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LFE Amp output question


Turbox
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hi all,

I have a question about the LFE subwoofer output on the amplifier. i will try to keep it short....

You can feed the subwoofer from the left and right preamp outputs of the amplifier into the subwoofer.

Or

You can feed the Subwoofer from the LFE output on the amplifier.

I have tired both. What is the difference? Are there pro's and con's to either? Should i expect to hear a difference?

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No difference, your subwoofer really does suck. Want me to take it off your hands? I'll offer $50 unseen & unheard...you pay shipping, mmmmmmkay???

( no clue as to your question but it will remain an open offer to buy for only the next 10 minutes... I don't have all day to wait ya'know)

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hi all,

I have a question about the LFE subwoofer output on the amplifier. i will try to keep it short....

You can feed the subwoofer from the left and right preamp outputs of the amplifier into the subwoofer.

Or

You can feed the Subwoofer from the LFE output on the amplifier.

I have tired both. What is the difference? Are there pro's and con's to either? Should i expect to hear a difference?

I assume you mean the LFE output on the AVR, preamp, or pre/pro, rather than on a power amp, which would be weird.

With movies, use the LFE output for sure. With a properly set up AVR or pre/pro, the subwoofer output will send all music and sounds below crossover (usually about 80 Hz) to the sub, AND also send the filmmakers' Low Frequency Effects below 120 Hz all the way down to 15, or 10, or even 5 Hz on some movies, to the sub. The Low Frequency Effects aren't necessarily available at the preamp outputs (but music and ordinary mid bass through high treble sounds are), or if they are, sometimes are truncated as to frequency or dynamics. The maximum level filmmakers intend to put into your room (fs, i.e., "full scale") are 105 dB for each of the main channels, and 115 dB for the sub (via the LFE output).

With music on CD (2 ch + sub), the two methods may be about the same. For multi channel SACD, I'd use the LFE output, in case their mix contains less restricted dynamics or bass frequency response through the sub output.

I use the subwoofer output (containing low music and sounds if bass management is set for it, and also LFE, which is why the sub output is sometimes called LFE) for everything.

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Fair enough Gary, this is exactly what am doing. Now we'll get to the real question. As you would expect, the LFE is a composite of all the low freuqency signals that should be sent to the Sub. regardless of which channel it was for left, centre, right, or otherwise, example, movies.

I am using a La scala for my centre channel, which as we all know is lacking on the bottom end. I would have thought, that any lack in bass would have been picked up by my sub from the composite LFE output of the amp as discussed above. With that said, I've still always felt that the centre was lacking on the bottom end... below say about 60-70Hz. I am not expecting alot of bass from the centre channel, 40, 30, 20 etc etc. It might just be me...

So for Fun i connected my KPT684/Crown XTI to the centre channel output along with the La scala, that seemed to fill in the bottom end of the centre channel.

I just would have thought that the LFE output would have taken care of all of the lower frequency heavy lifting.

Is it just me?

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Fair enough Gary, this is exactly what am doing. Now we'll get to the real question. As you would expect, the LFE is a composite of all the low freuqency signals that should be sent to the Sub. regardless of which channel it was for left, centre, right, or otherwise, example, movies.

I am using a La scala for my centre channel, which as we all know is lacking on the bottom end. I would have thought, that any lack in bass would have been picked up by my sub from the composite LFE output of the amp as discussed above. With that said, I've still always felt that the centre was lacking on the bottom end... below say about 60-70Hz. I am not expecting alot of bass from the centre channel, 40, 30, 20 etc etc. It might just be me...

So for Fun i connected my KPT684/Crown XTI to the centre channel output along with the La scala, that seemed to fill in the bottom end of the centre channel.

I just would have thought that the LFE output would have taken care of all of the lower frequency heavy lifting.

Is it just me?

Hmmmm....

Is your main crossover (not the LPF for LFE, which should be 120Hz) to the sub about 80 HZ (the usual)? I have a Belle Klipsch center, not a La Scala, but they are supposed to have similar bass. My Belle, in my room, from my listening position, has a little peak at 60 Hz (before taking a nose dive below that), which is reduced when crossing over to the sub at the (THX & Audyssey) recommended 80 Hz. I missed that peak, so I turned up the sub a few dB for this and several other reasons, and I'm happy.

So, all I can think of is that when crossing over to the sub at the usual 80 Hz may rob you of a peak you like ... or ... if your sub is located in a very acoustically different place than your center La Scala, there may be a null in the room near 60/70 Hz, or below, or above. Moving the sub may help? Otherwise I'm at a loss.

Edited by Garyrc
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The Klipschorn and LaSala can be xo lower than 80 Hz if using only one subwoofer. This will leave a little more bass in the mains and center to help balance the bass in the room. A xo of 50-60 Hz may work well. Even distribution of bass can also be accomplished with multiple subwoofers.

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Did I read LFE/sub output on a receiver, integrated amp.

Better use the sub/LFE out.

The mains should be relieved from the deepest bass they cannot reproduce properly. This offloads the speakers and amp section in the integrated/receiver.

Even with very capable mains like the larger Klipsch Palladiums or the Dynaudio S5.4 I have I set the crossovers to 60Hz, I want the impact/slam from the mains but the true LF from the subs.

You would have to use truly huge mains capable of true 16Hz performance @ high SPL to negate the need for subs. And how many speakers fit that bill, not even the imposing Wilson Alexandria X2's, once you relieve these from 40hz down, and add a proper sub array. These is no mains in the world that rival the displacement and extension of a sealed array.

I do not see why you would not use a LFE/sub out for a powered sub? unless the crossover point is fixed and ruians the mains/sub match in your room.

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