Oh. However, my amp doesn't have a power out for the subwoofer.

Don't need it...if your subwoofer is powered. (your subwoofer plugs into the wall?)

(If it doesn't....disregard all of the above...lol)

No, b/c the center for 5.1 likely is voice without bass. I'd use one of the channels, after you determine that the sub input is line.

its complicated , lol

If you give up and feel like spending money, I highly recommend the RSL Speedwoofer 10S.

One thing for certain is that with any surround sound system...the powered subwoofer is the most important part.
I have my 5.1 set-up so that it is on with all tv watching...movies, news, Jeop..all.
The subwoofer is awesome...I will never part with it.

PLUG A RCA CABLE FROM THE RECEiVER INTO THE POWERED SUB.

Good lord You boyz are turning me into nota

PS here's the manual for your receiver, pay special attention to pages 33-36.

There's no RCA jack on his sub...

The photo of the back of a sub that's above is not the OP's sub, but someone elses.

all of this talk about subs and speakers is so confusing

https://res.cloudinary.com/jerrick/i...001ebabb00.jpg

Oh whoops nevermind Sorry

So OP is saying you had the RCA receiver and 5 speaker SET, and you're replacing the broken RCA receiver but you want to use the RCA speakers and the sub doesn't have an amp, it was powered by the RCA receiver?

You will need an amp to power the rca sub or you will need a powered sub like the sun fire or similar. You can buy a crossover and feed off the main L/R as suggested but youre not gonna be very happy.

OP made a comment about "no power outlet" so I presumed the sub had a power cord, and thus its own amp...but who knows?
If all else fails, Dayton has a nice sub with pre in, line in, and adj gain and xover for under 150. I have a few of these and they're very nice for the money. https://www.parts-express.com/Dayton-Audio-SUB-1000-10-100-Watt-Powered-Subwoofer-300-628?utm_source=google&utm_medium=cpc&utm_campaign= 18197889536&utm_content=&utm_term=&gadid=&gclid=Cj 0KCQjw48OaBhDWARIsAMd966CabPo0_kqKwQQBR-Z-Ihs2GU_oNN8GvwMF8K4AidrEIMxjNWWsCxEaAvA7EALw_wcB

^^^ Nice subs....at incredible low prices!
Plus free shipping. It can't be cheap to ship a 15" sub and enclosure.

The SW does have a power cord but my new receiver has no port for it. I'm just going to fool around with running the SW off of another channel just for balance.

I did a google. I found the following which shows pics of the sub
https://www.ebay.com/itm/234696485145?hash=item36a5002919:g:ZiwAAOSwJzxjIC7 R

The back of the sub has 4 wires coming out, red/black for input, and purple black for "control" which I think is where the power comes from (via the stereo?)

I also found the following.
https://www.hometheatershack.com/att...rca-jpg.17563/

Here's another person on the 'Net trying to do the same thing. I haven't read the whole thread, but maybe they solve the problem.

https://www.hometheatershack.com/threads/help-with-using-an-rca-rt2870-subwoofer.23351/

I saw that thread and read it through. It seems that w/out the appropriate Power out port from the receiver I can't power up the SW. Matching components from other systems is just a pita.

thanks all.

Usually matching components between systems isn't hard. Usually, I believe, it's either a single pair of speaker wire and driven by the amp by speaker level inputs, or a power cord and an RCA connection with line level input and self powered/amplified.

What you're dealing with is an odd/unusual setup. I've never seen anything like it. Granted, I wasn't in the business, but I've never seen a sub that didn't fit into one of the two styles of connections that I listed above, and yours is different.

looks like a passive subwoofer that probably has the amp built into the old reciever. This is not customary. You can use something like this if you want https://www.amazon.com/Nobsound-Hi-Fi-Subwoofer-Channel-Amplifier/dp/B08D6G9CB7/ref=sr_1_2?crid=17GD5JBQU5713&keywords=subwoofer+a mplifier+home+audio&qid=1666289904&qu=eyJxc2MiOiI1 Ljc4IiwicXNhIjoiNC43NSIsInFzcCI6IjMuNjgifQ%3D%3D&s prefix=subwoofer+ampli%2Caps%2C103&sr=8-2&ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840

it is a chipamp so its not really 300w but is probably plenty.


I would be more inclined to just spend a bit more on an actual decent powerd sub however:

even this super cheap monoprice unit is probably better than the rca one and would hook right up to your receiver
https://www.amazon.com/Monoprice-108248-60-Watt-Powered-Subwoofer/dp/B009GUTJ34/ref=sr_1_2?crid=348W469MZIGAF&keywords=powered+sub woofer&qid=1666290175&qu=eyJxc2MiOiI2Ljc3IiwicXNhI joiNi4wOSIsInFzcCI6IjQuNzUifQ%3D%3D&sprefix=powere d+subwoofer%2Caps%2C114&sr=8-2

people like these cheap klipsch as well which will be like 10x better than what you had I would think

https://www.amazon.com/Klipsch-Reference-R-10SW-Powered-Subwoofer/dp/B00MH42BBI/ref=sr_1_1?crid=348W469MZIGAF&keywords=powered+sub woofer&qid=1666290292&qu=eyJxc2MiOiI2Ljc3IiwicXNhI joiNi4wOSIsInFzcCI6IjQuNzUifQ%3D%3D&sprefix=powere d+subwoofer%2Caps%2C114&sr=8-1&ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840

The key wording on the RT-2870 is "Home Theater Powered"
Different than a regular 'powered subwoofer'

Flatbutt, You would be better off dumping the RCA sub and getting a real powered sub that
will have an Ac cord to go to the wall and usually a RCA cable that will connect directly to your
reciever. If price is a concern go to Costco and they have a lower level Klipsh sub that will
more than likely totally out perform the RCA. Most good subs are going to be in the $350.00
to $1000.00 range. A good sub will also have a gain/volume knob on the back so you can dial
it in to seamlessly match with your other speakers. The cheap subs will not have an array of
connections on the back which limits there functionally. I've seen better subs at Goodwill than
the RCA sub you are trying to use, respectfully.