Room calibration

Posted by: Boltron

Room calibration - 10/06/12 06:32 PM

So I decided to measure to frequency response in my room. I am using a calibration mic with spectrum analyzer software (TrueRTA). As sound sources I used Audacity to create multi-channel PCM files with pink noise. I first used Audyssey to calibrate and then made my own tweaks.

My first question, am I correct to use pink noise over white noise?

In a typical room, what kind of spread would I expect to get after calibration? I seem to be getting +-5 db more or less from about 25Hz to 15KHz. Is this good, bad?

When measuring/adjusting frequency response, I am focused on the Front, Center and LFE. I approached this task by trying to adjust Front, Center and LFE individually and then combined. Is this a good approach?

It's funny, I have never tried measuring room response like this before, I always assumed it was pretty straight forward to do. Ha, once I started to plan for it, I discovered that there are tons of details to think about.
Posted by: JohnK

Re: Room calibration - 10/06/12 10:18 PM

Yes, pink noise should be used, as it's more nearly similar to music in its spectral distribution than white noise is.

The improvement from the results before room equalization would be the most significant measure, not the +/- numbers themselves.

One point that isn't entirely clear is how you're making adjustments to room equalization. You speak of using Audyssey first and then your own "tweaks", but Audyssey room eq isn't tweakable.
Posted by: Boltron

Re: Room calibration - 10/06/12 11:24 PM

Yes, in fact I discovered it is. You can set it to Manual and then it makes available a 5 channel equalizer that you can apply to different speakers. It also allows you to "copy" the equalization curves it set as a starting point. In addition I get an old fashioned tone control for bass and treble.

I like Audyssey but I find for movies there isn't enough of a high frequency roll off. And in playing around with the settings trying to find a way to lower the high end I discovered the manual stuff.

I am now able to start at the point Audyssey sets and then make my "tweaks". I need to do more experimenting but after my adjustments today, I think it is going to work out well.

Finally, manual adjustments are nice but I lose Dynamic EQ and Volume. I don't use Dynamic volume but I do/did use EQ. I guess I will know soon enough if I will miss it.
Posted by: JohnK

Re: Room calibration - 10/07/12 01:13 AM

No, that's incorrect. There's a choice as to whether to use the Audyssey adjustments or to turn Audyssey off and attempt a manual equalization, but the manual settings can't be applied to the Audyssey results. Dr. Kyriakakis has commented several times on this, for example here, and has emphasized that manual settings aren't possible while retaining the Audyssey equalization results. Again, there's a choice, but Audyssey can't be tweaked.
Posted by: MarkSJohnson

Re: Room calibration - 10/07/12 07:47 AM

That's why you're losing Dynamic EQ and Volume; you're turning off Audyssey.
Posted by: Boltron

Re: Room calibration - 10/07/12 10:31 AM

Thanks for the clarification and link. My intent was never to disable Audyssey, just make some minor adjustments.

Oh well, I like to tinker so no harm done.
Posted by: SirQuack

Re: Room calibration - 10/07/12 10:57 AM

you know what they say about tinkering...
Posted by: Boltron

Re: Room calibration - 10/07/12 03:28 PM

I might go blind?
Posted by: fredk

Re: Room calibration - 10/09/12 07:13 PM

Originally Posted By: Boltron
I might go blind?

No, but your Tinker Toy might fall off.