Good stuff Matt. For my soundproof dedicated basement theater, I went with an ERV to do the cross exchange with fresh air intake and it is a game changer. The room gets stuffy all closed up after about 30 mins or so, ERV is on a smart switch and cycles on and off at automatic intervals and within minutes the room is transformed. It's reasonably quiet. No other cooling needed since it's a basement. Just have an exhaust fan in the closet to deal with the equipment ventilation.
That’s a good idea. We spec ERV’s with the HVAC as well. Since I am in Florida and AC is like 24/7 I personally just have a fresh air duct directly into the return.
Really great info. I have a mini split and I’m able to run it very quietly but wish I’d known more to push for other solutions. My theatre air does get stale.
And I bet it’s still what sets your room noise floor. The best of them are very quiet for a fan in the room. But when the true room noise floor is 20dBA or less, that AC still adds noise. My subwoofer amps have fans rated at 13dBA each, they are inside of acoustically treated ducted housings in the amp. Those amps are in an open rack inside a closet with a solid core gasketed door. I can hear those fans running inside my theater through all that! It’s not loud, don’t get me wrong. I can hear it. It bugs me that anything like that is raising my noise floor.
Thanks for the info, Matt. How do you maximize the STC rating of the walls while creating so many HVAC openings where the sound escapes from? Are putting flexible ducts through baffles effective? I've seen it don't on UA-cam videos for music studios in the past.
It's a good question. If you wanted the highest possible STC you can't have any openings, but thats also not very realistic. Every scenario is different and I use different techniques. However, I don't use flex duct in a baffle typically. The key is to use professionally engineered products. Most DIY mufflers create more problems than they solve. I use engineered siliencers mixed with decouplers, acoustic flex duct, etc. However, I only use flex duct where breakout noise is a non-issue. For example, in my own theater, there is nothing above the theater. Flex duct has high breakout noise. However in my scenario the breakout is just into an attic space. Not a major concern. I suppose you could argue that it might create sound leaks to the outside but those would be relatively minor. What I can say is that the in-situ measured STC between my office and theater, which has a jumper vent and common partition wall, is 62. When you consider that the highest measured STC of even the best walls in the best labs is rarely much higher than 65-70, an in-situ of 62 is very good.
I would recommend calculating the air velocity at every stage of the air pathway (plenum, duct, grille vent face,etc) and then keep all velocities less than 250 feet per minute. Worked for me at least. 100% inaudible HVAC on full blast with double stud construction ~NC20 space. Also be careful about transition pieces made out of galvanized steel. Can become noisy with expansion and contraction as the conditioned air changes temperature.
That was essentially what I did and what we do when designing theaters. We spec duct size to keep air velocity below a certain point. In cost no object theaters we spec acoustic turning veins, mufflers, all metal parts damped and insulated, all ducts acoustically lined, decoupling between ducts and hvac unit, etc. For the average person this gets really expensive. I have a ton of cheap alternatives that work nearly as well. It seemed too much to go into for this video.
@@PoesAcoustics "I have a ton of cheap alternatives that work nearly as well. It seemed too much to go into for this video." Nonsense! ;). Such real world experience is what sets your channel apart from other channels. BRING IT ON!
@@nattydj8646 hah ok I’ll think about how to do that. Personally I think the DIY mufflers are designed badly. I am surprised people find them to work. Real professionally designed silencers never look like that. They don’t have a labyrinth inside of them for a reason. All those tight turns add back pressure and cause the formation of turbulence.
@@PoesAcoustics that would be a great “myth” or common practice to explore. And hvac in general deserves more attention since it is foundational and often overlooked.
It can be a mistake to spec too big of an air conditioner in a humid climate because it cools so well that it then doesn't run as often so it doesn't pull the humidity out. Just something to be aware of. 1.5 ton doesn't sound like too much though, especially factoring a higher heat load. You probably spec'd your AC appropriately rather than too high. The issue with putting the supply right by the seats is that when the unit is running convection cooling can happen to the people in the room (although your velocity should be fairly low), which sometimes causes people to socialite between hot and cold when the AC is running or isn't running. I did the same as you, my HVAC for the theater also supplies my office. I figured if I'm in the theater I'm not in the office, so, don't have to be too picky about balancing it lol. Thankfully my gear is in an equipment room outside the theater, so that helps with the heat a lot. I highly recommend using commercial synthetic carpet to avoid mold.
This is true for conventional one stage HVAC systems installed the USA, but with ducted "mini split" heat pump systems, it's much less of a concern because the inverter compressor can modulate how much cooling or heat it produces. Typically a 18,000 BTU system can modulate down to about 3-4000 BTU if that is all that is needed to heat or cool the space. Waste of money though to buy a 18,000 BTU unit if all you need is 4,000 though. The bigger BTU units can move more air though to Matt's point about air exchanges. Highly recommended to perform your own "manual J" for any serious theater room project. Anything else is just a guess...
My equipment is in a closet too. But the closet produced so much heat that it impacts the cooling. We used dead vents or crossovers for returns so it dumps hot air into the stairwell. Not my choice actually. I wanted the returns ducted directly but the installer refused. I wanted a dead vent only for the theater because of noise issues.
@@bartl006 thanks for the info bart! In my theater I used a commercial unit so the return is ducted, which saves having to have a noisey air handler someplace. not to mention the square footage that takes up.
You mean because I have a dedicated system in my upstairs? It was included in the total cost of the build. But figure around $15,000 for something similar and I pay an annual maintenance contract to have someone come out and check both units. They clean the units inside with an antibacterial spray. Check temps, etc. I think I pay $100 a year or so for that. I supply my own filters and I use 3” thick filters. We have had no problems so no repairs. It’s just the cost of the filters and maintenance. And you certainly don’t need to pay that. In Florida the drip lines get bacteria in them that causes water to backup and as I learned the hard way on my parents house, is extremely costly if missed. We found that bleach or vinegar does not in fact work all that well. I decided to pay someone else to come in and blow out those lines for me and then clean them to avoid any chance of a backup. I treat it like insurance. Plus I have better things to do with my time and would rather spend that time building my business or with my family. I know many enjoy house maintenance chores and certainly it’s a way to save. Is that what you were looking for?
@@PoesAcoustics yes thank you. I appreciate the details. I’m in the process of buying my first home now. I’m specifically looking for homes with nice basements. And it’s important for me to have a solid hvac. I’m seeing what I could afford and what I’d have to compromise on
@@RogueAesthetica look into ducted mini splits. You can get one to handle just the theater for not too much. We did a job with a dual zone ducted mini split. 22k btu and 10k btu. We used one zone for the theater and one zone for the equipment and projector. Total cost was $8500 in hardware. I forget labor. It likely was thrown into a larger bit of work.
Thanks, answered my question completely
Good stuff Matt. For my soundproof dedicated basement theater, I went with an ERV to do the cross exchange with fresh air intake and it is a game changer. The room gets stuffy all closed up after about 30 mins or so, ERV is on a smart switch and cycles on and off at automatic intervals and within minutes the room is transformed. It's reasonably quiet. No other cooling needed since it's a basement. Just have an exhaust fan in the closet to deal with the equipment ventilation.
That’s a good idea. We spec ERV’s with the HVAC as well. Since I am in Florida and AC is like 24/7 I personally just have a fresh air duct directly into the return.
Really great info. I have a mini split and I’m able to run it very quietly but wish I’d known more to push for other solutions. My theatre air does get stale.
And I bet it’s still what sets your room noise floor. The best of them are very quiet for a fan in the room. But when the true room noise floor is 20dBA or less, that AC still adds noise.
My subwoofer amps have fans rated at 13dBA each, they are inside of acoustically treated ducted housings in the amp. Those amps are in an open rack inside a closet with a solid core gasketed door. I can hear those fans running inside my theater through all that! It’s not loud, don’t get me wrong. I can hear it. It bugs me that anything like that is raising my noise floor.
Thanks for the info, Matt. How do you maximize the STC rating of the walls while creating so many HVAC openings where the sound escapes from? Are putting flexible ducts through baffles effective? I've seen it don't on UA-cam videos for music studios in the past.
It's a good question. If you wanted the highest possible STC you can't have any openings, but thats also not very realistic. Every scenario is different and I use different techniques. However, I don't use flex duct in a baffle typically.
The key is to use professionally engineered products. Most DIY mufflers create more problems than they solve. I use engineered siliencers mixed with decouplers, acoustic flex duct, etc. However, I only use flex duct where breakout noise is a non-issue. For example, in my own theater, there is nothing above the theater. Flex duct has high breakout noise. However in my scenario the breakout is just into an attic space. Not a major concern. I suppose you could argue that it might create sound leaks to the outside but those would be relatively minor. What I can say is that the in-situ measured STC between my office and theater, which has a jumper vent and common partition wall, is 62. When you consider that the highest measured STC of even the best walls in the best labs is rarely much higher than 65-70, an in-situ of 62 is very good.
I would recommend calculating the air velocity at every stage of the air pathway (plenum, duct, grille vent face,etc) and then keep all velocities less than 250 feet per minute. Worked for me at least. 100% inaudible HVAC on full blast with double stud construction ~NC20 space.
Also be careful about transition pieces made out of galvanized steel. Can become noisy with expansion and contraction as the conditioned air changes temperature.
That was essentially what I did and what we do when designing theaters. We spec duct size to keep air velocity below a certain point.
In cost no object theaters we spec acoustic turning veins, mufflers, all metal parts damped and insulated, all ducts acoustically lined, decoupling between ducts and hvac unit, etc. For the average person this gets really expensive. I have a ton of cheap alternatives that work nearly as well. It seemed too much to go into for this video.
@@PoesAcoustics "I have a ton of cheap alternatives that work nearly as well. It seemed too much to go into for this video." Nonsense! ;). Such real world experience is what sets your channel apart from other channels. BRING IT ON!
@@nattydj8646 hah ok I’ll think about how to do that. Personally I think the DIY mufflers are designed badly. I am surprised people find them to work. Real professionally designed silencers never look like that. They don’t have a labyrinth inside of them for a reason. All those tight turns add back pressure and cause the formation of turbulence.
@@PoesAcoustics that would be a great “myth” or common practice to explore. And hvac in general deserves more attention since it is foundational and often overlooked.
Thank you for the knowledge.
My pleasure!
Don’t think I’ve ever heard anyone touch on this topic. Really good info.
Thanks
It can be a mistake to spec too big of an air conditioner in a humid climate because it cools so well that it then doesn't run as often so it doesn't pull the humidity out. Just something to be aware of. 1.5 ton doesn't sound like too much though, especially factoring a higher heat load. You probably spec'd your AC appropriately rather than too high. The issue with putting the supply right by the seats is that when the unit is running convection cooling can happen to the people in the room (although your velocity should be fairly low), which sometimes causes people to socialite between hot and cold when the AC is running or isn't running. I did the same as you, my HVAC for the theater also supplies my office. I figured if I'm in the theater I'm not in the office, so, don't have to be too picky about balancing it lol. Thankfully my gear is in an equipment room outside the theater, so that helps with the heat a lot. I highly recommend using commercial synthetic carpet to avoid mold.
This is true for conventional one stage HVAC systems installed the USA, but with ducted "mini split" heat pump systems, it's much less of a concern because the inverter compressor can modulate how much cooling or heat it produces. Typically a 18,000 BTU system can modulate down to about 3-4000 BTU if that is all that is needed to heat or cool the space. Waste of money though to buy a 18,000 BTU unit if all you need is 4,000 though. The bigger BTU units can move more air though to Matt's point about air exchanges. Highly recommended to perform your own "manual J" for any serious theater room project. Anything else is just a guess...
My equipment is in a closet too. But the closet produced so much heat that it impacts the cooling. We used dead vents or crossovers for returns so it dumps hot air into the stairwell. Not my choice actually. I wanted the returns ducted directly but the installer refused. I wanted a dead vent only for the theater because of noise issues.
@@bartl006 thanks for the info bart! In my theater I used a commercial unit so the return is ducted, which saves having to have a noisey air handler someplace. not to mention the square footage that takes up.
You mind telling us how much you paid to have the hvac installed and what maintenance is like?
You mean because I have a dedicated system in my upstairs?
It was included in the total cost of the build. But figure around $15,000 for something similar and I pay an annual maintenance contract to have someone come out and check both units. They clean the units inside with an antibacterial spray. Check temps, etc. I think I pay $100 a year or so for that. I supply my own filters and I use 3” thick filters.
We have had no problems so no repairs. It’s just the cost of the filters and maintenance. And you certainly don’t need to pay that. In Florida the drip lines get bacteria in them that causes water to backup and as I learned the hard way on my parents house, is extremely costly if missed. We found that bleach or vinegar does not in fact work all that well. I decided to pay someone else to come in and blow out those lines for me and then clean them to avoid any chance of a backup. I treat it like insurance. Plus I have better things to do with my time and would rather spend that time building my business or with my family. I know many enjoy house maintenance chores and certainly it’s a way to save.
Is that what you were looking for?
@@PoesAcoustics yes thank you. I appreciate the details. I’m in the process of buying my first home now. I’m specifically looking for homes with nice basements. And it’s important for me to have a solid hvac. I’m seeing what I could afford and what I’d have to compromise on
@@RogueAesthetica look into ducted mini splits. You can get one to handle just the theater for not too much. We did a job with a dual zone ducted mini split. 22k btu and 10k btu. We used one zone for the theater and one zone for the equipment and projector. Total cost was $8500 in hardware. I forget labor. It likely was thrown into a larger bit of work.
@@PoesAcoustics thanks I’ll look into that. Any suggestions for a person that hates the look of mini splits on the wall?
My mini split is quieter than my mini fridge.
That doesn’t surprise me. I don’t typically put a mini fridge in a theater for the same reason. Noisy.
@@PoesAcoustics no kids in your theater either🥴
@@garyharper2943 I have two kids in my theater right now. They are quieter than a mini fridge too.
@@PoesAcoustics Great kids…very impressed.