Hi there GDA; and Welcome to the forum!
I play loud guitar, bass, and drums ~110 dB peak with c weighting is what I measured in my California studio before I moved out.
You play your drums rather quiet!
Typically, drums come in around 115 dBC, and higher. It seems you play yours gently, which is good for the family and neighbors!
70dB is a lot, but something I want to shoot for
Achieving 70 dB isolation in a home studio is a MAJOR undertaking. And I mean VERY major. This is big money we are talking about. You mentioned a budget of US$ 20k, but you should add another zero on there (seriously!) if you want 70 dB isolation. I'm not joking about that extra zero....
To put this in perspective: The dB scale is logarithmic, not linear, so every time you go up by 20 dB, that implies ten TIMES the sound intensity... and probably ten TIMES the cost to obtain.
Think of it like this: Let's say you need to isolate a volume of half a cubic meter, such as for an iso box for a speaker cabinet. You can get 10 dB isolation for that with a thick cardboard box, and it would maybe cost you 50 cents to a dollar or so. To get 20 dB of isolation, you could use thin plywood: a box made from 6mm plywood will do just fine for that. Cost: maybe 5 - 10 dollars or so. To get 30 dB of isolation, you need something like a house wall: a stud frame with 12mm drywall on each side, and insulation in the cavity. Cost: maybe 50 - 100 dollars. I think you can see where this is going... To get 40 dB isolation, you'd need to build a very thick brick or concrete box, or a basic two-leaf decoupled MSM wall: Cost: maybe 500 - 1,000 dollars. 50 dB of isolation would need a rather more massive two-leaf wall for the box, with a larger air gap. Maybe 5,000 dollars. For 60 dB isolation, each leaf is going to be very massive, there's going to be a very large air gap, and it is going to be completely filled with suitable porous absorption, and sealed absolutely air tight. For 70 dB, we are now out of the realm of normal home construction, and into some very serious industrial type construction. You now need a proper floating floor, for sure, likely separately isolated foundations, very, very massive walls, etc. And lots of money...
Not trying to scare you off! Just pointing out reality... Getting high isolation is a huge undertaking, because the dB scale is log, not linear. Most home studio builders get around 50 dB for their studios, and are very happy if they can get 55: over-the-moon-jumping-up-and-down-ecstatically-euphoric if they get 60 dB. The best-isolated studio in the world is arguably Galaxy Studios in Belgium. It took the many years, many millions of dollars, and the very best efforts of one of the leading experts in acoustic isolation... and they get about 100 dB of isolation.
That's my long rambling way of saying: maybe 70 dB is a little too ambitious!
Now, having said all that, you do have the advantage of concrete walls in your case, which implies high mass, so you are starting off with a good advantage. That makes it easier to get to good isolation. But! The walls are only on the sides: there the ceiling, doors, windows, HVAC, and electrical system, to consider. And for extreme isolation, you would need extreme measures for all of those.
Looking more for soundproofing than acoustics
Acousticians tend to shy away from the word "soundproofing", as it doesn't have a technical definition, can't be measured, and means different things to different people. Instead, we use terms like "isolation" and "Transmission Loss". So in your case, isolation is more important than acoustic response.
Sorry it I seem to be splitting hairs here, but it's important to make sure we all mean the same things when we use technical terms!
Budget would be around $20K if possible.
More about that later...
One issue (the biggest) is the amount of HVAC mechanical. These ducts serve the kitchen and the laundry room (see image 2).
For high isolation, that's a major problem. You would need to enclose those in boxes having mass similar to that of your walls...
The second issue is the electrical box at the end of the space. I would need to add access to this, which I imagine would be a hassle and degrade the sound isolation, or relocate, which would add cost.
For extreme isolation (70 dB), the access door for getting to that would have to have the same surface density as that of the wall itself, plus multiple independent seals. Not impossible, but it would probably be cheaper to just move the entire panel to another location. Definitely not cheap to do that either, but still cheaper than a complex and massive door in the wall of your studio, with multiple seals.
The ceiling is 9'.
That's great!
Gives you plenty of space for the isolation that you will need up there.
The first issue is the windows. While I'd love to have windows, I'm worried about the sound isolation to the neighbors and the cost to do it right
You cna keep your windows, but you'd need to replace the glass with something massively thick, to have te same surface density as that of the wall. Have you ever seen the very thick bullet-proof glass that they sometimes use in banks and armored cars? Have you seen how thick that is? That's not thick enough for what you need, for 70 dB isolation... It would have to be thicker...
There are two ducts to the family room, and one to the kitchen in the space. These could be relocated, but not to ideal locations
Your HVAC ducts can either be boxed in, or relocated, whichever is cheaper. But the isolation issue doesn't stop there: what about the sub-floor above you? What is that made of? If that's a thick concrete slab, then that's good, and you can can probably get high isolation, maybe 60, but if it is a typical OSB on joists floor, then you are probably out of luck at doing this cheaply: You would have to remove that floor, and pour a concrete slab up there, then do your inner-leaf ceiling below that.
How hard is it to isolate the ductwork?
It's thin sheet metal, so it has very little isolation on it's own. It also "pipes" sound rather well from one location to another: put a boom-box close to a register in one room, and you'll hear that through many other registers in the house. Play a drum kit at 110 dBC next to one register, and... well, you get the point!
Isolating the duct-work is possible, and doable for low to medium levels of isolation, but for extreme levels of isolation it would be far better (and cheaper) to just remove it completely, and route new ducting through a different path. The same applies to any water pipes, gas pipes, electrical conduit, sewer pipes, etc.
I'm planning on using an inside out ceiling, but is getting around 70 dB of isolation in either of these spaces possible?
In simple terms? On a budget of 20 k, not, it is not possible. On a budget of 200k: probably possible, but difficult.
Any opinions on which space I should start planning on using?
This is just for a rehearsal room, right? Not for mixing? Then either one could work, but you probably need to go for the one that has the highest initial isolation, to make it a bit easier to get the extra isolation you need. I would suggest buying a sound level meter, setting up a good sound system with a sub, capable of producing 120 dBC, play really loud bass-heavy music through that, and check the levels in and around the house, all over, using "C" and "Slow" on the meter. Do that for each of the two rooms. That will give you an idea of how much isolation you are getting at present, so you can figure out how much extra you need in each case. Based on that, you can decide on which room makes the most sense from the isolation point of view, then start looking at construction techniques and materials that can produce the isolation level you decide on in the end.
I hope I haven't dampened your enthusiasm! The point I've been trying to make is that getting 70 dB of isolation in a typical house is HUGE! And expensive. Getting 60 is already hard (and expensive), but doable. Getting 50 is a realistic goal, and is a level that most home studio builders shoot for.
- Stuart -
- Stuart -
