Subwoofer Question - What is LFE and How Does it Work?

[Benedict_Arnold]

On subwoofers. What is it, how do I select it and what settings should I use on my Marantz 7010? The subs I can figure out myself - theres a knob setting marked "LFE" and the right input channel is also marked "LFE". Simples.

Currently I have two Polk PSW110 10-inch 100 watt nominal units, one of which is kind of rumbling, rasping even, like it's got a blown speaker or something, but maybe I've got it plugged in wrong. It's still under warranty though, so it can go back to Polk for repair / replacement if needs be.

I'm also bidding on one on Fleabay, hopefully going to cost me under $100, so I'll have two working units, one being repaired. I'll be on the lookout for a fourth one in due course so I can have two at the back, two at the front. I'm going to "daisy chain" the two front ones to one subwoofer channel, the others off the second subwoofer channel. RG6 (shielded coaxial - much like UK co-ax for your TV) cable for the long runs through the walls / ceiling, then "proper" coaxial subwoofer cable between the walls and the subs. 4 x 100 W nominal should be enough in a 19 foot x 12 foot six room, don't you think?

 

[chebby]

Low Frequency Effects.

 

[Benedict_Arnold]

Low Frequency Effects.

And what is that when it's at home?

 

[The_Lhc]

Low Frequency Effects.

And what is that when it's at home?

The words are in English you know.

 

[spiny norman]

And what is that when it's at home?

The LFE input/setting on the sub is an unflitered full-range input, and so requires the amp/processor/receiver to do its own filtering so only sub-bass (or, in the case of a surround soundtrack, the '.1' bit) is fed to it, not all the other frequencies.

On content with a dscrete '.1'/LFE channel, such as most modern movies, this will be done automatically by the AV processing provided you've 'told' the processor you have a sub connected, and set the main speaker size appropriately (with small speakers on your main channels, some of the bass for those channels will also be fed to the sub.

When using a sub with the preouts of an amp with unflitered output on those preouts, for example when supplementing a pair of small speakers with a sub for two-channel music, you need to use the crossover control of the sub to set the upper roll-off of the sub so it stops working as the main speakers kick in. Otherwise unfiltered full-range signal will be sent to a similarly unfiltered sub, which will try to reproduce higher frequencies for which it isn't designed. And will thus sound horrible.

 

[Benedict_Arnold]

Low Frequency Effects.

And what is that when it's at home?

The words are in English you know.

Yeah, but does that mean I only get really low frequency stuff, vibrations basically, or will the subs still work to augment bass tones, say between 120 and 20 Hz?

 

[spiny norman]

Yeah, but does that mean I only get really low frequency stuff, vibrations basically, or will the subs still work to augment bass tones, say between 120 and 20 Hz?

Depends on how you have the sizes of the main speakers set, and the Low-Pass Filter for LFE setting. The Audtssey auto-set-up should look after all this for you, but it's not infallible, and a little adjustment from the Audyssey settings can often help tune the sound to your taste.

 

[Benedict_Arnold]

People on another forum are telling me I need subs that go down to 20 Hz and are at least 15 inches in diameter and 300 W RMS. Four of them for that size room. The Polks only go down to about 40 Hz and are only rated for 100 watts nominal.

Can someone phone Jodrell Bank and see if they still need those radio telescopes?

 

[spiny norman]

People on another forum are telling me I need subs that go down to 20 Hz and are at least 15 inches in diameter and 300 W RMS. Four of them for that size room.

Ah, well if you will go listening to people on other forums... ;-)

 

[expat_mike]

I think he mispelled the first post title. It should be 'What is LIFE and How Does it Work?'

 

[spiny norman]

I think he mispelled the first post title. It should be 'What is LIFE and How Does it Work?'

Nah, he's into home cinema: that and life are mutually exclusive.

 

[Benedict_Arnold]

I think he mispelled the first post title. It should be 'What is LIFE and How Does it Work?'

Gave up on LIFE when I got married :-(

 

[Benedict_Arnold]

Anyway...

A bit of a brain f*rt on my part, I'm just going to run a flipping long RCA subwoofer cable from the back of the source-end wall plate to a splitter behind the desitination-end one, fit an RCA cable splitter and run a second subwoofer cable to the other wall plate, or run two long subwoofer cables, one to left, and one to right, so I can decide whether I want left and right sub fields or front and back.

 

[7760]

Low Frequency Effects.

"Extension", actually.

 

[FunkyMonkey]

Low Frequency Effects.

"Extension", actually.

Effects