Your Anecdotal Experience with Mini-splits or Ducted HVAC in

[DrummerMan]

Hi,
I'm converting my 2 car detached garage in the LA area into a one room studio for mostly personal film scoring work, which includes a good amount of (sometimes very quiet) acoustic instrument recording. I will be sealing the outer leaf of stucco, putting a wall where the car opening is, then insulating and using Resilient Channels with 2 or 3 layers of sheetrock/green glue for the inner leaf, and I am on a fresh 8" slab of concrete. Now I need to figure out an HVAC system that's quiet enough without having to turn it off every time I'm recording something quiet.

I've always been led to believe that a ducted system with the appropriate duct silencers and baffle boxes in place would be the quietest way of having AC and fresh air, but EVERY SINGLE TIME I talk to an HVAC person (I think I've talked to 4 at this point), they push Mini-Splits with a separate fresh air intake. I understand the mini-splits are easier, install-wise, take up less space and require less power, but what I DON'T want is to have to shut the AC off every time I need to record something like a solo sparse clave track (it happens).

All these HVAC guys claim to have done a bunch of studios and have experience with the needs of quietness but even when I go through all the explanations and processes behind what I want, they either look confused or go back to the mini-split thing. I feel like I'm having the same conversation over and over again and expecting different results, so you'll understand if I'm feeling a little insane?

The last guy basically told me that the 72-80db of noise from a ducted unit (which would be parked outside and behind my garage) would be so great that I'd still be shutting it off for quiet takes if I felt that the 30db of noise from a mini-split in my space would be too loud, and that he couldn't in good conscience install it because of this. As much as I'm frustrated by this continued refusal to accept my way of thinking, I don't want to ignore what seems to be a potentially valid argument. So?

Would anybody care to share their actual experience with having mini-splits in a 2 car garage sized space? Do you feel the need to shut it off when recording delicate spacious things?
What about those of you (if any) who've actually gone through the process of running a well thought-out full ducted system for such a small space: are you hearing that as well?

My wife had mini-splits (Mr.Slim's I think) in her old gallery space and they made a terrible whining high pitched (maybe vibrational?) noise when they cycled on, even though they were installed new and kept getting serviced to try and fix the problem. I'm imagining that even a slight low frequency hum through the walls from an outside unit would be easier to deal with, but obviously I have no direct experience with this.

So I reach out to you, the community(s). Any help would be greatly appreciated.
Thanks!
-Geoff



PS - I'm posting this on a few different sites because they, for the most part, seem to have different regulars coming from different areas of experience. If you're one of those folks who frequents more than one of these forums I apologize for you having to see this multiple times?

[A.David.MacKinnon]

There's a mini-split in my control room. It's loud enough that I have to shut it off when I need to do critical listening (like checking for noise on room mics etc, etc). if it was in the live room it would 100% have to be shut off while tracking.

[JWL]

I think your concerns are very valid about noise. Every mini split I've worked with was turned off during recording.

But for me the fresh air thing is an even bigger issue....

[llmonty]

I had one in a 2 car garage-sized space that was a one room control/live room. It was on opposite side of where the mics were, up high on the wall. I would say it was about as loud as my sound dampened PC that was also in the room. I could definitely hear the mics picking it up on headphones between takes. I didn't worry about it for things like drums and electric guitar, or of course DI stuff. I did turn it off for quieter things.

Part of the challenge would be remembering to turn it off. The nature of the sound blends into the background. Also, amps, equipment and people throw off a lot of heat. turning off starts to get impractical.

I didn't have the fresh air return (EVR) and it does get stale after a while. Totally fine session to session, but I kept the windows cracked when not recording.

Based on this, I would say you are right in your thinking. I wouldn't necessarily NOT get another minisplit, but I would definitely get the air returns with it, which increases costs a fair bit. And the layout of the room would have to work. The outside unit IS very quiet. I absolutely did not hear it from outside at all. I almost wished it were louder, to help mask any of the leaked sound.

[losthighway]

Not to hi-jack, but I'm wondering myself how essential, and how effective silencer boxes are in these kind of smaller recording buildings are. They seem to be only DIY with varying degrees of success, but I haven't read a lot of accounts comparing a small HVAC system with, or without silencer boxes in-line with the ducts. I've also ready that flexible, tubular duct work carries less sound than the rigid rectangular stuff.

Anyone?

[digitaldrummer]

I have a Mitsubishi MR. Slim in my studio and for drums and loud guitars, it is never a problem. for vocals, I usually try to turn it off but it depends... the other thing I do is position the mics. if I point the mics null toward the source of the noise and surround the singer with gobos (which I will do to make the room "smaller") it works just fine really. or I just line up the gobos in front of the unit (to block any direct noise) and that usually does it. same thing for acoustic guitars.

then again my room is 25x19 with 15' high ceilings. YMMV in a smaller room.

Mike

[DrummerMan]

Thanks for all your thoughts!

The internet consensus seems to go along with what you all are saying and my original line of thought. Oddly enough, the only forum person recommending a mini-split for my situation (though for different reasons) is same author who inspires and informs a large majority of the quality DIY studio buildouts these days, including my own. Go figure... I still think I'll go with a ducted system if at all possible though, mostly because of the same reasons llmonty stated.


The GOOD news is that I finally had an HVAC guy come over yesterday who was recommended to me by another big studio in town and seems totally in line with what I understand the best practices for a studio situation to be. Very knowledgeable on his own and obviously has done this more than once before. So, keeping my fingers crossed!

Not to hi-jack, but I'm wondering myself how essential, and how effective silencer boxes are in these kind of smaller recording buildings are. They seem to be only DIY with varying degrees of success, but I haven't read a lot of accounts comparing a small HVAC system with, or without silencer boxes in-line with the ducts. I've also ready that flexible, tubular duct work carries less sound than the rigid rectangular stuff.

I can only speculate, but I would think that silencer boxes would be just as effective and necessary if not more in a small space, since without them it's just going to be a direct line from my studio to the outside world. In a larger complex, there'd at least be a bunch of attic space and built-in twists and turns where the sound could dissipate.

In terms of flex vs rigid, yes, it is my understanding that flex duct is better (the flexier the better) because it doesn't carry the vibrations that solid sheet metal would.


I now know that I'll be dealing with 12" ductwork, which is bigger than I expected so I've got less room for my baffle box construction. I may only be able to make one for the supply side and have to buy or make an inline duct muffler like this kind of thing for the return side because I'm squeezing all the ductwork into the ever decreasing ceiling which I just went through the process of raising up by 2'.

I'll let you all know how things go as I proceed!

[losthighway]

I can only speculate, but I would think that silencer boxes would be just as effective and necessary if not more in a small space, since without them it's just going to be a direct line from my studio to the outside world. In a larger complex, there'd at least be a bunch of attic space and built-in twists and turns where the sound could dissipate.

In terms of flex vs rigid, yes, it is my understanding that flex duct is better (the flexier the better) because it doesn't carry the vibrations that solid sheet metal would.


I now know that I'll be dealing with 12" ductwork, which is bigger than I expected so I've got less room for my baffle box construction. I may only be able to make one for the supply side and have to buy or make an inline duct muffler like this kind of thing for the return side because I'm squeezing all the ductwork into the ever decreasing ceiling which I just went through the process of raising up by 2'.

I'll let you all know how things go as I proceed!

Thanks man. I jump in because I think I'm a few months behind you in the "new studio" quest so all of these things are rolling around in my mind. A quick trip to the John Sayers forum confirmed everything we've been contemplating concerning baffle boxes. I also came across a pdf of some very specific designs that Rod Gervais came up with for silencer boxes if you're interested. I like the idea of buying a manufactured one like the one that you linked (this is maybe where I doubt some of my carpentry skills). I'm wondering if that design is just as effective- for my own idiot proofing.

[DrummerMan]

I would LOVE a specific design layout. I've so far been just going on what I can see in pictures and read about online. If its something emailable you can send it to the gmail address geoffthemann

Thanks!

[roscoenyc]

we had a Mitsubishi Mr Slim in our old location and it was absolutely fantastic. This was a one room plus kind of set up (larger main room w a couple booths). We'd turn it of every once in a while when we were doing something super quiet but we were really bummed when we couldn't use it at our new place due to landlord mounting issues.

I recommend them all the time. If you really want to save energy costs get one that does dehumidifying also.

[losthighway]

I would LOVE a specific design layout. I've so far been just going on what I can see in pictures and read about online. If its something emailable you can send it to the gmail address geoffthemann

Thanks!

I emailed. Did you get it?

[DrummerMan]

Yes. Thanks! Busy weekend but I'll probably delve into it tomorrow...