Acoustic Messurement Troubles

[Ryan Silva]

I am trying to get a hold on my control room acoustics, and I am kind of under-informed on the process.

1. If I don?t have a measurement mic, will a 414 b-uls due?
2. I have tried using 'Pink Noise' to get my sample, is this correct?
3. What should I be looking for with my freq analyzer?
4. When I view my sample through Wav Lab it seems that there is a rise in low end starting at about 100hz then up 5db by 50hz. Then why do I tend to find my mixes having to much low end on other systems?

Gear used

Mics: 414 b-lus or Shure 141
Pre: Focusrite Platinum (very flat)
Monitors: Event ARP6s

Thanks for the time

[thunderboy]

The 414 is far from flat, so it probably will not yield very useable information.

jt

[Phiz]

I would suggest reading this wonderful piece by Ethan Winer (whom is active on this message board).

[leigh]

I've been working on treating a new room lately, and here's what I've been doing. Mind you, I'm self-taught with this stuff, though this isn't the first time I've done this process.

1. If I don’t have a measurement mic, will a 414 b-uls due?

The standard for a measurement mic seems to be a) omni and b) small-diaphragm condenser. I've been using a "tape op" omni mic, but something similarly cheap like the Behringer ECM8000 would work too.

What I found with mics is that the uneven frequency response of the room is going to far outweigh any minor variances in the mic's frequency response, so in a pinch, any decent modern mic should get you in the ballpark. Before starting room testing, I tested a half dozen mics by putting them about a foot away from a monitor and building a foam tunnel around them. This gave me a rough baseline for the frequency response of the monitor/mic combination (as well as the other elements in that system: mic pre, a/d converters, cables) before adding the effects of the room. The variances between mics were fairly minor, and since the "tape op" mic was the only decent omni I had, I went with it.

2. I have tried using 'Pink Noise' to get my sample, is this correct?

If your only analysis tool is a real time analyzer (RTA), then this is your only option to see the whole room response at once. However, with a computer application that has a spectragraph, and will hold and display the peak values, you can sweep a sine wave and get a better signal. "Better" meaning better-defined, because sweeping a sine wave is not affected by ambient noise like your computer's fan, or traffic noise outside the window.

I've been using a demo version of Spectrafoo Complete, but that only gives you a couple weeks time. Check here for some free/shareware apps, or use versiontracker or download.com or whatnot. Look for something with both a spectragraph and a test tone generator.

3. What should I be looking for with my freq analyzer?

The absence of huge peaks/spikes, and dips/notches. As even as possible (or, really, as close to the baseline freq response of monitor/mic, which isn't even to begin with). You won't ever get a flat line, unless you're viewing the freq response on a 1/3 octave RTA which is a very coarse readout.

4. When I view my sample through Wav Lab it seems that there is a rise in low end starting at about 100hz then up 5db by 50hz. Then why do I tend to find my mixes having to much low end on other systems?

??? Because your mixes have a lot of low end? Sounds like maybe you bring bass up while mixing to hear more bass from your monitors. Of course this winds up being too much bass on "other systems", as most consumer audio stuff these days has bass boosting.

Leigh

[I'm Painting Again]

A simple and effective thing to do is just sweep a test tone through your system through the audible range and take careful notes as to your percieved volume at and around the listening position..this gives you an ear training as well as a practical real world analysis of your CR environment..