Subwoofer cable?

[March Audio]

Some people say subwoofer should use 75ohm coaxial cable, some cable claim themselves are specialized for subwoofer.

What actually the difference between a normal RCA cable, say Canare 4E6S, vs a 75ohm cable, for subwoofer usage?

Does distance matter in this consideration? Since usually we put subwoofer somewhere in the room which may far away from your device.

No the characteristic impedance is irrelevant for audio frequency signals. Any normal audio screened cable will be fine. Worrying about the capacitance of long cable runs is also irrelevant considering the low frequency (less than 120Hz).

If your system has issues with ground loops a cable with a low resistance shield will minimise the problem, but it's just a fundamental problem with single ended (RCA) interconnections. I have never experienced any problems with very small diameter cables that can be tucked out of sight under skirting and carpet edges.

The whole driving subs with high level speaker outputs has never made sense to me. RCA sources will have lower noise and distortion than almost any speaker output. Taking the source from the speaker connections doesn't make integration better.

 

[MediumRare]

I have read that statement (same signal = easier integration) many times but have never understood why that should be so. I have never found that to be the case for me or the subs I have set up for friends since sub/mains position, room effects (modes, SBIR), filter and speaker crossover phase, amplifier and driver characteristics, speaker cabinet design (e.g. vented/sealed), etc. play a bigger role than having the same signal to both. And in general I have no desire to drive my mains full-range. What is the reasoning behind the desire to send the same (electrical) signal to both?

Just trying to learn, you’re making persuasive points.

 

[Sal1950]

I got the RCA cable for my distant sub (25 or 30 ft) from SVS. Their individual sub cables are fairly inexpensive plus when I needed it I got lucky and ran into a 50% off close-out sale. I called them and asked why so cheap and a nice guy on the phone told me they were the exact same cable as their current ones but had changed the color of the covering on all their RCA's and were closing out the leftovers in the old color. It really was a super deal for a cable that long since the normal cost is very reasonable.
https://www.svsound.com/products/soundpath-rca-audio-interconnect-cable
Now it looks like they're swinging to the wireless sub system for around $120

 

[SIY]

Featuring clear signals and low data loss, the Mediabridge subwoofer cable comes with a single solid center conductor. This metal carries strong signals from the audio output ports to your subwoofers. These frequencies can travel to as far as 300 feet.

This is curious.

 

[egellings]

The 75 ohm cable does not have to be sourced and terminated in 75 ohms for living room lengths if carrying analog audio.

 

[MediumRare]

Featuring clear signals and low data loss, the Mediabridge subwoofer cable comes with a single solid center conductor. This metal carries strong signals from the audio output ports to your subwoofers. These frequencies can travel to as far as 300 feet.

That’s quite a house! Is the 300 ft vertical or horizontal?

 

[mansr]

That’s quite a house! Is the 300 ft vertical or horizontal?

Why not both? What cables do they use in the vehicle assembly building at Cape Canaveral?

 

[MediumRare]

Why not both? What cables do they use in the vehicle assembly building at Cape Canaveral?

What does Nasa use for their "subwoofers"? Probably this: https://www.grainger.com/product/GRAINGER-APPROVED-Lamp-Cord-4DPD6 or maybe this https://www.amazon.com/Shielded-Ethernet-Cable-Solid-Spool/dp/B008Y3X8YU?th=1

But whatever it is, it better be tidy! https://workmanship.nasa.gov/lib/insp/2 books/links/sections/files/401.pdf

 

[Speedskater]

I think that the Mediabridge cable company needs to study how electricity really works.

 

[Sal1950]

Why not both? What cables do they use in the vehicle assembly building at Cape Canaveral?

I think that the Mediabridge cable company needs to study how electricity really works.

For sure, everyone knows its much harder for electricity to run uphill than down.
Just like water, right?

 

[mansr]

For sure, everyone knows its much harder for electricity to run uphill than down.
Just like water, right?

Like this?

 

[Sal1950]

Like this?

Yea, that's the ticket.

 

[Sam Ash]

I've gone through some pretty bad experiences with long runs of RCA cables and subs. However, I'm wondering if the Canare LV-77S manages to resolve this effectively? EMI is one aspect with ground loops being the worst. Balanced cables eliminate this but most entry level gear only feature unbalanced interfaces.

Has anyone out there found an effective way to resolve this?

 

[JeffS7444]

I've gone through some pretty bad experiences with long runs of RCA cables and subs. However, I'm wondering if the Canare LV-77S manages to resolve this effectively? EMI is one aspect with ground loops being the worst. Balanced cables eliminate this but most entry level gear only feature unbalanced interfaces.

Has anyone out there found an effective way to resolve this?

What kind of cable lengths are we talking about? For situations where more than a few meters of cable are needed, a wireless connection may be a better choice.

 

[Sal1950]

Has anyone out there found an effective way to resolve this?

The above option of wireless is a good one, SVS sells a nice system for doing a wireless install.
I use SVS RCA cable for my long run sub (around 30') without issue. You might call SVS tech and talk to them about your problem.

 

[egellings]

Either the transmitter of a balanced cable would be the way to go.

 

[DonH56]

I've gone through some pretty bad experiences with long runs of RCA cables and subs. However, I'm wondering if the Canare LV-77S manages to resolve this effectively? EMI is one aspect with ground loops being the worst. Balanced cables eliminate this but most entry level gear only feature unbalanced interfaces.

Has anyone out there found an effective way to resolve this?

Better shielding will help with EMI but not a ground loop. For a ground loop, you could pick up an isolator such as one of these: https://smile.amazon.com/s?k=ground...x=ground+is,aps,214&ref=nb_sb_ss_ts-doa-p_5_9

 

[Sam Ash]

Thank you for all the kind input. I'm told the sure approach to this problem is to stick to a balanced workflow. The alternative is to incorporate an isolation transformer for the room in question although it is an expensive route to take.

 

[raindance]

They have the picofarad measurement somewhere on their non amazon site. Its like 17pf/1000ft. Its pretty low. The bluejeans cables are like 13pf. I know there was an immediate impact on my record player when I used meadiabridge ultra RCA's over what came with it (project generic phono cable).

Turntables are a different ball of wax to subwoofers because a moving magnet cartridge is sensitive to capacitive loading. Parallel capacitance, which cables exhibit, can reduce only high frequencies on the way to the sub. So it's not a spec I'd look at for a subwoofer cable.

 

[DonH56]

Thank you for all the kind input. I'm told the sure approach to this problem is to stick to a balanced workflow. The alternative is to incorporate an isolation transformer for the room in question although it is an expensive route to take.

Isolation transformers are many of the solutions in the link I provided. You can get them from $20 to $1200+. You can also buy direct boxes from any pro audio supplier (e.g. Sweetwater Sound) that will allow you to isolate the ground path (usually with a switch). Another alternative is the Ebtech HumX powerline isolator, https://www.amazon.com/Ebtech-Hum-P...ywords=ground+isolator&qid=1630327370&sr=8-24 It only handles about 6 A or so IIRC so you would probably put it on your preamp and not the sub(s).

Note XLR/balanced connections will not always break a ground loop; you may have to manually lift the shield at one end, or buy cables that already have the shield lifted, to break the loop. But going balanced gives you that option since the signal path is independent of the shield path that is usually connected to the safety ground.

FWIWFM - Don