Building a new Drum Room

[Jason Morris]

We'd all want the biggest room but get to work with what we have.

Yep! It would be great to have a nice big drum room, but we try to make the best of what we have to work with!
And then we let technology fill in the rest!

 

[kmetal]

I think I'm going to have to go with either straddles or superchunks in each corner, including the wall to ceiling corners. I'm leaning towards superchunks. I know they are more costly than a straddle type corner trap, but I have a lot of the mineral wool already, and the stuff I am using is easily available to me, so I don't mind the expense.

Yeah those soffit traps eat space for breakfast. Glad you considered it tho.

The straddle traps are cheaper, but, the big consideration is they are more effective at absorbing bass. This is because standard fluffy insulation is better at bass absorption than rigid, due to a more optimal GFR. (Gas Flow Resistivity)

Did you order rigid or limp mineral wool batts?

Either way both trap styles are good and it wont make or break your build, especially since your adding so many. But if LF absorbsion is to be maxxed, straddeled is the way to go. Ive seen super chunk style where they cut fluffy batts into triangles and incorporated them in the bottom and top quarters of the trap, since bass builds up most in trihedral, 3 way corner junctions.

Considering my 8' ceilings (which are still considered 'too low' for good drum sounds) should I cover the entire ceiling with mineral wool? If so, should I then cover that with plastic sheeting to recover some of the mids and highs?
Floor is going to remain reflective of course.

.

8' ceilings in a drum booth can sound good.

Id cover the area over the kit without question, and probably no plastic.

Id most likely cover the entire ceiling as well, probably no plastic.

It might make sense asthetically to leave the perimeter of the ceiling untreated or not, depending on how it meets up with your ceiling bass traps.

Off the top if my head, i tend to default to completely covered ceiling or 85% covered. No plastic (unless fiber dust concerns you. For me personally id cover in thin plastic for that reason. You can get like .3 mil (3 mil?) Plastic sheathing in a roll for cheap. Its in a big box like aluminum foil or wax paper. The effect of plastic is IMHO, much exaggerated as far as the real world. Cover your speaker in with some plastic wrap or a shopping bag, stand a few feet away and see how little it matters. Ive done this alot.

That said your cymbals probably dont need any HF reflections back into the mics.

Either way i think the difference is negligible. Even spaced slats dont liven things up as much as it looks like they would, ftom my experiences at least.



For ceiling id use 2" rigid with a 2" airspace. 4" rigid with a 2" airspace if youve got the headroom. Or use a 1" airspace. The 4" rigid gets you alot of absorbsion in the low mids. Your ceiling approaches becoming a huge bass trap with 4" and a 2" airspace. 6-8" rigid makes a true bass trap, but 4 with space is damn good considering its the entire ceiling.

That said, even 2" with no airspace will give you good broadband absorbersion. Low ceiling reflections generally arent useful. They are acceptable tho, just not directkt over the kit.

The cave's drum room has 10' ceilings and 3- 2'x4' panels (2" rigid) with i forget how much air space behind them, maybe 6".

My concern is that as a drummer I don't want the room TOO dead. But I also wonder if "totally dead" is the best option for a room as small as mine.

You can add as you go. I like totally dead around the kit, then less as you move away from it.

Totally dead can be cool. But i was surprised at how decent the drums sounded in the cave booth, which was only like 8x10 and 8 ft tall. It had 2x4' panels along the walls and an almost bare ceiling. I tacked a couple small scrap foam peices to the ceiling, but it was mostly bare. Each wall and ceiling was splayed tho. We started tracking vocals and amps before i installed ceiling treatment, and it sounded good so i never finished it.
Perhaps i could have improved it more? Cant say, but the splayed ceiling is what i attribute to not 'needing' ceiling treatment.

would spending time creating REW files be worthwhile in a live room? or is that more useful for control rooms?

It could be interesting. Id say its most useful if youve got some funny rings your trying to pinpoint. Other than that its more for general interest.

With tracking rooms you can move the mics and kit around to optimize the sound. And your shooting for flattering, not flat. This is why measurement is more 'mandatory' in control rooms, where listening position and speakers have less wiggle room.

I'll attach some screenshots from the triad site. I have much better photos in the chaos of my drives and cloud, but youll get the point.

Drums are in the main room, booths are the booths. The control room window gives perspective of the layout.

 

[kmetal]

Here's one of the tracks i recorded in the booth. 5 mics, and i think the door was shut, some of the songs we left it open partially and had a room mic. No samples, no mastering. I could probably do a better mix now but in 2012 thats how it came out that day. Yamaha kit.

 

[kmetal]

Oh yeah, the wiggly wall. If you like the look then sure. I just worry about unpredictable angles in a small room. The wiggles arent going to greatly effect the efficiency of trap to any big degree. They could slightly improve or worsen the mids and highs.

Id opt either a convex shape like a barrel, or a slanted (splayed) wall. I like the splay because its got a predictable reflection pattern, and a continuously deepening bass absorption, from shallow side to deeper side.

Ill post screenshots from normandy. You see the slat wall on the side of the drums is splayed in two directions! We called it the williy wonka wall. Lol no right angles at Normandy. Quite the test of my carpentry skills and sanity. The mis-cut pile wasnt too big. Each board had a slightly longer lenght then its neighbor. ( i didn't frame the wall or sheetrock it, but refinished the interior treatment from bare wall)

The kit in the main room, which doesn't show up well in the pic, is in front of a convex wall.

The window wall of the booth is also splayed in 2 directions.

Again sorry for the lame screenshots. Traidrecording.com is the site.

Eventually i hope to post/publish the build diary of the two studios.

I think after seeing the finished product, id prefer visually if the slats were horizontally rather than up and down.

 

[Jason Morris]

The straddle traps are cheaper, but, the big consideration is they are more effective at absorbing bass. This is because standard fluffy insulation is better at bass absorption than rigid, due to a more optimal GFR. (Gas Flow Resistivity)

Do you have any links to articles providing more detail about that? I'm not doubting you, but I have read conflicting comments about that and I am not sure what to believe.
I think I read where one of the guys from GIK acoustics said fluffy insulation was better at absorbing bass, but only when it was like 18" thick!
The specs for the Fire and sound batts, and what I saw regarding absorption coefficients on Bob Golds website seem to indicate that the mineral wool is better than the fluffy stuff for the depths I am willing to go. Im not wedded to the idea. I have plenty of fluffy insulation left over too. I just want to do what is going to work the best.

Did you order rigid or limp mineral wool batts?

I guess it's technically rigid? I think its more medium density than high density though. the specs are posted above, but I dont know if they tell you what you are looking for?

Or use a 1" airspace.

The stuff I have is 3", which I guess would leave like a 1/2" airspace if I went with the plan of placing the batts into the cavities of my inside out ceiling.

 

[Jason Morris]

Oh yeah, the wiggly wall. If you like the look then sure. I just worry about unpredictable angles in a small room.

I do like the look of it, and I was more interested in the varying depths of said wiggly wall than breaking up the reflections.
My wife likes the look of it as well, which is a plus.

BUT functionality would trump aesthetics.

I had initially planned on having wood slats on all of the walls. I think during my investigation I determined that might not be the best idea.
What are your thoughts? Use them? leave them out entirely? or just use a few, spaced far apart so as to be aesthetically pleasing but not have much affect on the acoustics?

 

[kmetal]

Do you have any links to articles providing more detail about that?

I should have may evidence if im going to make statements like that. A corner trap would fairly easily reach 18" depth from front face to corner. But i was talking from memory. I think studio tips had some info on it, and i am pretty sure GS had the thread i was thinking of. I think the thread were Eric Desart introduces the superchunk, there is test data. Originally on studiotips which is defunct i think, but still acessable. There's a gross amount on GFR, but there was one about the super chunk with fluffy.

The only firm reference i can surely think of is Rods bass designs in the book often use a rigid front with fluffy. If there was something better Rod would use that. His methods arent always cheapest, but i generally believe are most effective and cost effecient. It may have something to do with the fact that the fluffy is being ysed behind a rigif panel. Or it may just be that the rigid panel gives a clean fininsh look and is resistant to bumps and pokes.

I will look around to try and find that info, but i guess i would have call my statement conjecture until i provide proof. Although rods book is i guess some sort of proof. Normany employed rigid with fluffy behind it in the control room, and fluffy only in the booths. Again not trying to wiggle out of firm proof of my claim.

I guess it's technically rigid? I think its more medium density than high density though. the specs are posted above, but I dont know if they tell you what you are looking for?

Its it the consistency of styrofoam roughly? If you hold it up flat does it maintain is form or flap around.

It would probably say "rigid mineral wool" on the package.

I had initially planned on having wood slats on all of the walls. I think during my investigation I determined that might not be the best idea.
What are your thoughts? Use them? leave them out entirely? or just use a few, spaced far apart so as to be aesthetically pleasing but not have much affect on the acoustics?

Hey man if you like the wiggly go for it.

Id err dead around the kit. Then id probably add slats in sections. Maybe angle them away from the kit and or towards absorption areas. My biggest purpose for slats is for selectively absorbing bass frequencies. Like the 60 or 125hz boom in your room. They also look cool, but they are also very common. Ive been playing around with squiggly strips of plywood, as an idea for my next studio.

You could maybe add slats just to your bass traps in the corners. You could also do the wall you look at when playing the kit with slats, and a curtian for variable liveness but consistently tuned trapping. Id probably be looking at something that with a couple slat sections on each side. Something about slats on the wall/ceiling traps looks good in my minds eye. It might help add visual seperatation and highlight the cool angle of the super chunk.

I am alot less afraid of reflection than i used to be when i first got interested in acoustics. In regular rooms reflections are often nasty so it gives the impression that live is bad. Well designed rooms that are lively are a different animal.

Id honestly kill around the kit and do the ceiling and bass traps. Then id experiment with different amounts and locations of absorbsion. When it was good, id then do the slats, tuning them to the room mode. Then make sure the room still had the right level of life/death and cover it all up with fabric.

I was surprised to hear how much trial and error and listening (a novel concept) rod used in the powerstation. They just kept adding laquer coats till it sounded right. Ditto for normandy live room. The normandy control room was rebuilt 3 times from '78 to like '86 till it was amazing. Then i redid it in 2012 making some slight changes.

 

[kmetal]

Im still trying to find the proof, but you can also do a super chunk style but with fluffy. Theres alot of comments that say less dense insulation is for bass traps, but like my comment, dont include a data sheet.

This is as close as ive gotten. Andre (Avare) doesn't supply a data sheet, but he id very very knowledgeable and well respected.

https://www.gearslutz.com/board/stu...59555-insulation-superchunk-corner-traps.html

Ive only seen him incorrect once when rod presented a data sheet on the Noise Reduction of a wall with steel vs wood. Ive read hundreds or more of andres posts.

Im gonna keep diggin, but id feel personally comfy stopping right there and using fluffy to fill the cavity. Its my nuerosis that wants the data sheet.

 

[Jason Morris]

I should have may evidence if im going to make statements like that.

No worries man. I hope you know I wasn't trying to call you out. I'm just looking to find consensus among the various people I look to on the inter webs for. guidance.
Besides, it occurred to me I have both. I can just try them a. couple different ways and see how things go.

The only firm reference i can surely think of is Rods bass designs in the book often use a rigid front with fluffy.

I need to crack it open again. I need to re-read his acoustics chapter.

If you hold it up flat does it maintain is form or flap around.

It's floppy.

On a isolation related note...

I did as you suggested a few posts back and ran a sine (and saw) wave thru a speaker in my drum room and checked the levels 3 feet from the door with an SPL meter.

I tried to hit 100db in the drum room, and when I stepped back out side that room, with both doors closed I was getting readings at the noise floor level of the house, which, granted is not great. (about 54db)
UNTIL I hit that 30hz tone. Then I was hitting around 90db in the drum room and 72 right outside the door.

 

[kmetal]

Glen and Andre both advocating fluffy.

https://www.gearslutz.com/board/bas...3763-fluffy-insulation-rigid-superchunks.html

Ugh. I hope i dont have to go on a three week rabbit hole dive for a test sheet! Or worse re-read 87 pages on GFR that will go over my head still. Ahhh the joys of obsessive thinking....

 

[Jason Morris]

This is as close as ive gotten. Andre (Avare) doesn't supply a data sheet, but he id very very knowledgeable and well respected.

Ahh that's a good find! Thanks man. I will try the light 'n fluffy and see how that goes! I have a ton of it left!

 

[Jason Morris]

Glen and Andre both advocating fluffy.

Your google-fu is unmatched sir! I was looking for info on this the better part of the afternoon!

 

[kmetal]

No worries man. I hope you know I wasn't trying to call you out.

Oh totally dude. Im from Massachusetts i sound angry even when saying "this is awsome!"

No offense at all. I was just trying to aknowledge my claim unsubstantiated.

Besides its def ok to call me out, or anyone for that matter. Acoustic threads are full of myths.

It's floppy.

I made my first panels ever from that stuff and they were kinda lumpy looking when covered with fabric, fine behind slats.

I tried to hit 100db in the drum room, and when I stepped back out side that room, with both doors closed I was getting readings at the noise floor level of the house, which, granted is not great. (about 54db)
UNTIL I hit that 30hz tone. Then I was hitting around 90db in the drum room and 72 right outside the door.

Nice work testing. So isolation is solid, and 30hz is the resonant frequency of the walls... Also the resonant frequency of the AC. Im pretty sure more mass is the only way to lower the resonant frequency.

That missing section of the outer leaf near the garage may be the culprit. It might be leaking that frequency.

I meant to comment on how nice the pffft sound was in your vid, when you opened the door. Its a sign they are sealed up well.

 

[kmetal]

Your google-fu is unmatched sir! I was looking for info on this the better part of the afternoon!

Gracias.

 

[Jason Morris]

That missing section of the outer leaf near the garage may be the culprit. It might be leaking that frequency.

Yeah I hope so! That is getting dealt with tomorrow!

I meant to comment on how nice the pffft sound was in your vid, when you opened the door. Its a sign they are sealed up well.

Awesome! Sometimes I don't even know for sure how well I did something, so its good to hear!

 

[kmetal]

On the isolation-

Have you entered your room dimensions into a mode calc? Im wondering if the fundamental is also around 30hz or 60hz or 125hz.

I like these tools for easy and quick.

https://amcoustics.com/

 

[Jason Morris]

I have, sorta. the room is an irregular shape with that little L section by the door. not sure how that factors into the room modes.

otherwise the room is about 13'3" x 10'4" x 8'1"

That doesn't really count the area by the door though

 

[Jason Morris]

Not sure if this helps or not. I have only fiddled with REW a little bit, but from what I can see it looks like the room mode is more around 45. I didnt really test that with a sine wave though.
I went from 60 (which seemed fine) to 30 which gave me the crummier reading.

 

[kmetal]

Its good that the room modes arent also 30 or 60 im pretty sure that would make things worse. It is also good to know that 45hz is a peak, since a kick drums fundamental is usually around 50hz. So if theres excessive boom or thinness in the kick you know the drum or mic is in a hot or cold spot. Overall 20db swings in a pretty untreated room that size is not bad at all. If you tune your resonators to 80 or a 100hz youll catch the 2nd harmonic (2nd peak after the lowest 45hz) and broadband bass traps will smooth the rest.

Its good to not see any weird peaks at gross frequencies like 4k.

Im not an expert or even intermediate at chart analysis.

Isolation-

If both leafs are the same thickness and mass, they will have the same resonance frequency. This is why with windows you use one pane thats thicker than the other. If that new wall section doesn't do the trick, it may be worth considering and additional drywall layer if the current isolation isnt acceptable. Especially if the leaves are the same.

The resonant frequency cuts thru the wall like a hot knife cuts butter. When you have different resonant frequencies for each it makes the two leaf system more effecient.

The other thing is a larger airspace between the leaves, which you wouldnt change now. But up to 4" of air space increases low frequency attenuation. After 4" theres diminishing returns.

 

[Jason Morris]

Its good to not see any weird peaks at gross frequencies like 4k

The REW file only shows 30-500hz. I'll attach the whole graph here. FYI, I did this measurement at 80hz.

If that new wall section doesn't do the trick, it may be worth considering and additional drywall layer if the current isolation isnt acceptable. Especially if the leaves are the same.

I guess that's the tough part of an inside-out design. Tough to add an additional layer. Unless I go between the joists, I guess. I'll give that some thought.

But up to 4" of air space increases low frequency attenuation. After 4" theres diminishing returns.

There is a minimum of a 4" airpsace between all of the leaves. More in some spots.