Originally Posted by ralfwolf
I disagree. If the receiver in question does have a LFE "cuttoff" function, then that certainly would do what you say. In the DD spec, the .1 channel is a separate channel but is *not* a full response channel. The bitrate reserved for it would not allow it to be used for a good full freq channel. Also keep in mind that the LFE channel is *not* ALL of the low freq info in a given track. The amount of content sent to LFE vs main channels is up to the source mix. The crossover settings on the receivers redirect *additional* content mastered to go to the mains to be sent to the sub instead. Although it is very clear that LFE channel is not synonymous with sub output, I have never seen a receiver's bass management send parts of LFE to the mains. It's usually all LFE+main signal below crossover to sub if sub exists and mains set to small or LFE only sent to sub if mains set to large or LFE sent to mains if configured for no sub. If there is a receiver that has bass man that slices up LFE, I'd love to know which it is so I can go check it out.
BTW, there should be no phase issue. Signal is still mux'd within the receiver so no variable delays to cause any phase problems.
You're not paying attention to what I wrote.
I am well aware of what LFE is and how it differs from redirected bass. And I am desribing receivers and pre/pros that do NOT have any sort of "LFE cutoff" setting. What I am saying is that when any channels are set to SMALL, the way that the low-pass filter of the processor (the chip) works is that the full-range signal of those channels set to SMALL is first digitally summed with the LFE channel (the full LFE channel), and that then, the processor's crossover setting (really just the low-pass filter portion of the digital "crossover") is applied to that entire summed signal. As I hinted, this is done to prevent phasing issues that can occur if the LFE channel and the full-range signal of those channels set to SMALL are not digitally combined prior to the application of the crossover's low-pass filter. If they are treated independently, phasing issues between the LFE channel and the separately low-passed and redirected bass (which CAN contain overlapping info with the LFE channel), can and do occur. It is also, apparently, from an engineering design standpoint, "easier" for the chip to function this way.
If all channels are set to LARGE, then the LFE channel is not low-passed at all.
Read the OP's initial post. That he knows what I am saying is how many receivers/pre-pros operate is no accident. He has done his homework. There has been extensive discussion of this subject (the truncated LFE issue) here in these as well as other forums of this, unfortunately, inescapable "error". Perhaps this "error" has since been corrected, but I know that it was a major issue with processors, that received considerable attention, a few years back.http://www.google.com/search?hl=en&q...=Google+Searchhttp://www.hometheaterhifi.com/volum...rs-9-2002.html
This behavior can be confirmed with an audio frequency sweep that is reserved strictly for the LFE channel. Do you have the AVIA calibration DVD? If so, it has a track called "Low Frequency Sweep, LFE" that is exactly that. It can be used to confirm whether or not your processor behaves the way that I am describing. Observe (listen to) what happens to this sweep when all the speakers are set to SMALL, and the commonly used 80Hz crossover setting is used, versus the behavior of the sweep when all the speakers are set to LARGE.
BTW (and it is totally irrelevant to what we are discussing), although I, myself, consider it to be improper or incorrect bass management, there ARE processors that send LFE to both the sub and the mains when an LFE+Main-type setting is used. This is not how my Denon operates and it is not how most receivers operate. But I know that there are some HKs, SONYs, and (IIRC) Yamahas that operate this way. I have argued/pointed out that this is not true several times in the past and have been proven wrong by the owner's manuals for these particular products.