Medium sized office space, live room makeover

[ScottPetersen]

Hello there,

Long time reader, first time poster here. I work as a sound designer for a computer game company. Due to many factors, I finally have a space dedicated to recording my foley/vox work some live instrument recording with a modest (!) 10K budget to spend on materials and labor, some of which I will do myself. We have just recently finished ripping the carpet out of the roughly 17x22x8.5' space (metal stud, drywall/drop down acoustic ceiling tile) and are ready to put the laminate flooring in. Meanwhile, I have been poring over all of my resources and scouring the internet for more information on how to tackle the acoustics of the room. A minor/major factor in my plan is the ability to re-use the majority of acoustic treatment when we inevitably move in three years, once our office space lease is up. The shape of the room lends itself very well to a short wall of acoutic hangar bass traps and then some bass trap paneling angled down the long walls. I may or may not want the panel traps to be full height, the major factor there is access to outlets and network ports. The real problem for me is figuring out how much diffusion to put in and what kind. I really don't quite understand the resonant slat diffusors (yet) so I am loathe to spec them, and I am sure I can do couble duty bass trap/diffusion on most of my panel traps and even on the low bass hangar area, but I just don't really have the feel for what is the right amount.

This is a live only space, any monitoring done here will not be critical.

So, whaddya think of this plan?

Grey=existing walls
Brown=bass hangars
Yellow=diffusion panels
Orange=bass/mid-bass panel traps

Should I treat the 5'4"x7' window?
Should I include hangars behind the angled panel traps?
Should I angle the panel traps at all (or maybe sawtooth them)?

Thanks for lookin,
Scott Petersen

 

[knightfly]

You mentioned Foley work - yet you mentioned NOTHING about sound PROOFING, only Acoustic treatment. Is there something I missed, or don't you care about outside noises making it onto your Foley tracks?

Office spaces are notorious for flanking noise (sound getting over the tops of walls that stop just above the ceiling grid, traveling through continuous floor structure, etc - Is your door just a typical single, hollow core door with marginal ( or NO) seals?

As to slat absorbers, they work really well to minimise room modes in specific frequency ranges, which can be determined with a couple of simple spreadsheets - the advantage is that they do NOT muffle highs but DO help control flutter echo, so they don't mess up recordings made with otherwise high resolution gear.

Portable treatments of various kinds are a great DIY way to handle a lot of problems, especially if you're gonna "go mobile" every so often - Sound PROOFING, however, has to be a permanent "leave behind" deal almost exclusively.

If you can post more info on your surroundings/quiet needs (and maybe your DIY abilities/willingness), I'll try to help you sort out priorities for your budget and ways to get there.

Even three years is a long time to make crappy SFX if it can be avoided... Steve

 

[ScottPetersen]

Thanks for the reply knightfly,

Yes, I totally neglected to mention my sound isolation needs in my first post (being eager to get to it and all). This space is in a virtually abandoned wing of an already quiet office space. All mechanical systems can be controlled by me and I am very good at stern warnings so my co-workers know to avoid that area and me when we record. Therefore I need absolutely NO isolation treatment in the room...really . That said, the door is solid core and the wall opposite the door/window is a full-height firewall which really does help minimize any flanking noise. I would also like to mention that the acoustic treatment I build might not have to be portable, just transferrable. For example, I could easily re-use the bass hangars in a new room even if I have to cut all of them to a new size to fit the new space.

I am truly a DIY kind of guy. I have done a fair amount of construction in the past, including the building of two separate basement studios with great isolation but dubious acoutic performance and a fair amount of finish carpentry, electrical, plumbing, painting, upholstering, etc. I have no fear of the job, just the dangerous tools used to do the job.

Here are some room mode calcs I have made.
12' 4" ceiling height
8' 6" ceiling height

And an RT60 plot of questionable accuracy
All of these were made with the Acoustic Function Box

I am unclear as to wether the acoustic tile should be treated as the "true" ceiling for the room modes or the concrete ceiling above.

Thanks again for any and all help.

Scott

 

[rushfan33]

Scott, those dimensions are close to those of a Jail cell. Are you THE...... na!

 

[ScottPetersen]

nyuck.

 

[ScottPetersen]

bump.

 

[knightfly]

"Should I treat the 5'4"x7' window?" -

Probably not. you may want to record dialog, and having a live surface your vocal talent can speak into from a few feet away with a directional mic canceling out most of the return from the glass will give a bright sound but still controlled.

"Should I include hangars behind the angled panel traps?" -

No, panel traps need rigid fiberglas or mineral wool about 1 inch behind them and fixed. it's part of the design parameters.

"Should I angle the panel traps at all (or maybe sawtooth them)? " -

Actually, rather than use panel traps there I would suggest building slat resonators which are tuned to the three frequencies your modal dimensions will most exaggerate, which are 103, 137, and 183 hZ (see first attachment, ScotPModes2.JPG, and the specs for all three resonators, along with a markup of your plan showing where they should go. If you want to keep these portable, you can build two of each that are half height, then stack them. That way they will be movable (except for the 103 hZ one, it would still be a bit large)

You can find basic plans for the design of these here

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

Although at least one of the measurements in the corner absorbers isn't quite right for 45 degree angles.

Doing the room this way will give bright areas, absorbed areas (the right side mostly) and if the overall room is too bright, you can always hang 1" rigid fiberglas over some of the slots without losing the effect of smoothing out your modal problems.

"I am unclear as to wether the acoustic tile should be treated as the "true" ceiling for the room modes or the concrete ceiling above." -

At lower freq's your suspended ceiling is nearly invisible, so I used the full height for mode calcs.

You may want to build a couple of Gobo's for more portable acoustic control - one of these could be placed in front of the glass for when you want less live conditions. There are plans on this forum for Gobo's, several members have built various types.

Getting kind of tired (13 hour day from hell, after 4 hrs sleep) so if I forgot anything holler... Steve

Here's the room

 

[knightfly]

And the first absorber

 

[knightfly]

The second absorber

 

[knightfly]

The third absorber

 

[knightfly]

Your room modes, with problem areas circled -

 

[ScottPetersen]

Wow.

Thanks very much Steve. I am going to need to pore over this for a couple of days. I really appreciate all the work you put into this. After you recover from your day from hell , could you maybe explain the rationale behind locating the slat resonators in their respective corners? I mean, how do you know which corner to put the resonator tuned to 103 Hz or 137 Hz? Seems like such a black art to me still.

S

 

[knightfly]

"Seems like such a black art to me still" -

It is. :=)

Seriously, I'm short on time right now but will get you an answer (Oh, you wanted a CORRECT answer? Those cost more, and take longer... :=)

JK, I'll catch you in about a day... Steve