Ground loop help

dagame27

I've been getting a ground loop hum, much louder in my right speaker. I verified when I swapped interconnect channels, the hum moved. When I unplug my right channel interconnect from the amp, it goes away entirely. If I plug into a different channel of my 5 channel amp, it comes back. Thoughts? I've swapped new wires, and tried cheater plugs...very confused!

F1nut

Off the top of my head I'd say you have a bad solder joint on the ground pin of that right channel RCA jack in your amp.

dagame27

Thanks. Would that still be the case when swapping wires and interconnects to a different channel of the amp? The buzzing is still there.

SeleniumFalcon

Usually what works for me is to get the system as basic as possible, a preamp connected to an amp with nothing connected to the preamp. If no noise add each source device one-at-a-time until the noise is heard. This will determine which connection adds the noise.

dagame27

I've troubleshooted a bit this morning. With everything unhooked beside speakers and amp, no buzz. When hooking up either preamp or processor direct...buzz. if I switch amp connections, moving speaker wire and interconnected to different channel...still buzz.

SeleniumFalcon

So the preamp into the amp causes noise with nothing connected to it, correct? Both channels or just one channel?
Why two preamps? What is the Integra doing?

dagame27

I tried each preamp independently. I typically use the anthem for 2 channel, with the ht bypass to integra for ht. Correct in that the noise is there with nothing into either preamp

msg

That's what I was gonna ask, re: front section - wondering if Jesse meant the preamp side.

What else do you have in this system? Component list and paths might be helpful; something may jump out.

Is there coax service-in connected to any component that is part of this system?

Any changes recently?

I had a recent similar experience that appeared after some power source adjustments with consolidation. I set up HT bypass using my 2ch integrated, but also still have a second amp connected for center channel. Originally, these were connected to two different power distribution points, though I think they are still on the same circuit, so I was confused when I started getting hum.

Current working solution was to get all components on same power source (PS Audio Dectet), with ground lift plug on the second amp. I don't like using those plugs, but couldn't figure it out otherwise and planned to revisit at some point, along the lines of what Ken suggests with simplification. I have a lot going on in that system now.

jbreezy5

“I verified when I swapped interconnect channels, the hum moved.”

“I've swapped new wires…”

So the hum followed the interconnect, but you removed the suspected IC and replaced it with another IC and hum still there?

SeleniumFalcon

Since both preamps cause the problem look for what is common to both. For example, the connecting cables between either preamp and the amp. Also placement, try placing the two channel preamp in a different location or even better use a longer connecting cable and holding the preamp move it around as much as possible to see if the noise changes.
Does either the left or right channels of the two channel preamp cause the same noise in the right speaker?

jbreezy5

SeleniumFalcon wrote: »

Since both preamps cause the problem look for what is common to both. For example, the connecting cables between either preamp and the amp. Also placement, try placing the two channel preamp in a different location or even better use a longer connecting cable and holding the preamp move it around as much as possible to see if the noise changes.
Does either the left or right channels of the two channel preamp cause the same noise in the right speaker?

^^^^^ ^^^^^ ^^^^^

Additionally, make sure the ICs aren’t touching each other or other cables. Hum can occur due to close cable proximity.

skipshot12

Did the hum just show up?
Or did the hum start after changing something?

dagame27

Thank you all for the help. I'll try separating cables next. I hadn't changed anything prior the hum starting. However, I did notice hdmi issues with the integra....I figured that was the culprit, but now I am unsure.

Navy_Goat

dagame27 wrote: »

Thank you all for the help. I'll try separating cables next. I hadn't changed anything prior the hum starting. However, I did notice hdmi issues with the integra....I figured that was the culprit, but now I am unsure.

Did you add another electric load to the same circuit or a near by plug around the same time the hum started? New lamps or other devices nearby or on the same circuit can cause problems.

dagame27

I've added nothing electrical that I can recall. I'm going to unhook everything again early this week to see of I can figure it out.

skipshot12

dagame27 wrote: »

Thank you all for the help. I'll try separating cables next. I hadn't changed anything prior the hum starting. However, I did notice hdmi issues with the integra....I figured that was the culprit, but now I am unsure.

Ok then,
If the hum just showed up that has me scratching my head...

Did this happen while you were playing music?
If not, did the hum start the next time you fired her up from a shutdown?
How loud do you play your music?
Have you noticed any recent heating up issues with any of your gear?

Trying to start from scratch here.

F1nut

dagame27 wrote: »

Thanks. Would that still be the case when swapping wires and interconnects to a different channel of the amp? The buzzing is still there.

The grounds are all connected together.

dagame27

I unhooked everything up again to simplify. The issue seems to be from the amp. The hum is present with RCA's connected, regardless of which preamp I use. When RCA's are unhooked, the buzz is gone from that speaker. Contrary to what I noticed prior, whatever RCA I remove, that speaker goes silent. To F1's point, does this sound like an amp ground issue? Anything else it could be? Suggestions to fix?

txcoastal1

Take a piece of wire and if there is a ground screw on either or on the pre and amp chassis , touch that wire to both and and pre

If either do not have ground lug then go from a screw to back of chassis

msg

dagame27 wrote: »

Thanks. Would that still be the case when swapping wires and interconnects to a different channel of the amp? The buzzing is still there.

When you posted this response, were you saying that there's a buzz/hum with one of the 2ch source channels no matter which of the 5 amp channels you choose?

How many amp channels available? Is this the B&K 200.5?

(I seem to have missed a buncha messages during course of reading, ie, weren't visible, when I had previous questions. weird.)

dagame27

Correct. Buzz is present even when moving speaker cable and interconnect to another channel on my b&k. There are 5 channels, and I run a 3.1 system.

F1nut

The grounds for all your channels are connected, think of it as one big ground. If one channel has a faulty ground they are all affected. Nothing short of finding that fault is going to fix the problem.

dagame27

That makes sense. Thank you. What is the process to troubleshoot and fix the faulty ground?

txcoastal1

txcoastal1 wrote: »

Take a piece of wire and if there is a ground screw on either or on the pre and amp chassis , touch that wire to both and and pre

If either do not have ground lug then go from a screw to back of chassis

I will further explain. When expanding my HT to include atmos I introduced a 2nd multichannel amp. When I got it all hooked up I had a ground loop hum. I took a piece of wire from the back of the pre-pro chassis and touched the back of the 2nd amp and ground loop hum disappeared.

My racks are a pair short rolling data cabinets. I installed a rack mount screw into the cabinet and a wire from both the pre and the amp chassis to that screw as a common. This eliminated the hum.

dagame27

I'll give that a shot....have to find some bare wire!

txcoastal1

dagame27 wrote: »

I'll give that a shot....have to find some bare wire!

Use a RCA cable and touch the center pin to each chassis

dagame27

I tried using an RCA from amp to either preamp...no dice unfortunately.

F1nut

dagame27 wrote: »

That makes sense. Thank you. What is the process to troubleshoot and fix the faulty ground?

You have to find the one RCA jack that has the faulty ground connection, which is likely a cold solder joint. That will require opening the amp and reflowing the solder joints on the negative connection of every RCA jack.

Of course, you can always take it to a repair firm.

skipshot12

F1nut wrote: »

dagame27 wrote: »

That makes sense. Thank you. What is the process to troubleshoot and fix the faulty ground?

You have to find the one RCA jack that has the faulty ground connection, which is likely a cold solder joint. That will require opening the amp and reflowing the solder joints on the negative connection of every RCA jack.

Of course, you can always take it to a repair firm.

Think F1 has a bead on the offending issue…
I hate chasing bad ground connections, especially on vehicles!
It’s a b**ch but sometimes the only solution is to start somewhere and eliminate as you go.
Good luck and don’t get frustrated.