R/E/P > Acoustics in Motion
Free EQ room correction in a small room, Room EQ Wizard Rocks!
Thomas Jouanjean:
"You can't fix a time domain problem in the frequency domain"
There is just no way around it. I have never heard good results from EQing a room and using DSP correction.
But if the results made a positive impact on your work, then it's all good.
bruno putzeys:
Thomas Jouanjean wrote on Mon, 30 August 2010 12:24
"You can't fix a time domain problem in the frequency domain"
Of course you can. Time and frequency domain are the same thing seen from different angles. One reason why people don't believe it is because traditionally EQ's are minimum phase whereas acoustical problems are not, meaning that after correction you still have a smeared impulse response. If the EQ is a full FIR correction you can, in principle, correct everything...
BUT ONLY...
...in one spot in the room. Or n spots if you have n speakers. The issue has nothing to do with time vs frequency domain but with the fact that the room is a space and you have only two points (a pair of speakers) to control it by. If you have a dip at a certain frequency / spot, you will have a bump at the same frequency elsewhere. Correct the dip and the bump elsewhere gets worse. Room correction restricts you to sitting in one exact spot. That is why it doesn't work practically. However, if you are happy to have your head nailed down in one precise location you can remove everything. Echos, everything. Just don't move your head.
Thomas Jouanjean:
bruno putzeys wrote on Mon, 30 August 2010 06:30
Thomas Jouanjean wrote on Mon, 30 August 2010 12:24
"You can't fix a time domain problem in the frequency domain"
Of course you can. Time and frequency domain are the same thing seen from different angles. One reason why people don't believe it is because traditionally EQ's are minimum phase whereas acoustical problems are not, meaning that after correction you still have a smeared impulse response. If the EQ is a full FIR correction you can, in principle, correct everything...
BUT ONLY...
...in one spot in the room. Or n spots if you have n speakers. The issue has nothing to do with time vs frequency domain but with the fact that the room is a space and you have only two points (a pair of speakers) to control it by. If you have a dip at a certain frequency / spot, you will have a bump at the same frequency elsewhere. Correct the dip and the bump elsewhere gets worse. Room correction restricts you to sitting in one exact spot. That is why it doesn't work practically. However, if you are happy to have your head nailed down in one precise location you can remove everything. Echos, everything. Just don't move your head.
And thus, in my book it doesn't work in practice and has no real interest in studios. A good room should be quasi isotropic. Not a mediocre nail head sized sweet spot with everything even worse everywhere else.
I've also noticed severe degradation (in order of importance) of depth, "timbre" and stereo. Sound gets ghost like too.
Though I will recognize that the Trinnov guys etc, are all good engineers with excellent technique and deep knowledge of their field.
I've also good hope that these systems can compensate for some particular problematic speaker behaviours (phase issues etc). But I leave this discussion to speaker designers though.
Sorry I always sound like an old grumpy grandpa when these systems pop out
bruno putzeys:
Thomas Jouanjean wrote on Mon, 30 August 2010 13:53
And thus, in my book it doesn't work in practice and has no real interest in studios. A good room should be quasi isotropic. Not a mediocre nail head sized sweet spot with everything even worse everywhere else.
Indeed, I only wanted to point out that time vs frequency domain is not what lies at the root of this. Which doesn't mean that it works, unfortunately! (sorry for the hordes who hawk these things, and even sorrier for those who buy them).
Thomas Jouanjean wrote on Mon, 30 August 2010 13:53
Sorry I always sound like an old grumpy grandpa when these systems pop out
No worries mon vieux, you're not alone. *waves cane*
brett:
I notice no weird modes anywhere when I walk around the room. As I said the low end was pretty evenly rolling off after acoustic treatment. The only real issue was a mode at 100-160 in the upper bass low mids. Using a some minor cuts and boosts it fixed the problem. In a small home studio my work space is only between my monitors and they are only 3 feet apart. So where else would I be making decisions but here in the small area where I know it is accurate?
As said prior, I would not try and eq the highs, nor use eq to fix a null, but using eq to reduce energy that is omni directional does work, at least in this situation. You would be a fool if you thought a eq was going to make the entire room accurate. But the measurement mic is located where it needs to be and that turned out outstanding in my opinion.
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