Connecting a subwoofer - AVS Forum
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post #1 of 16 Old 01-23-2014, 08:48 AM - Thread Starter
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Hello, I was wondering if there is any harm in connecting my subwoofer directly to my TV through the RCA-out from my TV to the Pre-Out RCA-in to my subwoofer? Please advise. Thanks.

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post #2 of 16 Old 01-23-2014, 08:50 AM
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RCA out on TV to RCA in on sub? Likely not a problem. What are the make and model numbers of your TV and your sub?
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post #3 of 16 Old 01-23-2014, 09:19 AM - Thread Starter
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The TV is a Sony KDL46XBR4 and I just picked up a Klipsch RPW-10 subwoofer. I thought I could hook up this subwoofer to my existing home theater system Sony DAVHDX975WF, but a couple of audio people at the store told me I can't do that because the receiver doesn't have a pre-out connector. If I tried to use existing subwoofer connection (passive), they said that either the subwoofer will go bad after a while or my home theater system receiver will go bad. I never understood the reasoning behind this at all despite them trying to explain it. So as a work around I thought I could plug in the subwoofer directly to the TV since I assume that it is pre-amp RCA-out. Of course I am doing this because I am not ready to invest $1500 in buying a new receiver/speakers right now (plus I don't have space in my house to keep the kind of speakers I want to buy eventually).  Any thoughts? Any risks? Thanks.

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post #4 of 16 Old 01-23-2014, 12:57 PM
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If your sub has speaker level inputs you may use it, driving it with the speaker output from the AVR. You'll have to chop the speaker cord to do it. I'd jury rig a Y connection, so that you can use both the new and old sub together. OTOH you can add a real AVR now and use your existing speakers with it.

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post #5 of 16 Old 01-23-2014, 01:43 PM - Thread Starter
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I understand what you are saying, but I went to two electronics shops and both of the guys said the same thing thing to me: If I connect any subwoofers/speakers to my home-theater-in-a-box system, my new speakers/subwoofers or my old receiver can get damaged and it may just stop working one day.  OTOH, if I buy a new receiver and try to connect my old home-theater-in-a-box speakers to a normal receiver, than the speakers may get damaged. Sounds to me like you don't agree with these things, correct?

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post #6 of 16 Old 01-23-2014, 01:56 PM
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What is your powered subwoofer brand and model ?

If your subwoofer has SPEAKER IN or Speaker level inputs, you can connect another set of speaker wires from the HTIB subwoofer connector to the subwoofers speaker in. NOTHING will get damaged. IF the electonic shop says otherwise, I would start looking for another electronics shop.


You can use your 5 small speakers to a NEW AVR as long as you set the speakers to small and dont play it too loud smile.gif


EDIT : You may have missed to mention that the new sub is powered, hence why they said something might get damaged
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post #7 of 16 Old 01-23-2014, 02:20 PM - Thread Starter
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The subwoofer is a Klipsch RPW-10. It is a 10 inch powered sub. Very nice... I really like it. And the HTIB is a Sony DAV-HDX975WF which does not have a pre-out sub connector. It only has a connector for the passive subwoofer that came with the package. So when I bought the subwoofer from there, they knew it is a powered subwoofer and they told me not to connect it to a HTIB system. I bought it anyway because it was on a nice discount. They said HTIB systems are only designed to work with the speakers that come with the system and nothing else. They said I cannot swap speakers with other any other speaker or I will damage either the speaker or the HTIB receiver.  And I also cannot swap the receiver with any other receiver because then I will damage the HTIB speakers. I don't understand how two electronics stores can give me the same lie! Should I start a new thread with this question?

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post #8 of 16 Old 01-23-2014, 03:02 PM
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Their not lying, their just inexperienced. I have connected my powered subwoofers to my HTIB in the past without any damaged. Connecting another passive subwoofer to the HTIB is the one that could cause damaged.

Just check images on your subwoofer, it has Speaker level inputs, just connect another set of wires from the HTIB subwoofer output to the Klipsh speaker in and ENJOY.

Connecting a powered subwoofer to an HTIB is one of the best thing you could do as the "subwoofer" in the HTIB is its weakest point.
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The subwoofer is a Klipsch RPW-10. It is a 10 inch powered sub. Very nice... I really like it. And the HTIB is a Sony DAV-HDX975WF which does not have a pre-out sub connector. It only has a connector for the passive subwoofer that came with the package. So when I bought the subwoofer from there, they knew it is a powered subwoofer and they told me not to connect it to a HTIB system. I bought it anyway because it was on a nice discount. They said HTIB systems are only designed to work with the speakers that come with the system and nothing else. They said I cannot swap speakers with other any other speaker or I will damage either the speaker or the HTIB receiver.  And I also cannot swap the receiver with any other receiver because then I will damage the HTIB speakers. I don't understand how two electronics stores can give me the same lie! Should I start a new thread with this question?
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post #9 of 16 Old 01-23-2014, 07:43 PM
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Quote:
Originally Posted by royalleader View Post

I understand what you are saying, but I went to two electronics shops and both of the guys said the same thing thing to me: If I connect any subwoofers/speakers to my home-theater-in-a-box system, my new speakers/subwoofers or my old receiver can get damaged and it may just stop working one day. 
Are they engineers? Or salesmen? I'm an engineer. A sub with speaker level inputs is intended to handle the high voltage output from an amplifier. Its high input impedance prevents the source HTIB amplifier from delivering enough current to damage it, or the HTIB. The exception to this would be if your HTIB had tube driven amplifiers, which is not the case. You would want to turn the sub volume of the HTIB down, if it has that capability.
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They said I cannot swap speakers with other any other speaker or I will damage either the speaker or the HTIB receiver.
So long as the impedance of the speakers and the amp driving them are compatible there's no problem doing that either.
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I don't understand how two electronics stores can give me the same lie!
They can't give you accurate information if they don't know it themselves.

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post #10 of 16 Old 01-23-2014, 09:31 PM - Thread Starter
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Thank you for your response. Yes, the HTIB receiver has the ability to go +/-6db. So how do I know if the impedance of the speakers and the amp driving them are compatible?

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post #11 of 16 Old 01-24-2014, 03:50 AM
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I would not worry about the impedance of the small speakers, their small and most likely be a walk in the park for any amplifier. Anyways the impendance should be stated at the back of the speakers or at least printed on the manual. Most of the time it would fall from 4 to 8 ohms, which is well in the operating range of most amplifiers.
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post #12 of 16 Old 01-24-2014, 04:13 AM
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According to the owner's manual (PDF), the speakers on that Sony system are rated at 3 ohms. (The sub is rated at 1.5 ohms.)
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post #13 of 16 Old 01-24-2014, 07:10 AM
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Quote:
Originally Posted by eljaycanuck View Post

According to the owner's manual (PDF), the speakers on that Sony system are rated at 3 ohms.
That being the case you'd need an AVR with a 2 ohm rating, which is rare. For that matter 4 ohm rated AVRs are the exception, most are rated for 6 ohm minimum loads.

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post #14 of 16 Old 01-24-2014, 01:14 PM
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Do you think the HTIB has resistors inside to protect the amp ? , thats one hell of a load for an HTIB amp
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post #15 of 16 Old 01-24-2014, 01:58 PM
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Do you think the HTIB has resistors inside to protect the amp ? , thats one hell of a load for an HTIB amp

Not necesarily. They may be trying to get power up while keeping voltages down. See this a lot in rack systems and car audio.
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post #16 of 16 Old 01-25-2014, 03:11 PM - Thread Starter
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So I assume this is what the guys at the electronics stores were talking about... they did mention the ohms being different... I guess this is where the incompatibility comes from which could potentially cause damage to either the speakers or the amp or both. Thanks.

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