Sound Control Problems with HVAC

[sndtechie]

Hi,
I'm in the process of building a project recording studio room in the basement.

One of the major problems with this is that the HAVC unit fan runs at a noise floor of about 60 Db(A weighted). Very Loud.

The second major problem is that the project room will need some sort of air exchange system that will isolate the room from the HAVC noise source.

The third problem is that the rest of the basement is used as a woodworking/electronics shop. The woodworking generates a lot of dust even with an air cleaner and shop vac attachments.

The current HAVC unit is a high boy Heil that is about 15-20 years old. I'm looking at maybe replacing this unit with a Carrier 90i System or Ream system. But the budget is tight.

One of the questions I need answered is can the blower motor be replaced on this Heil unit with a quieter unit or should I just replace the whole HAVC system. Does anyone know if blower motors are rated in Db or sones or is this something the manufacturer doesn't provide in the tech info.

I’d like to get a quiet blower motor so that when the studio room is completed the outside room noise level is as quiet as possible. If a new HAVC unit is really quiet then I will not need to design a special sound trap pelumn chamber for air exchange to the studio room.

The entrance to the studio room is being place under the staircase which I'm sealing up to make a sound lock from the HAVC system. but I might use the under the staircase space as a old style reverb chamber since the sound it has is sort of nice. But I was also thinking of using this space as the air exchange isolation pelumn chamber with a forced intake/outake fan system. The project studio space is going to be a room which is 11 feet by 14 feet with a 80 inch acoustic panel ceiling.

Does anybody have any suggestions or done anything similar in a basement?

[beenthere]

Not in a basement, but we've done 3 small studios.

Look up Ksound Studioes on the web.

We did that one also.

No special hvac equipment, just design the duct system to be quite.

[beenthere]

Originally posted by beenthere
Not in a basement, but we've done 3 small studios.

Look up Ksound Studioes on the web.

We did that one also.

No special hvac equipment, just design the duct system to be quite.

Heres a link.

http://www.ksoundstudios.com/

[sndtechie]

This project is a real challenge in terms of using a very limited space. Many of the techniques used in building a real studio just don't apply to this type of room. Acoustically speaking what I'm attempting to do should not even be considered by anyone who understand the word Acoustic. But I like a challenge so I'm back at it once again after being down and out for the last 10 years.

That's a nice size studio you've got there. The last time I had a studio running everyone who owned a studio in the area would bring tapes over to see if they had room problem by using my studio as a reference. I've been in the music biz for the last 35 years. I've been in some of the very best class A studio' on the west coast. I've solved some of the most bizarre audio problems you never want to encounter.

Everything is easy to do if you have a ton of money in this biz but currently I'm trying to do this on the least amount of money possible. You don't want to know why.

The space I have to work with is very limited and your suggestion is a good one but it would require me to rip out all the existing ductwork that runs through the basement. Some of the older ductwork is insulated with asbestos and would cost an arm and a leg to have removed. It cost enough to have it all sealed when we bought the house.

One of the other things is that this is going to be just a project studio for slapping ideas to digital tracks. I'm not even going to attempt to use it for anything commercial.

It doesn't have to be perfect just a reasonable quiet space to work in. I can live with a 20 to 30 Db noise floor. I just don't want to deal with a constant background sound of the HAVC system running when I open a vocal mic. If I have to I'll not even bother installing any air exchange system and just open the door every hour or so and ventilate the place with a fan and the outside window. Not the best solution but it will work if there isn't any other cost effective solution available.

[Toolpusher]

Your getting close to the design life span of any system,
Upgrade to a variable speed unit, High eff furnace.
You'll save money on utilities and have less noise.
Get better comfort from the new system.
The ductwork would need looked into, varaible speed units are not a cure for bad ductwork.

[beenthere]

The picture makes that studio look much bigger then it is, of course thats only half of the studio.


Your idea of a chamber to absorb the air noise is a good one for a budget project.

[sndtechie]

of the studio is where all the fun toys are to play with. That's all we're building. Thanks for the info on the life span of the HAVC system it makes the decision a little easier to make.

[dan sw fl]

Originally posted by sndtechie
One of the major problems with this is that the HVAC unit fan runs at a noise floor of about 60 Db(A weighted).

One of the questions I need answered is can the blower motor be replaced on this Heil unit with a quieter unit or should I just replace the whole HVAC system.

Does anyone know if blower motors are rated in Db or sones or is this something the manufacturer doesn't provide in the tech info.

... quiet blower motor so that when the studio room is completed the outside room noise level is as quiet as possible. If a new HAVC unit is really quiet then I will not need to design a special sound trap pelumn chamber for air exchange to the studio room.

The project studio space is going to be a room which is
11 feet by 14 feet
with a 80 inch acoustic panel ceiling.

Does anybody have any suggestions or done anything similar in a basement?

150 SQ. FT. basement room generally only would need
100 to 150 CFM.

1. Distance and
2. Slow air flow rate ( larger duct)
3. Duct Material ( soft )
4. Variable Speed Air Handler (slow)
are your best friends in
minimizing sound generation and transmission.

Like I would be able to tell you anything about sound, L.O.L.

1. Air handler unit (AHU) location is extremely significant. MAXIMIZE DISTANCE from room.

2. AIR FLOW MUST BE < 400 FPM ( Feet/ Minute).
150 CFM at 400 FPM = >
0.38 Sq. Ft or 60 Square Inches
for supply & return ducts, diffuser and register.

3. Use Fiberglass instead of metal.
Soft is obviously better.

Duct liner specs:
http://www.certainteed.com/NR/rdonly.../0/3033011.pdf

4. Slow speed ( 50%) will amaze you with perhaps
" ~ five-times+ " decrease in noise generation.
Stop-by a local A/C Showrooom for variable speed AHU demo
and measure the noise difference at various operating levels yourself.

http://www.trane.com/Residential/Pro...ableSpeed.aspx

"What is an air handler?

The major components enclosed in an air handler's cabinetry are the blower and motor, controls, heater compartment, and an evaporator coil. This is why it is also sometimes referred to as a fan coil. A standard air handler, like the single stage furnace, delivers the same amount of airflow no matter what the temperature inside.

Trane's variable-speed air handler has Comfort-R Enhanced mode, like our variable-speed gas furnace, allowing the coil to cool down quickly and the blower to slowly ramp up and ramp down or to operate at 50 percent of the cooling air speed in the FAN ON position.

This provides greater humidity control, quieter operation, maximum air circulation, temperature distribution, and air filtration for greater control of your home's indoor environment."

Wall construction and special acoustic ceiling tile
should take care of all other necessary sound attenuation.

[sndtechie]

So whats up these days. The studio is finally getting built and E and me are going to finish the rest of the house this year. Give me a call is you get a chance. 12:00 to 1:00 pm is the best time to get a hold of me on the weekdays.

[cem-bsee]

visit the MOTHER OF SOUND site -- LOTS of good info =

no straight walls
walls of SOLID wood
corners cause echo -- normally

isolate blower motor with rubber mounts
stiffen it's cabinet sides
stiffen any metal plennums
add stick-on insulation or mastic to them -- same for any metal ducting
have isolation joints between plenum & ducting
have GENTLE sweep CURVE in ducting into room
precondition room before use, say 5- 10F beyond normal, probably cooler.
have most electronic equip outside of room, especially the amps

[deejoe]

Acoustical type 1" lining installed internally to both supply and return mains for a distance of 10 ft from the unit both ways should do it.
make sure the duct size is increased to permit this lining without choking it. Example; 18 x 10 = 20 x 12.

[sndtechie]

this is one of the best discussion site's on the net I've ever posted to. Thanks for all this information Guys because your suggestions have inspired me to believe that this nightmare of building a studio in such a small space might just get better results than I orginally set out to achieve.

A big thanks for all the suggestions.

[docholiday]

Install a residential package unit outside and make sure the duct work is sufficient.