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  1. #1
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    Oct 2019
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    Finding a contractor who can guarantee a Noise Criteria rating

    Hi all. First post here. Hope I'm asking in the right place. I am not yet an equipment owner so I did not go to the AOP section. My question also straddles the line between residential and commercial.

    I found a few old threads on this but not addressing my specific question.

    I'm currently building a small recording studio in a detached residential building. It will be what I'd call a semi-professional facility. Most of the build is DIY and consequently I'm drowning under the weight of the various steep learning curves involved. So I'm hoping I can find a professional to hand over the HVAC part of the build to.

    In short, I'm wondering if it's feasible for someone like myself to find a contractor who can guarantee a particular NC (or RC or NR) rating. I figure if that's in the contract, I don't have to get into the weeds on what kind of equipment is necessary and micromanage the project. After testing, the system will either pass or fail & payment will be dependent on that. I figure that's common practice on some jobs but probably never in a residential environment. I live in the Portland, OR area.

    I'll provide some details on the build.

    It's a single room. No separate control room. Size is about 2800 cu ft. There is an adjacent storage/equipment room (800 cu ft, insulated) that can house equipment and ductwork. One option would be to use that room as an exchange chamber for the main room. This has been suggested on a number of audio forums. But either way, that room also needs to be heated and cooled.

    I'm soundproofing using room-in-room construction. So it will have a pretty high level of isolation, be very well insulated and air tight. I will definitely need ventilation. The general wisdom suggests I could use a ducted mini-split, with an ERV or HRV mixed in somehow. The system would be ducted to baffles outside each of the two walls. So that's two baffles for intake and two for exhaust. I'd be shooting for NR 15-20 at the most.

    I figure I'll need a 1 - 1.5 ton system that can be adjusted based on how many people are in the room. 80% of the time I expect it will just be myself and the equipment. But I'd expect up to 6 people on some occasions.

    I've tried talking to a couple residential contractors. They seemed to be just winging it with their responses. We could "try" this or we could "try" that. Oh, you should get an XYZ system, it's rated at 19dB... This does not inspire much confidence. One guy sounded like he had some good ideas but then never got back to me with a quote.

    I'm concerned that my job is too small for a commercial contractor but out of scope for a residential one. Which is why I'm concerned I may need to go the DIY route -- although I'd prefer not to and am not asking for that kind of advice here.

    So, any suggestions on finding the right person for the job? Or am I kind of screwed here? I figure if I need to hire architects and engineers to make this happen, then yes, I'm going to have to DIY and hope for the best.

  2. #2
    Join Date
    Jan 2010
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    Central Texas
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    I set up a ducted mini-split for a a customers recording studio. If it wasn't for the plastic tarps, that I had draped all over his equipment, fluttering due too the air movement you wouldn't have even heard the unit run. The key is oversizing the ducts and grille sizes to reduce the static pressure and face velocities of the air.

  3. #3
    Join Date
    Aug 2002
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    Southold, NY
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    Agreed
    Ducted mini with oversized ducts.
    As far as gaurantees hire a mechanical enginering ferm and let them gauntree it.

  4. #4
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    Oct 2019
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    Thread Starter
    @sgraefe

    Sure, that makes sense but it goes back to my question. Am I going to be able to find a contractor who can calculate the proper sizes and airflow in order to meet a certain NC? Or do I have to do all that legwork and then hand it off, hoping that after all is said and done that it meets my needs? From what I understand, most residential contractors follow a cookie cutter approach and would want to size the system to meet a typical situation. In my case, it would be like a studio apartment.

  5. #5
    Join Date
    Aug 2002
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    Southold, NY
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    Designing and installing in a sound studio is difficult
    Varying heat loads. Equipment on or off, # of people, lights, slow easy playing of heavy metal.

    I would use a standard Manual "J" but install multiple systems, 3 or more ducted minis to be able to meet the varying loads.

  6. #6
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    Aug 2009
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    Beatrice, NE
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    Money will be your problem. A good resi guy could do it but will be expensive, a commercial guy will do it but it will be done as a fill in project when they have a couple days to fill and they will not be cheap. A couple small systems instead of one larger one my be your best solution as has been suggested. However 2 - 1 ton units will be more expensive than 1 - 2 ton. Oversized duct and grill with liner will keep the sound down along with proper register selection.

  7. #7
    Join Date
    Mar 2015
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    Tx
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    Quote Originally Posted by M7CC View Post
    @sgraefe

    Sure, that makes sense but it goes back to my question. Am I going to be able to find a contractor who can calculate the proper sizes and airflow in order to meet a certain NC? Or do I have to do all that legwork and then hand it off, hoping that after all is said and done that it meets my needs? From what I understand, most residential contractors follow a cookie cutter approach and would want to size the system to meet a typical situation. In my case, it would be like a studio apartment.
    As said, PAY a mechanical engineering firm to design & spec material. Then put out for bid. You tell a small contractor he might work his tail off designing & installing then not get paid because he is 1db too loud , not going to be much interest. I did 4 recording studios and no way would I have done them without a plan with a PE stamp.

  8. #8
    Join Date
    May 2014
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    Bay Area California
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    PE stamp is the way to go. Guessing this homeowner doesn't want to pay for that.

    Homeowner does need to supply the equipment load. No one can figure anything without that.

    Larger ducts, yes.

    Equipment mounting, be sure it is not close to the recording equipment.


    Had a call a few months after getting into the trade. Professional recording studio. Complaints of equipment picking up noise from the HVAC equipment. Told them to call a sound engineer.

    My boss was totally pissed. He said I should have recommended that we put cork pad under the unit. I probably laughed. Because I really have little self control. Told him something along the lines of 'this is out of your league'. Keep in mind I'm a rookie on my first job out of trade school.

    Anyway, the next time I went out there, there were some sort of air cushions where the cork pads used to be. Yup, I was correct, my employer didn't have a clue what he was talking about. And I likely told him that. Not in front of anyone else, but yeah, that's just the way I roll. Can't remember for sure. After all, it was well over 35 years ago.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  9. #9
    Join Date
    Oct 2019
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    Thread Starter
    Sounds like the answer is as I suspected.

    I appreciated BNME8EZ's response. It sounded pretty spot on:
    Money will be your problem. A good resi guy could do it but will be expensive, a commercial guy will do it but it will be done as a fill in project when they have a couple days to fill and they will not be cheap.
    Yes it is a balance of time and money. Unlimited money would hire the architects and engineers. Unlimited time would learn the ropes and do most of the work myself.

    I will look into the PE option. I found one locally today but haven't contacted him yet. But I have no idea of the cost yet. If the cost of engineering & design gets close to that of materials, it probably ain't going to happen.

    There are also a few guys out there who will do a holistic acoustic design for DIYers like myself. I've been resistant to the idea since most of the ones I've found are a hemisphere away or only want to work six figure plus size projects. But I may still go there. It would probably involve me building the baffles and installing the (minimal) ductwork, providing the general plan to a local contractor to do the installation, charging and tuning of the HVAC system.

    @BBeerme, I saw your story in an earlier thread. Sounds about right. Even if I was going to have a local contractor do all the work, I'd have to find someone "good" and that just ain't easy. That's why I thought the NC requirement would help. In my recent experience, finding a "good" contractor to do what they normally should know how to do (not the weird audio stuff) is a total crap shoot, even with what you can find in terms of reviews. It's a lot harder than it should be IMO, but I digress. In any case, thanks for the responses.

  10. #10
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    Oct 2019
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    Why don't you make a contractor visit your place and inspect. Have a chat with him and try to get some ideas as to how he thinks this going to be done best. This way you will be having some cue to proceed. Think it would be more cost effective

  11. #11
    Join Date
    Sep 2005
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    Atlanta GA area
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    We have a sound studio in downtown Atlanta we did the system upgrade (included a re-duct) for...
    They seem to be happy with it (bunch of 20-something geeks... grin)
    Note we will not mention any names.

    First off: you really need a 'sound booth', separate from your control room... may as well plan that in now!
    Note the sound booth would be a third room, albeit it can be a small room...

    Suggestion: Condition that spare room, then use Xfer ducting, possibly with very small booster fans.

    Oversized ducting with very low air velocity (the blowers for the latter may be hard to find) is your best bet to keep the noise down.

    Given your 'loads'... I would suggest at the least 2 stage equipment, or better variable capacity equipment.
    Note your application, due to the quiet requirement, will probably cost at least three times what a similar job for a 'backyard shop' would cost... maybe even 4-5 times.

    And as noted above... a small HVAC shop will probably not be interested in a job: where not meeting unusual specs = no payment...

    Let us know what you figure out...
    GA-HVAC-Tech

    Your comfort, Your way, Everyday!

  12. #12
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    Apr 2003
    Location
    St. Louis
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    Mechanical engineering firm can design what you want.

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