Originally Posted by beastaudio
To get one thing out first, this is assuming you listen in xx.1 or xx.2 and are using the LFE channel for LFE only, not LFE plus main.
Yes, in my case, I am using a 7.4 system, with the 4 subs carrying LFE and bass from all the mains, crossed over.
I want to address this as I have always felt your approach is a major No-no when it comes to setting up your system.
Movie mixes as has been said are mixed with content up to 120hz on the LFE channel, thus the reason why this is the standard.
Yes, I understand your point and I do not disagree with it. Having worked for Dolby for 25 years (and helped define their bass management requirements) I am familiar with the concept. In an earlier post
in this thread I discussed some possible reasons why filtering LFE at, say, 80 Hz could be an option. My previous processor, a Tag McLaren AV32RBP, allowed LFE filtering at 80 Hz, 120 Hz, and none. It was rather illuminating to try them all. My current processor, the SSP-800, originally had the LFE filter set to 250 Hz IIRC, and that was not at all satisfactory, particularly with various 5.1 music. As it is not user adjustable in the SSP, they revised it for 80 Hz, which is an excellent "compromise" choice for movies and music. In other words, any degradation one might feel is being inflicted on movies is more than offset by the benefit in music quality.
If I had an 8801 with adjustable filtering, I'd probably still use 80 Hz for everything for the reasons discussed in the referenced post. That's just my preference based on what I like to hear. But I also said in that post that this is something tweaky users such as ourselves in this 8801 forum might like to experiment with and decide on their own. At least y'all have the luxury of being able to adjust it!
Now back to the LFE channel, if you are cutting it off at 80hz, that means there is content in movies that you are completely missing as it is NOT redirected to anywhere, as there is nowhere else for it to go.
Basically, if you run your LFE channel at anything below 120hz for movies, you are just leaving the 80-120hz of LFE content to not be reproduced at all.
As you stated in another post, it's not completely
Originally Posted by beastaudio
if the mixer chose to put an effect solely on the LFE channel, at say, 100hz, and you are crossing it at 80hz, you will miss it (Well not completely, as it will be reproduced in the rolloff, but at a much much lower level)
Let's put some objectivity into this. The diagram below shows 4th order lowpass filters at 120 Hz (green) and 80 Hz (red). It is the difference between these curves that we are talking about. At 120 Hz the difference is 8 dB, and at 100 Hz it is 6 dB.
If you are willing to sacrifice that to prevent the mix from sounding "boomy" then that is all good, but I prefer to have each channel reproduce as much of the intended content as possible, and in the case of the LFE that is leaving it at 120hz
I take no exception with your preference. I am just suggesting that other points of view also have merit. Did anyone going to Jurassic Park in DTS come away complaining there was not enough bass?
Well, that was 80 Hz worth of LFE.
Another thing to consider: Why 80hz XO for your mains? A simple answer is by 80hz, the response become omnidirectional (You really shouldn't be able to locate the source of the sound). Unless you have VERY capable speakers, a subwoofer is usually better suited to take over at this point, and much more efficient in reproducing these frequencies.
I agree on all points. While my L/R mains are pretty capable (Aerial 7B), I deliberately cross them over at 80 Hz to afford the maximum bandwidth to the subs which, as a group, counteract my room modes. They are all driven from the same mono signal, but each is EQ'd and timed by a JBL BassQ processor which was instrumental in solving some nasty lumpy and non-uniform bass. While it is a little out of date (does not reflect the addition of 4 ULS-15 subs), the basic concept is covered in this post
in case that is of interest.