Which subwoofer connection is better--LFE coax or high frequency speaker cables? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 17 Old 10-19-2012, 02:15 PM - Thread Starter
Advanced Member
 
Lord Vader's Avatar
 
Join Date: Dec 2004
Posts: 666
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
My subwoofer bit the dust, so I had to purchase a new one. In the meantime, I had a question I'm hoping someone can answer. Pardon my sudden forgetfulness or brain fart, but I was wondering: which would be the better way to connect a new subwoofer--via the single coax LFE cable that I currently use from my Onkyo 3008 to the sub, or via speaker cables to the black and red connections, which would provide for a high frequency connection. I can't remember the differences between the two. Moreover, I honestly don't recall what high frequency and LFE is on a subwoofer.
Lord Vader is offline  
Sponsored Links
Advertisement
 
post #2 of 17 Old 10-19-2012, 02:29 PM
AVS Special Member
 
JHAz's Avatar
 
Join Date: Mar 2009
Posts: 4,025
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Liked: 164
LFE is a channel of content., not an output It's the .1 in5.1 or 7.1 movies. The output you'd use from a receiver is a subwoofer out, not an LFE out. It will carry both the LFE and any redirected bass from the crossover the receiver applies between the sub and the other speakers. Some subs call their "line input that bypasses the sub's internal crossover" an "LFE" uinput, however. That's what you usually should use to go INTO the sub, if available. You come OUT of the receiver's subwoofer output.

Speaker cables are not "high frequency" and in fact the left right and center may contain frequencies at least as low as what's in the LFE channel. Generally speakeing, speaker cables carry higher power levels than line level sub (or other preamp outputs) will.

AFAIK, it's the unusual receiver that mixes the LFE channel back in to the left/right/center if you don't connect a sub. So connecting to the high level speaker outputs on your receiver to the sub probably means throwing away the LFE channel in its entirety. (If I'm wrong about this somebody will correct me . . .)
JHAz is online now  
post #3 of 17 Old 10-19-2012, 02:36 PM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,375
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 354
Quote:
Originally Posted by JHAz View Post

LFE is a channel of content., not an output It's the .1 in5.1 or 7.1 movies. The output you'd use from a receiver is a subwoofer out, not an LFE out. It will carry both the LFE and any redirected bass from the crossover the receiver applies between the sub and the other speakers. Some subs call their "line input that bypasses the sub's internal crossover" an "LFE" uinput, however. That's what you usually should use to go INTO the sub, if available. You come OUT of the receiver's subwoofer output.
Speaker cables are not "high frequency" and in fact the left right and center may contain frequencies at least as low as what's in the LFE channel. Generally speakeing, speaker cables carry higher power levels than line level sub (or other preamp outputs) will.
AFAIK, it's the unusual receiver that mixes the LFE channel back in to the left/right/center if you don't connect a sub. So connecting to the high level speaker outputs on your receiver to the sub probably means throwing away the LFE channel in its entirety. (If I'm wrong about this somebody will correct me . . .)
I'll correct you. biggrin.gif

If you tell the receiver you have no subwoofer, (which you would do if you're connecting the sub at speaker level), then the receiver will automatically re-route the LFE channel to the L/R speakers. All DD and higher receivers are required to do this Dolby. It's part of the "DownMix" specification.

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
post #4 of 17 Old 10-19-2012, 02:39 PM
AVS Club Gold
 
craig john's Avatar
 
Join Date: Oct 2003
Location: Lancaster, PA
Posts: 10,375
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
Liked: 354
Having said that ^^^, I would recommend to the OP that he connect the sub via the subwoofer output, and NOT at speaker level. Most receivers have a more rigorous and complete Bass Management System than the meager systems built into subwoofers. Better results can almost always be attained using the BM in the receiver.

Craig

Lombardi said it:
Perfection is not attainable, but if we chase perfection we can catch excellence."

My System

craig john is offline  
post #5 of 17 Old 10-19-2012, 03:43 PM
AVS Special Member
 
JHAz's Avatar
 
Join Date: Mar 2009
Posts: 4,025
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Liked: 164
I am very far from thinking I have a comprehensive handle on this stuff, but it is things like the following from a 2000 Dolby publication that muddy the waters for me:

“Another benefit to using the LFE channel when carrying explosive bass signals is that dsmaller stereo systems may not be able to handle such high levels of deep bass without significant stress. Since the Dolby Digital downmix process discards the LFE sighal, these low-frequency signals will not present any difficulty for these smaller systems.” http://www.scribd.com/doc/14598101/Dolby-51-Production-Guidelines. Sec 5.3.3, at p 5-4. Note this is in the context of going to stereo from 5.1.

IIRC, when you encode your mix to dolby or DTS you can set how the down mix will work, although there are default values that people may or may not fiddle with. Moreover, since the receiver itself is a 5.1 or 7.1 device, it may not get the dolby downmix, or perform the downmix as provided in the metadata, and may do it's own thing. I'm just not sure we can be certain that we don't lose the lFE channel when we don't connect to the sub channel . . .
JHAz is online now  
post #6 of 17 Old 10-20-2012, 01:03 PM
AVS Special Member
 
Roger Dressler's Avatar
 
Join Date: Jul 2000
Location: Oregon
Posts: 8,882
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 740 Post(s)
Liked: 345
Maybe I can shed some light. Let's separate two categories of products that decode audio: a source (STB or DVD player), and a surround processor (AVR, prepro).

The surround processor has to support many codecs and formats, and manages a wide range of speaker configurations. It has a processing blocks called speaker management and bass management. This handles various downmixing in case the speaker system has no C or no surrounds, or it reroutes the bass if some are large and some are small, or a subwoofer is present. In these products, LFE is never discarded.

OTOH, a source product ignores speaker management. It decodes to stereo or 5.1, intended to feed speakers directly (a TV) or to feed into a processor or AVR. The assumption is made that if no surround processor is being used (e.g., a TV set), it would be best to discard the LFE and activate dynamic range compression. This is built in to the DD decoder chip.

Deadwood Atmos theater
AV7702 Atmos 7.4.4, SSP-800 PLIIx 7.4
Aerial Acoustics 7B/CC3B fronts, B&W CWM8180 surrounds, Tannoy Di6 DC heights, Hsu ULS-15 subs
Roger Dressler is online now  
post #7 of 17 Old 10-20-2012, 02:06 PM
 
BeeMan458's Avatar
 
Join Date: Jun 2012
Location: Magalia, CA
Posts: 8,374
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 801
Quote:
Originally Posted by Roger Dressler View Post

OTOH, a source product ignores speaker management. It decodes to stereo or 5.1, intended to feed speakers directly (a TV) or to feed into a processor or AVR. The assumption is made that if no surround processor is being used (e.g., a TV set), it would be best to discard the LFE and activate dynamic range compression. This is built in to the DD decoder chip.

And if you follow the above, you've been doing this stuff too long.

...................................tongue.gif
BeeMan458 is offline  
post #8 of 17 Old 10-20-2012, 04:10 PM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,129
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1650
Quote:
Originally Posted by Lord Vader View Post

which would be the better way to connect a new subwoofer--via the single coax LFE cable that I currently use from my Onkyo 3008 to the sub, or via speaker cables to the black and red connections.
If you have a receiver with LFE output that's what you use. The sole purpose of the speaker level inputs to the sub amp is to allow you to hook it up to an older receiver or amp that doesn't have an LFE output.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is online now  
post #9 of 17 Old 04-24-2013, 06:23 PM
Member
 
Tripp McNealy's Avatar
 
Join Date: Feb 2013
Posts: 21
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I'm trying to educate myself on the best way to hook up my new 5.1 system and came across this older thread.

Currently have:

Cambridge S30 (Left and Right)
Cambridge S50 (Center)
Unknown rears (for now)
Klipsch RW-12d (Subwoofer)
Denon AVR 1913

My question is about hooking up the sub. I understand that the LFE is preferred, but in my situation I would have to run the cable 20 feet. But the spot for the sub is already prewired with regular speaker wire. Given my system, would you advise that I have someone run the coax cable or just use the existing high level inputs?

Also, would I be sacrificing much if I used a wireless subwoofer transmitter/receiver like Rocketfish instead?
Tripp McNealy is offline  
post #10 of 17 Old 04-24-2013, 06:39 PM
AVS Addicted Member
 
sivadselim's Avatar
 
Join Date: Oct 2004
Location: CO
Posts: 16,085
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 54 Post(s)
Liked: 69
Quote:
Originally Posted by Tripp McNealy View Post

I'm trying to educate myself on the best way to hook up my new 5.1 system and came across this older thread.

My question is about hooking up the sub. I understand that the LFE is preferred, but in my situation I would have to run the cable 20 feet. But the spot for the sub is already prewired with regular speaker wire. Given my system, would you advise that I have someone run the coax cable or just use the existing high level inputs?
If you can pull the coax, I would recommend you do that.

Is the spot pre-wired with two channels of speaker wire or only one? If two, and assuming your sub has an adjustable low-pass filter, you could use the speaker cable and connect the subwoofer to the AVR's L/R speaker level outputs (or to your L/R speakers' inputs) and set the AVR up as having NO SUB connected (Audyssey should detect this, too, when wired this way). However this is not at all ideal as your small S30s would not only be receiving a full-range front channel signal but the LFE channel, as well. Additionally, calibrating and adjusting the subwoofer's output level and its low-pass filter setting correctly is not as straight-forward with this sort of wiring scheme.


Quote:
Originally Posted by Tripp McNealy View Post

Also, would I be sacrificing much if I used a wireless subwoofer transmitter/receiver like Rocketfish instead?
I don't know anything specifically about that particular product, but people have used similar products successfully. Provided you use Audyssey to calibrate your setup, any delay in the signal that that system might add should be compensated for by the AVR's channel delay (distance) settings.

"All men are frauds. The only difference between them is that some admit it. I myself deny it."
sivadselim is offline  
post #11 of 17 Old 04-25-2013, 07:48 AM
AVS Special Member
 
KidHorn's Avatar
 
Join Date: Nov 2003
Location: Derwood, Maryland
Posts: 2,962
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 223 Post(s)
Liked: 238
Quote:
Originally Posted by Tripp McNealy View Post

I'm trying to educate myself on the best way to hook up my new 5.1 system and came across this older thread.

Currently have:

Cambridge S30 (Left and Right)
Cambridge S50 (Center)
Unknown rears (for now)
Klipsch RW-12d (Subwoofer)
Denon AVR 1913

My question is about hooking up the sub. I understand that the LFE is preferred, but in my situation I would have to run the cable 20 feet. But the spot for the sub is already prewired with regular speaker wire. Given my system, would you advise that I have someone run the coax cable or just use the existing high level inputs?

Also, would I be sacrificing much if I used a wireless subwoofer transmitter/receiver like Rocketfish instead?

The primary reason to use a sub cable instead of regular speaker wire is sub cables are coaxial and hence shielded. Other than that, there's not much difference between the two wires. Shielding is important if the wire is picking up a signal from your electical wiring. What happens is you will get a 60 Hz hum. If you don't get this with the regular speaker wire, then it will work as well as a subwoofer cable.
KidHorn is offline  
post #12 of 17 Old 04-25-2013, 09:09 AM
AVS Addicted Member
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,387
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 762 Post(s)
Liked: 1175
Quote:
Originally Posted by Lord Vader View Post


...which would be the better way to connect a new subwoofer--via the single coax LFE cable that I currently use from my Onkyo 3008 to the sub, or via speaker cables to the black and red connections, which would provide for a high frequency connection. I can't remember the differences between the two. Moreover, I honestly don't recall what high frequency and LFE is on a subwoofer.

LFE cable to the sub has the following wonderful advantage:

Allows setting the remaining speakers in the system to small, which offloads bass from the both speakers and the power amplifiers in the AVR.
arnyk is online now  
post #13 of 17 Old 04-25-2013, 01:12 PM
AVS Addicted Member
 
sivadselim's Avatar
 
Join Date: Oct 2004
Location: CO
Posts: 16,085
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 54 Post(s)
Liked: 69
Quote:
Originally Posted by KidHorn View Post

The primary reason to use a sub cable instead of regular speaker wire is sub cables are coaxial and hence shielded. Other than that, there's not much difference between the two wires. Shielding is important if the wire is picking up a signal from your electical wiring. What happens is you will get a 60 Hz hum. If you don't get this with the regular speaker wire, then it will work as well as a subwoofer cable.
Yes, using speaker cable with RCA connectors to connect the sub's line-level connection can be problematic in this respect, but he was asking about using speaker cable for the high-level inputs on the sub; the speaker-level inputs. With a high-level signal, this interference is not a concern.

"All men are frauds. The only difference between them is that some admit it. I myself deny it."
sivadselim is offline  
post #14 of 17 Old 04-26-2013, 12:23 PM
AVS Special Member
 
KidHorn's Avatar
 
Join Date: Nov 2003
Location: Derwood, Maryland
Posts: 2,962
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 223 Post(s)
Liked: 238
Quote:
Originally Posted by sivadselim View Post

Yes, using speaker cable with RCA connectors to connect the sub's line-level connection can be problematic in this respect, but he was asking about using speaker cable for the high-level inputs on the sub; the speaker-level inputs. With a high-level signal, this interference is not a concern.

You're right. Sorry about the response. I read a similar thread where someone asked is using regular speaker wire was OK and I responded to the wrong thread.
KidHorn is offline  
post #15 of 17 Old 04-26-2013, 02:46 PM
AVS Addicted Member
 
sivadselim's Avatar
 
Join Date: Oct 2004
Location: CO
Posts: 16,085
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 54 Post(s)
Liked: 69
Quote:
Originally Posted by KidHorn View Post

You're right. Sorry about the response. I read a similar thread where someone asked is using regular speaker wire was OK and I responded to the wrong thread.
No biggie.

Still haven't heard from the poster as to whether he has two channels of speaker wire running to the sub or only one. If one (which is quite possible, based upon what we've seen with pre-wire jobs in these forums before), then your answer may be relevant to the question that might come next.

"All men are frauds. The only difference between them is that some admit it. I myself deny it."
sivadselim is offline  
post #16 of 17 Old 12-22-2013, 05:17 PM
Newbie
 
cheglie's Avatar
 
Join Date: Nov 2013
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10

I have Infinity Interlude IL50 Powered towers.   I ran the two subs in the speakers with a single Y pre out connection for so many years.  Was very happy with movie sound, but not 2 channel music.  Recently detached pre out and run them as full size speakers with the speaker wire controlling the whole she-bang.  My Marantz NR1603 seemed to like this set-up and audessey took care of balancing the sub w/mid and tweets.  Granted I have already dialed in the subs with the R.A.B.O.S.  Front L/R,  Center ILC25 and surrounds IL10 are all set to LARGE.  It is like having a new speaker system.  Has never sounded so good for HT and stereo listening.  The fronts L/R are so much more dynamic!  And now the Subs are running in stereo.  There is more bass available than I would ever need to tap into.  I can understand that if someone is running ity-bity sattelites this would not make sense.  But I also wonder why this is not a more popular method or discussed method for this set-up?.  Granted not many powered towers in existence these days.

 

Side note.  I wonder if I set my center and surrounds to small if their lows would be sent to front L/R?

cheglie is offline  
post #17 of 17 Old 12-22-2013, 07:49 PM
AVS Special Member
 
Roger Dressler's Avatar
 
Join Date: Jul 2000
Location: Oregon
Posts: 8,882
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 740 Post(s)
Liked: 345
Quote:
Originally Posted by cheglie View Post

I wonder if I set my center and surrounds to small if their lows would be sent to front L/R?
It would if the L/R are large and Sub = none. That would be a good idea since the bass from the center/surrounds is probably not fully presented by those speakers (when in large mode), and you do not want LFE feeding them, either.

Deadwood Atmos theater
AV7702 Atmos 7.4.4, SSP-800 PLIIx 7.4
Aerial Acoustics 7B/CC3B fronts, B&W CWM8180 surrounds, Tannoy Di6 DC heights, Hsu ULS-15 subs
Roger Dressler is online now  
Reply Subwoofers, Bass, and Transducers

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off