Hey all.

I’ve been using Vanco products for many years and have been satisfied. But I’ve never had to call their support line until now….. eek.

So I have a 280535 (edited) analogue audio balun with ground loop isolation. It has a ground screw on both units and also metal RJ45s, which I presume means I can use a shielded cable to ground the two units to one another….but the instructions don’t speak to what kind of cable is required to go between the two units nor what to do with the two grounds.

Just curious if anyone can offer any insight. I have an un-shielded cat6 cable in place. Running a new cat6 would not be impossible but would be very laborious. My thoughts are that if I have a shielded cable I can ground either end and the two boxes would be connected via the shield. If I’m using an un-shielded cable, do I ground both ends? I have confirmed with a continuity test that the RJ45 is connected to the ground screw.

I called their tech support and the fellow on the phone was no help. He said he’d have the audio specialist call me but to be honest based in my conversation with this guy I have zero confidence that anything was happening after he hung up thr phone.

Hoping someone here can offer some assistance.

Thanks!

Craig

Tech support called me. The expert is on holidays but someone else wanted to get back to me.

They say a shielded cable is up to me. Not needed. Ground one or the other but not both as it’s a closed system. I don’t see how it’s a closed system without the shielded cable bonding the two together but that’s what they said.

Craig

It sounds like you're dealing with a technical support issue related to a closed system and the use of a shielded cable.

Can you check the part number? When I searched, it came up with a Digital to analog converter with S/PDIF and Toslink inputs.

The baluns I found were 280535 and I didn't see a ground screw.

Not sure I would sweat it unless you have hum and if you do, maybe ground the end that's closest to the head end.

I have used audio baluns in many homes and only one that has hum- thinking of using S/PDIF and converting to analog at the far end to see if it makes a difference. If I switch the receiver at the far end, I can convert to optical, so hum will be unlikely unless it's in the signal.

You are correct. It’s a 280535. I have the DA converter at home and looked at the wrong box.

You are also correct in that it’s different than what you see on line. I’ve used this balun many times. I was surprised to see that the product in th box is different than on the website. When tech support called me back he said that they changed the design and now it has grounds, a metal enclosure and shielded RJ45 connectors. I mentioned to him that the documentation was not updated as it matches the previous version. He took note.

I am dealing with a very minor hum. When I wire subs I run an RG6 and a cat6. This run is about 60ft and the coax isn’t suitable (loss of signal over the distance) so I’ve used the cat6 and a balun. The electrical for the sub is run back to the same surge protector as the receiver and the signal cables are not run parallel to any electrical. I switched to a balun and the signal level improved quite a bit but now I have the subtle hum. The balun I used is a cheaper Calrad model I happened to have with me. I’m going back and hoping that this one with ground loop isolation will fix the issue. There was no hum with the coax. The Calrad balun I used had been in use on my own system in my garage with no hum. So I don’t think the Calrad balun is creating the hum.

Craig

Ground loop isolation means.... no ground reference between components!
If you ground both ends, you have re-established the ground and are now NOT ground loop isolated.
That is why you do not ground both ends.

In normal use, you do not ground either end. No shielded cable and no shielded plugs, that can carry a ground to the other side.

Some audio equipment requires a ground reference in order to work (very rare these days). That is what the ground terminals are for. Whichever equipment is requiring the ground reference, you run a short ground wire from that ground terminal to the equipment chassis. And NO where else.

True baluns have a small transformer in them. Make sure the little black box is not up against other electronic equipment. Those coils are antennas as well and will pick up hum from sources very close by.

Thanks for the reply Brad. The Calrad baluns have the male connector as a pigtail and so can’t be more than 3 inches away from the equipment. The Vanco baluns have a set of female RCA connections so I can use a longer RCA and mount them a little further away.

Just don't have them sitting right against a power supply or other source that usually emits a lot of RF and you should be fine.
If you do get noise with the new baluns, try spacing any cable connected to the baluns a few inches away from others (especially HDMI cables). I seen that before, when a noisy HDMI cable was laying with other cables (the hum did sound different from your typical 60hz ground loop hum however). Also seen that interfere with IR blocks.

There's no reason that the coax should lose signal over 60'- your sub line out should be plenty to prevent it because 60 feet just isn't a long run. I would find out if the coax is pinched- losing the distance between the center conductor and shield reduces noise rejection.

Have you used a different piece of coax to see if it helps? I would also use my inductive probe from my signal tracer (Fox & Hound or any other) to find out if the hum is induced, or caused by bad grounding. Just because I have seen it work, try connecting the shield of the coax to the ground screw on the AVR or whatever is at the head end- it may eliminate all of the hum.

I doubt the Vanco analog audio balun will increase the signal strength in order to combat line loss- it may and I have seen slightly hotter output from PAC isolation transformers used for car audio (you could try using an isolation transformer if this proves to be a ground loop- Jensen and Edcor are two of the better brands).

Subs and power amps generally aren't powered through surge protection unless the outlet used for each is specifically labeled for those and protecting a sub that's 60' from the rest of the system isn't quite the same as if it were next to the rest of the system. Maybe you could use separate surge protection at the sub- it could eliminate the hum. I know some Munster power strips had Amp and Subwoofer labeling, but those were terrible- I connected one with their Dr Noise POS that was used to sell their stuff and when I turned the level control up, I could hear a baseball game broadcast- when I used it with my $7 Office Depot power strip, it was silent. I still use that power strip 25 years later and with the power going out last weekend complete with arcing at the transformer 75' from my house, nothing cooked.

There’s a lot of good info in there. Thank you.

Since we’re on the subject of the coax I’ll put a bit more info out there. What brought me back to the guys house was that the sub was turning off sometimes. I figured the signal getting to it wasn’t hot enough and it wasn’t sensing it al of the time. I tried turning up the sub volume on the AVR and then backing off the volume on the woofer (it was about 3/4). Out out from the coax was still intermittent. So I switched over to the balun and it was a touch louder. Not remarkable. But very consistent. No more sub shutting off. But I have the barely audible hum. Switched back to the coax and I could get sound at all. Back at the receiver if I unplug the co-ax and put my fingers on the end of the connector o can hear the sub humming upstairs. So I feel like there is still a physical connection but yeah… some how the coax must be killing the signal. Probably some damage as you mentioned. So with the coax out of operation I’m wanting to use a balun but no hum.

The only outlet near the sub is the one it’s using that goes back to the surge protector. But I could unplug it and try it in a cheapo. The AV is on its own dedicated circuit so it would still be using that outlet. Just not the rack mounted surge protector.

There is a conduit in lace from the TV to the rack. To access it for the sub I’d have to pull base boards and cut into it but I could do it if needed. There is an HDMI in the conduit. It’s a Vanco active cable. 70ft I believe. I’ve used Vanco active cables many many times and never experience noise issues.

Craig

Have you checked the coax for problems? I would inspect the ends, especially if either/both are bent sharply. If F to RCA adapters were used, I would replace them with compression RCA ends but first, I would substitute a different piece of coax to very the problem.

The first thing I was going to recommend is drop the input sensitivity on the sub and increase the output, but you already did that-

Ah, the joys of Custom Installation.....

I’m using F connectors with RCA adapter as I have many times. That said I’m out of the ones from my regular supplier and got these from……. Amazon. I’m sorry.

I’ll replace the ends with some better ones.

Thanks!

Use an ohmmeter to check for unexpected connections to building ground. There should be no connection to building ground in the Balun wire. It’s interesting to measure the voltage difference between building ground and neutral. Don’t expect zero, but it should be low.

If the wire between Baluns runs parallel to power wiring, it is possible that coupling will induce hum. You may be able to measure this with a high impedance millivolt meter. Remove the Balun from one end of the connection and measure the voltage on the raw wire. Be sure to measure the resistance from these conductors to building ground too.

I think it might be more accurate to say that breaking a ground loop prevents a connection between the audio/video or network grounding- one of the definitions from when I was working in 12V audio was "A ground loop occurs when the ground from an audio circuit or power supply impinges on the other.

The problems we generally see are on the cable feed when the installers don't do their job correctly, part of the system is using one phase of the electrical service feed and something else is using the other phase or if the wiring has resistance on the neutral and/or ground. This applies mostly to power supply using DC, but it can cause problems for us, too. OTOH, I have eliminated ground loops/noise in 12V and AV systems of the type we commonly work with by connecting a cable shield to the chassis of a piece of equipment.

Breaking the connection on the two conductors in an unbalanced audio/video feed often solves the problem but a lot depends on how this is done.

Good point about the balun picking coupling with power cords or possibly, power transformers.

I’m pretty sure the electrical was not run close to my cables. But I’ll double check. I’ll check for connection to ground as well. Thanks!!