Tools to measure room acoustics ?

Posted: Mon Jun 05, 2006 10:34 am

Hi.
Im about to design a studio ( conrol room and recording room) and i am wondering, which tools can i use to measure the rooms frequency issues. by ear i can hear alot of dips in certain frequencies, but i want to be sure that i have also properly fixed these frequencies after i have applied bass traps, mid/high absorbers and diffusors. I have seen some people use the SMART system and run pink noise through the speakers, is this the best way? does anybody use other tools for this? Thanks for your time, cheers.
A.

Posted: Mon Jun 05, 2006 11:16 am

You can use a variety of stimuli such as random noise, quasi-random noise (MLS), and swept sine waves with similar effect. There are many many programs out there, but one that stands out in my mind is Room EQ Wizard. Not only is this an excellent program, but it's free. Whiel it won't provide you with the same level of functionality as big names such as Win MLS, Easera, TEF et al, it will provide you with more than enough functionality to do what you need.

You will need a flat small diaphragm test omni mic. If you don't have one, pick up a cheap Nady CM-100 or Behringer ECM-8000 - they're more than good enough to get the job done.

If you'd prefer not to learn the software I can send you a test tone that you could record and give back to me for data analyisis.

Are you very close to being ready to do this? Let me know, and if you have any more questions, fire away.

Posted: Mon Jun 05, 2006 11:57 am

David,
thanks for the reply. Im about a month away from conducting my tests, im off in a couple of minutes to check out a fiberglass provider( im in El salvador). So im still gathering materials. Small diapfragm omni...hmmm i dont know if the local providers will carry nady, i do know they carry alot of behringer i might have some luck there. Room eq wizard, where can i find this program? it will show the increase and decrease in DB of frequencies, right? where do i place mic, mix sweet spot? probably the best place, maybe i should also move it around in different areas, huh? Wow thanks, i apreciate the help. hey good job on the abosrption cloud design i might make one similar to your design. i will let you know when i am eady for analysis. once again, thanks alot.
A.
p.s. would a large diaphragm condenser with an omni pattern work as well?

Posted: Mon Jun 05, 2006 2:51 pm

When measuring a mix room, measure with the mic at the sweet spot. Tracking rooms are open to interperitation on how to measure them, but I have soime basic un-official ideas I like to use. When it gets close to time to measure, ask me about these.

Avoid large diaphragm mics since their respopnses will never be linear, especially from off axis. Pick up an ECM-8000; it will serve you many times over. You could spend a good deal more and get an Earthworks, DPA, or something if you'd like a mic that will be equally useful for recording music.

I'll be here when you're ready.

Posted: Mon Jun 05, 2006 10:55 pm

A lot of peeps are using ETF ( www.etfacoustic.com )

I don't know if David's 'TEF' was a typo of ETF or a seperate program.

but ETF works great here. I use it with the ECM-8000 ( or *did* until the dogs stole it Evil or Very Mad

)

Paul

Posted: Tue Jun 06, 2006 10:39 am

Paul: No, TEF was not a typo. I was referring to Goldline's hardware based solutions. Also, I was speaking of the big names, meaning the high end stuff, a category in which ETF woudn't be included.

I don't like to reccommend ETF anymore ever since I found REW. I don't see why you would pay for ETF when REW can do a kick ass job for free. Sure ETF can do MLS, but who needs MLS? Certainly not people measuring studio and home theater audio systems.

Posted: Tue Jun 06, 2006 4:39 pm

Hey David,

How does this REW work?
I read about using pink noise and stuff, (because sweeps and mls sounds awkward) and that's really a step backward. ETF is bad enough by itself.

Bert

Posted: Tue Jun 06, 2006 7:19 pm

Hi Bert!

Quote:

...and that's really a step backward

What is a step backward?

Posted: Wed Jun 07, 2006 3:42 am

When you have an uncorrelated signal like plain noise, I don't see how you can derive time information. Missing this is a step backwards, IMHO Very Happy

I know you were referring to this REW on the studiotits pages, but I've not really followed that. Is there a link to rew? So that I can start nagging about it? Twisted Evil

bert

Posted: Wed Jun 07, 2006 7:33 am

Hi David,
I’ve admired your work and advice from several forums for a while now.
Could you possibly help me with a bit of room analysis?

I’ve built four corner traps and a few wall panels based on the designs from John Sayers' site but am unsure of how to finish. Don’t know if I should finish the corner traps with slats or leave them at the Muslin-covered stage. Not sure how to decide on slat spacing for optimal frequency tuning. I haven’t done any room analysis yet cause I’m not totally sure what to do.

Would you be willing to send me that test tone and give me some analysis advice? I’ve got an Earthworks omni which should work just fine.
Thanks for any help!
derek

P.S., Room info (if helpful):
The room is about 21’L x 14’W. The ceiling has two covered air ducts (about 3’ wide) running the length of the room. The ceiling height below the ducts is 6’5”. The ceiling height for the rest of the room is 7’3”.

The floor is covered in a tight weave carpet, but I’m investigating hardwood.

The walls at this point are just thin painted wood paneling.

Posted: Wed Jun 07, 2006 12:57 pm

Hi snyderman.

Email me with the button below this post and I'll send you the necessary info and the file. Please include the description of your room and pics if possible.

Posted: Wed Jun 07, 2006 4:56 pm

proudtower wrote:

When you have an uncorrelated signal like plain noise, I don't see how you can derive time information. Missing this is a step backwards, IMHO Very Happy

I know you were referring to this REW on the studiotits pages, but I've not really followed that. Is there a link to rew? So that I can start nagging about it? Twisted Evil

bert

http://www.hometheatershack.com/roomeq/
Should be nice to hear your opinion ( Twisted Evil

after trying it or carefully looking at it <> nagging just for nagging)

Posted: Thu Jun 08, 2006 3:14 am

Wow.... this is difficult.
Confused

Can I trust this?
Very Happy

Posted: Thu Jun 08, 2006 4:32 am

Fun program
But no match for the real stuff, I guess.

Posted: Thu Jun 08, 2006 1:42 pm

proudtower wrote:

Fun program
But no match for the real stuff, I guess.

Proud, thanks for the more than extensive analysis.
I really didn't need all those minor details .......

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