.1 LFE question (1 Viewer)

[AlanZ]

I should know the answer to this but for some reason I am unsure of myself tonight. When you are running DD-DTS, does the subwoofer get both a discrete signal (.1) and whatever is below the crossover point for the other five speakers? Or does it only get the summed bass from the five main channels and there is no discrete signal? For some reason I kept thinking that a sub would only reproduce bass from the 40Hz crossover point (Studio-100's) and below. I completely forgot that there was a separate signal going to the sub irrelevant of where the crossover is set (assuming all speakers set to small) please help me with this brain-fart.

 

[Doug BW]

The subwoofer gets the .1 (LFE) channel plus everything below the crossover frequency for any small speaker. (Of course since the crossover is not a "brick wall", the sub also gets a little bit of the stuff above the crossover frequency as well.)

You might be interested to know that many receivers run the LFE channel through the low pass filter of the crossover. This means that if you have your receiver's crossover frequency set to 40 hz, you may be throwing away a lot of the bass above 40 hz in the LFE channel. (See this article for more information.) You may well be better served by setting your crossover frequency to 80 hz.

 

[Brian Fellmeth]

You might be interested to know that many receivers run the LFE channel through the low pass filter of the crossover.

My God, I had no idea. This is... shocking. This is idiotic. I hope my receiver isn't doing this bonehead move.

 

[Edward J M]

I hope my receiver isn't doing this bonehead move.

It probably is.

Theoretically, the LFE channel can extend up to 120 Hz. In reality (as the article states), there is hardly any LFE ".1" signal content in the 80-120 Hz region.

This is a good thing, because most of us with larger surround speakers do use an 80 Hz crossover to the sub, and I think the sound engineers who mix DVDs recognize that.

Heck, if I used an 80 Hz high pass for all my surround channels, I wouldn't want the sub playing the occasional 120 Hz signal from the LFE channel - it might be too easily localized at that frequency.

Regards,

Ed

 

[AlanZ]

Hmmm....this is kinda disturbing. When I was deciding between the Paradigm Studio/100's and the Studio/60's, I knew that I was going to have a sub in the mix. If I set the crossover in my mains to 80hz, then I would kinda feel like I would have been better off with the Studio/60's since I would cross them over at the same point anyway. What advantage do I have with the 100's over the 60's if I have a sub??

 

[Brian Fellmeth]

This is a good thing, because most of us with larger surround speakers do use an 80 Hz crossover to the sub, and I think the sound engineers who mix DVDs recognize that.

This is not a good thing. I cross my receiver at 60, and I don't want the LFE channel filtered. If the engineer put it in there, I want to hear it even if its high enough to localize to the sub.

 

[Zack_R]

The only way to know if your LFE high cut does this (provided your receiver manual doesn't say so) is to experiment with different movies. Adjust your LFE cut to it's highest position and your speaker crossover to it's lowest postion. Play a LFE heavy scene and then crank the LFE cut down. Replay the scene and see if there was any change to LFE.

 

[Edward J M]

Brian:

I agree, in theory it's not a good thing, but most of us have to live with it because precious few AVR's and pre/pro's have the capability to independently set the high/low pass filter points for each channel.

What I did say was it's a good thing the LFE channel does not have much bass content above 80 Hz, because most of us have to endure low passing it along with the bass from any surround speaks set to small.

I agree with you completely, you are probably losing some of the LFE channel if you are high passing all your surround speaks at 60 Hz, unless your AVR or pre/pro has the capability to separately set the low pass frequency for the LFE channel.

You might want to reconsider an 80 Hz crossover point for this reason alone.

Regards,

Ed