2nd bedroom Soundproofing advice needed

[timothyallan]

Hi guys, I've been lurking for a while now but it's time to get out of the shadows and ask a question

I am getting some nice studio monitors in a couple weeks, and am going to need some soundproofing. I've attached a rough layout of the room below.

It is a townhouse, so I own it, and can mess around with it more than renters could. From what I can tell without cutting holes is that it is wooden studs, with just plain ol drywall.

There are two shared walls which I have to worry about.
I went over to the neighbors place the other day (the one on the opposite side of the closet), and got him to listen while I cranked my existing speakers. He couldn't hear a lot of the mid/high range, but could really hear the sub. Im guessing that anywhere from < 300Hz is going through the walls.

I'm not sure how I want to lay out the 'studio' with my existing gear (keyboard,sampler & monitors), but I thought I'd see if anyone here had soundproofing advice for the room first of all.

Thanks guys,
Tim

BTW I would like it to be as painless as possible on my wallet

 

[knightfly]

Bass is an absolute BITCH to control thru shared walls - the only thing that really works is MASS. Since you own it, you might be able to put up two more layers of sheet rock on the shared walls, then Resilient Channel and two more layers of rock, caulking EVERYTHING - but odds are you'll still get flanking noise over the partitions. This would have to be looked at to see if you could beef that part up, or the wall treatment wouldn't do too much good. Common floors are another area for concern - if you vibrate your part of the floor, it will travel to the neighbors too.

The lower you go in frequency, the harder it will be to isolate. If you can spare some headroom, you might want to think about a floated room. Another option would be heavier duty monitors and no sub - you didn't mention what monitors you're getting?

Painless on yer wallet?!? Boy, are you in the wrong hobby... Steve

 

[timothyallan]

"Painless on yer wallet?!? Boy, are you in the wrong hobby... "

No kidding. I think I am going to going to dive right into the debt hole with a pair of Mackie HR824's. I am not getting the optional sub, as I think these babies will knock my socks off as it is.

The floor and ceiling are what I was wondering about... I was planning on dumping some mass into that one wall on the left, but didn't know how the floor would transmit bass, or if the bass would just go over the wall.

As for doing a raised floor, that may be an option. I haven't found too many examples of doing a raised floor over an existing one. I had seen a couple examples when building a new house/garage/whatever. Does it just need to be resting on some rubber/neopren? and does it also need to be constructed of something other than plywood? How much would it raise the floor to be effective? (I'm 6'3" and its 8' ceilings)

What about putting some bass absorbers in the corners, and doing the wall. Would that have any effect on bass getting out, or would it just make the room less reflective?

Also, the closet on the other side of the room, it is filled with boxes and clothes, so I am thinking that I won't have to pay much attention to it... i hope

Tim

 

[knightfly]

The HR824's don't need a sub for most stuff, as you said - The closet can act like a bass trap, you might be able to swap the doors for custom cloth-covered rigid fiberglas (Owens Corning 703, or equiv.), which would help the bass trap thing. I'm not positive, but I believe that bass traps lower the amount of bass OUTSIDE the room as well - my theory is, since bass traps work by converting some of the sound energy to heat, that once that energy isn't audible it can't leak out; also, since all modal resonance frequencies are maximum pressure/minimum velocity at boundaries, if you lower the energy at lower frequencies it would have the most effect at the walls/ceiling/floor.

One thing you need to realize, just in case you're gullible enough to take a total stranger's word on something, is that I am speaking from a small amount of experience and about 12 YEARS of study (off and on), said study beginning after I built the world's second worst room for acoustics/sound proofing thinking that "It couldn't be that hard"... Since then, I've discovered that every thing you learn just helps you realize how stupid you are - I figure that if I continue to study acoustics, I will be a complete moron in another couple of years... Anyway, that's my disclaimer so ask away, at least you know what the answers are worth... Steve

 

[timothyallan]

"12 YEARS of study (off and on), said study beginning after I built the world's second worst room for acoustics/sound proofing thinking that "It couldn't be that hard"."

Hehe, I have been researching for a couple months, and have discovered how complex this whole process can be. It's definately not something you want to do more than once.

Is there any online stuff regarding shared walls, bass, and the like? I have the sae site, Johns, and a few others, but nothing that shows exactly my scenario. I know I cant be the only one with 2 shared walls who wants to soundproof a room. I wish I had a basement

Another thing I was looking at, in that picture in the first post: Would it make the most sense to place the monitors so that they are against the shared wall, pointing towards the closet on the other side of the room? That would give the longest distance between the sound waves and a rear wall. However, I don't know if that may just make things worse with the Mackies being so close to the shared wall. They should theoretically fire forward, and not pummell the wall that they are flush against, correct?

Tim