Originally Posted by info_dan
Thanks for testing! I see a few issues in your test though:
In the first phrase, you say "LFE channel attenuated". In the last phrase, you say "left front is not attenuated". Which was it, LFE or left front?
Also, if your surrounds are set to small, then the sub was playing the low frequencies from the surrounds. To improve your test, either:
1) Put ALL your speakers as large, not just the fronts
2) Or create a "2.1" wave file (Left + Right + LFE only)
3) Or make ABSOLUTELY sure that there is complete silence in the center and surround channels.
Also, make sure that the AVR is in "Direct" mode (not Pure Direct), because all these THX & Dolby, and so on, might re-mix signals.
every point well taken. someone else a while ago had reported results that he claimed indicated sub was getting all bass even though he had fronts set to Large. he also did his test with a You Tube test tone on 2 channels but it was identical on both channels so in effect is a mono signal
but he had it with PLIIx engaged so even if his center & surrounds were unplugged, the processing would have sent their bass to the sub because it probably sensed an identical 2 channel tone as mono and directed it to the center channel. the only way to tell for sure what happens with the fronts & sub is to use a true 2 ch source and not use processing:
1. in Pure Direct mode with a calibrated MCACC preset
2. in Pure Direct mode with MCACC OFF preset
3. in Direct mode with a calibrated MCACC preset
compare results to see the effect of xover and:
1. how MCACC effects bass mgmt
2. how MCACC being completely turned off effects sub output in Pure Direct mode. just because you're in Pure Direct doesn't mean all of MCACC is turned off, because the part that sets the channel preamp levels is still on unless it's completely turned off. if the new receiver doesn't have a MCACC Off preset, then select one that hasn't been calibrated, say M4-M6 which should all be zero'd out as defaults (unless M1-M3 had been data copied to one of them)
BTW - Eventually, after several tries, I was able to duplicate that guy's results so it wasn't his measurements that were suspect. but the use of the Dolby Prologic decoder heavily influences how the bass mgmt system gets used. I unplugged the sub, unplugged the center & surrounds, turned off the center & surrounds in the setup menu, then engaged PLIIx & sure enough, using the Xover reduced the volume of a mid-20's mono (or double stereo) test tone in the fronts. which is what he observed. his test could have been flawed by using Dolby IIx processing with the monophonic nature of the test tone, or the Xover really does have an effect on what gets sent to a Large speaker. hard to tell from his test conditions.
I haven't done any more testing of his theory since then. most of my own "interpretations" are based on Pure Direct mode and what I see on the Velodyne sub's RTA when I have fronts as Large, then add the sub in Plus to see the combined effect, I then EQ the combined. at least that's what I did before getting an Audyssey based SVS EQ
using the SVS unit, I bypass the Velodyne's EQ'r.Edited by ss9001 - 5/6/13 at 2:22pm