# COAX LFE. Better?



## hotbutta (Dec 5, 2010)

Can coax (RCA type) cable be used to connect the LFE channels? thanks


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## sga2 (Nov 14, 2009)

hotbutta said:


> Can coax (RCA type) cable be used to connect the LFE channels? thanks


If the receiver has an RCA sub pre-out and the subwoofer has an RCA line level input the sub should be connected via RCA in lieu of speaker-level inputs. If both components have balanced XLR connectors, that woud be even better than RCA. 

I use Belden 1694a coax with RCA connectors for my subs.

Regards,
sga2


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## RBTO (Jan 27, 2010)

Not all coax is good for audio purposes. It is primarily designed to carry high frequency signals (radio frequencies) and does that quite well, however, some coax has a copper plated steel center conductor and mylar shielding with an aluminum drain wire, and is not be the best for low frequency (i.e., audio) signals. Coax can also be stiff and not nearly as flexible as cable designed with audio in mind. A cosmetic feature of audio cable is its more compact size, since most coax will be considerably larger in diameter (Beldin 8216 is an exception).
You can't do wrong by going with some good (not super good) quality audio cable with gold plated end connectors attached (molded on). Monoprice, Parts Express, and others have a lot to offer. _*There are no special cable requirements for the LFE channel*_ (over regular audio cables). If anything, the signals are less demanding than regular audio since they don't have high frequency content. _Shielding is important_, however, since any 60Hz picked up will be very noticeable in the LFE channel. I've used medium high quality audio cables with stranded wire construction for my LF connections with great success and satisfaction. They are flexible, and haven't failed me yet, in terms of performance.


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## chas (Jan 28, 2007)

Blue Jeans Cable has a little info (and a nice choice of cables) on their subwoofer cable page:
http://www.bluejeanscable.com/store/subwoofer/

Their Tartan line has some very inexpensive alternatives:
http://www.tartancable.com/subwoofer-cables/index.htm


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## lcaillo (May 2, 2006)

There is no problem electrically using coax. The only problem is the flexibility of the cable and any reliability in the connections if not made properly.


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## Anthony (Oct 5, 2006)

I use RG59 coax for all my RCA connections (LFE, digital, component video, audio). The RG59 is pretty flexible compared to the double shielded RG6 stuff, and the connections are fine. I am using Canare cable, but Belden makes fine coax cables as well. They both publish their loss per foot specs as a function of frequency and they are more than adequate for the audio band.

Blue Jeans cable is a great source for cables. Many of their cables are the same connectors and cable as I've made myself, and they're pretty cheap compared to AudioQuest, Monster, etc.


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## hotbutta (Dec 5, 2010)

Man,you guys are great. Thank you.


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## gsmollin (Apr 25, 2006)

You need only shielded cable for this connection. 

I don't recommend coaxial cable because it is usually too stiff. Coaxial cable is for controlled-impedance applications at 50 or 75 Ohms, such as RF transmission. RG-58 is 50 Ohm cable that flexible enough, but is almost always available with only BNC connectors because they are 50 Ohm connectors. RG-59 is available with RCA* connectors because of component video applications, but this is just unnecessary for audio, and you get absolutely no advantage to using a controlled impedance cable when your I/O is totally uncontrolled impedance.

* RCA connectors are not controlled impedance connectors anyway. Some vendors have produced RCA connectors that get close to 75 Ohms if you don't push the frequency too much. But once again, this is all pointless for a subwoofer connection, unless it is over 10 miles long.


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## Anthony (Oct 5, 2006)

I disagree. You _may _need shielded. Coax can still pick up noise if the sub cable runs along power lines in a bundle or rack. And since power is at 60Hz and that's usually right in a subwoofer's range, any noise picked up from power will be audible.

However, if you don't have the noise problem, you can get away with non-shielded.

And yes, no RCA is a true 75 Ohm connector, although Canare claims to keep it close for certain frequency ranges. But you don't need the impedance match for the audio band, as mentioned earlier.


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## Andre (Feb 15, 2010)

I used the same Belden 1694A that I wired the house with to make all my custom lenght audio and video coax cables. I used the Canares for all the video, of course this is all mute now with HDMI. My audio cables used the same wire (I bought a spool) and a less expensive compression/crimp RCA


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## Anthony (Oct 5, 2006)

That's the other thing about DIY coax -- crimp connections. After soldering more XLR (balanced) and RCA connectors than I care to admit -- I will never go back now that I have a couple of good coax crimpers.

It's the difference between 3 minutes crimping and 10 minutes for soldering.


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## Andre (Feb 15, 2010)

And you don't have to worry about cold solder connections


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## moggi1964 (Jun 7, 2008)

I have the Blue Jeans Cable LC-1 Analog Audio Cable on a 14ft run. Nice and flexible and does the job.


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## gsmollin (Apr 25, 2006)

Anthony said:


> I disagree. You _may _need shielded. Coax can still pick up noise if the sub cable runs along power lines in a bundle or rack. And since power is at 60Hz and that's usually right in a subwoofer's range, any noise picked up from power will be audible.
> 
> However, if you don't have the noise problem, you can get away with non-shielded.
> 
> And yes, no RCA is a true 75 Ohm connector, although Canare claims to keep it close for certain frequency ranges. But you don't need the impedance match for the audio band, as mentioned earlier.


If you are responding to my post, as I said, "You need only shielded cable."
Coaxial cable is built to provide a controlled characteristic impedance to wavelengths shorter than the length of cable in use. This is important for RF and high speed digital cables, but adds no benefit to audio signals, unless you are going miles.


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