ducts and vents - see pic

M

mncheetah

New member
I'm building a basement studio and I need some advice on the best way to terminate the flex duct to a vent while retaining maximum soundproofing and space.

I want to put resilient channel and drywall on the ceiling, if I cut a vent into the ceiling, there will be a hole for sound to get through to upstairs - that is a no no. It's more important that there is more soundproofing through the ceiling than on the other side of the wall.

Is there a way to somehow route this through the wall and use the wall cavity from top to bottom? If so what is the best way to do this? My flex duct is 6" in diameter and I am using 2x4 studs. Keep in mind that I will also have to drill holes in the studs for electrical and cable runs.

Thanks in advance.
 

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Hi, just a few questions first. Do you own this building? Where is the duct in the pic coming from. Another duct? Is this a supply or a return? And which ever it is, where is the other one? If this is just a supply duct, do this. Put your lips on a bottle where no air will excape, and blow. What happens? Thats what will happen with the duct. Nothing! You can't force air into a closed container(remember all the soundproofing, and sealing and closing off every hole that sound can find to get in), unless you are compressing it. If your studio is soundproof, it is airproof except for the supply/return ducts. In order for the hvac to work, it pulls air out of the rom from one duct, and supplys fresh treated air from another. ESPECIALLY in a studio. This is the one thing a lot of fly by the seat of your pants homestudio builders choose to ignor untill the room gets stinky-smelly- hot. Heres a suggestion. If you are truly soundproofing a room, you are airproofing it. Address this boogie man first, and completely. Then go on to the rest of your planning. You will be glad you did. And this is beyond the scope of me and MOST other builders expertize. You need to (1)read alot, and ask questions to the right people(i.e.-hvac professionals, or(2) hire professional help-design and installation and (3)once designed, GET A PERMIT! And why? If you own your home and do alterations that require a permit, and you DON'T, you void your insurance, and put your home, family, neighbors at risk, among other things. You put a lot of money into your studio gear and construction. Consider this as just another piece of equipment, like that new digital mixer you want. It goes in the signal chain some where between the fan and your wall.;) Now, I don't like to rain on peoples parade, but if your an adult homeowner, you know I'm right. So does your local building inspector.
fitz :)
 
Assuming I have a permit...

My house, my basement...

I have both supply and return flex ducts running into this particular room.

Now how do I do this?;)
 
.:confused

that was a reply to Rick Fitpatrick from before that the forum decided to double post for me. It wasnt a response to you. Relax. Thank you for your help.
 
ghost smost-who cares

I'll try this again. Are these ducts connected to existing house ducting? If so, you've given a direct path for sound to the other rooms, thereby defeating all your soundproofing. If it is a seperate hvac system, then your planning is viable.(The transistion issue was of no concern if the ducting in the studio had already short circuited your soundproofing efforts.):rolleyes: And assuming you have a permit, then the documents you provided to BID, showing your hvac details, shoud provide the answer to your question.
fitz
 
yes, all ducts come from the same furnace, so I guess I'm screwed. I was hoping the insulated duct would cut down on sound transmission, I guess I was wrong, but I have no choice, I dont want to suffocate. oh well. Priorities are priorities.

Thanks for help guys.
 
No sarcassim here

Hello, like I said, I'm not a professional in this field, but my dad always said theres more than one way to skin a hvac.:D Perhaps a modified plenum between your exist supply and return ducts and the new ducting/grills. Not really being able to see what your ceilling construction/exist. ductwork is like(and not being a hvac designer) I can't offer real solutions. Maybe some of the other members can give you some ideas of how they have solved this problem, as it is the grandaddy of the "sound/air proofing delima" How loud is it possably going to be in your studio? Thats the real issue here. We all want to achieve the IDEAL studio criteria. But sometimes, compromise is closer to the end result than absolute acheivement of professional standards. You are in a home, so you have already compromised that goal.(Or maybe not. Many home studios achieve professional studio isolation)Take a hard look at what you are trying to achieve here.(You probably already have!) In the way of soundproofing, and who you might be recording. Do you really need 130 db of isolation between your basement and the rooms above? At midnight? Maybe you need some alternatives, such as a vocal booth, or amp closets, etc. Mind you, the booth scenarios still have the same hvac problem. But they are one step removed from the existing structure. And you might be able to float it. Anyway, I wish I could whip out an autocad detail for you to build from. I won't pretend I have any professional expertize at this, just suggestions for solving them by either pro design, or amateur trial and error. Good luck. This is a problem for everyone building a home studio. Unless of course, your building from the ground up. Maybe thats the way to go! Maybe I should shut up. No problem.
fitz
 
Basements per se, or furnaces aren't the norm here in Aust., but ventilating an air-tight studio is still an issue.

Rick's suggestion about a modified plenum chamber is possibly worth consideration. One thing I recall seeing mentioned here in the past, is to have a lot of bends in the ducting.........I presume the idea is that by doing so, sound waves will be affected enough to minimise the audible level at the duct outlets. If you can make a plenum with internal baffling as well as some form of "filtering" material it may just be part of the answer for you.



:cool:
 
Ductless split systems....

I've been doing some research on the HVAC issue as well, since I'm in the planning stages of my next studio.

First, your isolation is only as good as your weakest link....if you tie all your duct lines into the main system, with straight pipe, non-insulated, then there was almost no point in building high isolation walls, as the sound will just propagate through the HVAC. In this case, the ducting acts like a big window...

The next gotcha is that most rooms in a standard construction have cracks and poor seals, which allows for air exchange to occur. With typical studio construction you are very concerned with these gaps and cracks, and seal them up....now, you are solely relying on the HVAC system to exchange the air. Stick three sweaty musicians in the room, add a couple tube amps plus all that class-A recording gear, and you've got stale, hot/humid air in a matter of minutes!

Ok, so the situation looks pretty bleak, but I've found somethng that looks pretty promising. It's called ductless split air conditioning (or heat pumps). Basically, this system operates a little like a central air conditioner unit, except there is no ducting, only a small hole in the wall is required. The compressor/condensor (whatever it's called) sits outside, and a small fan unit and control sits inside. This will take care of the heat/cold and humidity issues, leaving only the fresh air issue to be solved (ductless split systems do not take in fresh air). In some circumstances you may get by with just opening the door and fanning fresh air in every now and then. There's probably a clever solution to the fresh air issue...perhaps by running a pair of small, well insulated ducts into an adjacent room (or outside), with a low speed fan. Needless to say, the requirement for ventilation should be lessened by the presence of an air conditioning unit such as the ductless split type.

I'll be watching this thread with interest.

Kris
 
Well here's what I ended up doing (see pic) - each "wall run" (from end of flex to where vent will go), was a total of about $15 at Menards -

1 90 degree boot adapter - 6" diam to 2.25"x12"
2 sheets of pre-bent sheet metal - 2.25"x12"x24"
1 90 degree register for vent - 2.25"x12"

duct tape to seal tiny air spaces

- this still allows space below for running cable
- this will eliminate the need for cutting holes in the ceiling.

There may have been a better way, but this makes the most sense for my budget and my situation.
 

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mncheetah - Your solution looks OK, the only suggestion I would make is to use rigid fiberglass "duct liner" in that last peice (in the wall). It will help deaden the sound entering the flex duct.

Cheers
Kevin.
 
It's probably a lot different here in North Carolina, but when I had to tackle the basement studio thing, I ended up exempting the HVAC ducts from the room altogether. It didn't solve the stuffiness problem altogether (although in a fairly large room, it was seldom an issue), but it stopped the propagation through the duct problem and the temperature was always quite pleasant. I had to build my framing around the ducts and insulate, plus rez channel and all, but it helped a lot.

Ironically, I had to end up breeching this to put a duct in when we were selling the house in order to have it count as heated space. Yet, in order to make it comfortable in that room, we had to close the duct down tightly.

During the Minnesota winter (as opposed to August), just crank up the tube amps!
 
mncheetah's Homemade Port Design! :)

Hey mncheetah! How's your Studio coming???

Hope you don't mind me asking you a few questions - we have the same problems to solve in regard to Ducting (among other things)..

Assuming that we've both opted for a conventional HVAC system due to either a restricting budget, or a space that will ONLY allow such a system:

I liked your design and construction of your narrow drop down vent oulets (as you illustrated in your photo)

Assuming that the photo I saw was an OUTLET..

Let me understand what you did there:

In order to mimimize the transferance of sound thru the main supply flexible ducting, you choked the outlet a bid by building a narrow skinny drop off the flex striaght down through the wall, then you created a ported 90 degree opening which would throw the air straight out, as opposed to dropping it down. Yes?

And I wonder if this SAME design, would also be good for the RETURN?

But of course, with a feed and a return within the same room, you'd have to keep them a respectable distance from each other...

And as someone else suggested, perhaps the skinny drop port should be constucted of fiber board as opposed to sheet metal to further minimize conductivity of sound - yes?

And did you say that you actually bought an adapter that snugged up against the flex duct which allowed you to cut the flex and connect that skinny drop port directly to it? yes?

Well I thank you for taking the time to answer my questions ....

My web page is here:
http://www.locationstudio.net

Hope to hear more about how your studio is coming .....

Regards..
Mike
rocknroll@ucwphilly.rr.com
:D
 
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Ducts

I addressed the hvac issue early in the construction of my studio and was concerned about the whoosing noise of the air coming into and leaving the room. What I was told to do was to install baffles in the ducts, or make the flex duct make a few "S" turns. I see that you have no room for that. so hard board duct and baffles will be an option. I had flex duct in the attic and put hard board toward the ends of the ducts, and I installed 4 baffles in them staggered about 6" apart on the last 2 feet of the duct. One receiver in each room, two in the control room, return duct in the hall. I keep the receiver directed at the wall to keep them from blowing onto any mics.
For the return air I left enough space under the door to let the air return. The doors to the rooms are about 6' apart and connect through a hall way. I haven't had any problem with sound bleeding or whoosing noises.
I wired each room to seperate breakers...
and kept my snake, and panels as far away from any outlet as possible. I went into the slab with snake and went into the attic with the electrical wiring. I kept the outlets at least 6' feet from the snake/panels. No 50/60 hz hum here...inless its an old amp I'm recording.

My 2 cents worth

Gidman
 
It's called ductless split air conditioning (or heat pumps). Basically, this system operates a little like a central air conditioner unit, except there is no ducting, only a small hole in the wall is required. The compressor/condensor (whatever it's called) sits outside, and a small fan unit and control sits inside. This will take care of the heat/cold and humidity issues, leaving only the fresh air issue to be solved (ductless split systems do not take in fresh air).
Click to expand...

Living in So california, energy is a big issue. Despite having a full central heat/air system in the house, I won't be tying my garage studio into it. Otherwise I'll be heating/cooling every room in the house whenever I'm in the studio and vice versa, or I would have to go around and close / open every vent in the house every time I was using the studio, plus I would need to install an independent thermo and switch to regulate the studio air temp, break a hole in the garage wall leading to the house to access the venting system, and given that my studio is about as far away from the Heating/AC unit as it can be, with every other room in the house closer (and the way house vents leak air), the whole place will get some air first, so it will take longer to heat/cool. That can get expensive out here.

Thus, I will need an independent system, much like you describe above, DrFrankencopter. I had not heard of ductless split A/C, it does sound like the portable units I'm lookingat though. I was originally going to go with a small room air processing unit like an ionizer to keep whats in there as fresh as possible, and a small exterior portable Air Cooling / Dehumidifier / Heater unit, which can be had for under $1,000, and for my sized studio, most likely around 600 bucks. The only thing I would have to do is vent it in and out properly, but I don't think that will be a huge issue.

I've already priced some units, but the key issue for me will be venting. Ideally, I want a unit outside the studio vented in through a small hole, and then using the basic principle that mcheetah employed, I'd run a duct up inside the wall, using fiberboard. That will reduce interior noise, and still allow for control, as the unit will have a thermostat built in. Most of the units have a rear vent exhaust port, but that will be a non-issue if it is outside the room. Then all I would need would be an air outlet, again merely a matter of proper venting to prevent sound exchange.

For me, this seems the most logical, cost efficient, and sound efficient way of going about it.

I should be looking into options in a few weeks, and when I do, I'll let you all know what I come up with.

Bushice
 
In response to ENIGMACODE

In order to mimimize the transferance of sound thru the main supply flexible ducting, you choked the outlet a bid by building a narrow skinny drop off the flex striaght down through the wall, then you created a ported 90 degree opening which would throw the air straight out, as opposed to dropping it down. Yes?

Yes.

And I wonder if this SAME design, would also be good for the RETURN?

this particular pic was for supply, I will be doing the same for return.

And as someone else suggested, perhaps the skinny drop port should be constucted of fiber board as opposed to sheet metal to further minimize conductivity of sound - yes?

I believe he suggested to use rigid fiberboard as a liner, not as a replacement of the sheet metal.

And did you say that you actually bought an adapter that snugged up against the flex duct which allowed you to cut the flex and connect that skinny drop port directly to it? yes?

Yes, HVAC section of Menards, Home Depot, Lowes will have all kinds of adaptors for this. I'm actually using 3 different adapters for this, please see above for description.

Well I thank you for taking the time to answer my questions ....

You're welcome. Good luck.
 
Whoever said there is more than one way to skin this... is correct.

If you have air ducts linking rooms to provide airflow (hot or cold), you can reduce the amount of audio going through them simply by making bends in the ductwork, putting in "traps" which are nothing more than metal boxes made out of the same material inline with the ductwork, full of foam. The foam will of course reduce some of the airflow, so you put the foam at the end of the duct right above (or below) the vent depending if its a floor or ceiling installation. I've done this before and it works fine. Make sure you can get at the box with the foam in it (use a hinged cover, etc) because the foam will become saturated with dirt, smoke, lint, dead bugs thus needing to be replaced every so often. If you can't figure out the foam block idea, you can put three staggered filters much like a muffers, and achieve similar results like so:

/\ /
airflow----> / \ / --- airflow -->
/ \/

/|\
three filters __/


You may have to cut and paste this message into notepad, for courier non-proportional fonts.


My favorite way to heat/cool a room is to run 1/2" tubing 6-8" apart back and forth on your existing floor, resting on ordinary bricks. Pour cement on top of that to cover the tubing by about 3/4-1", and you now have a giant floor sized radiator.

Pump hot water through the tubing, and the floor/room gets warm. Pump very cold water through the tubing, the floor/room gets cold. Aside from some gurgling if you don't purge the air out correctly, its a very quiet system. Hot water is easy to obtain, any ordinary hot water heater will do, and you connect the hot water heater inlets and outlets to the piping in the floor, with a pressure valve to the water mains on the inlet side to refill the system or add water as nececssary. Also have at the lowest point, another valve, so you can purge. A few air bleeding valves along the way are helpful.

Cooling the water requires a condensor system much like central air. Same principle, and you need to be able to switch the water flow between the hot water heater and the cold unit. Some countries seem to like heat pumps better, and if that floats your boat, swell, its a good solution. heat pumps usually require less installation hassle than having a seperate heating and cooling units.

Regardless of the heating/cooling method you choose, this is the quietest system you can install. No airflow noises, no filters to change, its really nice. The drawback is that you are heating and cooling the air in the studio, rather than circulating it and filtering it along the way. Cold, smokey stale air is just as nasty as natural ambient smokey stale air - its just colder :)

hope I helped.

And yes, I'm a fucking comedian too :)
 
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