What you always need to remember is that there are lots of different ways of measuring things like frequency response (it seems like a simple thing - but it's not).
Just to pick an example to show you what I mean:
Let's assume that you had a pair of speakers that measured perfectly flat in an anechoic chamber.
And let's assume that your room has somewhat flexible walls, and some drapes, so maybe it's rather "live" for midrange, but "dead" for low bass and very high treble.
Now, let's put those speakers in that room and measure them....
If I put a microphone three feet in front of the speaker, and use a fast measurement technique, I'll be measuring just the sound coming directly from the speaker.
(I'll have finished my measurement before the sound reflecting off the walls has had time to get back to the microphone.)
With this measurement, I would expect a result more or less like the anechoic one - pretty much flat.
However, how about if I turn on a pink noise test tone, then take a measurement 50 milliseconds later?
Now what I'm going to be measuring is a combination of the sound coming directly from the speaker and the sound reflecting from the walls.
So, now, my measurement is going to show a peak in the midrange (because more midrange is being reflected back to my microphone than bass or treble).
In fact, if I wait longer before taking my measurement, or sum measurements over a longer window, the peak will be higher (because midrange will "build up" over time).
And we haven't even discussed the fact that almost all speakers have a rather different frequency response on axis than off axis.
This means that, if you were to measure them in an anechoic chamber, you'll get different measurements by putting the microphone in different places.
It also means that you'll get even bigger differences between those different measurement techniques.
A microphone placed directly in front won't hear much of the "to the side frequency response" at 5 milliseconds.
However, the longer you wait, the more contribution you'll get from sound that's leaving the speaker at all different angles - and bouncing around until it gets to the microphone.
So, which is these measurements is "right"?
All of them.
If you're wondering what I'm getting to here, it's this.....
Dirac measures a combination of direct and reflected sound... using their own proprietary analysis methods and settings.
Therefore, you shouldn't necessarily expect the Dirac graph to agree with one you make using REW (which uses some other method).
They MIGHT agree quite closely, or they may be considerably different.
And, since your brain acts as a sort of spectrum analyzer, it applies its own priorities, time constants, and "time windows" to what you hear.
(So it's possible that none of those graphs will agree precisely with what you hear.)
The upshot of all this is that you need to use the various tests and graphs as tools to help you figure out what's going on.....
But, like most tools, you can't always take what they tell you at "face value" unless you truly understand the context.
And you need to take all the information together to get anywhere near a complete picture.
(For example, in the example I gave, with the room that had much less absorption in the midrange than at the frequency extremes,
a T60 vs frequency plot would show you that the room was much more reverberant in the midrange, and less so at the frequency extremes.
You could either adjust this with room treatments, or take it into account when interpreting your other measurements.
In that case, you would
expect a graph made with a short window setting to be relatively flat, and you would
expect a midrange peak
in a graph made with a slow window, or with a meter and pink noise test tones - and take that into account.
And a pro, with lots of experience, would clap his hands, and note that the echo sounded rather sharp, and took a long time to die down.)
These are the things I would think I need to do next...
-Figure out why I have a dip at 7k in my speakers.
-Should measure in REW all speakers and subs independently AFTER Dirac, right? The sub graph is per Preset 2 like Tony said to set it up as. Maybe Dirac flattened a lot of that already.
Also notice I changed the thread title since now I need help with tuning and REW, hope that is ok to do.
regretted it ever since.
