sub wiring - whats the diff?

miandsh2000

whats the diff between the LFE input, red and white RCA inputs, and the speaker line inputs?

can i just use the LFE? what am i gaining or loosing by doing that?

this is used mainly as a HT setup.

thx

SuperDave

The LFE input is a low frequency filtered input. Depending on your source, it usually tops out around 100 HZ. Your receiver may be configurable. Also for home theater this channel is the .1(5.1,7.1) special low frequency effects channel that carries all the thunderous effects on your movies. I use the LFE for audio and home theater on my LSi25's and they sound great. You definitely want to use it for home theater, and you can experiment if you want for home audio. I leave mine in LFE.
Good Luck
SuperDave
Yamaha RX-V992
Panasonic DVD-A310
Sony XBR 27"
DVR
Polk LSI 25 Fronts
Infinity CC3 Center
Infinity RS1 Rears
Monster THX Cables

McLoki

SuperDave wrote:

The LFE input is a low frequency filtered input.

I think you are mistaken on this. The LFE input is unfiltered (bypasses the crossover built into the sub) and should be plugged into the filtered (sub output) of your AVR. (SUB set to ON in AVR)

The line level left and right (white and red RCA's) use the filter built into the sub and can take a full range singal from the left and right channel of your avr and will filter out everything except the bass based on the crossover setting you use in the sub. (SUB set to ON in AVR (if plugged into your sub ut slot - turn crossover frequency as high as you can)) (SUB set to OFF in AVR (if plugged into your line level outputs for your front left and right speakers))

The speaker level inputs take a high power full range signal (like the one going to your left and right speakers) and not only filters the sound but drops the power down to line level so your sub amp can re-amplify the signal for your bass. (it will also pass the non-filtered speaker level input though to your speakers if you hook them up that way.) (SUB set to OFF AVR)

IMO - the best sound for home theater is by hooking up using the LFE input. If you have problems getting the sound to integrate well with your main speakers, go ahead and try one of the other two choices.

SuperDave

You are right the filtered part comes out of the receiver sub out not the sub, but the intended input to the LFE is a filtered input from the sub out.
Whew

miandsh2000

tell me if my comprehension is correct here.

since i will be setting up my speakers (right, center, left, rt surround, center surround, lt surround) as small, i can use the LFE hookup and it will send the bass only to the sub. this will also send my low frequency to the sub when listening to music.
the only thing i have to hook up to the sub is my LFE.

is there a case when i would use the LFE and the speaker level inputs?

SuperDave

right just the LFE, never both, one or the other

McLoki

miandsh2000 wrote:

is there a case when i would use the LFE and the speaker level inputs?

You would not use both. In most cases the LFE is your best choice. Where things start to get hairy and you may want to try the other inputs is if you do not have a variable crossover in your AVR *AND* your main speakers do not have a -3db point down to at least the crossover frequency.

i.e. - you have a small set of sattelight speakers like the polk RM-6600 series that only plays down to about 150hz. If your AVR had a fixed crossover for your subwoofer at 80hz you would not hear anything between 80 and 150 hz. In that case you could hook the sub up with the right and left speaker outputs from your avr (line level or speaker level) and adjust the crossover on the subwoofer so it can play the missing frequencies.

If your main speakers will at least play down to the crossover point of your avr (usually 80-100hz) *OR* if you can adjust the crossover to a level that your speakers can play, usually the LFE input is your best choice.

Clear as mud?

Michael

PolknPepsi

My stereo receiver does not have an LFE jack or variable crossover so I have to use the crossover on the sub. I can use the RCA or speaker binding posts to get a signal and I like speaker level.

Everything works well..........

kmartin971

http://www.onhometheater.com/product/20020215.htm

Red this review it explains the sub question you have perfectly!

"The $780 PSW 650 is a very serious subwoofer. It's self-powered, with an internal 165W amp capable of supplying 250W for short-demand peaks. It can be connected to systems with line-level or speaker-level signals and it even has its own 80Hz low-pass filters on both inputs -- a nice touch for systems without adequate bass management. The PSW650 also sports an LFE input that bypasses its own low-pass filters for when a processor's output is already filtered. (You don't want to double low-pass filters!)

Most subwoofers make you crouch down behind them if you want to make adjustments. The PSW650 has a discreetly placed level control on the front panel. I hate audio gear that makes me kneel before it (or behind it), so I definitely approve."

tommyboy

hey fellas,

just a quick question from a polkie. If you have towers that can handle 80 to 150hz, does that mean you are better off using the LFE out or will it still sound better with speaker connections from the fronts?

aaharvel

depends on the slope of the LFE. If it's a sorry 6db/octave like in most subs i've seen, I would run the subwoofer crossover in conjunction with the receivers. I've made this argument before.

http://www.polkaudio.com/forums/showthread.php?t=36742&highlight=case+crossover

Willow

miandsh2000 wrote:

tell me if my comprehension is correct here.

since i will be setting up my speakers (right, center, left, rt surround, center surround, lt surround) as small, i can use the LFE hookup and it will send the bass only to the sub. this will also send my low frequency to the sub when listening to music.
the only thing i have to hook up to the sub is my LFE.

is there a case when i would use the LFE and the speaker level inputs?

Depends on what type of speakers you use. Sub/sat..use speaker cable method. Anything else (unless stereo receiver with no LFE) use LFE out

SuperDave

I use the LFE to drive the low end (lsi25s) so my receiver doesn' have to work so hard

SuperDave
Yamaha RX-V992
Panasonic DVD-A310
Sony XBR 27"
BrightHouse DVR
Polk LSi25 Fronts
Polk LSiC Center
Infinity RS1 Rears
Monster THX Cables

r.camacho1

Does anybody know what would happen if you plug into both inputs if you use a y-adapter?

charliez

Does anybody know what would happen if you plug into tape rec output on AVR, since my sub does not have an LFE input??

McLoki

You would need some sort of a low pass filter to keep the subwoofer from trying to play high frequencies.

Other than that - it should work.

Michael

TheReaper

The tape rec outputs are fixed volume outputs. You want variable outputs, so that when you turn up the volume on your receiver, the volume on the outputs goes up also.

McLoki

Good catch - didn't think of that.

Your best best would be to go inline with your front speakers and set your front speakers to large. (provided your sub has high level inputs and outputs...)

Michael

charliez

Hi Folks. Thanks for your comments. I´m really quite happy with the sound hooked up through left RCA in. But I know that double filtered is present. Do you think that going through speaker level will improve the sound?
The fact is that my sub need 30' of wire to reach the AVR. So, going through speaker level I´ll need a lot of cable to run.

In my AVR I can tweak: -Crossover for all channels (It´s clear to me) but
-LFE Mix Level (???)
-LFE High Cut (???)
Any recommendations for those two settings??

Thanks