8 ohm amp - AVS Forum
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post #1 of 6 Old 10-04-2013, 11:38 AM - Thread Starter
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I have an onkyo receiver that does 8ohms. I have a couple 4ohm subs laying around that are better than the sub I'm using now. My receiever has two sub outputs. Can I somehow run the 4ohm sub by using both outputs without blowing my receiver?

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post #2 of 6 Old 10-04-2013, 12:20 PM
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Exactly what model of subwoofer is involved?

The brief answer is "That won't work."

The subwoofer outputs on receivers are low-voltage line-level signals. They're designed to be plugged into external amplifiers which then drive the subwoofers. They won't work when connected directly to speakers. Powered subwoofers have amplifiers built into them (often called "plate amps") and are the type most often used. If the subs you have contain builtin amplifiers, the fact that they're 4 ohm speakers doesn't matter. If the subs you have do not have builtin amplifiers, either you have to purchase amplifers for them or they have to (somehow) be connected to the front speaker-level outputs of the receiver. The method for connecting them depends on the subwoofer design. Hence the need to know their exact models.

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post #3 of 6 Old 10-04-2013, 12:22 PM
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Probably not. If it has two sub outputs most likely they are low level (RCA) outputs to go to powered subs or external amps. If they are indeed high level (speaker post) type outputs then it may be possible, but not recommended. You can wire your subs in series to bring the impedance up to 8ohms and connect it to a single output.

Edit: Looks like Seldon Ball has beat me to the answer and more thoroughly at that.
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post #4 of 6 Old 10-04-2013, 12:49 PM
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Quote:
The brief answer is "That won't work."


How do you know that won't work without knowing the subs OP has and whether they are active or passive? If he has active subs, the impedance mismatch is immaterial as the amp on the sub, um sure, is designed to handle whatever load the drivers have. He would only be routing the pre-amp signal from avr to the sub.

Also, if he has passive subs, the pre-amp signal from avr goes to the external amp, which should be 4-ohm stable to run 4 ohm subs. In either case there is no load on the avr, whatsoever.

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post #5 of 6 Old 10-04-2013, 12:49 PM - Thread Starter
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Thanks for the responses guys. Looks like I most likely won't be able to do it. My sub just sucks so I'm grasping at straws lol. The model of the sub is jl audio 10w1v2-8

Onkyo TXSR607, Mythos 8 Center, Studio Monitor 350's, Klipsch S-10 surrounds, Bic F12 sub

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post #6 of 6 Old 10-04-2013, 01:02 PM
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Yup. Unfortunately, that's just a "driver" in home-audio-system parlance. It needs to be put into a (properly designed) box and have an external amp connected to it.

You might want to consider perusing the Do-It-Yourself speaker forum. I suspect someone there would be able to provide pointers for how to do that. http://www.avsforum.com/f/155/diy-speakers-and-subs

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