How to connect passive speaker to AV receiver

Discussion in 'GENERAL AV Discussions' started by sagittariansroc, Jun 25, 2008.

  1. sagittariansroc Enthusiast

    sagittariansroc
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    Hi
    I have bought a used Onkyo TX-SR602 and I had got a set of old el-cheapo Home theater speakers from a friend that I plan to use before I move to my own place. Now the speakers are 15W passive and the sub is 50W passive. The output of the receiver is 85W per channel, so I was wondering if I can power the sub from the front speaker outs, instead of buying an amplifier for the sub (because I will eventually buy a powered sub). I understand that one can do that, but I have no idea how to connect the front L and R both to the sub AND to the front satellite speakers. I would really appreciate any help and thanks a lot for your time.
    Sagi
  2. j_garcia Audioholic Jedi

    j_garcia
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    If the sub has speaker level inptus and outputs, you would connect the L&R speakers to the sub and the sub to the receiver. This will usually involve the sub having a built in, fixed crossover for the main speakers.

    If the sub doesn't have speaeker outptus, you can simply use two sets of wires, one to the main speakers and the other to the sub, though this means no crossover at all for the sub to get the full range. If the receiver has A and B speaker outputs, you can also do that as an alternative - I'd put the sub on the B output as it is likely limited to full range.
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  3. sagittariansroc Enthusiast

    sagittariansroc
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    Thanks a lot for your helpful post. I really appreciate it. I am afraid I don't know what a crossover is. I googled it, and it seems to say that some subs have a crossover control, etc. This one doesn't have ANY control on it. It just has a couple of speaker wires (red and black) coming out of it. That's it. No ports, no other cables, no controls whatsoever. And it is made of plastic.
    So I guess I have two options in this case- But, say, after connecting the L and R speakers to the receiver as usual, where do I connect the two wires from the sub? To the Left, or Right, or either, or both? I mean there are 4 options, and only two wires.
    Regarding the second option, since I do have zone 2 output, it is easier to understand. But I do remember an earlier post saying this puts too much stress on the receiver as the sub has low resistance? Also, of the two options, which one would be preferable given the kind of sub I have?
  4. TLS Guy Audioholic Overlord

    TLS Guy
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    Do NOT connect the left and right speaker outputs to the sub, you will blow your receiver instantly. You can not power this sub with that receiver. You will need an amp between your LFE out and the sub. DO not even connect the sub to either the left or right outputs, as this will almost certainly drop the impedance too low and cause damage.
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  5. sagittariansroc Enthusiast

    sagittariansroc
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    I certainly do not wish to blow up my receiver! OMG! So there is really no way other than to get an amp between the receiver and the sub? I was going to buy a better speaker system later- so it would be pointless to buy an amplifier for powering a crappy passive sub for two months! I wonder if I can use the B/zone 2 output then...
  6. TLS Guy Audioholic Overlord

    TLS Guy
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    No, because if the sub and left and rights play at the same time, then they will be supplied by the same amps, unless you can get the surround channels to supply zone 2, and not have surrounds. However I doubt you could send both left and rights to both surrounds. Anyway you would need a crossover to keep the mid and HF out of the sub. It would sound absolutely dreadful if you didn't. By the sound of it, it seems that sub is a poor unit anyway and will be more of a detriment than an asset. I would counsel patience until you can set things up correctly.
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  7. sagittariansroc Enthusiast

    sagittariansroc
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    That is a very sound advice- indeed, the sub seems to be a liability. I will wait two months to hear bass- it wouldn't be too bad... :p
  8. j_garcia Audioholic Jedi

    j_garcia
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    The sub only having one input does mean it will be an issue, however you will not blow up your receiver by connecting it. If you connect it to either the R or L output, it will be fine, you just won't get the bass from the opposite channel. An amp would be the ideal way to do this as mentioned, however I would say just wait at this time.

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