Help with room tuning

[DM1]

I tested my room response with a sound meter, and found the erratic bass response that Ethan Winer describes as "typical" for an untreated room. With a white-noise level of 85db, I have a 22db variance, from a low of 80db at 100Hz, to a high of 99db at 150Hz, back to a low of 78db at 210Hz. (I've attached a crude graph of my measurements. Forgive the linear X-axis.)

As I understand it from the great articles on Ethan Winer's site (e.g. http://www.realtraps.com/art_vibes.htm) the best solution is bass traps. But until I can afford those, I'm curious what strategy will most likely reduce the effect of my room's acoustics. Plus, I'm having difficulty getting my head around the physics. Hopefully someone can help me understand:

1) Changing my listening position just moves the frequency at which the null occurs, right? (That's what it seems like: as I increase the test tone frequency, and move my head around, I can hear the null getting closer to the speakers.)

2) In an untreated room with the type of response I'm seeing, is it possible to position the speakers and listening spot such that the worst nulls and peaks occur at less critical frequencies? Or does the physics of sound essentially guarantee that something between 40Hz and 250Hz will be boosted/attenuated?

3) Will mixing at a lower level reduce the number of reflections enough to minimize the effect of my room acousitcs?


(FWIW, I have my speakers facing the long way into the room, and my listening position isn't centered, either horiontally or vertically. i.e. my ears are closer to the floor than to the ceiling, and closer to the left wall than the right.)

 

[Ethan Winer]

DM,

> Changing my listening position just moves the frequency at which the null occurs, right? <

Right.

> is it possible to position the speakers and listening spot such that the worst nulls and peaks occur at less critical frequencies? <

You can make things a little better, but not nearly as good as you need to mix with confidence. More important, positioning may help the raw LF response, but it does nothing to reduce low frequency ringing in the room which is just as important.

> Will mixing at a lower level reduce the number of reflections enough to minimize the effect of my room acousitcs? <

No, you get the same skewed response but now it's just softer.

> the best solution is bass traps. But until I can afford those <

Go to the hardware store and buy four large bags of bundled fluffy fiberglass. Leave the fiberglass in the plastic wrapper, and just stack one bundle in each corner of your room. It will be the best $100 (or less) you ever spent.

--Ethan

 

[GamezBond]

how do i make a graph like that for any of my recordings?

 

[Ethan Winer]

Gamez,

> how do i make a graph like that for any of my recordings? <

That's not a graph of a recording, it's a graph of the room response. If that's what you want to do, see THIS page on my company's site.

--Ethan

 

[DM1]

Go to the hardware store and buy four large bags of bundled fluffy fiberglass. Leave the fiberglass in the plastic wrapper, and just stack one bundle in each corner of your room. It will be the best $100 (or less) you ever spent.

Ethan,

Thanks very much for the answers. Slowly, I learn!

I took your advice about the fiberglass. It helped, no question, though I fear not enough that I can mix with confidence, as you say. The worst null is now at 80Hz, a scary frequency to lose for a guy who writes everything in E.

So I wonder: is there a strategy I can follow to determine where the worst reflections are coming from? Or is it just a matter of trying the big packs of fiberglass in different positions until something works?

 

[Ethan Winer]

DM,

> is there a strategy I can follow to determine where the worst reflections are coming from? Or is it just a matter of trying the big packs of fiberglass in different positions until something works? <

If you read through my various articles you'll see that the best place for bass traps is in the room corners.

--Ethan