Crossover for LFE channel?? - Denon 4306

[Tomorrow]

This brings me full circle to my original question. The LFE does have a crossover value on my receiver. The earlier discussion said this is a "top cut" as opposed to a "bottom" cut that applies in the case of all other speakers. So what is it top-cutting.... the LFE signal? And if the small speakers are set to 120, it still seems to me that I'm left with a dead zone between 80 and 120.

Thanks for your patience!

Doh...I just reread your original post.

I am not familiar with this setting and capability. Maybe one of the Denon 'sperts will chime in. If it truly IS a top cut, I would only guess that this setting allows for the diversion of some, but not all, of the LFE to the mains. Strange...but then nothing in modern audio surprises me anymore. It seems it should really be a bottom cut...saving the sub from some non-producible or potentially harmful signals. But I dunno.......

 

[abetaque]

These are the different sets of speakers that I can set a crossover for:

Front
Center
Surround A
Surround B
Surround Back
LFE

I can set a different value for all of them.

Maybe a real simple hypothetical will help me out:

Front 80
Center 80
Surround A 120
Surround B - Not connected.
Surround Back - Not connected.
LFE - 100

Assume that the crossover on my sub is bypassed.

Under this hypothetical, what is happening when using a DD 5.1 source with:

1. Signals sent through the LFE output on my receiver?
2. Signals sent to the Surround A speakers?

Thanks!

 

[Tomorrow]

These are the different sets of speakers that I can set a crossover for:

Front
Center
Surround A
Surround B
Surround Back
LFE

I can set a different value for all of them.

Maybe a real simple hypothetical will help me out:

Front 80
Center 80
Surround A 120
Surround B - Not connected.
Surround Back - Not connected.
LFE - 100

Assume that the crossover on my sub is bypassed.

Under this hypothetical, what is happening when using a DD 5.1 source with:

1. Signals sent through the LFE output on my receiver?
2. Signals sent to the Surround A speakers?

Thanks!

Does your manual state whether the LFE crossover is top or bottom cut? Have you tried xover settings, say of 20 and 120 on the LFE to see what happens with the speakers (and sub)? Trying that may give us a clue as to what you're dealing with.

 

[Nick250]

These are the different sets of speakers that I can set a crossover for:

Front
Center
Surround A
Surround B
Surround Back
LFE

I can set a different value for all of them.

Maybe a real simple hypothetical will help me out:

Front 80
Center 80
Surround A 120
Surround B - Not connected.
Surround Back - Not connected.
LFE - 100

Assume that the crossover on my sub is bypassed.

Under this hypothetical, what is happening when using a DD 5.1 source with:

1. Signals sent through the LFE output on my receiver?
2. Signals sent to the Surround A speakers?

Thanks!

1. All LFE material under 100Hz goes to the sub. I don't know what happens to LFE above it. Perhaps it gets redirected to the mains. At this point I would set the LFE crossover as high as you can because you want your sub to receiver all LFE and keep all LFE away from your mains. That is the way just about all receivers do it anyway, without giving you the choice. To do this properly your mains must be set to small. Is that how you have them set? This is important for us to know because it will probably change the options your receivers presents to you.

2. All surround frequencies below 120Hz go to the sub and all frequencies above 120Hz go to the surround. There is overlap, but you get the idea.

Nick

 

[abetaque]

Thanks a lot Nick. I think that answers my question. (BTW - All of my speakers are set to Small).

 

[mulester7]

1. All LFE material under 100Hz goes to the sub.

.....not if the LFE is set to top-cut the sub signal at 60, Nick....does choosing 60 on the LFE automatically do something with the main's regiment signals?....Buck, where you at?....you've mentioned before listening with your main's regiment bottom-cut at 40, and your sub getting 40 down from the LFE on certain types of music....we ain't done with this yet.....

 

[MDS]

'top-cut' and 'bottom-cut'

Using the correct terminology may help to explain this stuff a bit better. There are 'high pass' and 'low pass' filters (ie crossovers). A 'high pass' filter lets the highs pass - in other words it lets the frequencies above the xover frequency pass onto their destination (taking into account the slope of the xover, such frequencies are not exactly the one set). The 'low pass' filter does the opposite - it lets the lows pass.

The xover frequency you set for all channels other than LFE are high pass. Consider that the whole reason you set a xover is so that you don't send the speaker frequencies that are too low for it to to handle effectively. Bass management is pretty standardized and receivers employ both a high pass and low pass filter for each channel but YOU get to set the high pass only. The typical high pass filter is 2nd order (12 dB per Octave) and is combined with a 4th order (24 dB per Octave low pass). So if you set a xover of say 100 Hz and set the channel to Small, the receiver will start attenuating the signal below 100 Hz - at about 50 Hz there will still be some signal going to that speaker but it will down about 12 dB (assuming the normal 2nd order slope). At the same time, the frequency an octave above that xover (200 Hz) will be cut by 24 dB so that mostly 100 Hz and below go to the sub. Note that this is why the standard recommendation is to set the xover at at least 1/2 but preferably closer to 1 full octave above the lowest frequency that the speaker can effectively reproduce. Due to those slopes, the speakers will still get some signal below the xover frequency (but greatly attenuated) and the sub will still get some signal that is above the xover (even more attenuated). The blending of those two portions of the signal is what allows the seamless transition as if one speaker gently handed off the signal it can't deal with effectively to the sub.

Now if the Denon also allows you to set a xover for the LFE channel, then it is a low pass. As stated above, LFE always goes to the sub if you indicate in the setup that a sub is present. The LFE channel may contain frequencies all the way up to 120 Hz, but generally only contains much lower frequencies. If you set that xover to 100 Hz and the LFE channel does contain frequencies all the way up to 120 Hz, then you will chop off a portion of it (actually it will be attenuated somewhat - not entirely dropped). I don't know what value a receiver that does not allow you to change it would use, but I don't see any reason to set the 'LFE xover' to a low value unless for some strange reason you feel like you only want the very lowest frequencies to go to the sub.

 

[Nick250]

.....not if the LFE is set to top-cut the sub signal at 60,

I don't know what you mean by this. In the receivers I have personal experience with, Denons 3806, 1705 and Onkyo 595, all LFE frequencies ALWAYS go to the sub if you told the receiver that a sub is connected to the receiver, repeat all frequencies. Further on these receivers you can not modify this, it's fixed. You can play with these crossover frequencies on the back of the sub, but as I stated previously it's best to defeat these controls and use the receivers bass/lfe management.

Nick....does choosing 60 on the LFE automatically do something with the main's regiment signals?

Maybe, if the mains are set to large. Again, most systems including THX specs mandate a crossover of 80Hz if I am not mistaken.

Mule, it seems to me that what you are wanting to discuss goes far beyond the scope of what the OP asked. You are far off on a tangent it seems to me. That being the case I think perhaps you might consider letting others more familiar with bass management on modern av receivers such as rjbudz (or me or Buck or others) advise the OP on this simple setup issue and start a new thread if you really want to get into different aspects of this. Just my opinion.

Regards, Nick

 

[mulester7]

......Gentlemen, 120 hz, is a lot lower than most of us think....I've been using my Paradigm X-30 here lately to send mono signals to my high small cannons from 150 hz down....at 150 hz, any midrange talking you may get is VERY muffled and usually indistinguishable....at 80, you may or may not be able to tell what key you're in with music, and ALL you have to go off of is the very lowest stuff from say a bass guitar, you hear NO voices talking or singing....at 50, forget it, you don't have a clue what key you're in with music....24 db's of rolloff is very effective around 100 hz....MDS, great post....cleared up much....sure, high-pass and low-pass filters....to me, it's just been more quickly clear, to say bottom-cut and top-cut knowing which one to use.....

 

[mulester7]

Mule, it seems to me that what you are wanting to discuss goes far beyond the scope of what the OP asked. You are far off on a tangent it seems to me. That being the case I think perhaps you might consider letting others more familiar with bass management on modern av receivers such as rjbudz (or me or Buck or others) advise the OP on this simple setup issue and start a new thread if you really want to get into different aspects of this. Just my opinion.

Regards, Nick

.....Nick, I believe you're right, and bravo for speaking your thoughts in the right manner....I guess I have heard things about LFE and never experienced it is my reason for wanting to learn more....but just answer me this, and I'll quit....can, or cannot, a receiver's LFE be set at different values to send on to the sub?....good man, Nick.....

 

[Nick250]

.....Nick, I believe you're right, and bravo for speaking your thoughts in the right manner....I guess I have heard things about LFE and never experienced it is my reason for wanting to learn more....but just answer me this, and I'll quit....can, or cannot, a receiver's LFE be set at different values to send on to the sub?....good man, Nick.....

I have not seen setting LFE to different values, but the OP has it on his 4306. The standard for the highest LFE frequency is 120Hz. Here is a guess. LFEs above say, 90Hz might be directional. Perhaps in some situations a user might want to redirect the highest frequencies of the LFE to his mains. I think I will go to the Denon site take a peek at the 4306 manual and see what I find. Here is an AVS Forum thread on crossovers that delves into all things about them.

http://www.avsforum.com/avs-vb/showthread.php?t=632922

Nick

 

[abetaque]

Just a little more information..... the LFE is adjustable from 80 to 120.

 

[billy p]

Thanks For The Link

http://www.avsforum.com/avs-vb/showthread.php?t=632922

NICK!
It answered one question in which I deliberated about and that was the disableing of the sub!I know this sounds DUMB but I was not sure how to accomplish that because turning up the sub to me means going down the Hz scale not up. I know I'm thick still learning..

 

[AVRat]

This is a unique feature on the new 28/3/4-series Denons. Since your rears require a higher x-over point and to get the full LFE signal, set the LFE X-over to 120. Don't know why Denon added it, maybe for THX purposes.