Originally Posted by pinoy ako
Mr Bob, sorry for the noob question, what is the significance of the "FLAT" setting?
You mean after all this discussion of your Sub's protection you still didn't know what Flat does to begin with? Gosh!
ARC builds in a roll off of the lowest frequencies to protect Subs that need it. If your Sub doesn't measure as being good down to at least 20Hz that roll off starts earlier (at higher frequencies). You'll see that in the dashed black line Targets curve for the Subwoofer approaching the left side of its chart. If your Sub DOES measure good down that low the roll off is imposed anyway, pretty much mostly out of sight off the left side of the chart. The "FLAT" high pass filter option for the Subwoofer in the Advanced section of Targets eliminates that low frequency roll off.
For subwoofers without internal protection, this is BAD. You can damage the subwoofer if low frequencies are allowed to bottom out the cone motor.
It's even worse for subwoofers that can't function down that low to begin with, as ARC will apply boost to the low frequencies to try to compensate -- i.e., to try to get their output back up to "flat" down there. As you can imagine, this is why it is an "Advanced" option.
You should only enable Flat for the Subwoofer (Targets > Advanced) if the red Measured curve for the Sub shows it is already producing good output all the way down to 20Hz (the left edge of the chart) AND you know your Sub has its own built in protection against damage from the lowest frequencies, so it doesn't need ARC to do that protection for it.
And re Max EQ Frequency: Yes, ANY changes you make solely in the ARC Targets window do not require re-Measurement. Just Accept those changes, re-Calculate and re-Upload.
By the way, if you get confused as to what you've done in there, the Auto Detect button in Targets will restore the values ARC originally calculated for Targets based on the raw Measured data.
--BobEdited by Bob Pariseau - 7/15/13 at 11:27am