LFE vs Sub out with Large speakers and no sub - AVS Forum
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post #1 of 15 Old 09-29-2010, 09:34 AM - Thread Starter
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Hi,

I am setting up a home theater and have a question on bass and lfe.
Currently i have two Tower speakers for the fronts and a receiver.

THe fronts are full range and have 8 inch subs with built in 225 watt amps.
They also have lfe inputs.

I do not plan on purchasing a sub as these fronts produce plenty of bass, are self powered and sound great.

My question now is, which of the following should I do:

1. use the receiver to set the front speakers to large and redirect the lfe to the fronts as apposed to a sub

2. connect the sub out on the receiver to the lfe in on the front speakers, leaving the fronts as small and having the lfe signal sent to the sub out

3. can i do both? or is that just useless?

I am trying to understand the difference. I'm under the impression that if i use the receiver to send the lfe ouput to the fronts, the receiver will have to use its own crossover and then the lfe signal will then be processed by the internal crossover built in my fronts.

However, if i connect the sub out to the lfe in, won't this bypass the internal crossover of both the speakers and the receiver?

Will the same types of sound be reproduced, ie the .1 in surround sound?

Mainly I just want to know the difference between the two configurations, and which will work or sound better.

THanks,
-Will
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post #2 of 15 Old 09-29-2010, 09:40 AM
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Lets start by finding out which make/model of speakers you have.

When all else fails - RTFM!

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post #3 of 15 Old 09-29-2010, 09:43 AM - Thread Starter
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I have klipsch sp-1 in the front, yamaha rxv1800 receiver
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post #4 of 15 Old 09-29-2010, 09:44 AM
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Chances are those 8'ers aren't going that low. Unless this is a very small room a single 12" or 15" sub will mop the floors with those two 8s. If you really want a nice sounding HT you'll want a good sub that extends down close to 20hz, lower if possible.

After checking your model...

Yeah it goes to 30hz not bad but that's not really a subwoofer, just a woofer...you'll really benifit big time with sub...for HT that is...for music you'll be fine without a sub.

A sub will introduce you to freq. that are so low you can't hear them (movies have material well under 20hz)...but you can feel them...and so will the dishes in your house.
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post #5 of 15 Old 09-29-2010, 09:51 AM - Thread Starter
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i understand what you mean about having a 12 or 15 inch sub, however the room isn't extremely large. I think the speakers can handle 30 hz, but the lfe are supposed to be unfiltered

so in general, with large fronts, would you use the receiver to send the lfe to the fronts, or use the sub out to the lfe inputs?
would the latter be unfiltered?

If the signal is unfiltered won't the lfe carry 20hz?

Maybe i will look into getting a sub, but i still want to understand the differences.
THanks for your help
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post #6 of 15 Old 09-29-2010, 09:53 AM - Thread Starter
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ahh, i see what you are saying.

HOwever the specs say the subs can handle 22 hz, should i still try and get a sub that can do better?
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post #7 of 15 Old 09-29-2010, 09:58 AM
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Quote:
Originally Posted by Beep13 View Post

ahh, i see what you are saying.

HOwever the specs say the subs can handle 22 hz, should i still try and get a sub that can do better?

Klipsch specs that speaker to 30hz at 3db roll-off. I doubt you'll hear anything below 25-27hz. I have a 'sub' that plays down to 32hz - and is invisible past 28hz.

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post #8 of 15 Old 09-29-2010, 10:01 AM
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As for your question...most use an 80hz xover..this sends everything below 80hz to the sub via the LFE connection. You can go lower but this will force you speakers (in your case your midrange) to play lower... the best thing to do is try different settings and see what sounds best.

If your woofer is only wired to the plate amp and you cross at 80hz you really have a 2way system and your forcing the midrange to play very low.... not sure what the crossover points are on that model.

Most speakers that extend to 30hz use the woofer up to a few hundred hz and then roll off to the midrange...this would be a real 3-way design. Have you looked for the manual for this speaker..does it have a xover that goes to the woofer?
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post #9 of 15 Old 09-29-2010, 10:08 AM - Thread Starter
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As Knucklehead pointed out, the specs are listed above. The crossover is at 125 Hz, but not sure if the sub is only wired to the amp or not. You make a good point.

Knucklehead,

Thanks again for the info, just one question, I looked at the spec before and it mentions the subwoofer amp is rated for 22hz and the the lfe inputs are unfiltered. Since they would go directly to the sub amp, couldn't the subs handle the 22hz? I think the 30hz limit you mentioned is just for the mid range speakers, and not the lfe/sub amp. Or am i missing something?

Im not sure what the sub itself can handle. I couldn't find any specs on just that subwoofer.

Thanks guys,
-Will
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post #10 of 15 Old 09-29-2010, 01:54 PM
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At 30hz you have a 3db drop...this is how speakers are generally rated...from this point like most subs the volume will drop like a rock as the freq. goes lower... it won't be able to handle notes lower than 30db at your desired volume. Most people would not call a driver with a 30hz bottom end a sub, it's a woofer. The amps 22hz rating is irrelevant, and no the 30hz rating is not for the midrange it's for the woofer.

30hz is very good for a speaker....it should be great for 2-channel music...for movies you'll want all the content below 30hz that you missing. To play low notes the drivers have to move lots of air (displacement) the louder you crank it the harder those 8"ers will have to work even at 40hz...this is why subs are popular...they allow you to take the strain off your mains allowing them to really perform.
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post #11 of 15 Old 09-29-2010, 05:20 PM
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Quote:
Originally Posted by cdy2179 View Post

At 30hz you have a 3db drop...this is how speakers are generally rated...from this point like most subs the volume will drop like a rock as the freq. goes lower... it won't be able to handle notes lower than 30db at your desired volume. Most people would not call a driver with a 30hz bottom end a sub, it's a woofer. The amps 22hz rating is irrelevant, and no the 30hz rating is not for the midrange it's for the woofer.

30hz is very good for a speaker....it should be great for 2-channel music...for movies you'll want all the content below 30hz that you missing. To play low notes the drivers have to move lots of air (displacement) the louder you crank it the harder those 8"ers will have to work even at 40hz...this is why subs are popular...they allow you to take the strain off your mains allowing them to really perform.

What he said.../\\

For strictly HT use I'd buy a good set of bookshelf speakers with matching center and decent surrounds - and the best sub I could afford. For music I'd buy the best towers I could afford - and avoid built in powered 'subs'. I've been that route with Infinity IL50s. Every place I put them either the bass response sounded good or the mid-highs sounded good - placement with built in powered subs can be quite problematic. For music they just never seemed right in the bass department - too much emphasis on bass. I like a neutral sounding (flat) speaker. If you like bass then by all means give the built ins a try. I like balanced music - I have a pair of Infinity IL40s - one step down from the IL50s that are nearly 10 years old. They measure flat from 38-20,000hz + or - 2db. I get so enough bass with them when playing music I've gotten up to make sure the subs aren't on. Yes - I have two but only for movies. Proper placement is critical - if I move the IL40s back toward the wall 6" it stifles bass response - they are about 2 1/2 feet from the wall now and thats where they sound best.

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post #12 of 15 Old 10-04-2010, 08:35 PM - Thread Starter
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Thank you both for your time and patience, I greatly appreciate it!
You have helped me out big time. I really prefer learning how something works, and an explanation of an answer rather than just a quick reply and solution.

I have been looking for this information for quite some time know. And general search results are very unclear.
From what you both said I have a clear understanding of how this works now.

I understand how frequencies work and cutoffs ectd. I am just not well versed with speakers and home amplifiers. There are many things that aren't clear, like the amp and the speakers having different frequency ranges and cutoffs. Also, how the individual speakers behave in a full range speaker.

You have both definitely shed some light on these areas, so thanks again.

I will trust both of your advice and go with a sub. Then i will use the sub for all lfe out and bass management.

Maybe later on down the road i will look at replacing the fronts.

For now, based on my setup, what sub would you recommend? Or isn't brand really that important as long as i get one with a good frequency range?

Thanks again,
-Will
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post #13 of 15 Old 10-04-2010, 09:22 PM
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Quote:
Originally Posted by Beep13 View Post

For now, based on my setup, what sub would you recommend? Or isn't brand really that important as long as i get one with a good frequency range?

Thanks again,
-Will

What are you willing to spend? What is the size of your room?

I would suggest at least trying a $300 subwoofer for 30days and see that you are missing
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post #14 of 15 Old 10-05-2010, 05:21 AM
 
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Get an internet direct sub. Look at CHT (Chase Home Theater used to be called Tweak City Audio), SVS, HSU, Epik and ED. All of them make good subs.
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post #15 of 15 Old 10-05-2010, 07:36 AM
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If you don't use a sub (i.e. you receiver is set to "no sub" & mains are "Large") your receiver will NOT send the LFE to the speakers. What it will do is send a watered down 1/2 volume (-10db) LFE signal to the speakers.
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