Acoustics for a music room

[Cammo]

HI everyone,

I am from Sydney, Australia. I am a professional musician (well, drummer actually) :lol: eager to learn more about acoustic treatment.

I have been building a music room in a new house. The sound proofing has been done and i am thinking about acoustic treatment for when i move into the house, which will be very soon.

the room is 19' by 14' with 9' ceilings. The floor is concrete slab and all walls and ceiling are plasterboard.

I plan to put compressed fibreglass (3") diagonally over corners to trap bass frequencies. And some framed boxes (pegboard face) filled with the fibreglass on the walls around the room. Perhaps alternating with panels of the fibrglass covered with burlap for more absorbtion (cardboard backing).

I have read a bit on the web, but i still have some questions:

1.) Am i better off putting lino on the floor rather than carpet? and if so, how do i treat the ceiling?? Full absorbtion or same as walls? If i suspend the burlap covered fiberglass from the cielings, am i best hanging it away from the ceiling say 4"?? Is cardboard better than a rigid panel. Cardboard side facing the floor or ceiling?

2.) I have read that the pegboard boxes work well over a fairly wide frequency range. Does it matter if the fiberglass absorber touches the pegboard which is 1/8", or should the pegboard be free to vibrate?? Should i put a panel on the back of these boxes and should the edges of the boxes be sealed??

3.) Is the burlap alone enough to keep the fiberglass contained??

4.) Is there anything that i have ommitted that would be worthwile for a room such as this?

I mainly intend to use the room for serious band rehearsals/performance which will be mostly acoutic jazz oh yeah and practice ofcourse .

I do not envisage the room to be a proper recording studio although i intend to do some recording.

I know that a good sounding room is a pleasure to play in, but what lengths should i go to seeing that recording is not the primary purpose??

Thanks,

Cameron

[dymaxian]

Greetings! Sounds like you've got a nice space out there.

1.) Am i better off putting lino on the floor rather than carpet? and if so, how do i treat the ceiling?? Full absorbtion or same as walls? If i suspend the burlap covered fiberglass from the cielings, am i best hanging it away from the ceiling say 4"?? Is cardboard better than a rigid panel. Cardboard side facing the floor or ceiling?

I'd recommend making the floor reflective, and the ceiling either really well diffused or absorptive. With a ceiling higher than 8' you can get away with putting diffusion up there, but it'd be easier to build a 703 cloud (or scattered clouds in different spots). I'd hang 4" thick panels 4" off the ceiling, wrapped in burlap as you said. But leave off the carboard.

2.) I have read that the pegboard boxes work well over a fairly wide frequency range. Does it matter if the fiberglass absorber touches the pegboard which is 1/8", or should the pegboard be free to vibrate?? Should i put a panel on the back of these boxes and should the edges of the boxes be sealed??

They work ok. You will probably be happier with a slat resonator, as John has designed, or Ethan Winer's panel traps, or a combination of the 2 (or all three!). As far as the pegboard-box thing goes, the back of the box should be caulked and sealed airtught. I don't think it'll make too much difference whether the insulation touches the front panel or not; the theory is for the whole box to resonate, and for the insulation to dampen the resonation. Sound will get into the box thru the insulation no matter where you put it.

The more varied your absorbers are, the wider absorption you'll have in the room. That'll give your room a more even sound over the low freq's.

3.) Is the burlap alone enough to keep the fiberglass contained??

That should work just fine.

4.) Is there anything that i have ommitted that would be worthwile for a room such as this?

You haven't said too much about mid and high freq absorption, but in my opinion your room will sound better for your use if you make it more live than dead. The panel traps, slat absorbers, and pegboard boxes will help this- they'll even out the low freqs for you without soaking up highs.

I think the amount of treatment you're describing will give you a great sounding rehearsal room. You should be able to use it as a recording room easily.

Good luck!

Kase
www.minemusic.net
"to hell with the CD sales- download the MP3s and come to the shows!"

[Jeff_Free_Bass]

You will probably be happier with a slat resonator

I was also considering adding pegboard/fiberglass , but what are " slat resonators"

[z60611]

I read somewhere that standard pegboard (like one would get for the workshop to hang stuff on) has the wrong distribution of hole size vs surface area to be optimal. PegBoard like materials, where you drill your own holes (or buy pegboard and drill bigger ones) work better.

[dymaxian]

I was also considering adding pegboard/fiberglass , but what are " slat resonators"

Something like this;

http://www.johnlsayers.com/HR/index1.htm

I read somewhere that standard pegboard (like one would get for the workshop to hang stuff on) has the wrong distribution of hole size vs surface area to be optimal. PegBoard like materials, where you drill your own holes (or buy pegboard and drill bigger ones) work better.

Yeah, apparently the determining factors for the resonant frequency of this type of absorber are the volume of the box and the total area of perforations in the face. Standard pegboard will work, but it needs more perforated area to get it down to the zone where you'll need it's absorption most.

But even if you use standard pegboard without altering it, mixing these kinds of absorbers with slat resonators and panel traps will give you a pretty even room sound.

Kase
www.minemusic.net
"to hell with the CD sales- download the MP3s and come to the shows!"

[deanp920]

Kase,

Standard pegboard will work, but it needs more perforated area to get it down to the zone where you'll need it's absorption most.

This is not correct.

Standard pegboard is peforated such that the absorbtion will peak in the low mids, around 300Hz, depending on the depth.

Less perforation is necessary to lower the frequency at which the resonator will absorb most effectively.

Dean

[dymaxian]

Hey Dean- thanks for setting me straight. I haven't built any of these myself; got the theory backwards.

Kase
www.minemusic.net

[z60611]

Thank's Dean. It seems my "buy pegboard and drill bigger holes" was backwards. So much for read once, let years pass, and try to remember...:P

Three places that talk about pegboard are
http://www.saecollege.de/reference_m...requencies.htm

Master Handbook Of Acoustics (4th edition) Chapter 9-33, pages 218 to 225, has lots of useful details and graphs. e.g. "In commonly available perforated materials, such as pegboard, the holes are so numerous that resonances at only the higher frequencies can be obtained with practical air spaces."

Room Acoustics (Heinrich Kuttruff, 4th edition, 6.3 pg 151-158)

[jazzman_in_pa]

Standard pegboard with 1/4" holes has perforation of nearly 5%. Low frequency absorption starts to get more interesting at somewhere near 1%. A home theater designer over at the AV forum uses wood putty to plug up the holes to tweak frequencies.

Or if you're into recycling, you can always use chewing gum.

Lee