Sub woofer connection (1 Viewer)

[Mike Broadman]

Here's yet another newbie-rrific question:
My receiver has two methods allowing me to connect a subwoofer: 1) the speaker wire thing, just like the other speakers; 2) A plug-in cable thing (like earphones).
I'm now using the second method, but what's the difference?

 

[RyanDinan]

Mike,
One is speaker-level, and the other is line-level. If you use the speaker-level connection, you're using your receiver's amplifier to power the sub. If you use the line-level, you (have to) use your sub's amplifier (if your sub has this RCA-type connection, and has it's own A/C cord, it's self-powered). More often than not, you want to use your sub's built-in amp. It probably has more power than your receiver could give it, sounds better, and will reduce the amount of work your receiver has to do.
-Ryan
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[DaleB]

Must be early for me, did not quite get the earphone analogy
however, that is the preferable way in most cases. Using the speaker connectiion will have the sub crossover limit the bass to your mains, so the subwoofer handles all the bass. The receiver or preamp has a built in crossover filter to do the same thing.
There is a lot more you may need to know about how to set up, calibrate the sub level, what to set the crossover at, etc. etc. if you use the speaker connections.
Using the receiver to do the crossover is generally easier and compatible with most systems, it also simplifies the hookup procedure so you don't need long runs of speaker wire if your sub is at some distance from the main speakers (which sometimes it might have to be for best response).
Some may argue the crossover in the sub is better than most receivers and it's better to do it that way. But with the advent of THX, and other processing modes, it's generally better to do it the way you did. Using the speaker cable method is generally more applicable to purists who have all separate components, and do most listening in stereo, with little or no concern for home theater. Of course, there are always exceptions.
[Edited last by DaleB on September 06, 2001 at 10:25 AM]

 

[Mike Broadman]

Sorry about the bad earphone analogy. I meant that it's an RCA-type connection as opposed to the speaker-wire type.
Yeah, my sub has its own AC power chord, RCA input, power switch, and "volume" type knob.
I see, so I'm using the amp in the sub now. Cool.
I like the way it is now. I can turn the sub on or off depending on what I'm watching or listening to. It sits right behind my couch, so I "feel" stuff. Kick-ass.
This has probably been done to death, but does the location of the sub make a big difference? I've heard many conflicting things, but many have said that it's best to put it in the front corner. My living room is small, so that means it would be right next to my right speaker. Could this cause a problem? Right now the sub sits behind the couch, which is convenient for me to turn it on or play with the volume. It also is a good place to put the mail.
I like my set-up, I guess I'm just checking to see if I missed something.

 

[Mike LS]

You normally get the best performance out of your sub by having it in a corner. As to which corner....that'll depend on your room.
A good suggestion for finding the best placement for you sub is to place the sub on the floor directly in front of where you sit to watch a movie. Right where your feet would be.
Then you should play some bass-heavy music and slowly walk around the room against the walls and decide where the sub sounds the best. When you isolate where that is (9 times out of 10 it's in a front corner), that's where you should put your sub.
In answer to your question, it won't matter if it's right next to one of your front speakers. My SVS is about 3 inches behind my left front and there's no problem there at all (except you can't see the sub as well as I'd like, but that's vain).
Anyhow, play with it and see what you get.
BTW, nice # of posts. Gotta love when you get to 69!

 

[ThucN]

Just one important point:
Hooking up a powered sub via the speaker-level inputs does NOT use your receiver's amp to power the sub.
I believe the technical explanation goes something like this (I'm no expert):
The sub's speaker-level inputs have a very high impedance, thus drawing nearly no current (and thus no power) from the receiver. However, the sub uses the voltage signal that is present at the speaker-level input as the music source for its own amplifier.
[Edited last by ThucN on September 06, 2001 at 09:34 PM]

 

[DaleB]

Thanks for explaining about the powered vs. unpowered sub as having nothing to do with using the speakers output of the receiver to the sub.
Confused me for a second there, but by the second cup of java it all came into focus!
I almost always assume people have powered subs but I know that not always the case, so it is a good point to make.

 

[Mike Broadman]

So, either way, the sub's own amp would be powering the sub's sound?
If, hypothetically, I had a sub without a built-in amp, would I then need a seperate amp to power it?

 

[Inspector Hammer!]

Mike, on your sub you should have two knobs, one that says 'Low pass frequency' control, and the other that says 'Level' control. Turn your 'low-pass frequency' control all the way up and leave it thier, this will insure that you sub is getting all of the available low-end in any given soundtrack. Next turn your 'Level' control up until the bass coming from your sub matches the amount of bass from your mains. This will ensure that your sub will sound uniform to your mains, and it won't draw all the attention to itself.
The use of a calibration dvd like 'Avia' or 'Video Essentials' and a radio shack sound pressure level meter is Highly recommended for super accurate sound from your system. Good luck.
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"How can I heal, when I can't feel time?"
Leonard from Memento

 

[ThucN]

Yes, Mike, a powered sub uses its own amp whether it's hooked up via speaker-level or line-level inputs.
A sub without a built-in amp would need a separate amp (or receiver) to power it. Obviously, this setup would require the use of speaker-level connections.
About John's advice to turn the 'Low-pass freq' control all the way up: this is correct assuming that you're connecting your sub using line-level, and using the receiver's crossover.