Solved! question regarding Receiver and subwoofer

[udi.zam]

Hello,
i've read couple of questions regarding connecting my receiver to the sub, but couldn't find the answer. yet.
so my receiver (Onkyo) has coax output to the sub, and my sub has both coax and 2-wire input.
BUT
the problem is that the receiver is quite far from the sub and the wire goes through the wall (it's a new house) meaning even if i would find 30 ft. coax wire, i wouldn't be able to insert it to the in-wall pipe.
so, the solution i'm seeking of, is how to convert the coax out to standard 2-wire, and then back to coax.
i've read that it's not recommended somewhere, but still could find a dedicated product
http/www.ebay.com/itm/Speaker-Wire-A-V-Cable-to-Audio-Male-RCA-Connector-Adapter-Jack-Press-Plug-/262896922641

what do you think?

 

[USAFRet]

It's a dollar. Try it. It will probably work.
But try it before you feed the wire through the wall.

 

[Corwin65]

Every-time you convert something, you lose a little.

Why not just run the 2 wire and be done with it?

 

[Lkaos]

Dont you have wall connectors to the coax wires? Just use a cable to the wall socket...

 

[udi.zam]

It's a dollar. Try it. It will probably work.
But try it before you feed the wire through the wall.

unfortunately i did, but a strong low wwwwooooo.... is coming out of the sub (do you know what is the technical term for that?). i think it may be a grounding problem as when i touch the sub it improves (wwwoooo.... is dramatically reduced).

Anyway, i'm supposed to be an electronic engineer so a bit embarrassed i can't find the reason by myself i know that coax should simply be a better shielded signal so maybe running the sub signal through a 2-wire for such a long way is a problem. on the other hand, sub is for <150Hz frequencies which do not tent to suffer from noise.

 

[udi.zam]

Dont you have wall connectors to the coax wires? Just use a cable to the wall socket...

running speaker wires through he wall simply mean that when building the house, hollow pipes where embedded in the walls running from the receiver should be, to all where speakers should be (2 front, 2 rear and sub). that eliminate the ugliness of wires running around the leaving room.
there's no connectors. just a preparation for the standard 2-wire speaker cable, but the coax connectors that are usually a bit bigger just don't fit in the pipe.

 

[udi.zam]

Every-time you convert something, you lose a little.

Why not just run the 2 wire and be done with it?

i've run the wires through the walls, but the sub i/f is coax so i must somehow convert. i'm also wondering if using 2-wires instead of coax is good in general. coax cables are usually used for digital signals (low power), while the 2-wires for speakers are used for analog with rather high power.

 

[americanaudiophile]

There are wireless sub woofer adapters if you need them.
https/www.bestbuy.com/site/rocketfish-wireless-subwoofer-transmitter-receiver-kit-black/6965266.p?skuId=6965266&ref=212&loc=1&ksid=776e5d49-4a2b-4261-be78-e2ec3c41bd04&ksprof_id=16&ksaffcode=pg265324&ksdevice=c&lsft=ref:212,loc:2&gclid=EAIaIQobChMIkPPYrYXa1gIVAWSGCh1kZQI6EAQYAiABEgIlnvD_BwE