DIY Room Testing Mics

  • Thread starter Thread starter peritus
  • Start date Start date
You don't have an anechoic chamber? Sheesh!!!! lolz :D

I guess I need to read up on some of this stuff too, I should be getting a set of monitors within the next few weeks. Nothing major but it'll be my first set so I can put the headphones down, weeeeeeeeeeeeeeeeeeeeeee :cool:
 
:o One last question... Which direction do I point the mic when doing the room? I know it's an omni mic.. But... Just wanna be sure...
 
peritus said:
:o One last question... Which direction do I point the mic when doing the room? I know it's an omni mic.. But... Just wanna be sure...
Click to expand...

:D Any way you like.

OK, most omnis still have a slight rolloff of high frequencies off-axis. So point it the direction you would face when mixing. However you are really focusing on low frequency nodes, so it's not that critical.
 
Thanks MS....

Okay... I got three snapshots...

#1 is one close miked monitor....
#2 is mix position without "auto calibration"
#3 is mix position with "auto calibration"


closemicspeakerx0012bg.jpg

mixnocalix0016qr.jpg

mixcalix0012ar.jpg


Here's the manual's frequency response for my monitors...
ds30afreqresp8hg.jpg


Okay.. Now....
 
peritus said:
Thanks MS....

Okay.. Now....
Click to expand...

Your level coming in are pretty low, I think you need to crank up the gain some.

Also, the graph resolution is too low to make much of it.
 
mshilarious said:
Your level coming in are pretty low, I think you need to crank up the gain some.

Also, the graph resolution is too low to make much of it.
Click to expand...

Right on... I was half asleep... I'll be working on this more in the morning (when I get home)...
 
peritus said:
Right on... I was half asleep... I'll be working on this more in the morning (when I get home)...
Click to expand...

Okay.... I officially hate the A & H software... Even when I zoom all the way in... It's a vertical zoom and not a horizontal zoom... There must be something I can use that's better....

Also... The following is the best I could get (red peaks) with all gain parameters set at max (RTA prog volume, interface output volume, interface input volume, interface preamp volume [This one is set as high as it can get without clip light lighting up])....Oh yeah.. I had to use ear plugs! Is this high enough to gauge my acoustics?

Close mic monitor (no auto calibration):
closemicspeakerx0022sr.jpg
 
peritus said:
Okay.... I officially hate the A & H software... Even when I zoom all the way in... It's a vertical zoom and not a horizontal zoom... There must be something I can use that's better....

Also... The following is the best I could get (red peaks) with all gain parameters set at max (RTA prog volume, interface output volume, interface input volume, interface preamp volume [This one is set as high as it can get without clip light lighting up])....Oh yeah.. I had to use ear plugs! Is this high enough to gauge my acoustics?
Click to expand...

Yeah that's plenty loud, you won't peg it because it is broad spectrum noise. Also you don't want to turn up your monitors, because the performance could change at high volume. Leave them at 85dBSPL.

I just said it was too quiet before because it was like -96dBSPL and you don't want to confuse your room with converter & preamp noise ;)

I think for free RTA there is also Rightmark? Or something like that.
 
Thanks, as usual!

Here is my mini-tour of free/trial rta products for a room measuring beginner...

RightMark (free): Majorly geared towards sound interface benchmarking and not accoustics (but the concept and html exporting are sweet).

Audacity (free): Good for recording the test mic's signal, but the spectrum analyzer is lacking many, seemingly normal, features.

TrueRTA (demo): Demo is useless for this purpose (1 octave resolution only).

SigView (demo): This one comes in second in the "I feel confident in" list, from a capability perspective. However, it's not as user friendly as I'd like and the demo lasts 21 days.

AcoustiSoft EFT (demo): This comes in first for sheer brute-capability. I know the answer is in here somewhere. It's rather newbie-proof though, and you aren't able to do any saving (in the demo).

Fre(a)koscope (free): Looks simple and cool but it's VST and I'm running a Pro Tools rig these days. I haven't bought the fxpansion VST wrapper yet (On a side-note, I found out today that the fxpansion VST wrapper is bundled with the UAD board(s) and that's awesome and probably old news!)...

Allen & Heath: Bah!....(see previous posts)....


After a solid day's worth of reading and testing software packages, my choice is the EFT. I just have to figure the friggin' thing out.

I've read some interesting text on the subject of acoustic testing (not sure of a link to this info)... Basically, it's a much better choice to use a software that averages a duration of the test signal, rather than a snapshot (and for obvious-to-me reasons).

What really got me was the following post from Ethan in 2003....

headache3497346tn.jpg


Back to the drawing board....

P.S. Any recommendations on which spectrum analyzer settings?

i.e. this kinda stuff (screenshot from SigView):
thisstuff9ng.jpg
 
Oh yeah, your room will have peaks and nulls, no question about that. And yes, you will need treatment. But I don't completely agree with Ethan as testing establishes a benchmark for before and after treatment. Maybe you will discover you still need more treatment. Also, different spots in your room will perform differently, and I think it's important to know what those spots are like before you stick a mic there for tracking.

And yes, half-step intervals are not sufficient for measurement. That's kinda the problem with the A&H software, that's not even 1/12 octave resolution.

I use the FFT in Wavelab which when cranked up, yields 0.2Hz resolution. But it ain't exactly free. I think there is a demo, or at least there was for v4, it doesn't let you save, but you can printscreen the FFT.
 
Hey peritus, not that I have a lot to conribute to this one, but I just wanted to thank you for sharing the info in this thread. Hopefully, you'll keep it coming, and ultimately let us know what works best for you for this. Looks like you're really doing your homework, and I'm anxious to do some testing of this sort in my own studio soon.
 
I agree with Jeff, very interesting stuff we all need to be aware of. Some good info in this thread.

Joel
 
Here's sample from me, this is off in an untreated corner of my room so you can see a few issues. There is also an issue with sub calibration, because it's a close miced sub and single monitor, so the sub is 3dB too loud.

Even so, you can see some nice ugly nodes:
 
You must log in or register to reply here.
Back
Top