Need help setting up subwoofer

[bookasan]

I have been into audio for many years, but have always been an old school, 2-channel stereo kinda guy. I have also used quad receivers and had no problems setting up the systems and using them. I want to add a subwoofer to what is currently a simple stereo set up. I am doing this on a budget, and trying not to spend any more money than I already have, but I did just get a passive subwoofer and a power amp. Now my question, how the #$@& do I hook it up?

Here are the Pieces....1) Receiver with A, B and center channel speaker outs(A and B can't be used at the same time), NO subwoofer out. 2) 2 main front speakers, 3) a passive subwoofer with stereo speaker inputs and sattelite outputs ( I believe it has a built in crossover), and 4) a stereo power amp.
I understand the signal from the power amp goes to the speakers, but where do I get the signal from the receiver to the amp?
Can this be done with just a receiver and a power amp? or am I missing some pieces of the puzzle.
Sorry about the brain farts, but this is my first attempt at a non 2 channel stereo setup.

 

[Don C]

Are there any Pre-out jacks on the receiver? What model of receiver is it?

 

[bookasan]

The receiver I have hooked up now is a Sony STR-AV1020, but I am only using it when I watch movies. My wife is one of those turn it up, turn it down type, and it is the only receiver I own with a remote. I am not sure off the top of my head if it has a pre out, but I have about a dozen vintage receivers that do.
So I would just take the pre out of the receiver into the amp?

 

[chichi]

I'll have a stab at it.
Is the centre output used at all? I'm gathering that its not, so i reckon you might be able to run that into a line out converter, then run that into the power amp which in turn would run the sub.
Anyone feel free to correct me because I don't actually use a sub yet.

I think it could also be beneficial to have a cross over before the power amp because then it wouldn't have to deal with the higher freq that dont actually end up coming from the sub.

Anyone mind telling me if I'm on the right track with this or am i way off base?

Chris

 

[Rob Babcock]

What sub do you have? A good many of them have line level and high level (speaker wire) inputs. If that's the case, run the L & R cables from your receiver to the subs speaker level inputs. There should then be speaker level outputs on the sub, near the inputs.

If you don't have high level inputs on your sub, things will be trickier. You'd need an impedance coupler of some type (not super expensive, but you probably won't find one at BB). Otherwise if you have a tape or processor loop that would be usable. Depending on the sub you have you might need an external X-over.

If you can post the specifics we can probably talk you thru it.

 

[bookasan]

The sub is a JBL SB-1. It has 2 pairs of speaker type terminals marked To: sattelite speakers and 2 pairs marked from Amplifier output. The power amp is a B&K ST-140 stereo. I don't have the receiver with me (I am at work), but I have several receivers I could use. None of which have dedicated subwoofer outs. I also am using a DVD/VHS combo going into the receiver.
Sub:

 

[bookasan]

sub front:

 

[bookasan]

here is the back of the power amp. This one is not my picture, but is the same unit.

 

[bookasan]

That didn't work. Here is the link to the completed auction.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=67786&item=5736460225&rd=1&ssPageName=WDVW

 

[bookasan]

What sub do you have? A good many of them have line level and high level (speaker wire) inputs. If that's the case, run the L & R cables from your receiver to the subs speaker level inputs. There should then be speaker level outputs on the sub, near the inputs.
QUOTE]


Actually, I did hook it up the way you mention, but it just didn't seem to have enough to really drive the sub. I really had to crank it.
Maybe just a different receiver would do the trick.
I was thinking if there was a way to drive the sub with the power amp...

 

[devo391]

Easy just connect the amp to the pre out's on the back of you receiver and then drive the sub from the amp, now that I think about it that would take your receiver's amp out of the "loop". There is probably a way to do this while leaving it looped I just cannot think of the trick right now. It is possible to do what I describe though and it would work great, I am sure someone here will know the trick to this. :scratch2:

 

[Rob Babcock]

Ah! A passive sub. That's the problem, I'm afraid- if you fed it more juice it still wouldn't help much. The sub would be louder but so would your mains. A lot of "old school" passive subs have the same sort of Xover in them to split the feed to your mains. That works but has two problems. One, it sounds like your mains are more sensitive than the sub. And two, the passive Xover network in the sub can interact with your mains, causing some strange nonlinearities.

The best thing would be to use an active crossover to feed your amp & a sub amp. But that's going to cost some money, and that's assuming you have a spare amp. You can probably get a used Rane of Audiocontrol for under $100, but then you'd need an amp.

As a last resort, you could try bass boost or engaging the loudness button so long as you don't crank things too hard.

 

[luvvinvinyl]

bookasan, pg 9 of the User's manual says that there is a centre channel line-level output, which you could run to the power amp, then to the sub. Try using the rcvr's soundfield controls to control the volume of the CC/sub.

(Checked on www.sony.com, under support documentation)

 

[bookasan]

Thanks luvvinvinyl

I forgot that sony had the manuals on-line. This receiver was a hand me down from Pops, and he lost the manual.
I will give that a shot.
I knew it would end up being something rather simple.

 

[luvvinvinyl]

I didn't know they were there, either, until I went looking on your behalf.

Pretty nice hand-me-down! 120 wpc. BTW, the docs on the surround says that the rears are only 10wpc. That may have had something to do with the unbalanced response, if you were using those outputs for the sub, in one of your previous attempts.

Let us know how you make out with the CC feeding the sub amp.

 

[bookasan]

Well, I tried a few different things and was able to get a signal to the subwoofer, BUT............one of the four woofers is blown :cry:
I did find out the reason I was having such a hard time getting info on the subwoofer, was because it is part of JBL's Pro line. I was looking in home audio. It looks like the replacement woofers are available at a list price of $39.00. I may replace it after the holidays.
I tried hooking it up to the center channel and got a signal to the sub, but I will have to play with the settings a bit to get it right.

 

[gyusher]

Crossover

Well, I tried a few different things and was able to get a signal to the subwoofer, BUT...

You need a crossover. . . You can buy an auto X-over at RadioShack (about 40 bucks)and a voltage converter to supply power then put it in the speaker level output as you can come out from that Sony but you cant go back in. . . This is a little rinky dink but it will work. Ask the Shack man to explain how to hook it up using speaker level output. Typically you come from the Sony to the crossover and then from the crossover to the speaker and the sub.

Line level is different there you come off your pre out to the crossover and back to pre-in from the crossover. I use a Subwoofer with all my stereo gear. The ones that have ins and outs I use line level but the ones that dont I use speaker level. . .

Line level is best as the crossover takes the low bass off your receiver(amp) and directs that narrow band to the subs amp.