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Help - what materials to complete my studio door?
Old 25th June 2020
  #1
Help - what materials to complete my studio door?

Building a (very) small recording room off my master bedroom on a modest budget - it will only be for tracking guitars - probably 90% of the time acoustic, occasional vocals and if I can get it right, mixing recordings that may be full band, but not above 85db. Pretty light-duty, specialized recording room - no bass or drums, unless I'm playing that stuff via monitors as part of mixing. I'm really new to acoustics, though I've been reading what I can recently.

I'm working with limited flexibility on what I can do, given existing construction, and I started momentum on design & build before hearing of Rod G's book, which I've now read & I'm completely overwhelmed.

So, I'm going with a double-door assembly - one is a simple interior wood shaker door for aesthetics to me & wife's master bedroom (w/ consumer-grade weatherstripping) - behind that - my sound door. They'll be pretty close together - something around 3" apart. A 2-leaf system.


Sound door: 1 &3/4" solid core door - heavy duty jamb & hinges, Zero Int'l 770A seals w/ threshold & automatic door bottom.

Immediate question:
I need to determine thickness of door to choose hardware and so I need to make final decisions on materials. What material could I use to beef up my sound door a bit (on inside of studio), then finish with a material that will give me what I need for the frequencies I'll be generating in the room?

My door assembly can support weight up to 250 lbs, though I doubt I'll even need to go that massive. I'm not going full-on w/ the "super-doors" that Rod G recommends, as these are too heavy for my framing and will be more than I need in terms of isolation (no sheet lead). I've also read that super dense massive doors are best for low frequency (which isn't really an issue for me), but aren't as strong at mid / high frequency. True?

In any case, I'm considering attaching a heavy, solid piece of MDF to the solid core door, for the sake of mass - then what would be the best "finish" material? I suppose something absorbative for mid/high frequencies inside the room? If I go w/ MDF, do I need to cover that w/ a layer of nice finish plywood? Thickness?

I don't know how to go about determining frequencies, or what to do w/ that info afterward - any tips on a starting point? Rod's book says that thicker fiberglass panels help with higher frequencies - so, a 2" thick 703 panel?

Thanks all.
Old 25th June 2020
  #2
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Quote:
Originally Posted by oldschoolish View Post
Building a (very) small recording room off my master bedroom on a modest budget - it will only be for tracking guitars - probably 90% of the time acoustic, occasional vocals and if I can get it right, mixing recordings that may be full band, but not above 85db. Pretty light-duty, specialized recording room - no bass or drums, unless I'm playing that stuff via monitors as part of mixing. I'm really new to acoustics, though I've been reading what I can recently.

I'm working with limited flexibility on what I can do, given existing construction, and I started momentum on design & build before hearing of Rod G's book, which I've now read & I'm completely overwhelmed.

So, I'm going with a double-door assembly - one is a simple interior wood shaker door for aesthetics to me & wife's master bedroom (w/ consumer-grade weatherstripping) - behind that - my sound door. They'll be pretty close together - something around 3" apart. A 2-leaf system.


Sound door: 1 &3/4" solid core door - heavy duty jamb & hinges, Zero Int'l 770A seals w/ threshold & automatic door bottom.

Immediate question:
I need to determine thickness of door to choose hardware and so I need to make final decisions on materials. What material could I use to beef up my sound door a bit (on inside of studio), then finish with a material that will give me what I need for the frequencies I'll be generating in the room?

My door assembly can support weight up to 250 lbs, though I doubt I'll even need to go that massive. I'm not going full-on w/ the "super-doors" that Rod G recommends, as these are too heavy for my framing and will be more than I need in terms of isolation (no sheet lead).

In any case, I'm considering attaching a heavy, solid piece of MDF to the solid core door, for the sake of mass - then what would be the best "finish" material? I suppose something absorbative for mid/high frequencies inside the room? If I go w/ MDF, do I need to cover that w/ a layer of nice finish plywood? Thickness?

I don't know how to go about determining frequencies, or what to do w/ that info afterward - any tips on a starting point? Rod's book says that thicker fiberglass panels help with higher frequencies - so, a 2" thick 703 panel?

Thanks all.
We do not even where in the world you ar recommend any specific material. The finish is one of looks. You say that the limit is 250 lb (I guess you are American). Then calculate from that backwards.

Quote:
I've also read that super dense massive doors are best for low frequency (which isn't really an issue for me), but aren't as strong at mid / high frequency. True?
Huh? Compared to what?
Old 25th June 2020
  #3
Thanks Avare -

I hear you on the design message at the end. I'm new to this, and am willing to learn. Part of what I'm trying to figure out is how best to design this door for my needs. I understand that I can calculate different materials up to 250 pounds, but I'm wondering what the best materials are, and where to place them, for my purposes.

Yes, I'm American, door doesn't necessarily have to BE 250 lbs, I just don't want to go above that for structural purposes.

In terms massive doors better at lower frequencies compared to higher - I read that in Rod's book, in the context of adding insulating panels to door assemblies. I'm sure the context is really the most important part, but I was referring to what he says on p. 111 - "The weak point with your door assemblies is in high, not low, frequencies."

It's entirely possible that I'm misunderstanding or oversimplifying.

I guess what I'm asking is: Given what I'm trying to achieve w/ my space, and the door assembly I described, what materials would be best suited to add to the 1 & 3/4" solid core door that I'll have, in terms of add a moderate amount of more mass for isolation, but also material for absorption at the frequencies I'll be generating.
Old 25th June 2020
  #4
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Quote:
Originally Posted by oldschoolish View Post
Thanks Avare -

I hear you on the design message at the end. I'm new to this, and am willing to learn. Part of what I'm trying to figure out is how best to design this door for my needs. I understand that I can calculate different materials up to 250 pounds, but I'm wondering what the best materials are, and where to place them, for my purposes.

Yes, I'm American, door doesn't necessarily have to BE 250 lbs, I just don't want to go above that for structural purposes.

In terms massive doors better at lower frequencies compared to higher - I read that in Rod's book, in the context of adding insulating panels to door assemblies. I'm sure the context is really the most important part, but I was referring to what he says on p. 111 - "The weak point with your door assemblies is in high, not low, frequencies."

It's entirely possible that I'm misunderstanding or oversimplifying.

I guess what I'm asking is: Given what I'm trying to achieve w/ my space, and the door assembly I described, what materials would be best suited to add to the 1 & 3/4" solid core door that I'll have, in terms of add a moderate amount of more mass for isolation, but also material for absorption at the frequencies I'll be generating.
Where to start. For design specifications (and exclusions) are needed. It is understood that 250 lb is the maximum. Add up the components of the door to get the total weight. Start with the door weight. Why is lead excluded?

The quote is taken out context. Doors sized (massed?) to match walls have enough isolation at high frequencies. Can it be improved? Yes. Is it significant? No.
Old 26th June 2020
  #5
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Quote:
Originally Posted by oldschoolish View Post
I've also read that super dense massive doors are best for low frequency (which isn't really an issue for me), but aren't as strong at mid / high frequency. True?
Quote:
Originally Posted by avare View Post
Huh? Compared to what?
My understanding is that ideally the surface density (that's the mass per square metre/foot) of the door should be the same as the wall it sits in or at least not too far short of it. That will mean a heavy door with excellent seals but how heavy depends on the wall. That applies to both walls and therefore both doors if you are doing room in a room construction.
Old 26th June 2020
  #6
Thanks Avare & Starlight -

Got it. I excluded lead partly b/c of cost but also because it just seemed to increase the weight of the door so drastically & quickly. Good to know that a well-built door assembly (for sound) should be adequate for higher frequencies. I suppose I can fine tune frequency absorption after the build w/ treatments. Though I'm particularly focused on this specific spot in studio, as the door will be the surface immediately to my right in mixing position.

I think what I need to do is get actually measurements for my door assembly. I know this should be done first, and done right, but I'm limited due to existing construction, and with other variables & isolation vulnerabilities involved, I kind of approached the walls with a "this is the best I can do" mindset.

Walls are standard (American) 2X4 single stud wall on 16" centers. The wall the door is on connects to my master bedroom, & is 1/2" drywall. Plan on studio side is to do 2 layers of 5/8" w/ Green Glue in between. I know that RC could go further, but I think this would make my already very small room too small, so I've kind of given up on decoupling.

Anyway, I could also do an additional layer of 5/8" drywall w/ Green Glue on Master Bedroom side and this would help.


I suppose what I need to do is follow guidance in Rod's book about measuring db levels to determine what level of isolation I need.
Old 26th June 2020
  #7
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If there is not any insulation in the walls that is the first thing.

Re lead prices you are looking for mass. What is in your neighbourhood and how creative are you? Sheet and plate steel may available at surplus metal suppliers. Any dry docks and/or boilermakers? You may even be to get lead preinstalled doors from hospital and x-ray lab reconstructions/tear downs.

Easy one and needed: what is the weight of the door? Tell us the size and we can talk about materials by lb/ftยฒ.
Old 26th June 2020
  #8
Yes - it will be open cell spray foam insulation.

Interesting point about getting creative w/ metal suppliers - I can look into that.

Door(s) are already at my door guy's shop - I've purchased. The "sound" door is a standard 1 &3/4" solid core door. It's more than 90 lbs, under 100 lbs.
Old 26th June 2020
  #9
Door dimensions

Avare -

My sound door (pre-hung) is a 1 &3/4" solid core door. 32" wide X 82"* tall. Final height will be very close to that, depending on ultimate floor height w/ threshhold.

I've checked ebay & there is sheet lead in 1/16" thickness for around $300 that would add 73 lbs. to overall weight of door. So, the +/- 100 lb. original door, + 1/16" sheet lead, + one 70 lb. sheet of 3/4" hard plywood would basically get me to a "lighter" version of the "super door" that Rod G. recommends. Honestly, I need to do measurements, but if I went with that, my walls (in places) would likely become my weak point.

Again, I'd need to get data & run calcs on isolation needs.
Old 26th June 2020
  #10
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Quote:
Originally Posted by oldschoolish View Post
Avare -

My sound door (pre-hung) is a 1 &3/4" solid core door. 32" wide X 82"* tall. Final height will be very close to that, depending on ultimate floor height w/ threshhold.

I've checked ebay & there is sheet lead in 1/16" thickness for around $300 that would add 73 lbs. to overall weight of door. So, the +/- 100 lb. original door, + 1/16" sheet lead, + one 70 lb. sheet of 3/4" hard plywood would basically get me to a "lighter" version of the "super door" that Rod G. recommends. Honestly, I need to do measurements, but if I went with that, my walls (in places) would likely become my weak point.

Again, I'd need to get data & run calcs on isolation needs.
Great stuff! I hope your metal ferreting skills work out.
Old 26th June 2020
  #11
Thanks!

Avare, one last question though, and kind of gets back to my original question:

A single sheet of 3/4 mdf would add almost 100 lbs to my door for $30. So, I could easily take this door to same weight using that material. Is there some benefit of using lead or steel that outweighs using pdf? I can make a heavier, yet, thinner door, using the metal probably, yes, but are there any other isolation or acoustical considerations?

If it just comes down to mass / weight of door, I'd save the $$ & time looking for metal.

Thanks for your help.



https://www.homedepot.com/p/3-4-in-x...0000/304325742
Old 26th June 2020
  #12
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Quote:
Originally Posted by oldschoolish View Post
Thanks!

Avare, one last question though, and kind of gets back to my original question:

A single sheet of 3/4 mdf would add almost 100 lbs to my door for $30. So, I could easily take this door to same weight using that material. Is there some benefit of using lead or steel that outweighs using pdf? I can make a heavier, yet, thinner door, using the metal probably, yes, but are there any other isolation or acoustical considerations?

If it just comes down to mass / weight of door, I'd save the $$ & time looking for metal.

Thanks for your help.



https://www.homedepot.com/p/3-4-in-x...0000/304325742
I have always written it is about mass. Where are you getting the idea there is some other acoustic criteria? Certainly not from Rod's book.

Yes you can use MDF in acoustical terms.

Last edited by avare; 26th June 2020 at 06:55 PM.. Reason: Corrected spelling
Old 26th June 2020
  #13
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See posts 8 and 15 in the topic Storm Mastering - a mastering NE room in a military fort.
Old 26th June 2020
  #14
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Quote:
Originally Posted by avare View Post
I have alays written it is about mass. Where are you getting the idea there is some other acoustic criteria? Certainly not from Rod's book.

Yes you can use MDF in acoustical terms.
Maybe he refers to the fact that at a given point beefing up a normal door makes no sense as the sealing becomes dominant?
Old 26th June 2020
  #15
Thank you gentlemen, sincerely. Good to know I'm ok to proceed w/ MDF.

"I have always written it is about mass. Where are you getting the idea there is some other acoustic criteria? Certainly not from Rod's book"

Avare - yes, great question - again, I'm new and trying to be careful. Also, I don't know what I don't know, and I don't know any better! Rod's chapter on doors was helpful, but since I'm unable to (and likely not in need) to build his "super door", that means that I'm veering from his recommendations. So, cognizant of his guidance that it's not the just materials you use, but where you place them that can be very important, and without more info from Rod's book for my specific situation, I started looking around. I came across the website Acousticfields.com, with the guy Dennis Foley's series of videos.

Anyway, on one of his videos / articles, he talks about doors and other barriers should be constructed with the frequencies in mind that you'll be trying to control / mitigate, etc. He also talks about avoiding guessing, which makes sense.

I can't remember the term, but his door video talked about compressed layers of different materials. I can't seem to locate the exact one, but here's a video / article of his on walls & materials designed to address specific frequency ranges -

https://www.acousticfields.com/sound...chnology-wall/

He's not talking about doors specifically in this one, but there is one very very similar that I read/saw yesterday. To be clear, I'm not advocating for or against this guy Foley - some of his videos run counter to most of the other reading I've done, etc.

In any case, that's where I started to worry about materials and their relation to acoustics.


I'm pretty confident about achieving proper door insulation at this point - the next challenge is figuring out what treatment to put on the inside of the door, (if any), as this door will be on my right in my mixing position.
Old 26th June 2020
  #16
Old 26th June 2020
  #17


Thanks. But I'm going to have to place my speakers in the perfect position!
Old 27th June 2020
  #18
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Quote:
I can't remember the term, but his door video talked about compressed layers of different materials. I can't seem to locate the exact one, but here's a video / article of his on walls & materials designed to address specific frequency ranges -

https://www.acousticfields.com/sound...chnology-wall/
That explains it.

Acoustic Fields Mystery
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