Subwoofer wiring

[Mhkpilot]

I apologize in advance for my ignorance on this subject; I’m learning as I go. I’m building a dedicated home theater room in my house and have run 14-gauge in-wall/in-ground speaker wire in the walls/ceiling joists, to where the hardware will be located. I assumed that the subwoofer ran the same speaker wire that the speakers did, but just learned that it actually runs on “shielded RCA cable,” otherwise I’ll get a “loud hum.” This is according to HSU Research”s tech support. The sub in question is a HSU Research ULS-15 MK2. Since the speaker wire is already in the wall, it’s a bit of a bummer to learn this now, but the carpet hasn’t been laid yet so I can just run this ”shielded RCA cable” under the carpet pad around the perimeter of the room to the cabinet. My questions are: 1. Can I put RCA connectors on the already installed speaker wire in the wall and at least try it to see if there is a “loud hum” or is it a different kind of wire? The wire I ran was “GearIT 14AWG outdoor direct burial in ground/in wall CL3 CL2 rated / 2 conductors OFC O2 free copper.” 2: Where exactly do the RCA plugs plug into? A pic of the back of the sub is below. 3. if the connectors into the sub are RCA, are they the same on the other end into the receiver or are they typically banana plug type? 4. If I wanted to upgrade from a receiver to a processor down the road, as I understand it, these typically use XLR cable/connectors. Again, looking at the pic of the back of the sub, there are jacks for XLR cables. Does the XLR cable need to run from the Processor or amp to the sub directly or can I run the RCA cable to an amp, and from the amp run XLR to the processor? I’ve included a screenshot of the back of an Emotiva XMC-2 16-channel processor….I don’t see where the sub gets plugged in. I see jacks for sub height speakers but thinking that’s not where the subwoofer would go.
Any and all help would be greatly appreciated.

 

[lovinthehd]

Old passive subs (i.e. subs without their own amp) used speaker wire from an amp, but most modern subs with their own amps accept either xlr or rca connetion from pre-outs on a pre-pro or avr. XLR might be better if there's a long distance between your pre-pro and the sub, and since you have XLR on both pre-amp and sub, I'd just use that. No you can't take typical speaker wire and simply add rca or xlr terminations (but you could make your own cable with appropriate coax stock). Not all powered subs if used with the high level/speaker level connections would hum particularly, tho, but such connection can be of limited use, particularly considering your pre-pro's subwoofer management options. On your pre-pro, the three far right connections (looking at the photo) are for use with subs.

 

[TLS Guy]

I apologize in advance for my ignorance on this subject; I’m learning as I go. I’m building a dedicated home theater room in my house and have run 14-gauge in-wall/in-ground speaker wire in the walls/ceiling joists, to where the hardware will be located. I assumed that the subwoofer ran the same speaker wire that the speakers did, but just learned that it actually runs on “shielded RCA cable,” otherwise I’ll get a “loud hum.” This is according to HSU Research”s tech support. The sub in question is a HSU Research ULS-15 MK2. Since the speaker wire is already in the wall, it’s a bit of a bummer to learn this now, but the carpet hasn’t been laid yet so I can just run this ”shielded RCA cable” under the carpet pad around the perimeter of the room to the cabinet. My questions are: 1. Can I put RCA connectors on the already installed speaker wire in the wall and at least try it to see if there is a “loud hum” or is it a different kind of wire? The wire I ran was “GearIT 14AWG outdoor direct burial in ground/in wall CL3 CL2 rated / 2 conductors OFC O2 free copper.” 2: Where exactly do the RCA plugs plug into? A pic of the back of the sub is below. 3. if the connectors into the sub are RCA, are they the same on the other end into the receiver or are they typically banana plug type? 4. If I wanted to upgrade from a receiver to a processor down the road, as I understand it, these typically use XLR cable/connectors. Again, looking at the pic of the back of the sub, there are jacks for XLR cables. Does the XLR cable need to run from the Processor or amp to the sub directly or can I run the RCA cable to an amp, and from the amp run XLR to the processor? I’ve included a screenshot of the back of an Emotiva XMC-2 16-channel processor….I don’t see where the sub gets plugged in. I see jacks for sub height speakers but thinking that’s not where the subwoofer would go.
Any and all help would be greatly appreciated.

The answer to your question, is NO, you can not use speaker wire to connect a powered sub.

The big mistake you made, was that you NEVER EVER run ANY AV cable in wall without it being in conduit. Speaker and especially other cables fail, and you need to be able to change cables in minutes and NOT take the room apart. Since this is a new room, I would correct this now. It will just be a bit of sheet rock and paint.

 

[Mhkpilot]

The answer to your question, is NO, you can not use speaker wire to connect a powered sub.

The big mistake you made, was that you NEVER EVER run ANY AV cable in wall without it being in conduit. Speaker and especially other cables fail, and you need to be able to change cables in minutes and NOT take the room apart. Since this is a new room, I would correct this now. It will just be a bit of sheet rock and paint.

I did use conduit to run the HDMI cable to the projector but only to upgrade it later if needed. I didn’t think speaker wire would simply “fail” and need to be replaced; nobody is running 12/2 romex in conduit from outlet to outlet because it might fail someday. Why would speaker wire all of the sudden fail? Unless it get’s cut or pierced, it’s a copper wire just sitting inside a wall. Not trying to be a smart ass, I’m seriously asking. (…but won’t it always be Sheetrock and paint?)

 

[TLS Guy]

I did use conduit to run the HDMI cable to the projector but only to upgrade it later if needed. I didn’t think speaker wire would simply “fail” and need to be replaced; nobody is running 12/2 romex in conduit from outlet to outlet because it might fail someday. Why would speaker wire all of the sudden fail? Unless it get’s cut or pierced, it’s a copper wire just sitting inside a wall. Not trying to be a smart ass, I’m seriously asking. (…but won’t it always be Sheetrock and paint?)

Speakers are moving to active. That means that in future we will need balanced or RCA cables to the speakers, and not speaker wire. In addition all potential speaker locations should have AC power outlets. This is how you future proof an AV room. The major reason for conduit, is actually not failure but obsolescence. New active speaker designs are appearing in increasing numbers now, and offer much improved performance. Receivers are highly problematic and becoming increasingly so. The optimal location for amps is the speakers.

 

[lovinthehd]

Speakers are moving to active. That means that in future we will need balanced or RCA cables to the speakers, and not speaker wire. In addition all potential speaker locations should have AC power outlets. This is how you future proof an AV room. The major reason for conduit, is actually not failure but obsolescence. New active speaker designs are appearing in increasing numbers now, and offer much improved performance. Receivers are highly problematic and becoming increasingly so. The optimal location for amps is the speakers.

He doesn't have a receiver in any case. He's got an Emotiva pre-pro (and assume power amps)

 

[Mhkpilot]

He doesn't have a receiver in any case. He's got an Emotiva pre-pro (and assume power amps)

I don’t have a receiver yet or a processor. My question 4 related to the upgrade down the road from a receiver to a processor. I included a pic of the Emotiva for reference. I will most likely need to start out with a more economical receiver and upgrade gradually from there to an amp….then a processor….etc.

 

[lovinthehd]

I don’t have a receiver yet or a processor. My question 4 related to the upgrade down the road from a receiver to a processor. I included a pic of the Emotiva for reference. I will most likely need to start out with a more economical receiver and upgrade gradually from there to an amp….then a processor….etc.

Ah, didn't realize that with the posting of the Emotiva . There's not a particular "upgrade" from avr to a pre-pro....perhaps a longevity difference or better amp or processing possibilities (at higher cost too for the separates route). Some pre-pros like that Emotiva have xlr pre-outs but most avrs do not. It's not particularly necessary to have xlr in most home setups either, can be handy for long cable runs, tho. If you do start with an avr and want amp options be sure to get one with a full set of pre-outs. Many avrs do as well as pre-pros, particularly when acting as pre-pro alone (not using its internal amps) and yet can still be competitive with dedicated pre-pros price-wise (and measurement-wise).

 

[Mhkpilot]

Ah, didn't realize that with the posting of the Emotiva . There's not a particular "upgrade" from avr to a pre-pro....perhaps a longevity difference or better amp or processing possibilities (at higher cost too for the separates route). Some pre-pros like that Emotiva have xlr pre-outs but most avrs do not. It's not particularly necessary to have xlr in most home setups either, can be handy for long cable runs, tho. If you do start with an avr and want amp options be sure to get one with a full set of pre-outs. Many avrs do as well as pre-pros, particularly when acting as pre-pro alone (not using its internal amps) and yet can still be competitive with dedicated pre-pros price-wise (and measurement-wise).

Ah, thank you for this. I have heard that processors bring your theater experience to another level over avrs and I’m just beginning to research that. Right now I’m looking at the Yamaha Aventage RX-A6A and the Denon X3-3700H. I have a 5.1.4 setup and will most likely get an Emotiva Basx A6 amp to run the 2 surround rears and the 4 heights, and an A3 to run the front left, right and center. I’m just looking down the road as to what I may want to do in terms of any hardware upgrades in the future and the processors and higher end amps all seem to have XLR jacks, which is no big deal for me except for the sub, which I’d need to run it’s own cable to the cabinet.

 

[BMXTRIX]

I think you did things just fine, except running the wrong wiring to the subwoofer during the build out. Subs generally have coaxial cable (RG6 or similar) run behind the wall to them. Had you run 4 conductor speaker wire, you may have even gotten away with turning it into an XLR (assuming you used a pre-pro with a XLR output). I don't think speakers are going 'active' anytime soon. Decades of running things over standard speaker wires is in no direct likelihood of changing anytime soon, and when/if this occurs, it will not make standard speaker wiring disappear. Or very likely will not. I would think active speakers would also standardize on using category cabling (cat-5e/6) which is pretty easy to hide and use as its standard, but what do I know?

Unfortunately, just having two conductor, unshielded speaker wire at the location makes things difficult.

If the carpet isn't installed yet, then I would install a thin profile RG59 cable around the edges and poking out at the subwoofer location. As long as the distance isn't too far, it's a really small profile cable which will carry the signal without issue.

You might want to reach out to Blue Jeans Cable to see what options they have for you.

I use a mini-HR coax cable for all of my analog and digital audio needs and often for the last foot or two to the subwoofer connection. But, behind walls I always install standard coax which works great.

 

[Mhkpilot]

I think you did things just fine, except running the wrong wiring to the subwoofer during the build out. Subs generally have coaxial cable (RG6 or similar) run behind the wall to them. Had you run 4 conductor speaker wire, you may have even gotten away with turning it into an XLR (assuming you used a pre-pro with a XLR output). I don't think speakers are going 'active' anytime soon. Decades of running things over standard speaker wires is in no direct likelihood of changing anytime soon, and when/if this occurs, it will not make standard speaker wiring disappear. Or very likely will not. I would think active speakers would also standardize on using category cabling (cat-5e/6) which is pretty easy to hide and use as its standard, but what do I know?

Unfortunately, just having two conductor, unshielded speaker wire at the location makes things difficult.

If the carpet isn't installed yet, then I would install a thin profile RG59 cable around the edges and poking out at the subwoofer location. As long as the distance isn't too far, it's a really small profile cable which will carry the signal without issue.

You might want to reach out to Blue Jeans Cable to see what options they have for you.

I use a mini-HR coax cable for all of my analog and digital audio needs and often for the last foot or two to the subwoofer connection. But, behind walls I always install standard coax which works great.

What would you consider to be “too far” in regards to the cable run to the subwoofer? I’m looking at a distance of approx 35’.

I’m also in the process of restoring a 1987 Redline RL-20ii.

 

[William Lemmerhirt]

What would you consider to be “too far” in regards to the cable run to the subwoofer? I’m looking at a distance of approx 35’.

I’m also in the process of restoring a 1987 Redline RL-20ii.

I’ve run as much as 50’ of RG-6 with no issues at all. The absolute worst thing you might find is you have to bump the trim a bit. But I can’t even imagine you’d lose half of a db over that length.

 

[mtrycrafts]

... But I can’t even imagine you’d lose half of a db over that length.

That's why some amps, receivers have volume to 11

 

[William Lemmerhirt]

That's why some amps, receivers have volume to 11

 

[BMXTRIX]

What would you consider to be “too far” in regards to the cable run to the subwoofer? I’m looking at a distance of approx 35’.

I've used mini hires cable at lengths of at least 50' or a bit more without any issues whatsoever. If there is loss, I don't hear it. My subwoofer has a volume knob and my receiver has some adjustments as well.

I’m also in the process of restoring a 1987 Redline RL-20ii.

Nice! I am not a restorer so much. I have an old 86" GT Pro Performer frame that I may have painted and build up at some point, but I get out and ride a few times a week. Trying to relearn a hundred tricks my body no longer wants to do. Joint issues are not my friend right now.

 

[Speedskater]

With a little bit of luck, a 2 conductor speaker cable might work in an XLR balanced interconnect system.
Pro audio sometimes uses unshielded Cat5 cable for XLR balanced interconnects.
So a home might not have interfering sources near the cable. But then a new wall-wart could mess it up.

 

[BMXTRIX]

With a little bit of luck, a 2 conductor speaker cable might work in an XLR balanced interconnect system.
Pro audio sometimes uses unshielded Cat5 cable for XLR balanced interconnects.
So a home might not have interfering sources near the cable. But then a new wall-wart could mess it up.

I would probably try it unbalanced first over the existing cabling if I had to, but it sounds like he could just run some wiring around the edges and get away with it.

How would one use a two conductor cable in a system that calls for 3-conductors?

Cat-5e makes total sense. Actual XLR cabling in many installations is extremely thin and carried over pretty significant distances without any issues whatsoever. That's the beauty of the balanced audio design. But, cat-5e has the conductors necessary to make this happen. Category cabling is also far more diverse in use than most people give it credit for. It may actually stack up better for interference reduction than normal balanced audio cabling does.

 

[Speedskater]

An XLR interconnect is a 2 conductor cable with a shield. The shield does not always need to be connected at the receive end.
As the pros have noted with Cat5 cable, the shield is not always needed. So in a residence with little interference, a two conductor speaker cable may work as an XLR balanced interconnect. But has almost no chance of working as an RCA unbalance interconnect.

 

[Mhkpilot]

Why, technically, can’t speaker wire serve as RCA cable if the connectors were changed?

 

[lovinthehd]

Why, technically, can’t speaker wire serve as RCA cable if the connectors were changed?

Aside from "potential" why the hell would you need or want to do goofy cablng as has been proposed?