Room Tuning mic question

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SolomonsRequest

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I have read the awesome posts on this subject. First, let me explain what I have gathered about how to tune my room.

1. Generate Pink noise (I use Wavelab) and analyze its spectrum.
2. Play the same pink noise through the monitors and record it with a flat response mic placed where your head would be while mixing, then analyze that spectrum.
3. Compare the 2 spectrums and make adjustments to the room and monitor position, and after some trial and error get the spectrums as close as possible.
4. Try to stay away from EQ'ing the monitors, but if all else fails it may help.

Now, my room is well covered with acoustic foam (3 1/2 walls, ceiling, and floor carpeted), and the walls were built slightly off kilter to better randomize defletions. There is extra foam in corners for bass traps.

(Sorry this is long!! :o)) I haven't attempted all this yet, but I'm not getting accurate bass representation thru my Alesis nearfield monitors. My questions are this: I don't have a good flat mic, so for now I'm gonna use what I've got---which one is the flattest---Cad equitek 2, sm57, sm58, beta58, sennheiser 421. Lastly, am I missing anything in this room-tuning theory that I'm about to try?? Thank you much!!! S/R
 
Studying to become an acoustic engineer (and my father being one) I know the theory behind roomtuning, and you are quite right.

BUT you'll need the proper equipment: A dedicated speaker for producing pink noise, a flat mic and a spectrum analyser. I wouldn't trust my PC for the job, especially since (et seems to me that) your rooms sounds good.

You can rent all that... Check out Brüel & Kjær for more information on the measuring-instruments.

I would rent the service from somebody that knows what he's doing. Check Yellow Pages under "sound", "acoustics" or something like that.

Good luck!
 
Thanx Moskus! Truthfully, though I know I should, I don't want to put any money into that right now. I'm kind of hoping I can work with what I have, as my recordings have been satisfactory (to me anyway :o)).

But regarding your response about a "dedicated speaker"--wouldnt I want to run the pink noise through the same speaker I'm using daily for mixing?

take care, S/R
 
[Excuse my bad english, hate writing tech.english...]

The thing is: If you got good monitors they should play back with a flat response-curve (the whole specter at the same db-rate), so that's not a problem. The problem problem is mostly the room itself and to solve that it's best to use a dedicated monitor to generate pink or white noise, mainly because the monitor has its own noisegenerator that makes noise at a standarized level (the standards name in Norway its called "NS 8710" if I remember correctly). Most software doesen't follow this standard, and therefore the sound that is recieved through the microphone can't be examined with the accuracy that you need.

As you said, you can use your PC, examine the spectrum of your softwaregenerated pink noise, try to remember it, record it through a non-flat microphone, analyze it again, and so on... but you'll need much more accuracy than that, we're talking margins here. Of course you can try, but you'll hear the difference...:)
 
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I think you'll get more responses if you try your question over in the Studio building forum.

It sounds to me like you need some bass traps, normal acoustic foam will only stop high frequencies and you probably have some standing waves and cancellation going on.

Bass trap designs have been discussed over there.
 
The Behringer ECM8000 for $35 is a calibration mic and also makes a great acoustic guitar and drum OH mic.

I would imagine you want to use your monitors because the entire signal chain is what you are adjusting for, not just the room. But I could be wrong.
 
Basically, in most cases when you think there's something wrong with your speakers, and need to adjust them (or buy new ones), that it's actually the room that's making the speakers sound wrong.

If you got good speakers, check the room before you tweak the bass, middle and treble settings. Tweaking those settings will compensate for a poor mixing-room in a way that will affect the recordings.

I believe... ;)
 
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