Basement listening room: basic ideas during renovation

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lousyreeds1

All,

I'm about to renovate our basement and will have the opportunity to design a media room/guest room from scratch.  I won't want to get into complex built-in acoustic treatments, but I'm wondering if there are basic principles I can follow to set myself up for good sound.  Plan is as follows:

- Unfinished dimensions are 18'9" x 12'5".  I could in theory reduce the size of the space slightly if there are more optimal dimensions.
- Ceiling is low - joists are at about 7'.  Original plan was to leave them open - would it be better sound-wise to finish the ceiling and create a flat surface?
- Any materials I can use in construction that will help with sound without adding significant cost?
- Flooring would likely be synthetic carpet to deaden the space a bit.  Any alternatives I should consider?
- Finishes would likely include very basic acoustic treatments UNLESS it's cheaper/easier to incorporate this into the room design somehow.  Thoughts welcome.

Thanks in advance!

veloceleste

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Bob in St. Louis

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Re: Basement listening room: basic ideas during renovation
« Reply #2 on: 5 Nov 2019, 03:22 am »
- Berber carpet with the thickest pad they sell
- Run more conduit to places you doubt you'd ever want to have wires run to. (trust me).
- Don't let "this wall" be in contact with "those walls".

JLM

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Re: Basement listening room: basic ideas during renovation
« Reply #3 on: 5 Nov 2019, 12:18 pm »
Did similar 15 years ago when we built the house.  Overall very happy with the 8ft x 13ft x 21ft room, it's the envy of my small audio club, and additional costs were very low.  I consider it a near ideal practical listening room.  Initially it was spooky quiet, but quickly got over that.  The setup is mid-field with listening chair 10 ft from front wall.  My office is in the back of the room - I call the room my study.  Have added (10) GIK 244 panels that stand on the floor against the walls, (3) randomly filled tall bookcases on side walls, (3) carefully located subs near corners, and Dirac to help tame inevitable bass peaks/dips.

What I did right:

1.) Adjust room dimensions to Fibonacci ratios to minimize bass echo.  In your case 7ft x 11.3ft x 18.2ft.
2.) Built insulated staggered stud interior partitions (2x6 top/bottom plates with 2x4 studs) with drywall throughout (conduit won't be needed).
3.) Built drywall ceiling, insulated above.
4.) Used insulated exterior fiberglass door (with weather seals).
5.) Installed lined/insulated flexible ductwork (can't hear the furnace).
6.) Have office carpet on a pad over slab on grade.
7.) Ran dedicated circuits with dedicated ground for audio (as mentioned, install plenty of receptacles).

What I should have done differently:
1.) Builder refused to suspend drywall ceiling on gauge metal furring strips to isolate it from the floor above.
2.) Installed recessed can light fixtures (rated air tight and to be in contact with insulation) in ceiling, now sound transmits up and down.  Instead recommend using wall mounted light sconces. 

Note:
1.) Years earlier in another house removed a drop ceiling, thinking the open joists would diffuse the sound - wrong!  All it did was allow every sound to transmit up and down. 
2.) Bigger rooms are better, but proper shape is even more critical.
3.) Read Floyd Toole's "Sound Reproduction" 3rd edition, the consummate layman's audio guide to room acoustics. 
4.) You may want to add insulation under the carpet (not just a pad or thick carpet).  Look for speciality products.  We put "Insult-Tarp" under the slab when building.
5.) Concrete slab is the best floor, it's non-resonant yet absorbs vibrations. 
6.) The Cardas formulas for setup/room dimensions are spot on to what I did.
7.) My room is very similar to audio expert Earl Geddes' room which makes me very happy.

mcgsxr

Re: Basement listening room: basic ideas during renovation
« Reply #4 on: 5 Nov 2019, 02:11 pm »
I think you should do a little research on sound transmission prevention and soundproofing to determine to what lengths you are willing to go, in order to have a super quiet room.

I think you should consider the layout of the room and run dedicated AC lines to the relevant locations.

I think you should consider how long you intend to live there, and if there are simple things to include in your build to appeal to a future owner.

Lots of good advice so far.

I documented my build a few years ago, and am happy years later with the all the compromises I made (and ended up with).

IF you don't want to truly soundproof you have a few options for lighting and ease of construction.  I ended up not wanting true soundproofing but did spend time addressing the simple to implement sound transmission prevention ideas - JLM's list is comprehensive and excellent.

I did not use hat channel on the ceiling drywall either, and have 23 pot lights in my ceiling.  I can hear someone directly above me walking, and bass does transmit from the listening room to the rooms above - but at levels I can live with and so can all of them.

Love my solid core door and sweeps at the entrance - that makes a huge difference.  Believe that all the Roxul safe n sound I put in the ceiling and interior walls does help.

After framing and before the drywall goes up take as many pics as you can, and back them up.  Also consider reviewing ANYTHING that can vibrate after the walls go up - plumbing, HVAC etc.  I spent a few evenings with various tie downs testing it all to ensure I would not excite something once the room was done and the subs came in.

I ran all manner of wires to 3 potential locations.  I will live here for 8-13 more years, but after that someone else can figure out where they want the TV, or add the PJ I plumbed for etc.

I spent months drawing it all out, and then most evenings reviewing what compromises I needed to make during the adventure.

Rusty Jefferson

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Re: Basement listening room: basic ideas during renovation
« Reply #5 on: 5 Nov 2019, 05:44 pm »
Only thing I would disagree with other posters about is the ceiling.  If you don't need to isolate the room above, I wouldn't drywall it.  If possible, partially insulate the bay with non fiberglass insulation that can be left exposed  (wool, denim) and leave the irregular surface of exposed wood and insulation material, or just exposed wood.  Much better sound than a low hard surface that you have to make even lower by attaching diffusors to it to deal with reflections.


Mike-48

Re: Basement listening room: basic ideas during renovation
« Reply #6 on: 6 Nov 2019, 02:02 am »
I agree with @Rusty Jefferson about the ceiling. The dilemma is soundproofing vs. acoustics. Unfortunately, the better you get the soundproofing, the more reflections and resonances the room will have, and you'll have to deal with those somehow. The finished ceiling in my basement room is about 7 ft from the floor. It's too low, but without finishing it, there would be way too much sound exchange with the floor above. I use speakers that have tight vertical dispersion to avoid a lot of ceiling reflection.

A friend instead filled the joist space with insulation, and the result is more pleasant acoustically. However, he did not need, and did not achieve, any significant sound reduction from the floor above. That takes mass, and fiberglass or rock wool doesn't provide it.

For sound reduction from the room above, there is very little choice other than to finish the ceiling, preferably with something like QuietRock. Hat channel is more effective but has greater thickness, which will make the ceiling even lower. (That's why I didn't use it.) But unfortunately, a smooth ceiling is not a great thing in terms of in-room acoustics. If you don't have speakers already, you might look for some with controlled dispersion, to limit the amount of reflection from the ceiling.

I hope that you have fun with the project and get results you like!

P.S. @JLM hit the nail on the head in avoiding can lighting (among many other things). The fewer penetrations of the ceiling, the better. Floor lamps are ideal for an audio room.


Mr.Retro

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Re: Basement listening room: basic ideas during renovation
« Reply #7 on: 6 Nov 2019, 03:39 am »
On my basement ceiling I first painted the joist's then angled ceiling tile so one edge rests on the bottom of one joist and tucks up to the top of the other. It forms rows of angled "baffles" and works well for me. In some cases I have put insulation in the space above it.

JLM

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Re: Basement listening room: basic ideas during renovation
« Reply #8 on: 6 Nov 2019, 12:47 pm »
Isolation between your room and above versus losing headroom and possibly gaining diffusion will be your judgement call.  Extenuating circumstances should be considered.  In my case I have a washer, dryer, freezer, and refrigerator directly over the room with a dishwasher nearly so.  The master and guest bedrooms are 16ft away and the 2nd/3rd bedrooms are two floors above.  Floor construction consist of bamboo flooring over 3/4" plywood subfloor over 16" deep wooden trusses.  Most listening is done early in the AM while everyone else is asleep, thus little worry about noise transmission in or out of the room.  But I do hear every foot fall above which I attribute to the ceiling drywall being screwed directly into the trusses. 

Humans are very adaptable and so acclimate easily to their environments.  In this case I'm referring to room sizes/shapes and in particular 8ft high ceilings for those from western cultures.  Anything else seems "weird".  Good comments above recommending vertically controlled directivity speakers.  Speaker choice is very personal.  Options for such include MTM, vertical arrays, and wider than taller waveguides on tweeters.  As there is no perfect speaker each have advantages and disadvantages, but waveguides which are associated with controlled directivity designs is the latest of the three and gaining popularity. 

If you do read Toole's book, you'll find that room shape is critical for controlling bass peaks/dips, but more is needed.  With the dimensions I suggested above you will have primary bass peaks at 62 and 100 Hz, based simply on the room dimensions and the speed of sound.  Those dimensions will keep the harmonics of the two from matching at higher frequencies (124, 186, 200, 248 Hz).  Note that above 300 Hz (midrange) the bass wave effect is diminished.  Also needed is the use of multiple subs, carefully placed near corners.  I use three smaller subs that go low, but four would be better.  I also use room treatments: (6) GIK 244 "full range" 2ft x 4ft panels; (4) GIK 244 "range limiter" 2ft x 4ft panels; and (3) tall randomly filled bookcases.

lousyreeds1

Re: Basement listening room: basic ideas during renovation
« Reply #9 on: 6 Nov 2019, 07:18 pm »
Thanks to all of you for the immensely helpful responses.  This space will likely double as a guest room (listening position will be a sleeper sofa) and it's right under the baby's room - these realities create constraints related to aesthetics and noise isolation.

Because this space is right below the baby's room, we will probably have to finish the ceiling despite concerns about claustrophobic height and reflective surfaces.  My understanding is that leaving some space between the joists and quietrock would create better isolation, but the ceiling is already low; the naked joists are only 6'11" above the concrete slab in some places. 

Plan is shaping up as follows, per your collective input:

-Frame according to fibonacci ratio - 7'x11.3'x18.2'.
-Flooring will be thick synthetic carpet over pad over insulation/vapor barrier over slab.
-Lots of outlets on a separate, grounded circuit.
-Quietrock drywall and roxul safe n sound insulation in ceiling.
-Sconces instead of recessed lighting if practical.
-Simple acoustic treatments - likely the GIK basic package.

Further questions:

-Is it necessary to use specialty drywall and insulation on side walls, or can I just do this on the ceiling?  I assume this will be a significant added expense.

-Are there any less reflective materials I should consider instead of drywall, or am I better off just applying acoustic treatments later?  I can look at alternative wall materials, but not if they will be wildly more expensive than drywall.

-If recessed lighting becomes the only option for reasons related to marital bliss, resale concerns, or anything else, are there specific types of light that will minimize impact on isolation?

Many thanks!





youngho

Re: Basement listening room: basic ideas during renovation
« Reply #10 on: 6 Nov 2019, 08:15 pm »
In theory, you can cut strips of drywall to mount between the joists to the underside of the floor above. Eliminating gaps with lots of caulk as much possible, having more than one layer (without overlapping seams), and using a product like Green Glue between layers may help. You should put some insulation into the joists before finishing the ceiling. If it's possible to do more than one layer of drywall for the ceiling, that would be better, again without gaps or overlapping seams, also with Green Glue or similar. You should strongly consider channel and clips if possible.

I would advise reviewing the following: https://routledgetextbooks.com/textbooks/9781138921368/sound-isolation.php

1. No, standard drywall and insulation are probably fine, but again consider channel/clips, multiple layers, and Green Glue or similar.
2. No, unless you want to consider something like SoundPly, but probably not if you're on a budget
3. For recessed lights (and also plugs and switches on the walls), build isolating boxes along the lines of https://isostore.com/quietbox-recessed-light-soundproofing.html. If boxes like this are not possible for recessed lighting, then don't stress about multiple layers of drywall and channel/clips for the ceiling, since there's just no point.

Young-Ho

Rusty Jefferson

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Re: Basement listening room: basic ideas during renovation
« Reply #11 on: 6 Nov 2019, 10:13 pm »
......If recessed lighting becomes the only option for reasons related to marital bliss, resale concerns, or anything else, are there specific types of light that will minimize impact on isolation?
While the ceiling is open, rough wire a circuit for "pop in" led lights in the ceiling, and switches were needed.  Map out the location of where the wire tails are, and you can come back later drill the holes, wire them, and pop them in. No cans needed. If you don't need them right off the bat you can install them before resale.  My electrician talked me out of can lights in favor of these recently. They're great.
https://www.amazon.com/gp/product/B07C8L62YS/ref=ppx_yo_dt_b_asin_title_o06_s01?ie=UTF8&th=1

JLM

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Re: Basement listening room: basic ideas during renovation
« Reply #12 on: 7 Nov 2019, 11:30 am »
Gauge metal isolation channels are roughly the thickness of drywall, so shouldn't be a big worry, and way easier/cheaper than a second layer of drywall with Green Glue in between.  Note that any penetration of the ceiling  (like the suggested LED light) will lead to sound transmission.  If wall sconces are a no go, consider switched wall receptacles that lamps can be plugged into.  Agree that if ceiling mounted lights without something like the quiet box are "demanded" don't bother with isolation channels, double drywall, or Green Glue.  In that case try going with a single ceiling mounted fixture that would require only a single quiet box.

My mistake was getting sucked into the cheap price of the recessed cans ($10 with bulb), so I did six of them.