Originally Posted by nonstopdoc1
Do you guys set an upper frequency limit for the room correction or do you perform room correction on full frequency range?
This is always a good question, and in order to obtain an answer, you should experiment. And if you want a more objective answer than just the difference in how it sounds, you could try measuring the various options. Here are some examples. This was done with Dirac ver 1.0 (without DLBC of course), but the examples will be applicable to Dirac 2.0 as well.
First example is a typical custom target that attempts to boost the high frequencies (let's call this on Dirac Full Range). Not that my speaker has a natural roll-off above 4KHz, which Dirac is attempting to correct.
Second example is a custom target that follows the natural roll-off of the speaker in the high end (let's call this Dirac HF Roll-Off). Many Dirac users advocate this approach.
And the final example is a custom target with a correction cut-off at 4KHz, where the natural speaker roll-off begins (let's call this Dirac 5K Cut-Off).
Now, can we see a difference in REW measurements? First, compare Dirac off with Dirac Full-Range. In the high end, we can clearly see the boosted high frequencies. And the low end now reflects the 6dB bass boost in the custom target.
Now let's look at the Dirac Full-Range vs. Dirac 4K Cut-Off. No correction above 4K.
Finally, let's compare Dirac HF Roll-Off with Dirac 4K Cut-Off. Not much difference at all. Will it be audible?
So, now that we know the differences shown in the measurements, do our ears hear the same differences? TBH, since my hearing doesn't extend above 14KHz, I can't hear any difference. But with expectation bias, maybe you will hear a difference.
Finally, a quick example that reveals one of the key strengths of Dirac Live room correction, room reflections measured by the REW Impulse response (ETC) graph. Here is the ETC with Dirac off. A typical objective in a well-controlled listening room is to reduce all reflections below 20ms to -20dB or lower. Note several impulses extending above -20dB.
Here is the ETC with Dirac Full-Range. The overall level of reflections has been reduced considerably across the whole range. That is what Dirac does!