No speaker level output on sub...

Discussion in 'Archived Threads 2001-2004' started by Pat K, Mar 16, 2002.

  1. Pat K

    Pat K Stunt Coordinator

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    My receiver doesnt have a sub out, so Im running speaker level inputs to the sub. My receiver only has 4 connections for speakers, 2 front, 2 rear. I have the front two speakers hooked up, then the sub in the back connectors. I plan on adding two rear surrounds, but my sub doesnt have high level outs, just high level in. How can i do this? Can i just plug the speakers, and the sub into the connectors on my receiver? Will that mess up the impedence or anything? Thanks in advance.
     
  2. ColinM

    ColinM Cinematographer

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    I had an old Optimus that had In's only...

    Are you talking about A and B speaker systems, or do you have a Dolbu Surround system? The older surround systems had fronts and rears, no center...Speaker's 'A' and 'B' are just the same thing, same sound, not 'surround'.

    Anyway -

    If I had a system that was stereo only, A and B systems available, I'd run 'A' to the mains and 'B' to the sub.

    If you need the mains to do both the sub and the L/R speakers, simply jump the sub's inputs into the middle of the run. No problem with that.

    - C
     
  3. Harry Lincoln

    Harry Lincoln Stunt Coordinator

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    Pat, with your current setup the sub is only getting the bass from the rear channels, not the fronts. I wouldn't go plugging both the speakers and sub into the amp, although I'm not sure if it will damage anything.

    What type of receiver and sub do you have and what in/outs does the sobwoofer have? Is the subwoofer self powered?. What surround format does the receiver support?

    Harry.
     
  4. Pat K

    Pat K Stunt Coordinator

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    I have a Garrard Receiver (dont ask, it was cheap).. its actually really powerful, 260 watts, but it has 4 speaker inputs. A + B, and you can select only A, only B, or both. It has no sub out. The sub is a powered, 100w MTX 10". It has RCA ins and outs, and then it has speaker level ins, but no speaker level outs. If it had speaker level outs, id be fine, and plug my rear speakers into that. What Im asking is, with only 4 speaker connections on my receiver, how can i hook up all 4 of my speakers, and the sub, through the speaker level inputs?

    I have no sub out, i do have a audio-out that is at a constant level, and doesnt change with the volume.
     
  5. brucek

    brucek Second Unit

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    Pat,

    If you are able to physically attach the second set of wires (required to feed your sub) to either the "A" or "B" speaker terminals at the back of your receiver, then you'll have no extra problem with loading. The sub's speaker level inputs are not the same load as an unpowered speaker like your front (A) and rear(B) set.

    If you are using the "speaker level" inputs to your sub, it is a high impedance input. It's designed to have very little impedance effect when used in conjuction with a regular set of 8 ohms speakers. Input impedance is likely in the 10K range realized from a 20dB voltage divider.

    This means the circuit to the sub lives in the voltage domain rather than in the current domain like your 8 ohm speakers. This is a high impedance voltage bridge, the loading is minimal.

    brucek
     
  6. Doug Drake

    Doug Drake Stunt Coordinator

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    Pat - Someone may have said this already, but I might have missed it...

    You can connect both your main speakers and your sub to the Speaker A posts on your receiver, using the speaker level inputs to the sub. It will not damage anything, nor will it take anything away from your speakers.

    You would then use the crossover on the sub to blend it in with the main speakers (along with the sub's volume knob). Try setting it about 10hz higher than the rated low frequency response of your main speakers, as a starting point.

    Doug
     

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