Help,Vent Ducting. Sound transmission. S Bend?

[Booda]

I'm hoping to get some opinions on my plan here to get some Ventilation in my studio.

I've read in the past that putting 2 180* degree turns in a Air Duct line will help stop some of the Sound going through the line.

I have a pretty good sound Dead room. Neighbors 15' away and no complaints at 1am for many years (use to be 4am ) . I'm worried about cutting a hole in the room, even if it's only 3" w/ a tube running (possibly) all the way out side. There's some low end outside and I think w/ even a tiny bit of High end... it would sound like a stereo was on back there.

I know it's all trial and error... worst case... I patch up the holes and no vent.

If you look at the Pic... I plan to run 4" PVC and then when it get's a couple feet from my studio convert the line to 3". I don't know... But I feel like a 3" hole would let less sound in and out of the room. Should I just keep it 4" for max air flow?

Where the line is ORANGE and it's 3"... would putting a couple more bends in the line (like a S) help w/ the sound. It'll probably restrict the air flow but...

I'm going to start at the Studio- orange tube and go to the "T", just past the in-Line Fan and do some tests from there. For this winter I'm going to keep the A/C unit inside the garage and just use the Fan setting. (if I even need it) The in-line fan pushing the air from the garage may be all I need.

Then depending on how all this goes, I have the "T" in line so next summer I might put the A/C unit outside the garage. I'm thinking that when the A/C is On, it'll drown out whatever sound is coming through the tube.

Any Ideas on this setup?
It should be fine for Jamming and Loud recording. & turn it off while doing Vox and acoustic instruments.

I might line 1 foot of the ends of the 4" PVC w/ some thin foam to possibly help dampen the sound and vibrations.

Thanks for any help and if you read all this... thanks for that too.
B.

 

[RICK FITZPATRICK]

I've read in the past that putting 2 180* degree turns in a Air Duct line will help stop some of the Sound going through the line.

Ever put your lips solidly on a bottle and tried to blow air into it? You can't. Because its sealed. Same way(supposedly)with a studio. If its "hemetically" sealed, you need a "supply" AND a return. As to HVAC(heating, ventilation and cooling) for studios, you need LARGE ducts for moving large quanties of air, at SLOW speed.And each should have a silencer in the duct or a baffle box(plenum). The smaller the duct, the more noise it introduces.

Even for simple ventilation, you should have a supply and return though.


The subject of Studio HVAC is full of conundrums. You build a "soundproof" room, and then PENETRATE the shell..now you have to keep the Fan/environmental noise from entering the studio, and keep the noise in the studio from transmiting to the outside world.

You might read this. Interesting stuff about "active" noise cancellation too.
http://www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=644&start=30
fitZ

 

[miroslav]

Ever put your lips solidly on a bottle and tried to blow air into it? You can't. Because its sealed. Same way(supposedly)with a studio. If its "hemetically" sealed, you need a "supply" AND a return.

Like Rick said...you need a return.

But I'm not sure from your post...are you worried about light noise getting into the studio and messing up your recording...or noise getting out and bothering the neighbors?

I think people make too much about 100% isolation because of neighbors. I mean...I would only worry about that if I was building a studio inside an apartment, otherwise, if you insulate well enough, that little bit “stereo sound” getting out will ne be enough to irritate anyone…IMO.

Heck...the AC compressor will make MORE noise than your studio for the outside world!
And that's something else to consider. If you put that compressor inside the garage you will regret it. Get it as FAR AWAY from the studio walls as piping will allow.
They now have some of those new style AC units that use small compressors outside, and only require a 3" hole in the wall for the feed/exhaust unit. Mitsubishi makes them, among others.

I have traditional central AC, a big compressor outside, and return system in the attic. That feeds ducts throughout ...I have a large 12" duct feeding my studio, and my "return" is just the open door of the studio!
Oh...and you mentioned using a 3" pipe/duct. I would reconsider that too. You may get more force from the air with the smaller pipe, but it may be nosier in the studio than a wider diameter duct.
You don't want constant "whoosh" noise in the studio.

When I'm tracking drums, guitars or any DI stuff, I don't pay much attention to the AC...but for vocals, I may shut it off so there isn't even that little bit of whoosh....though at times I have also used shields/gobos, and that works OK too.

 

[Booda]

Yes, I'll have a Return

Thanks for the replys. YES, I will have a RETURN... otherwise the room will be pressurized... Should have mentioned it but I'm not worried about the Sound/Noise coming from it. It will be on the opposite side of the room.

Rick, I read page 3 of the Sayers link but didn't get to the info of A-N-C... will read more later when I have time. I searched there and E.Winters the last couple days... Looking for info on the S bend (2 180* turns) to help cut down sound, Fan noise coming into the room. I'm sure I read about this a few years ago and wanted to refresh my memory.

1. are you worried about light noise getting into the studio and messing up your recording...or noise getting out and bothering the neighbors?

2. If you put that compressor inside the garage you will regret it. Get it as FAR AWAY from the studio walls as piping will allow.

3. using a 3" pipe/duct. I would reconsider that too. You may get more force from the air with the smaller pipe, but it may be nosier in the studio than a wider diameter duct.
You don't want constant "whoosh" noise in the studio.

1. 80% = The Fan noise Coming through the duct Into the room is my main concern. 20% neighbors = but your right... when the AC is On, it'll drown out the music.
- not only do I record here, But I have rehearsals and late night jams often. The little bit of top end coming out and adding to the Low end that already escapes the building... it would sound like a full range speaker rather than a low end Muffle. Often in the summer time my neighbors sit on their deck 15' away... I think they actually like the music. or are just very cool.

2. Already tried it... barely audible in the studio. BUT I don't have a 4" hole in the side. For the Winter it will be OK. Just going to use the "FAN" setting. in the summer I don't want all the Moisture build up in the garage.

3. OK! This is what I was wondering... along w/ the S bend. I know the 4" to 3" conversion will cause the air to pick up speed but MORE woosh sound I don't want.

I was planning on starting w/ the 3" conversion (3" hole in the wall) and if need be cut the hole to 4". But I guess I'll just go w/ 4".

I should have also probably stated that the Studio is 10x15x8. Fairly small space to vent. If the least that I get out of this is Having some fresh air while Jamming and rehearsals, that will be ok. It seems like when I was younger, no one complained about having a place to jam and Now I hear "Damn it's hot in here" a little too often.

Thanks for your help and Input!!
B.

 

[Booda]

RICK, sorry... I found the info. Your link took me to page 3 so I thought that's where you wanted me to start reading. I went to page 1 and... voila, there's the info.

Thanks,
B.

 

[Innovations]

As for the two 180 degree bends...how many 180 degree bends does a trumpet have? Doesn't seem to stop the sound.

The important thing isn't just the bends, but having the ducts lined with sound deadening material. If the ducts are lined what the bends do is to force the sound waves to make contact with the deadening material rather than taking the straight shot and never touching it.

 

[Booda]

As for the two 180 degree bends...how many 180 degree bends does a trumpet have? Doesn't seem to stop the sound.

The important thing isn't just the bends, but having the ducts lined with sound deadening material. If the ducts are lined what the bends do is to force the sound waves to make contact with the deadening material rather than taking the straight shot and never touching it.

That's what I've been wondering.
I didn't see anything like a Duct w/ dampening on the inside of the tube at Home Depot... I'll look again... and I'll also go to a Heat and AC Co. and see what they may suggest.

What do you think about taking 1/4" or 1/2" foam and putting it inside the pvc tube... about 1 or 2 feet on both ends and inside the 90* elbow and " T " ? I might try that.

Thank you Innovations!