I have been messing with this issue now for a few days on my own, and felt it is time to share with my fellows at AVS.
I recently revamped my home theater system by adding the following:
Using an RDL FP-UBC8 unbalanced to balanced converter I am running my 5.1 direct outs from my Onkyo 805 to a pair of Face Audio F500TS to run my LCR. I am running balanced out from the RDl to the balanced in on my sms1 then out to a qsc pl380 that is currently running a defunct mfw-15 with a dayton dvc 15 driver in it (I know...overkill, but new subs are next). I have dedicated 20 amp lines for the amps as well as Furman power regulators and PFi units.
Here is the issue. I have gone ahead and set my gain stage from Onkyo to amps, and then ran Audessey. When I am playing a bass heavy track I am very familiar with, the bass level (and subwoofer excursion) are in line with the level of my mains. Problem is, when I get close to -0- on the Onkyo, the bass (and excursion of the sub) is lower in level while the mains are obviously getting louder. It seems like there is a limiter of sorts butting in and clamping the sub out signal. I have checked to make sure all limiting is off on the amps, but still have the issue.
Any ideas as I was fine with a Face f500ts running the sub before without issue? Making me wonder if it is something to do with the QSC PL380?
Getting things ready for a new theater room build at the new house.
Equipment so far- (8) SI HT18 in mini martys, speakerpower SP2-12000, Denon 4311ci (may replace), MINIDSP 10x10HD, Harmony Elite, Oppo BDP-103D
TBD- Projector, AT Screen, speakers, acoustics, control system