Originally Posted by maikeldepotter
With full-range frequency correction, directional speakers which are not sufficiently aimed at MLP/measuring location can exhibit exaggerated highs for those sitting closer to on-axis. If that happens, limiting the correction to the lower frequencies might give better average results. I believe at a Trinnov class held at Pro Audio Technologies such limiting was applied (up to 120 or 200 Hz IIRC).
Here is a slightly different view.
If using full range correction and with speakers that are not sufficiently aimed at the MLP, using wider microphone placement during measurement can help deal with that issue.
My speakers ARE aimed at the MLP and I do use full correction. What I have discovered with the 77 bazillion corrections I have done in my room is that if I use the very narrow spacing (as shown on the Dirac screen when measuring for a single seat) I can, on occasion have some upper midrange glare and/or high frequency "bite". That may be caused when Dirac sees a narrow band dip in that frequency range and creates the filter to fix it. It is not atypical that if I move to wider measurement positions (but not as wide as the couch diagram), that problem disappears. That same technique would also help deal with the problem you described.
One of the many beauties of Dirac on the RS20i (and maybe even the LS10) is that you can create filters using different measuring positions for separate groups of speakers. In my case, I measure LCR's as a group, surrounds as a group, heights as a group and LFE as a group and then place each of those groups into the same Dirac slot. I also, therefore, have the ability to use different mic placement for each of those groups. So I do use wider mic placement for the LCR's than I do for any of the other groups. I also don't need to concern myself with the mic being out of direct line of site for the LCR's by where I put the mic. And, for example, when I measure the surrounds, I don't use the same measuring positions I do for the LCR's as I DO need to be concerned about blocking the mic from the speaker because of the back of the seat. And lastly, this allows me to only remeasure that group of speakers if I make a change to that group. For example, I will be replacing my height speakers at the beginning of next month and will only need to re-measure those. In my case, the primary benefit of this feature is the constant "diddling" I do with my subs in trying to achieve what I know they are capable of. I only need to re-measure one speaker (4 feeds 13) and it takes a very short amount of time.
Lastly, Dirac does not seem to do much correction in the higher frequencies. In some cases, it looks like it does none.
All of that to say, I have not found any downside of using full frequency correction. I don’t know anything about how Trinnov does room correction so maybe there is more benefit of not doing full range for that product.