Originally Posted by jkozlow3
Thanks Mike. I'm pretty familiar with Audyssey (been using it for years) and I do use DEQ on the lowest setting with a RLO of 15.
You might be right about lying to the Denon AVR after running the Audyssey calibration without a sub. I may not be able to set the front speakers to small at that point and keep Audyssey enabled, as this would require me to indicate that a sub was connected in the AVR settings/GUI. I haven't tried that, as I currently DO have a sub (I'm experimenting with lying to the AVR, but the calibration was done with the sub hooked up). This may not be an option if I run Audyssey in an apartment without a sub hooked up at the time of calibration.
And of course, if I set the mains to large/full-range, the crossover setting has no effect, so there is no real way to keep sub-40Hz content from being sent to the mains. It seems odd to me that there is no way to prevent this. Surely I'm not the first person to have this need/desire to protect their bookshelf/monitors from damage due to low frequency LFE content????
You are very welcome! I will give you my thoughts on this whole protection issue for whatever they are worth.
First, I don't see the situation with LFE content as being particularly dire. Let's forget about LFE for a moment and just take a hypothetical example. Assume that we're listening to jazz (acoustic instruments) with no sub, and bookshelf speakers that have an in-room response of 60Hz. What happens to the musical content below 60Hz? I believe that the speakers simply roll-off naturally below 60Hz. The roll-off is faster if they are ported speakers, and slower if they are sealed speakers, but in either case they just play frequencies below 60Hz much softer than frequencies above 60Hz, until they are no longer audible at all. That means in our jazz example that we won't hear the low fundamentals of a kick drum or an upright bass. We will still hear most of the notes (and our brains will fill-in some of the missing information) but we won't hear the lowest notes at normal volume, or at all.
A problem only arises if we try to boost our MV, or use bass tone controls, or DEQ, to try to force those speakers to play frequencies louder than they are inherently capable of playing them. So, if we are listening to jazz at -20 or -15 MV, and we hit a low bass section and decide to increase our MV to -10 or -5, or even Reference, then we might have a problem. And it would probably be a problem for both our speakers and our amplifier, in that case. We would probably have distortion if nothing else. But at reasonable or "normal" volumes there shouldn't be an issue at all. We just wouldn't hear some of the low fundamentals of certain instruments with speakers that only went down to 60Hz.
I believe that the same reasoning applies to LFE sounds potentially going to Large speakers, or very low frequency sounds deliberately encoded into the front channels with films or electronic music. As long as we are operating at reasonable listening levels, our Large speakers will just naturally roll-off wherever they do, and there won't be a problem. It's only if we tried to push the speakers to do something that they can't, with trim level or MV, or whatever, that we would encounter a problem.
I also believe that Audyssey would not contribute to the problem with its filters set during calibration. When Audyssey does its pings, it is setting each speaker pair, independently of any other channels in the system, based on the measured F3 point of that pair. So, at the lowest frequency where one speaker is down 3db in volume, Audyssey will stop setting filters for that pair so that there will be no chance of boosting a speaker below its low frequency capabilities. So, Audyssey will provide its own protection to the speakers irrespective of Large or Small settings subsequently made by the AVR, or by the user.
DEQ is a bit of a wildcard in all of this, IMO, because it does boost bass across all channels. But it sounds as if you already have a good handle on that. One thing, which you probably already know, is that if you set your MV at -15 with an RLO of -15, DEQ will essentially not do anything. When you set an RLO of -5, you tell Audyssey to start engaging DEQ at a -5 MV. An RLO of -10 engages DEQ at a MV of -10, and so on. Audyssey's explanations of this have never been very clear, but there are graphs in the technical addendum of the FAQ which show the measured effects of DEQ at different MV levels, and with different RLO settings. So, for instance, a MV of -15 with an RLO setting of -10 would allow DEQ to do just a little bit of boosting. Again, you may have already understood that part.