Help Adding Passive Subwoofer to my Onkyo TX-SR702

[NolanG]

I would be extremely appreciative if someone who knows what they're doing would take the time to help a noob like me out! I have a Onkyo TX-SR702 receiver and some NRG acoustics speakers, theyre supposed to be high quality but for some reason the sub is passive. My onkyo only has two RCA outputs for a subwoofer. One is under preamp, and another under DVD I think. The sub is an analoug only and has two input and two output wire clips on it. I got a rca to speaker wire converter but it's not working straight from the receiver. I guess I need a pre amp (or amp, or both? Idk) and the story gets deeper haha....

I got an oldschool Onkyo p-301 preamp and a Yamaha m-70 amp. I would love to find a way to use these to power my subwoofer only. The pre amp only has RCA connections, maybe I can just hook it up to one of the L or R outputs? And the amp does have analoug outputs but I havnt been able to get any sound by using it.

To summarize I have a few questions; do I need a specific "subwoofer amp?", can a pre amp work without an amp? Could I just hook up the subwoofer to one of the analoug speaker outputs on my receiver? Any other help?? Thanks you guys!

 

[TLS Guy]

I would be extremely appreciative if someone who knows what they're doing would take the time to help a noob like me out! I have a Onkyo TX-SR702 receiver and some NRG acoustics speakers, theyre supposed to be high quality but for some reason the sub is passive. My onkyo only has two RCA outputs for a subwoofer. One is under preamp, and another under DVD I think. The sub is an analoug only and has two input and two output wire clips on it. I got a rca to speaker wire converter but it's not working straight from the receiver. I guess I need a pre amp (or amp, or both? Idk) and the story gets deeper haha....

I got an oldschool Onkyo p-301 preamp and a Yamaha m-70 amp. I would love to find a way to use these to power my subwoofer only. The pre amp only has RCA connections, maybe I can just hook it up to one of the L or R outputs? And the amp does have analoug outputs but I havnt been able to get any sound by using it.

To summarize I have a few questions; do I need a specific "subwoofer amp?", can a pre amp work without an amp? Could I just hook up the subwoofer to one of the analog speaker outputs on my receiver? Any other help?? Thanks you guys!

We need to know a lot more about that sub woofer and its connections. If the sub has speaker inputs and speaker outputs as well for the left and right speakers then it might be possible to power it from your receiver. The sub out from your receiver is a line out and can not power a passive sub directly. You do not need a pre amp, you need a power amp.

So if you connect the sub/LFE out to your power amp using either the left or right channel and connect the corresponding speaker out to the sub it should work. If not then you need to check the power amp to make sure it is still in working order.

 

[NolanG]

Thanks! The subwoofer does have a total of 8 holes in the back. It has two pairs of inputs and two pairs of outputs. So should I connect my four speakers to these?

 

[TLS Guy]

Thanks! The subwoofer does have a total of 8 holes in the back. It has two pairs of inputs and two pairs of outputs. So should I connect my four speakers to these?

I have no idea. I have no details about that sub you have or any details about it.

 

[ryanosaur]

Thanks! The subwoofer does have a total of 8 holes in the back. It has two pairs of inputs and two pairs of outputs. So should I connect my four speakers to these?

for anybody to help, we need to know what your sub is... make and model... a photo or link would be helpful (but I don't recall when they let you start doing that).

 

[NolanG]

It came in the nrg acoustics hj-17 bundle, I'll show a picture. Theres not much info about it online though.

 

[ryanosaur]

Speaker level connections: L/R Mains from reciever into the sub, then L/R output to the L/R speakers themselves.
Diagram on post 5 https://www.hometheaterforum.com/community/threads/trying-to-find-a-receiver-to-buy.352847/

 

[NolanG]

Thanks for the help, I'm sorry to hear that they're low quality speakers but anyway they seem decent, Oh well I'm exited to hook it up tomorrow. I've got a mini two speaker/sub combo hooked up to zone two which I play together with them, overall works well from how little I use them.

 

[lovinthehd]

Speaker level connections: L/R Mains from reciever into the sub, then L/R output to the L/R speakers themselves.
Diagram on post 5 https://www.hometheaterforum.com/community/threads/trying-to-find-a-receiver-to-buy.352847/

If it's a passive sub that's not likely going to work well impedance-wise for his receiver's amp section.

 

[Kvn_Walker]

Ouch, you got white-vanned. Anyway, don't play it too loud or you'll probably blow those speakers. But at least if you do, then we will be glad to help you find a good set-up!

 

[everettT]

Ouch, you got white-vanned. Anyway, don't play it too loud or you'll probably blow those speakers. But at least if you do, then we will be glad to help you find a good set-up!

Yup

 

[ryanosaur]

I'm not super familiar with that type of gear. The photo of the box says nominal impedance of 8 ohms. Is there something else that happens there, when you have a passive sub with the signal for both channels going through it? Thx!

 

[Darenwh]

Actually, if that passive subwoofer is like others I have seen from late 80's to mid 90's it has an internal crossover that sends higher frequency's to your regular speakers and sends the bass to the subwoofer. Think of it like you had a subwoofer in each speaker with a crossover to place the low frequencies to the Sub, then another (if not a full range individual speaker) to split mid frequencies to the woofer and high frequencies to the tweeter. JBL's Control SB5 subwoofer was one of these but not the only one out there. By sending the lower end to a single box they could configure any ported format that the manufacturer would like and could improve the overall bass that way. For instance, JBL's Control SB5 subwoofer used dual opposed subs on each side of the box (four speakers total, two being driven off right output and two driven off left) in a bandpass box to achieve decent results. No, they did not go especially deep (40 Hz) but they did a good job for what they were. These were designed to be used with the Control 8's to give some more and more powerful bottom end to those speakers.

 

[Kvn_Walker]

Actually, if that passive subwoofer is like others I have seen from late 80's to mid 90's it has an internal crossover that sends higher frequency's to your regular speakers and sends the bass to the subwoofer. Think of it like you had a subwoofer in each speaker with a crossover to place the low frequencies to the Sub, then another (if not a full range individual speaker) to split mid frequencies to the woofer and high frequencies to the tweeter. JBL's Control SB5 subwoofer was one of these but not the only one out there. By sending the lower end to a single box they could configure any ported format that the manufacturer would like and could improve the overall bass that way. For instance, JBL's Control SB5 subwoofer used dual opposed subs on each side of the box (four speakers total, two being driven off right output and two driven off left) in a bandpass box to achieve decent results. No, they did not go especially deep (40 Hz) but they did a good job for what they were. These were designed to be used with the Control 8's to give some more and more powerful bottom end to those speakers.

I have serious doubts that a white van manufacturer even used crossover components in any of the speakers. They most likely all run at full range, including the "sub." The bill of materials probably lies between $25 and $50.

 

[lovinthehd]

I think white van is it, at least my search for this gear on the internet leads me in that direction.

I'm not super familiar with that type of gear. The photo of the box says nominal impedance of 8 ohms. Is there something else that happens there, when you have a passive sub with the signal for both channels going through it? Thx!

Who knows what the speakers or sub actually measure but even if the sub is 8 ohm rather than a lower value, running off the same amp channel that would lower the impedance the amp sees....that you would use two channels to the single sub/summing to mono I've only seen in active subs so not sure how that might work at all. Personally I wouldn't bother using the speakers or the sub.

 

[Darenwh]

I agree that if it is white van then it likely is not going to be of the type I specified. But know that they do exist. I have not searched on the brand he has so know nothing of that brand.

 

[Kvn_Walker]

I had a pair of passive 12" subs from Radio Shack a long time ago. Not high end, but they weren't bad for what I paid. I think I had my main towers sitting on top of them.

They aren't a common thing anymore since most subs are powered now, but wouldn't be a bad option for someone who already has a high powered amp.

Believe it was this one here: https://audiokarma.org/forums/index.php?threads/realistic-12-passive-subwoofer-40-4050-restoration.473678/