Hey Kurt,
I probably should have been more detailed or clear, but didn’t want to hijack the thread too badly. But since you asked...
Basically, equalization and room treatments really don’t have a lot do with each other. If your room is made of glass and reverberates and echoes like crazy, there’s nothing equalization can do for that!
Check out this little chart below I recently came across on another Forum that shows the effects of treatments in a room (click on it twice and it should open in another window):
With the top row of boxes, the room has no treatment and has lots of reflections, as the ETC graph (column A) shows. The audible effect of the reflections is seen in the ragged frequency response with lots of comb filtering (column B). Notice that as treatments are applied (e.g. the rows progressing top to bottom), frequency response becomes less ragged and more linear.
But notice the “B” box in the last row: Even with optimal treatments in place, frequency response is still in need of equalization. So, even though the treatments tamed the reverberation, they did nothing for the anomalies in response.
Now, if your room is “live” like we see with the top row, you could use the 1/3-octave smoothing feature with response graphs generated by a program like REW. That would minimize the effects of the comb filtering and get you a graph that looks more like the one on the bottom row, and you could equalize based on that. And you’d get an improvement in sound quality even if you still have all the reverberation. But the equalizer has no effect on the room itself.
It’s commonly known that below about 500 Hz, the room influences the response of a speaker. EQ can help with that and make an audible improvement, but again, it’s really just providing some
compensation for the room. It’s not
fixing the room. There are treatments that can work down in this range, but from what I can tell from graphs I’ve seen they mainly absorb energy and reduce decay times; they don’t totally address response anomalies the way equalization can.
So hopefully you can see the difference between treatments and equalization: Equalization is not going to fix reverberation problems; that requires absorption and / or diffusion. But absorption is not going to fix any underlying problems with response that might be present. That requires equalization. Make sense?
Really, about the only room issue an EQ can address is a mode in the bass frequencies. But again, it really doesn’t “fix” the problem. It merely deprives the sound system of energy (amplitude) at the offending frequency. Fortunately this is sufficient for improved listening: Since the audio reproduction is “artificially” generated by an electronic system, it’s easy enough to employ electronic equalization to “artificially” address the problem. But of course that doesn’t
fix the problem - it won’t be a help if you invite a musician friend over to play his upright bass or cello in your listening room. There is no facility for equalizing built into an acoustic instrument.
Regards,
Wayne A. Pflughaupt
