SMALL Basement Project Studio Build Project

So, I'll probably go with the $29 per sheet of 48'' x 120''. The other local HVAC supply shops either didn't answer the phone or didn't carry it. Hopefully that's a reasonable price. I do have a question on the silencers though. I constructed them out of 3/4'' plywood. Internal dimensions are about 12'' x 12'', with three dividing boards creating the "S". My initial thought was to leave them as the ply, and maybe cover them with fabric (purely asthetic) or paint. Thinking on it more though, I'm not sure if I should add drywall to the outside of them, and if so where. My thinking is the drywall would help isolate them from the noise inside the rooms. The ones in the live room will be not quite in the corner - there will be about a 3-4'' space on the one side. Poor planning on my part because of a stud location, but it is what it is (think I'll use the "dead space" to store some mic stands and what not). The ones in the control room will be in the corner completely. I have illustrated the options the way I see them for the live room silencers. I'm pretty sure the treatment would be about the same for the control room, but if someone thinks differently please let me know. The differences between 2&3 and 4&5 being the layer of drywall on the silencer that will be up against my wall. Please check out the illustrations and let me know what I should do as far as adding the drywall or not. I was concerned that I would be creating a triple leaf because it would go: drywall, plywood, 12'' airspace (silencer), drywall, 8'' airspace (wall cavity), drywall The illustration shows a top down view from above. As always, feedback is very appreciated!!!

consider: you have a beefed-up double stud wall with both 2 layers of 5/8 GB. Then you make a gap in it. To make up for that leak you need to beef up again. Hanging a 3/4ply box on it will be step 1. Surrounding only the outer shell with another layer of 5/8GB equals (give or take) one wall. The 3/4ply weights about the same as the 5/8GB. To compensate for the OTHER wall, that also has a gap, you need to beef up the box with another set of 2x5/8GB. Since your box isn't a separated construction (as the walls are) you still are under-isolated. . . . you have the same amount of mass on the box but it lacks the space to separate layers. Oh well, sometimes you gotta live with what you got. It's "just" a little gap, right.. hmm. (adding gb as your last 2 options will not do the trick, the gap stays the same). bottom line: try, atleast, to match the mass of the whole wall(s) construction. and not only on the box.... gotta box in your ducts too. woooot? uhm. yeah.... or else your ducts will be the weak point. Put wool in there too to dampen the resonating-ducts..) aah, don't you hate it.

Hi Ro, Thanks for chiming in, let me see if I can digest this:

Surrounding only the outer shell with another layer of 5/8GB equals (give or take) one wall. The 3/4ply weights about the same as the 5/8GB.

So, you're saying that the 3/4 ply plus (1) layer of 5/8 GB equals approx. the mass of one (2) layer 5/8 wall.

To compensate for the OTHER wall, that also has a gap, you need to beef up the box with another set of 2x5/8GB.

So, you're saying I would need the 3/4 ply + 3 layers of 5/8 to equal the mass of the two wall assemblies.

Since your box isn't a separated construction (as the walls are) you still are under-isolated. . . . you have the same amount of mass on the box but it lacks the space to separate layers.

So, because the layer facing the room is connected to the layer facing the wall via the box, there is no "A" in the MAM. It is all coupled together.

Oh well, sometimes you gotta live with what you got. It's "just" a little gap, right.. hmm.

(adding gb as your last 2 options will not do the trick, the gap stays the same).

"Gap" as in???

gotta box in your ducts too. woooot? uhm. yeah.... or else your ducts will be the weak point. Put wool in there too to dampen the resonating-ducts..)

Box in the ducts? Inside the wall? The only place the duct exists is in the wall cavity. On the studio room side it would go directly into the silencer. On the non studio room side it terminates in a vent cover. Are you talking about building a soffit around it and stuffing with wool? What am I missing? Can you show me an illustration of the right way (even from another thread) so I can "see" it? THANKS!

Beyond all my questions to Ro above, I thought maybe another illustration might help. Since the penetration into the wall is not inline with the opening in the silencer I'm not sure that I'm losing the isolation (of course I would be way off!). I also searched the forum a bit for silencer installation and couldn't find much, but I did find this: viewtopic.php?f=2&t=11854&p=86965&hilit=silencer+installation#p86965 The poster talks about how they soffited around the ductwork inside the studio. Basically this would be the same thing I'm doing (if I cover the silencers in drywall) but my soffits would have 90 degree turns and be lined with ductliner. I do see a weak point in that the way the ducts are routed, I have a penetration on the outside wall in line with the opening on the silencer, leaving only one leaf of mass - the two layers of 5/8 on the studio wall. So, my question then would be, do I add 2 layers to the wall side of the silencer, knowing that I don't have a MAM system, just a beefier mass system? See illustration (side view):

hmm ... no expert here ... but I'll also be adding ventilation silencers to my build. Two ??? areas of your posted design: The initial openings for the air in/out give a look of 'congested' airflow ... maybe the baffle position??? Also ... you're not showing an exhaust fan in your design. Are you only using a single fan? Again ... I'm interested in this particular subject, and hope to learn from everyone. Thanks !

RJHollins, Thanks for stopping in. As for the baffles, that's not completely how they are built (or will be built). It was more just representational. The baffles actually are rotated 90 degrees, so if I drew them in this illustration, they would have looked like they sliced the silencer into three independent sections. Does that make sense? There are a lot of threads by more qualified people that state how much space the baffle should take up and still allow proper air flow. Again, my drawing was more representational than anything else. As for the one fan, I saw in several applications where the builder used one exhaust vent and one "dead" vent both going into an air exchange area - whether that was another room or outside. From my understanding, the static pressure will draw fresh air in through the "dead" vent as the exhaust vent pulls stale air out. I placed my exhaust toward the ceiling as to draw out hot air since I don't have an AC system in use. My two cents on the silencers is, if you can find a way to incorporate them without having to stick them in the studio space - DO IT! I'm restricted on keeping mine in there, but would love to not have to have them taking up the space. Hope that helps - and hope someone can weigh in on my weak points / silencer beef up issue ;)

mshetler.design wrote:

So, you're saying that the 3/4 ply plus (1) layer of 5/8 GB equals approx. the mass of one (2) layer 5/8 wall.

Jup, that's whay I'm saying :)

So, you're saying I would need the 3/4 ply + 3 layers of 5/8 to equal the mass of the two wall assemblies.

yes sir.

So, because the layer facing the room is connected to the layer facing the wall via the box, there is no "A" in the MAM. It is all coupled together..

uhm... I'm saying the mass on the box (using 1xply, 3xgb) is equal but it's not a MAM system. There's only one side which has mass. So that whole will be your weakspot. always. unless you make a silencerbox on the other side too ;). Remember the box will become a part of the wall. Nothing more than that.

Box in the ducts? Inside the wall? The only place the duct exists is in the wall cavity. On the studio room side it would go directly into the silencer. On the non studio room side it terminates in a vent cover. Are you talking about building a soffit around it and stuffing with wool?

Dunno where your ducts are, it wasn't on your initial drawing. If you have ducts INSIDE your MAM walls then that's cool. Then you don't even need two silencer boxes :). That means your drawing wasn't correct, to start with. so, what's your exact installation?

mshetler.design wrote:

Beyond all my questions to Ro above, I thought maybe another illustration might help. Since the penetration into the wall is not inline with the opening in the silencer I'm not sure that I'm losing the isolation (of course I would be way off!). I also searched the forum a bit for silencer installation and couldn't find much, but I did find this: viewtopic.php?f=2&t=11854&p=86965&hilit=silencer+installation#p86965 The poster talks about how they soffited around the ductwork inside the studio. Basically this would be the same thing I'm doing (if I cover the silencers in drywall) but my soffits would have 90 degree turns and be lined with ductliner. I do see a weak point in that the way the ducts are routed, I have a penetration on the outside wall in line with the opening on the silencer, leaving only one leaf of mass - the two layers of 5/8 on the studio wall. So, my question then would be, do I add 2 layers to the wall side of the silencer, knowing that I don't have a MAM system, just a beefier mass system? See illustration (side view):

I get what your saying. If you put another silencer on the other side of the wall your problems are solved. Again, the box will be an extension off the wall assembly. By making two boxes you will keep a complete MAM system beefy enough to isolate. The ducts OUTSIDE of the silencer, in your room, still are weakspots so box them in too (that's what I meant in my earlier post). Just "following" the noise, see where it hits a weakspot. If you don't do two silencers and have in/out lined up as per your drawing then you can compensate a bit by adding an extra layer as you did in option#2 on your latest drawing. however, you still don't have a MAM system so it's really "just" compensation. Is it worth the extra labor? sure! by the way, your silencer just needs two turns. you can save the extra space by making the box smaller that way (look at your picture where in inlet should be... waste of space there) ;)

Ro, Thanks for the message back. To clarify, there are no ducts in the room that are not inside the silencer. Since the silencer is going to butt up against the wall, the duct doesn't run anywhere other than the wall cavity. I'm not planning on doing silencers on the outside of the wall, just the set on the inside. However, this morning when I woke up, and was thinking about my project as I often do, I realized I could just move the vent locations on the silencers to avoid lining up the penetrations. AND, like you mentioned, I only need the two turns in there, giving me the space to do this. See attached illustration. I think this may be more on track, but would love to hear feedback from anyone.

After posting, I realized I still only had one leaf opposite of where the outside wall penetration was. So, I updated the illustration. My concern now would be that were I added the MAM System caption, am I creating a triple leaf with the small portion above the outside penetration? And if so, since it is such a small portion of the wall, do I need be concerned?

Three leaf????? Why do you want a three-leaf wall there??? That doesn't make much sense at all. Do you have too much isolation in the low end, and need to get rid of some? :) - Stuart -

Hi Stuart, Joking aside, I did not want to create one, but realisticly, if I drywall the studio facing side of the silencer, I would be creating this: Leaf One: (2) layers 5/8 drywall, 3/4 plywood Approx 12'' air gap Leaf Two: 3/4 plywood, (2) layers 5/8 drywall, wood stud Approx 8'' air gap Leaf Three: wood stud, (2) layers 5/8 drywall Keeping in mind that the 12'' air gap is hard connected by the 3/4 plywood on both sides as it is a box. SO - does that mean that the wall + silencer (Leaf One and Leaf Two) equals one combined leaf not two? Now I'm starting to get confused . . .

The box is small enough not to make it a disturbing 3-leaf installation. Like I said, as the box becomes part of the wall, surround it with GB that equals your wall. Skip the top/bottom pieces and fold around the box with more gb (add it to the top/bottom). Sound will go through your wall 'cuz of that new hole you created. It'll easily pass through you flexduct and enters the wall. The wool inside the wall will dempen the first bit, the rest penetrates (or tries to) the next wall. Since there's another big hole in there, it'll pass through and enters your silencer box. Now if you don't isolate that box well enough it'll creep through the box and becomes a soundpath after-all. THEN it'll pass through the hole in the silencer and enters your ducts... now, you told me your ductwork is INSIDE the wall, but your pics tell another story. And why do you need silencers if your ducts are inside the wall already? I'm confused...

now, you told me your ductwork is INSIDE the wall, but your pics tell another story. And why do you need silencers if your ducts are inside the wall already? I'm confused...

Ro, I'm confused on how my pic shows the ducts as anything other than inside the wall . . . ? Let me see if I can try and explain: On the studio side of the wall assembly, there is a hole. Through that hole is the flex duct. The flex duct spans the space between the studio side of the wall, the air gap, and the outter facing wall. On the outter wall there is a hole (covered with a vent cover). No where are there runs of duct inside the studio or outside the studio. The whole flex duct run is inside the wall. The picture shows that the flex duct enters the wall about half way up and exits the wall either top or bottom depending on which one you are looking at. Hope that helps make it more clear. As for the silencers, it was my understanding that: A) since I now have a big whole in my wall for the flex duct, I'll need to compensate for that with a silencer B) since there is an exhaust fan involved I'll need a silencer Am I really that far of base here? Thanks!

wait a darn minute, you're saying that you pic is the complete plan? no EXTERNAL ductwork? (I see the confusing here, you talk about the flex duct while I presume you'll attach external duct to the other side of the box). mmmmookay. I get it. then I'd really put up two silencers since it's really gonna be your weak-point, it's like a single wall there.

Ro, Sorry for the confusion. Yeah the room on the right of picture is a recreational (non-studio) room in the basement. It is the air exchange room of the system basically. I don't really have an option to put a silencer out there. That is why I was thinking on the top part of my drawing that I have labeled "MAM System" I'm still creating a MAM space before the pentration in the outer wall. BUT - my concern was if I put drywall on the silencer through the middle of the wall, I'd be creating, what appears to me, as a triple leaf. Do I need to worry about this?