Worst drum room ever?

OK. So, I recently moved into a new house.. Only problem is, the pretty lady who lives with me doesn't want me taking over the whole basement. I have s little room set aside for a control room, which is far from ideal, but I'm making it work. Building some bass traps and such.. And then I have a pretty tiny unfinished area of the basement that I am looking to turn into a drum room. I live on a nice cul de sac, and my primary concern is not being "that guy" that moves in ruins things for everyone with his infernal drumming. I am not looking to make a living or even supplement my income by recording bands. I want to play drums without annoying the neighbors, record my own crappy songs for my own amusement, and occasionally record drum tracks for musician friends around the globe. So, sound isolation and room treatment, without the unreasonable expectation that its going to sound like a multi million dollar facility. :D If you look at the quick sketch I did, you can see there are two water heaters in the room. My plan is to remove those, and replace them with a tankless water heater which will be located in another room. (with the furnaces). There IS another issue.. the water main comes out of the floor about 2 feet from the wall, and its about 2 feet high. I don't see a good way to deal with that other than to build a knee-wall around it, with panel in case I ever need to access it. Ceilings are 8' 4" from the concrete floor to the bottom of the joists above. SO what do you think? Is this hopeless or do you think I can make this a reasonable room to play and record in?

Hi Jason. Please read the forum rules for posting (click here). You seem to be missing a couple of things! :) That said, isolating drums is the most difficult, complex, and expensive of all isolation projects. Drums are the loudest of all instruments (115 dBC easily, 120 dBC played hard), and much of that energy is in the low end of the frequency spectrum, which just happens to the the toughest part to isolate. So wanting to isolate drums is a pretty big project. Not trying to scare you: just pointing out reality.

If you look at the quick sketch I did,

Unfortunately, the text is so tiny that it is illegible! I have no idea how big that room is, based on that.

I don't see a good way to deal with that other than to build a knee-wall around it, with panel in case I ever need to access it.

That's a complication that you don't need! I would look into having that moved to a more suitable location.

Ceilings are 8' 4" from the concrete floor to the bottom of the joists above.

That's good news! Your ceiling is a bit higher than most basements, so the chances are that you'll be able to get reasonably decent acoustics.

SO what do you think? Is this hopeless or do you think I can make this a reasonable room to play and record in?

If you have a good sized budget, then you can achieve isolation that won't annoy your neighbors too much. You should be able to get around 60 dB of isolation, of you plan this well and do it well, on a realistic budget. Otherwise, maybe 45 dB, with luck. - Stuart -

Hey Stuart, Thanks for replying and pointing me to the rules. Sorry I didn't check that before I posted. I increased the font size on the drawing and uploaded that. Hopefully it is more legible now. I also removed the water heaters from the picture. How loud am I: Im a rock drummer. Im pretty loud. I haven't had anyone go outside with an SPL meter to see how loud I am by my nearest neighbors yet. I will do that and report back. My Budget: Is flexible. I am hoping to keep it between 5 and 10K for the one room. But I can do things in stages and spend a little more if I need to. I have spent quite a bit of time here looking at posts, and I have built a studio before.. (many years ago) but I have since forgotten most of what I learned doing that build.

That's a complication that you don't need! I would look into having that moved to a more suitable location.

I agree that it is NOT ideal at all. I had a guy from the water company out to replace a buzzing check valve and water meter. I asked him about the possibility of moving the water main & meter. The upshot seemed to be that moving it a few feet to tuck it into the wall would involve breaking up concrete which could get costly. And I would still need some sort of access panel so the water company could get at it if need be. Moving it out of the studio area entirely would involve breaking up the basement floor and digging up the yard.. quite an extensive expense, which I don't think I am going to get the lady to go for. Trying to build a knee wall, and then using that corner for some bass trapping was the best I could come up with. My dad came up with the idea of floating the floor.. turning the water off at the street, cutting the water main right where it comes thru the floor, putting an elbow on it and running it back to the wall, between the 2x4's of the floating floor. I'm not convinced thats either a good idea or "to code". That dang water pipe is really vexing, but I'm not sure there is a good solution.

OK. I'm back. I have a bit more information and some tentative plans. I broke out the old radio shack SPL meter and my boys and I took some measurements. in the room where I am playing drums im hitting about 118db when I really wail on the drums. Around the house I got the following readings Dining room (directly above the room im building the drum room in): 88 dB Living Room: 72dB My Sons room (in the basement): 86dB The good news is that I took SPL readings at the edge of my property and I really dont see the neighbors as being a problem. I had a hard time getting much of a reading at all, and the drums were barely audible at my nearest neighbors property line. And most important, I think, is that I saw my neighbors on their deck hanging out.. I went inside and start wailing on the drums for a while, came back out and asked if they could hear the drums. They said "Nope, I didn't know you were a drummer! Drum away!" With that in mind, I think my focus is going to be controlling the volume level throughout the house so that the lovely redhead doesn't go bananas whenever I am playing, and controlling the sound of footfalls from above so that her goofy little dog doesn't make an appearance in my recordings when he is running around the house. Also, I want the room to not sound like a sack of monkey butts. The room im working on is in a basement towards the center of the house, below the formal dining room. The floor, and three walls are concrete. Walls are about 90" tall. No idea how thick. What I have determined so far: 1) I am NOT going to float the floor. Seems like there is no point. 2) I think I am going to build the three walls on the concrete sides of the room as per one of Johns designs where he has the wall inverted. Three layers of 5/8 drywall, with Green Glue between the layers.. Those layers of drywall facing out towards the concrete walls. There will be a 4" air gap between the concrete walls and the drywall. If I understand correctly (and please correct me if I am mistaken) The size of the room, at least as far as modes are concerned, is measured from the drywall. If that is the case my room should be 13' 1 1/2" long by 10' 5 1/4" wide, with 8' ceilings. I ran those numbers thru http://www.bobgolds.com/Mode/RoomModes.htm And while I cant say that I really understand what I am looking at, I did get - 1.1w / h < l / h < ((4.5w / h) - 4): Pass - l < 3h & w < 3h: Pass - no integer multiple within 5%: Pass and the Bonello graph didn't seem too terrible. (it should be attached here) Since getting the volume levels OUTSIDE of the house didnt seem as challenging as I first thought it would be, I thought about pushing the walls closer to the concrete in order to get a little more elbow room. But the dimensions I end up with, while larger, end up being marginally less favorable than with the slightly smaller room. So I opted for the smaller room. Does building the walls in this manner seem like a decent plan? Or should I rethink? 3) For the ceiling, I am planning on gluing some layers of 5/8 drywall to the existing subfloor (green glue between layers), tossing in some rockwool, Resillient channel, then three layers of 5/8 on the ceiling. 4) For ventilation I am going to do a couple of silencer boxes on the other side of the walls. There is an unused closet , beneath the stairs, on the other side of the double wall (bottom of the picture) regarding AC, I have a couple of options. I have a split furnace system, with a furnace dedicated to the basement. There is no central AC in the basement. I have thought about just buying a central AC unit for the basement, then tying in to that for heat/AC in the drum room. But then Im likely to get a bunch of sound traveling thru the duct work right? I'm really leaning towards a small mini-split system. Thoughts? 5) If you are wondering what the stupid box in the top right corner is, thats me trying to deal with that studio water main coming in thru the floor. That is just something I am going to have to work around, and this is what I came up with. So, knowing my limitations and goals, do you think I am on the right track?

in the room where I am playing drums im hitting about 118db when I really wail on the drums.

Yep. Sounds about right. That was on "C" weighting, right?

Around the house I got the following readings Dining room (directly above the room im building the drum room in): 88 dB Living Room: 72dB My Sons room (in the basement): 86dB

That's quite reasonable, actually. You are getting around 30 dB of isolation, which is about right for a typical house.

1) I am NOT going to float the floor. Seems like there is no point.

:thu:

2) I think I am going to build the three walls on the concrete sides of the room as per one of Johns designs where he has the wall inverted.

That's often called an "inside out" wall.

Three layers of 5/8 drywall, with Green Glue between the layers..

Do you want high isolation? 3 layers plus GG is going to get you a lot, for sure, but do you need that? It's certainly fine to do that if you want! But you might be good with two layers. You have figured out one half of the equation: "How loud are you?" Now you need to figure out the other half: "How quiet do I need to be?". You need numbers on both.

There will be a 4" air gap between the concrete walls and the drywall.

... and that gap will be filled with suitable insulation...

The size of the room, at least as far as modes are concerned, is measured from the drywall.

:thu:

I ran those numbers thru http://www.bobgolds.com/Mode/RoomModes.htm And while I cant say that I really understand what I am looking at, I did get - 1.1w / h < l / h < ((4.5w / h) - 4): Pass - l < 3h & w < 3h: Pass - no integer multiple within 5%: Pass and the Bonello graph didn't seem too terrible. (it should be attached here)

You don't need to worry too much about that for a live room (tracking room, rehearsal room). Room modes are more of an issue in control rooms, which must have perfectly neutral acoustics, but for live rooms, it isn't so necessary. Yes, it's still a good idea to stay away from really bad combinations, but it's not as critical to hit a really good one.

I thought about pushing the walls closer to the concrete in order to get a little more elbow room.

As long as the gap doesn't get less than about 4", that's fine.

So I opted for the smaller room. Does building the walls in this manner seem like a decent plan? Or should I rethink?

Get the room as big sa you can. Drums like space, air, ambiance to sound their best, so the bigger you can make it, the better. However you do need to balance that against against the need for isolation, and the practical limits of physics.

3) For the ceiling, I am planning on gluing some layers of 5/8 drywall to the existing subfloor (green glue between layers),

:shock: You cannot glue drywall to studs: it is very likely prohibited by code. And Green Glue is not glue anyway! Despite the name, GG is not adhesive, and cannot be used to stick things together. It is an acoustical compound, not an adhesive compound. So just nail up your drywall in the normal manner (or use screws), and also use GG between the layers if you want maximum performance, but don't ever glue layers of drywall t gather, don't glue your ceiling to the joists, and don't try to use Green Glue as an adhesive.

tossing in some rockwool, Resillient channel, then three layers of 5/8 on the ceiling.

That would work, yes, but have you considered the better way of doing it, by putting up a proper fully decoupled ceiling on top of your new inner-leaf walls? That would give you much better isolation.

4) For ventilation I am going to do a couple of silencer boxes on the other side of the walls. There is an unused closet , beneath the stairs, on the other side of the double wall (bottom of the picture)

Smart move! :thu:

But then Im likely to get a bunch of sound traveling thru the duct work right?

That's what your silencer boxes are for! :) Design and build them properly, and you can get pretty darn good isolation...

I'm really leaning towards a small mini-split system. Thoughts?

It's an option, yes, but if you want your drum room really silent, then you could get an AHU system instead, and put it outside the room. It's basically the same as a mini split, except the the indoor unit is designed to be used with ducts, instead of just hanging on the wall ("ductless"). That way, you would have all the noisy part outside the room, and just ducts taking the air in and out. - Stuart -

Hey Stuart! Thanks for responding.

Get the room as big sa you can. Drums like space, air, ambiance to sound their best, so the bigger you can make it, the better. However you do need to balance that against against the need for isolation, and the practical limits of physics.

Right. So im sort of on the fence about what to do along the concrete walls.. Since I am not super worried about sound getting out of the house and bothering the neighbors, and primarily concerned with sound going UP into the house.. I am wondering if it would be better to skip the three layers of drywall and the aig rap on the concrete walls, and just worrying about acoustic treatment along those walls rather than isolation. Isolation would be focused on the ceiling and walls facing towards the rest of the basement. Does that make sense?

You cannot glue drywall to studs: it is very likely prohibited by code.

Oh no! not going to glue the drywall to the studs. Im talking about cutting strips of drywall to fit BETWEEN the floor joists to beef up that subfloor "leaf", with green glue between those layers of drywall. Then batten them into place, put the cross bracing back, insulation between the joists, then resilient channel across the joists and two or three layers of drywall attached to the resillient channel. (which would comprise the second "leaf") Hopefully thats a good way of doing things?

That would work, yes, but have you considered the better way of doing it, by putting up a proper fully decoupled ceiling on top of your new inner-leaf walls? That would give you much better isolation.

That is a good idea. I will explore that. Thanks! :)

It's an option, yes, but if you want your drum room really silent, then you could get an AHU system instead, and put it outside the room. It's basically the same as a mini split, except the the indoor unit is designed to be used with ducts, instead of just hanging on the wall ("ductless"). That way, you would have all the noisy part outside the room, and just ducts taking the air in and out

How is that different from just using the furnace/Air handler unit (which is currently dedicated to the finished basement) and adding a Central air unit to that? And I understand that ventilation and AC are different right? At my last house I built a studio that had no ventialation beyond just the heating and AC. It was OK, but the studio was NOT a pleasant recording environemnt on burrito night,

Isolation would be focused on the ceiling and walls facing towards the rest of the basement. Does that make sense?

Not really! :) To isolate properly, even for only modest isolation, you still need to build a "room inside a room". If you are missing one wall, then you don't have good isolation, since you have direct mechanical connection from the outer leaf to the inner leaf. So you still need four walls and a ceiling. If you need isolation, then you could lighten up on the layers of drywall (going to 2 instead of 3, for example), but you still need something.

cutting strips of drywall to fit BETWEEN the floor joists to beef up that subfloor "leaf", with green glue between those layers of drywall. Then batten them into place, put the cross bracing back, insulation between the joists, ...

Yup! That's the right approach. But do check with a structural engineer to make sure there's enough extra load carrying capacity in your floor. There' probably is, but it's best to check.

then resilient channel across the joists and two or three layers of drywall attached to the resillient channel. (which would comprise the second "leaf")

That puts ALL of the weight of the ceiling, as well as the "beef", on your existing floor joists, in addition to what they are already carrying. That would likely be too much. Probably 15 psf or more. You'd likely find that that's beyond the load capacity of your floor. That's another reason why I'd suggest putting your new inner-leaf ceiling on top of the new inner-leaf walls. - Stuart -

To isolate properly, even for only modest isolation, you still need to build a "room inside a room". If you are missing one wall, then you don't have good isolation

Yeah, you pretty much confirmed what I was already thinking. Since this is the case, I think the room design I have posted above is about at good as its going to get in terms of maximizing floor space.

That's another reason why I'd suggest putting your new inner-leaf ceiling on top of the new inner-leaf walls.

OK. Then thats how I will do it. I just have to do some more research and figure out how. :) I dont know if you saw, but I had edited my previous post to address a couple other points you mentioned. Sorry about that. I re-read your answers and thought of a couple more questions, apparently while you were in the process of responding. :) Thanks again for taking the time to help me out.

HEY! I'm back. I haven't abandoned this project, just took my a little while to get some of the prep tasks completed. I managed to move to two water heater tanks out of that room. I installed a new tankless water heater in the other room. I also got some good news from a plumber.. It doesnt look like its going to be as tough as I was led to believe to move that water main coming out of the floor. The plan is to move it about 8 feet around the corner. So, no stupid knee wall in around a water main in my studio. :D I had hoped to get ab out 60db of isolation, but it may not be possible in that small of a space. I think if I can get over 50, I'd be pleased. Maybe that's still not realistic? Basically, the wife would just like to be able to have conversations or watch TV upstairs while I am playing. If we can make that happen, I'll call this endeavor a success. I had talked about doing the inverted wall. considering three of the existing walls are 4" thick concrete.. Does it make sense to do an inverted walls there? Am I really gaining any elbow room that way? Or is it just making things more difficult? Or should I just build "normal" 3-layer walls, framed 1" away from the existing concrete walls? If I build an inverted wall, It's 4 inch airgap (stuffed with insulation), plus 2 or 3 layers of drywall (maybe 2 layers of drywall one layer of MDF?), 3 1/2" of 2x4 framing, and the 3/4" for the slat resonator finish.. That wall would be 10 1/8" from the concrete. if I build a "normal" wall, I could build the framing just 1/2" from the wall right? The airgap would be "inside" the framing? So 1/2 from the wall + 3 1/2" framing + 3 layers of 5/8 + 3 1/2" of acoustic treatment + 3/4" for slot resonator finish = 10 1/8" So the net result is the same in terms of elbow room? There has to be something I am not considering properly. If you could let me know, I'd appreciate it. a few other questions I have.. 1) The Roxul Safe N Sound that is sold by Home Depot near me has a density of 40kg/m3. I was unable to find the density of the Owens Corning stuff sold at Menards but I am assuming it is similar. in terms of performance, is the roxul going to be better than just R13 (or R-whatever insulation you think i should get)? Should I use Mineral Wool in the ceiling and wall cavity or just fiberglass insulation? I dont care about cost difference really. I just want it to perform better. If I do opt for the inverted wall, should I use mineral wool of fiberglass on the drywall side, facing the concrete wall? 2) I am planning to support the ceiling on the joists of my inner walls, as you suggested previously. Should I bother with RSIC-1 clips and channel? I am willing to spend the $$ on that if it's going to help significantly. I know there is another question I had, but my brain just went blank. Anyway, thanks again for your advice on this. Jason

OK, so I'm back. Progress has been slow. I moved the water main to a new location, so that is not an issue for me anymore. I have started beefing up the ceiling above what will be my drum room. However, now that I have done so, I'm not completely sure it was worth doing. I think I recently read that unless I beef up the entire ceiling, not just the area I am trying to isolate, that it doesn't really do much good? In order to beef up the entire ceiling, I'd have to completely tear apart the finished basement, which is not in the cards. Also, I have a couple of issues I am trying to figure out.. In the attaached picture, you can see a space (labeled A). On the other side of that is the brick veneer of my home. If I seal that area up with drywall and acoustic sealant, am I essentially creating a small 3-leaf system once I have my drum rooms walls built? Should I fill that cavity with layers of drywall? just insulation? Or is it such a small space that I shouldnt be fretting about three leaves? Also, Above this ceiling is our 'formal' dining room (not used much). In the space labeled "B" you can see the ductwork feeding the vents in that dining room. Keeping in mind that I AM going to be building that decoupled "inner" ceiling we discussed several months back, what should I do about that duct and vent feeding the dining room? Oh, and you may notice some water spotting over in the corner.. My construction guy and I are pretty positive we resolved the issue. However, we are waiting for warmer weather to tear the siding off the house and test it thoroughly before we proceed with framing.

Well, I haven't gotten any responses in a while, but Im still plugging away at this. If there is some rule I missed, please let me know. I thought I gave the required info, but I may not have. I do spend a crazy amount of time researching on this site, and usually I can find an answer to my question.. But sometimes the sheer amount of information just sends me down the rabbit hole and I end up tearing my hair out. Anyway, To deal with those cavities in my previous post, I ended up cutting out all the sprayed in foam, putting in a couple layers of Closed-Cell foam (there were nails protruding thru from the other side of the wall), THEN I put in a couple layers of drywall, with backer rod and Acoustic caulk. THEN applied one more layer of 5/8 drywall over the top of that. I was careful not to leave any gaps or voids. Hopefully that was an OK way of dealing with it. Now, I am dealing with the two bays that have the EXISTING HVAC ducts that service the room above, which is the dining room. The bays have 2 layers of 5/8 drywall (with green glue, backing rod and acoustic caulk) in them UP to the cut-out for the vent. There WILL be the "inner leaf" ceiling, which I am planning to do as an "inside-out" ceiling, after finding some very useful posts by Stuart (thanks!) I have "beefed up" the subfloor, between the joists. ( that will be the outer-leaf ) I am going to build a "inside-out" ceiling, which will be the inner-leaf. The existing Flex-Duct that services the room above will be in the joists BETWEEN those two leaves. What is the best way to isolate those two ducts? I thought about ripping out the flex duct and replacing it with rigid duct, lined with certainteed duct liner (I cant find the john manville) . Then insulating around the duct with either pink fluffy stuff or mineral wool. Then tacking in another two or three layers of drywall (or maybe MDF?), below the duct and sealing it all up, effectively boxing it in. However, this would create a three leaf system in those two bays. I know three leaf systems are generally bad. Didnt know if this was an instance where the trade off would be worth it.

Anyway, To deal with those cavities in my previous post, I ended up cutting out all the sprayed in foam, putting in a couple layers of Closed-Cell foam (there were nails protruding thru from the other side of the wall), THEN I put in a couple layers of drywall, with backer rod and Acoustic caulk. THEN applied one more layer of 5/8 drywall over the top of that. I was careful not to leave any gaps or voids. Hopefully that was an OK way of dealing with it.

Perfect!

However, this would create a three leaf system in those two bays. I know three leaf systems are generally bad. Didnt know if this was an instance where the trade off would be worth it.

Sadly, I believe this is the best way to deal with it. Good work! Greg

OK. I'm still at this, though I am moving very slowly. I did finally get some walls up. As for those troublesome bays with the flex duct feeding the dining room upstairs, I ripped out that flex duct. Installed 2x12 rigid duct, sandwiched between layers of drywall, with green glue and duct liner. I used the duct liner on the OUTSIDE of the duct. I know that is not how it is intended to be used. I did this because where the sections of duct snapped together, there is a band around the duct. That band created a ridge that would not allow the duct to sit perfectly flush against the drywall, so I feared it would vibrate and buzz. So, I glued some duct liner to both sides of it the duct had some damping, and something to "squish" into. I guess I will have to wait and see if it works out ok or turns out to be a big oops. So right now my question is is regarding building a wall around the section of 2x12 duct I have feeding that bay. you can see that I have turned a section of 2x12 duct sideways to line a section of the outer wall, the Frankenstein'd some ductwork to create an elbow to join it to the duct feeding the bay. It works pretty good. The way I see it, I have two options regarding building around that duct. I can just build the wall inside out, as I have been doing for the other walls. and place the wall so that it is 1/2" away from the duct.. but that puts my wall 5" past my duct, and my room is already pretty small. I was also wondering if using 2x6 or 2x8 and notching around it would be a good idea. Or maybe a soffit of some sort, but im not envisioning how a soffit would work and save me any space in the room. So, here I am turning to you guys for advice. :) What d o you think?

In your older picture, it shows the flex duct running through one of the joist bays. What you should have done is just created a 3 leaf system in that single joist bay. What I mean is you should have stuffed insulation around the flex duct and then boxed it in with a few layers of drywall underneath of it. Done. Now, the only way I can think to keep your room as big as possible is to run your ceiling joists with the same orientation as your duct work. Your ceiling will have to drop at the edge to follow the profile of that new duct work. OR Do as I wrote in the first paragraph and run the duct work through the joist bay. Unfortunately I can't make out where in your room the original flex duct was in relation to your new 2x12 duct. Why was the flex in the joist bay and now it's perpendicular to the joists? Greg

Gregwor wrote:

In your older picture, it shows the flex duct running through one of the joist bays. What you should have done is just created a 3 leaf system in that single joist bay. What I mean is you should have stuffed insulation around the flex duct and then boxed it in with a few layers of drywall underneath of it. Done.

That is what I did, though I ripped out the flex duct and replaced it with 2x12. Then covered that with more drywall. So in TWO bays I have: 2 layers 5/8 drywall a layer of 1" duct liner (over compressed to about 50%) 2x12 rigid duct another layer of 1" ductliner (again compressed about 50%) 2 layers of 5/8" drywall. Battened in place with 1x2, and sealed with Green Glue accoustic Sealant. IN my last post, the duct you saw going across the bottom of the joists was what is FEEDING that duct. That was also 6" flex duct stretched across the bottom of the joists before i ripped it out and replaced it with 2x12. I did this because I thought I could just fit it between my inner and outer leaves. The "outer" leaf is an existing wall of the finished basement (the stairs to the main house). Now I am getting to the place where I am going to start building the inner leaf and I am trying to squeeze as much floor space out of this as I can.

Hey guys. This project has not died yet! :) I have actually gotten to a place where the room is pretty much sealed up. Doors are on and I can start testing to see how well I have done in the isolation dept. I am already a little worried about the amount of low-frequency rumble I am hearing out of the silencer box I have built. When the HVAC is running I can just barely hear very low rumble, and after hunting around with my SPL meter, it does seem to be coming from my silencer. I built two silencers, one for the inner and one for the outer leaf. They are connected with what I think is 3/4" thick sorbothane rubber. They each have 4 or 5 baffles in them, and the boxes themselves are built out of 2 layers of 5/8 MDF, and lined with 1" John Manville duct liner. I have uploaded a couple of images of one of the silencers as it was being built. The second layer of MDF is not applied in the photo. Also is a photo of how that silencer was mounted. Not sure if those will help or not. I DID upload a video. I know you guys like files to be directly uploaded to the thread, but it was just too large, and sometimes its easier to explain what one is dealing with via video. https://www.youtube.com/watch?v=V7nmlNk5H7k Any advice would be appreciated! edit: after uploading the photos I realized that the silencer being built is the one on the OUTER leaf, while the one mounted is the INNER leaf silencer. THey were both built in the same way, and just had their Ins/Outs in different places.

HI Jason, I don't think I've spoken to you before. So "Hi!". It's very difficult to see what's going on in the video I'm afraid. I think I kind of understand how you've built them, but I'm not certain. The silencers: what dimensions did you make the cross sectional path in your silencers? They look quite narrow and a bit shallow also, although that could be the angle of the picture. Silencers generally want to add a change of cross sectional area of at least twice the duct cross section, and ideally make this change twice (or more). This is usually achieved by increasing the cross section in the box, then decreasing (or increasing again) between the inner and outer leaf silencer, before returning to the double cross section within the other silencer and adding a large diffuser/grille on the inside of the room. It could be that the velocity is too high in the silencers. You mention that they are attached with sorbothane. How does that work with the one mounted vertically on a wall? If you screwed through the sorbothane then you create a flanking path directly to the stud work and this will probably produce more vibration then just screwing nice and securely into the studs. Also did you compress the sorbothane the recommended 20%? If it's under compressed it will often actually make vibration worse. Putting too much sorbothane is a common way of undercompressing it (the sorbothane has too little pressure on it per inch and the box just sits on top of it with almost no compression.) Also, how are the silencer's ducted together? Is there a flexible duct that joins the two, or is there rigid ducting? If you used rigid ducting how did you decouple the two silencers? Dan

Hey Dan, thanks for taking the time to comment! I appreciate it!

The silencers: what dimensions did you make the cross sectional path in your silencers?

Honestly, I don't recall. :/ I know that the cross section started out larger than the cross section of the flex duct feeding it, and each baffle was placed a little further apart, so that the cross section expanded.

It could be that the velocity is too high in the silencers.

I don't even have the silencers pushing any airflow yet. The rumbling I am hearing is not from the Fantech ventilation unit I have.. The rumbling is from the AC/Blower that is conditioning the REST of the house. That low frequency noise seems to be transferring into the my drum room. When the AC is running in the house, the ambient noise in my drum room is between 56 and 58db. (spl meter is set to c weighted, slow) I can just BARELY hear a low rumbling noise, and sticking my ear to the silencer box vent, it does seem to be emanating from there. Of course this is such a low frequency and it is so quiet that maybe im imagining things.

You mention that they are attached with sorbothane

I meant that the silencers were connected to one another with sorbothane. It's acting as a duct between the two silencers, passing between the leaves. The wall mounted silencer is actually screwed to the concrete basement wall and is not actually touching the inner leaf. That OTHER silencer.. The one on the "outter leaf".. well. That one is just sitting on top of the joists, and I fear is picking up vibrations they are rumbling thru into my room.

Also did you compress the sorbothane the recommended 20%

This comment has me a little worried as well. I am wondering if I was sent the wrong stuff. .. just checked my order history. YEP! I bought Neoprene, not Sorbothane. This is what I used to connect the silencers: https://www.amazon.com/gp/product/B01CT ... UTF8&psc=1

JasonMorris wrote:

The rumbling is from the AC/Blower that is conditioning the REST of the house. That low frequency noise seems to be transferring into the my drum room.

This is disconcerting. It seems your silencers are not really silencing! Have a measure with your sound level meter in other areas of the house when it is quiet, with the AC on. Is it as loud?

JasonMorris wrote:

When the AC is running in the house, the ambient noise in my drum room is between 56 and 58db. (spl meter is set to c weighted, slow) I can just BARELY hear a low rumbling noise, and sticking my ear to the silencer box vent, it does seem to be emanating from there

You seem to have reaaally loud AC :shock: what do you measure in the rest of the house when it is quiet but with the AC Blower on? If it's less than in the isolated room, then the only thing I can think of is vibration. Both sleeves need to be either very securely mounted, or resting on an absorbant material (eg. neoprene/sorbothane)

JasonMorris wrote:

one on the "outter leaf".. well. That one is just sitting on top of the joists, and I fear is picking up vibrations they are rumbling thru into my room.

This could possibly be the issue. You could screw some angle brackets to the outside of your silencer and screw them securely into the joists, then see if the situation improves. Is it just your AC you hear, at that specific frequency? Or does loud music being played in the studio also pass through your silencers without hindrance?

JasonMorris wrote:

I meant that the silencers were connected to one another with sorbothane. It's acting as a duct between the two silencers, passing between the leaves.

I'm struggling to picture this, can you do a quick sketch or something to describe what you mean. Do you mean that each silencer has a rigid sleeve padding through the appropriate leaf, and within the cavity the two sleeves/boxes nearly meet, and there is some neoprene between the boxes? Dan

It seems your silencers are not really silencing!

After poking around in there for a while, I . have changed my mind.. I don't think it is the silencer per say. I stuffed the vent of the silencer with mineral wool and placed a 3/4" piece of MDF over it and there was NO difference in the level of low end rumble heard in the room. I'm wondering if its just coming from the HVAC ducts running thru the floor joists. Its such low end it seems to be coming from everywhere. its really hard to pinpoint the source.

You seem to have reaaally loud AC :shock: what do you measure in the rest of the house when it is quiet but with the AC Blower on?

Yeah I am wondering if am doing something wrong with my measurements or if my SPL meter is not functioning correctly. I should have the SPL meter set to C weighting, SLOW, right? A weighting certanly LOOKS better, but I think thats because its not really looking at frequencies below 250hz?

what do you measure in the rest of the house when it is quiet but with the AC Blower on?

I will take measurements from around the house and try to be a bit more methodical in my testing methods and I will post back here after I have better numbers.

If it's less than in the isolated room, then the only thing I can think of is vibration.

I know its not LESS than in the isolated room, but the isolated room is only a few DB less. But my isolation must only be really poor in the really low end of the frequency spectrum becuase my family has said that the drums are dramatically quieter played in there. Quiet enough that they could watch TV or sleep while I drum. In the end, thats what I wanted, but my quest was for good low end isolation, and that stupid SPL meter is saying I didnt do it well enough!

You could screw some angle brackets to the outside of your silencer and screw them securely into the joists

I will have to double check with the guy that helped me build and install these things but I think we DID use angle brackets to secure them to the joists. I wonder if packing some insulation around the outside of the silencer would help?

Is it just your AC you hear, at that specific frequency?

There is just a low-end rumble heard throughout the room. Otherwise, the room is dead silent. When the AC kicks off, Im pretty sure I can hear my hair growing.

Or does loud music being played in the studio also pass through your silencers without hindrance?

When I play loud music in the other room (like 95db) and I check the SPL in my drum room, it looks like I am getting about 35DB of isolation. The music is barely audible, and only the low end of the music is heard thru the doors. I don't hear the music thru the silencer.

Do you mean that each silencer has a rigid sleeve padding through the appropriate leaf, and within the cavity the two sleeves/boxes nearly meet, and there is some neoprene between the boxes?

I think so. I basically stole Bigby's design. (viewtopic.php?f=2&t=15430) Attached are photos of the couplers HE built to pass thru the wall, joining the two silencers. I did the same thing (but wasnt smart enough to take pictures, becuase what could possibly go wrong?)

So it looks like my AC unit (which is old as dirt) IS pretty ridiculously loud. attached is a pic of what I am seeing from the SPL meter at the AC unit.. spoiler alert its 106db also attached is a screenshot of AudioTools RTA app and what it is seeing inside the studio.. Im sure its not super accurate considering its going thru the iPhone mic. but maybe still helpful?

That is unfortunately loud! You might be getting fine isolation in general, it's just so loud. Have a measure of ambient levels without the AC, inside the drum room and outside, and various locations around the house, then turn on the AC unit and take those measurements again. Subtract AC off from AC on measurements, this will tell you how much noise it produces in the house and how much isolation you're actually getting at the AC frequencies in your room. There might not be alot you can do about it though, aside from replacing the AC for a quieter unit. It's probably worth measuring your isolation in the room in general to though. Play loud music in the room, measure in the room and then outside the room with the doors closed. Subtract outside from inside measurements. That will give you the isolation values. Dan

Hey Dan, Yeah, I never realized just how loud that unit is! It is slated for replacement next summer, so I may just have to live with it till then. If you put your hand on the outside wall of our walk-out basement you can feel it vibrating. Im guessing that line coming into the mechanical room is vibrating a ton. I did a quick test by putting a monitor in the drum room and running some sine waves thru it at various frequencies and checking the isolation from 3 feet back from the door. I tried to hit about 100db IN the drum room, and I was getting 53-56 away from the door, which is actually the noise floor in the house when that AC unit is running! These numbers persisted until I got down to about 30HZ. Then I was at about 90 or so in the drum room and a little over 70 just outside the door. I'm not sure what I should expect to get at frequencies that low? In the end, the wife is happy, and I think I will be happy once I replace that loud AC unit.

OK, new question. I currently have the silencers for the exhaust side installed, with one silencer for each "leaf". I am getting ready to cut a hole in my wall to install the silencers for the supply side to bring in fresh air (im using a Fantech ERV) I have easy access to both leaves, and I am planning to have each silencer on the "outside" of each leaf rather than between the leaves. My question is concerning the silencer mounted on the INSIDE of the room when the walls were built "inside-out" I cant put the silencer flush against the sheathing, as the studs are in the way. Can I just secure the silencer to the studs of the inside-out wall and have a longer "duct" penetrate the sheathing to connect to the silencer on the other side? And when I say duct in this case I mean a duct built out of multiple layers of plywood or 2x material connected with neoprene. Im not talking about flex duct. Thanks! Jason

OK, so my last question was kinda dumb. There isn't really anywhere to attach the silencer to other than the 2x framing of the inside out wall, so that's obviously what I am going to do. As I start zeroing in on the end of this build, I am kinda jumping around from one task to the next, trying to busy myself with the things I can do on my own while I wait for my buddy to have time to help me out with some of the things that I need assistance with. One of the things I have been working on is acoustical treatment. I have taken a LOT of inspiration from Bigby's live room build, and also I have picked up a lot from reading Stuart's posts on treating small rooms. right now I have lined darn near every surface except the floor with Owens Corning Fire and Sound.. it has pretty much the same specs as Safe N Sound. I have also built bass traps in every corner, vertically and horizontally. As one would expect, the decay time of the high end is pretty much nil. Stuart mentioned 6 mil plastic stapled across the walls and bass traps to reflect frequencies above 1K. What I am uncertain of is how MUCH of these absorbent surfaces should be covered in plastic. I know my longest wall, which will be in FRONT of the drum kit is going to be a slat wall, so no plastic there. Do I cover the ceiling in plastic if my ceiling height is just over 8 ft? OR will that just create nasty reflections between the floor and ceiling? Should I cover three walls to the left, right, and behind the kit with plastic? Some of them? None of them? I'm feeling like I can get away with covering all of the corner bass traps in plastic?