that too when I did mines.. This is why, if I need to build a new studio one day, I'll plan a budget for already made doors with frames included.. Far more easy to put them there, levels and some Uretan around them and call the day !

My actual doors were safe and sound (door only) and costs 69$ CAD each
With frame already made with acoustic seals would cost around 350$ CAD each. But you can thrust they fit perfectly and will last forever..

It's very nice that we can follow your progress !
Have a good one !