Question on hooking up subwoofer - AVS Forum

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Audio Theory, Setup, and Chat

h2oluver's Avatar h2oluver
10:25 AM Liked: 10
post #1 of 7
03-14-2012 | Posts: 6
Joined: Feb 2012
I'm new here and not sure if this post should have gone in here or the subwoofer forum. Anyway I have a question regarding hooking up a subwoofer. I was looking at this http://www.audioholics.com/tweaks/sp...ofer-placement where is says to take the LFE out on the AVR and hook it to a "Y" splitter and use the line level inputs on the sub instead of using a single cable from LFE to LFE. There seems to be different opinions on what is best to do in the various searches I have done. Is there a benefit to doing this? I'm a newb to all this as my last audio equipment was bought in the early 90's and I didn't have a subwoofer. So any help would be appreciated.
underminded999's Avatar underminded999
10:52 AM Liked: 16
post #2 of 7
03-14-2012 | Posts: 378
Joined: May 2011
If the sub only has one line level input, then just use on line.

If the sub has L&R inputs, you may use a single line to L(normally), or use a "Y" for both. I believe that you may get a few added decibels, form the latter.
h2oluver's Avatar h2oluver
11:13 AM Liked: 10
post #3 of 7
03-14-2012 | Posts: 6
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The sub has both LFE and line inputs. By using the line inputs I should get a few more db's which is better right? Also by doing this I'm assuming that using the line inputs versus the LFE input, that will in effect put my subwoofers crossover into play versus the LFE which bypasses the subs crossover and uses the AVR's crossover for the subwoofer. Am I correct on that?
underminded999's Avatar underminded999
12:01 PM Liked: 16
post #4 of 7
03-14-2012 | Posts: 378
Joined: May 2011
Errrr... hold on.

I may have missed something in the translation.

Lets forget about the speaker line lever and only deal with RCA jacks.

How many subwoofer out RCA jacks does your AVR have?

How many RCA IN jacks does your sub have? How are they labeled?
JHAz's Avatar JHAz
12:08 PM Liked: 167
post #5 of 7
03-14-2012 | Posts: 4,043
Joined: Mar 2009
Quote:
Originally Posted by h2oluver View Post

The sub has both LFE and line inputs. By using the line inputs I should get a few more db's which is better right? Also by doing this I'm assuming that using the line inputs versus the LFE input, that will in effect put my subwoofers crossover into play versus the LFE which bypasses the subs crossover and uses the AVR's crossover for the subwoofer. Am I correct on that?

Generally, single cable to the LFE in will work just fine. While a Y splitter between the left and right RCA inputs will increase the level in to the sub, in the long run it makes no real difference. You could get exactly the same increase by turning the sub's volume dial up a smidge. Your sub's max volume is defined by the sub's capabilities and you can get there either way.

Where the Y splitter really helps is with subs that have an auto on feature. SOmetimes, the single input won't be hot enough to wake the sub up right away, and using the Y splitter alleviates that potential problem.
whoaru99's Avatar whoaru99
12:11 PM Liked: 67
post #6 of 7
03-14-2012 | Posts: 6,960
Joined: Dec 2004
Quote:
Originally Posted by h2oluver View Post

The sub has both LFE and line inputs. By using the line inputs I should get a few more db's which is better right? Also by doing this I'm assuming that using the line inputs versus the LFE input, that will in effect put my subwoofers crossover into play versus the LFE which bypasses the subs crossover and uses the AVR's crossover for the subwoofer. Am I correct on that?

If you have both L & R low level input and LFE input on the sub, generally you'd just use a single cable from the sub output to the LFE input. LFE input on the sub generally bypasses most controls on the sub, so that there is no conflict with the settings you dial in on the processor/receiver.

And, yes, it is true in some cases you get increased relative output from the sub using a "Y" to the left and right vs. either left or right alone (doesn't make it a more powerful sub, just means you have to compensate for a difference in gain). On one of my subs I measured about +4.5dB difference.

However, if using the LFE input this shouldn't be a factor because with just the mono input there is no need for the L & R summing circuit and the resulting gain difference when using just the L or just the R input. IOW, IMO, a single feed to the LFE input will produce the same level as a double feed to the L & R inputs.
h2oluver's Avatar h2oluver
12:20 PM Liked: 10
post #7 of 7
03-14-2012 | Posts: 6
Joined: Feb 2012
Ok. Thank you for all of the replies. Your explanations helped alot. I guess since it's simpler I'll just use the single cable hookup.
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