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Topic:
Very large job hum over cat5 balun
This thread has 34 replies. Displaying posts 1 through 15.
Post 1 made on Friday September 8, 2017 at 14:55
Dtruxal
Junior Member
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Edit: here are the plans for the racks. HE2 is the problem child.

[Link: imgur.com]


I have a 35,000 sq ft home I am working on. It has 2 racks in it. The first rack everything sounds good. When I shoot audio over to the second rack I am getting very loud humming over the whole system.

It currently goes from the source, to an audio matrix to the balun over cat5 to the balun, then to the amp and out to speakers.

I have tried new baluns, a ground loop isolator, by passing the matrix, and disconnecting the ground to the second rack.

Any other ideas I can try?

Last edited by Dtruxal on September 8, 2017 16:10.
Post 2 made on Friday September 8, 2017 at 15:07
Fred Harding
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I would suggest contacting the folks at Jensen Transformers.
On the West Coast of Wisconsin
Post 3 made on Friday September 8, 2017 at 15:21
Ernie Gilman
Yes, That Ernie!
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Fred's suggestion is an excellent one.

On the other hand, if you gave us a huge amount of information, including brands and model numbers, we might be able to help.

Some basic ideas, though, include this:
Is the hum always present at the same volume, or does it go up and down with the volume? This would indicate whether it's getting injected into an input or is more of a power amp situation.

Measure resistance between the ins and outs of every conductor of your baluns. It should be infinite. Many things called baluns are not baluns (look them up) but simply wiring adaptors. Wiring adaptors would not isolate grounds and could therefore contribute to hum instead of arresting it.

You say you're "working on" this system. Is all interconnection of everything done? I once had a client who had two surround systems in an apartment, with a common wall between them. He moved to an apartment where the systems ended up forty feet apart, so I ran harnesses from one room to the other.

At the end of one day I had been able to give him basic TV watching capability and there was hum, audible in the speakers and visible as a crawling bar on the TV... but the wiring was not finished. He wanted me to fix the hum right then and I told him we should wait until the system was done. Next day, I added the rest of the cabling and there was no longer any hum.

Hum had been caused by some ground loop(s) in the partially-wired system. When I actually ADDED more grounds by finishing the wiring, the ground loop problem solved itself!

If it comes to someone coming out to help, it might be nice for us to know what area you live in.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
OP | Post 4 made on Friday September 8, 2017 at 15:48
Dtruxal
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Plans

The hum in constant, it only changes when touching the inputs of the speakers.

I think all of the physical connections have been made. But I am not the tech handling that so I will have to check with him.

The baluns are muxlab500033, here is the plans for both racks. The HE2 is the one with the humming.

[Link: imgur.com]

Anything else I'm missing let me know.
Post 5 made on Friday September 8, 2017 at 15:49
lippavisual
Senior Member
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Ground loop.

Are the 2 racks powered from different outlets on the same circuit? different outlets on different circuits?

Are these circuit/s on the same phase of power??

Answer these questions and you can find the problem.

Usually, it's because the outlets powering your racks are on different phases of power within the electrical panel. If that's the case, the electrician should be able to move the one breaker so they share the same phase.

But, it could also be cable company not grounding their service at entry to the home/building. Are these at play too??
Post 6 made on Friday September 8, 2017 at 16:06
Ernie Gilman
Yes, That Ernie!
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"Ground loop" is almost a throw-away response.

Think about the analog RCA pair that connects, say, the analog outputs of a CD player to an AVR. If you start at the CD player's left output ground, you can trace a wire (the RCA cable's shield) to the AVR's left channel input; you can then trace to the AVR's right channel input; you can then trace back to the CD player's right output on the RCA cable's right channel shield; and this is connected together inside the CD player.

That's about as complete and obvious a loop as you can have. And it's all ground connections and wire, so that's a ground loop. The thing is, it isn't a PROBLEM ground loop.

That's why you can't just say "ground loop" and let it go at that.

We ignore ground loops all the time when we don't have hum or other problems. We usually don't run into circumstances where adding more cables -- more ground interconnections and actually more ground loops -- solves a hum problem.

So look for other things first.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 7 made on Friday September 8, 2017 at 16:14
Ernie Gilman
Yes, That Ernie!
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Now for something that might be helpful.

Do any of your components have three-wire power cords? That means their chassis grounds are connected to the house's power ground. That can cause a problem ground loop, depending on whether there's current flowing in the ground.

How about the grounds of a cable, antenna, or satellite dish? Are they grounded? Are you sure? Are they well grounded?

If you get brave and ADD a ground from one half of the system to the other, what happens?

And be sure your baluns actually isolate grounds. (The origin of "balun" is "BALanced to UNbalanced," meaning basically a transformer, which incidentally would separate the ground on one side from the ground on the other side. People who are sloppy at naming things, in particular CCTV accessory companies, have infected most of us with the sloppiness of calling an adaptor a "balun" when the product is just hot and ground of a BNC to two screw terminals -- no balanced to unbalanced at all.)
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 8 made on Friday September 8, 2017 at 16:34
Fred Harding
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My answer is the triage answer.
On the West Coast of Wisconsin
Post 9 made on Friday September 8, 2017 at 16:44
lippavisual
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On September 8, 2017 at 16:06, Ernie Gilman said...
"Ground loop" is almost a throw-away response.

That's about as complete and obvious a loop as you can have. And it's all ground connections and wire, so that's a ground loop. The thing is, it isn't a PROBLEM ground loop.

That's why you can't just say "ground loop" and let it go at that.

We ignore ground loops all the time when we don't have hum or other problems. We usually don't run into circumstances where adding more cables -- more ground interconnections and actually more ground loops -- solves a hum problem.

So look for other things first.

Jesus...you slay me Ernie.

We are on a freaking integrators forum. I'm pretty sure at some point in his life he has heard the term Ground loop. And when you hear that, it typically comes with the nomenclature that there is a PROBLEM.

Who gives a shit if there are ground loops that don't cause problems. Not needed for this post topic.

Read my post that actually gives him some thoughts for the reasoning of a ground loop being introduced.
Post 10 made on Friday September 8, 2017 at 16:56
lippavisual
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OP

After looking at your image, if you play any audio from Rack 1 out of the Sonance Amps located in Rack 1, do you get the hum?

If the answer is no, then the interconnects that are being used to connect from Rack 1 to Rack 2 are introducing the Ground loop to Rack 2.

Back to my original post, most likely your power outlets are on different phases.

EDIT: you could also try a powered audio balun, although that may not fix the original problem.

Last edited by lippavisual on September 8, 2017 17:15.
Post 11 made on Friday September 8, 2017 at 17:34
fcwilt
Senior Member
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A fool proof solution to any hum problem is to first locate the piece of equipment that is the source of the hum and then teach it the words.
Regards, Frederick C. Wilt
Post 12 made on Friday September 8, 2017 at 18:52
buzz
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On September 8, 2017 at 15:48, Dtruxal said...
The hum in constant, it only changes when touching the inputs of the speakers.

I'm not sure what you mean by this.

The baluns are muxlab500033, here is the plans for both racks. The HE2 is the one with the humming.

I agree with Fred, use a Jensen Transformer at both ends.

How far apart are these racks? Are they in different rooms? Do they connect to different electrical panels?

It seems unusual to me that a large, high quality system is using 3.5mm phone plugs for interconnects. What is the device that you are connecting to HE2?

Does this hum go away if you disconnect the cable feed?
Post 13 made on Friday September 8, 2017 at 23:29
Impaqt
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Those Muxlab pieces can hardly be called "Baluns" those are just sending line level over a cat cable.

I would first suggest using a true balanced line driver like the AudioControl BLD10/BLR10 combo

[Link: audiocontrol.com]
Post 14 made on Friday September 8, 2017 at 23:44
Dave in Balto
Super Member
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Hunting down hum is a pain in the Arse. I get random buzzing in my own system, haven't heard it in a while, but I did have to call the power company about my lights flickering and since then, the hum has been gone. My projector had an issue inducing Hum when its HDMI was plugged in, I wound up using a device to lift the ground.

For you, try connecting both racks to the same circuit with an extension cord to try to eliminate the phase issue. is there hum without the interconnects attached? stupid question (may have been answered) but tells a lot.

You have satellite and cable? does disconnecting one or the other or both make a difference?

usually for hum, I start by disconnecting things one at a time and see what is the biggest cause and work backwards.

If you have any grounded power cords, try a cheater plug to see if there is any culprit.

I love these guys, have saved me a ton of headaches.

[Link: ebtechaudio.com]
Hey, careful man, there's a beverage here!

The Dude
Post 15 made on Saturday September 9, 2017 at 01:22
Ernie Gilman
Yes, That Ernie!
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On September 8, 2017 at 23:29, Impaqt said...
Those Muxlab pieces can hardly be called "Baluns" those are just sending line level over a cat cable.

I would first suggest using a true balanced line driver like the AudioControl BLD10/BLR10 combo

You are right about using a balanced line if the problem is that hum is induced in the signal leads. That's not what everybody is telling to look for and solve.

Those units have shield connections. If you connect the shield at both ends, you will have interconnected the grounds of the two racks and you'll be back where you were -- with regard to ground loops -- at the start.

By the way, what ground isolator did you use? I must admit I have trouble looking at your rack setups and determining from that just what ground might be connected to what, so I'm asking outright.

When I shoot audio over to the second rack I am getting very loud humming over the whole system.

What, exactly, is connected to what? I'm looking for an answer along the lines of "preamp zone 2 RCA outputs to non-ground-isolated fake baluns to two pairs of a CAT5; other end of CAT5 has 2 RCA plugs on it that go into __________."

And yeah, what's "hum doesn't change but it changes when I touch the speaker leads?"
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
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