Hum from sr-5010 pre-out fr fl

[GuyInLA]

I have a 5010 that is only used for a pre-amp function. I usually connect it unbalanced to a mc275 and from there connect to martinlogan montis.
It usually has a beautiful sound. However, it has started to produce a hum on the montis woofers.

I hook the speakers directly to the marantz 5010 fl and fr and the output is clean.

Ive switched cables and got no change. Also ran a wired unbalanced to iPad with 1/8 inch plus and it’s clean so I’m pretty certain this is not the McIntosh.

I use the marantz for the built in connectivity and wireless. So I’m not thinking this is a regular ground loop as I can get clean sound skipping the pre out.

Does anyone have a Suggestion how I could further troubleshoot or remedy this easily? Other than a catchall troubleshooting step, is there a reason to think a reset may help? (Im pretty sure I tried this months ago).
I’d rather not have to send in for service but maybe that’s the answer? Maybe this is a common eventuality?

thanks all!

 

[Verdinut]

Since switching cables has not solved the situation, I think you might have a defective connection or chip and possibly a defective capacitor in the related pre-out circuit.

You would have to look for a reliable repair outfit in your area, preferably one authorized by Marantz.

 

[TLS Guy]

I have a 5010 that is only used for a pre-amp function. I usually connect it unbalanced to a mc275 and from there connect to martinlogan montis.
It usually has a beautiful sound. However, it has started to produce a hum on the montis woofers.

I hook the speakers directly to the marantz 5010 fl and fr and the output is clean.

Ive switched cables and got no change. Also ran a wired unbalanced to iPad with 1/8 inch plus and it’s clean so I’m pretty certain this is not the McIntosh.

I use the marantz for the built in connectivity and wireless. So I’m not thinking this is a regular ground loop as I can get clean sound skipping the pre out.

Does anyone have a Suggestion how I could further troubleshoot or remedy this easily? Other than a catchall troubleshooting step, is there a reason to think a reset may help? (Im pretty sure I tried this months ago).
I’d rather not have to send in for service but maybe that’s the answer? Maybe this is a common eventuality?

thanks all!

It sounds to me like you have developed a ground loop which you need to chase down.

 

[lovinthehd]

Well you don't have a balanced connection option to start with. I'd still suspect a ground loop hum generally....

 

[GuyInLA]

Yes I was inclined to think ground loop as well. Onviously, simplifying the setup is a great approach for diagnosing but just thinking…in the same room (same outlet circuits likely) I also have a denon x4400h connected to ml motion 60 XT (no pre-out/external amp) and I have zero issues.
I have not connected the denon to the mc275 because it’s too hard to get to the wiring as is.

the 5010/275 setup is connected to a panamax mr5100 (to provide enough outlets) but I don’t believe this is introducing the loop.

can anyone suggest a definitive procedure other than my current method of continually swapping cables to determine where the loop might be happening (meter across the pre-outs or something similar)?

I read about these isolator plugs but uncertain about them. If I were to go that way, might I need to acquire 4 ( 2 for the power on montis, 1 for the 5010 and 1 for the 275)? I wouldn’t guess this is emi over the interconnect, so the ground loop would result from the power connection, even if the loop is only noticed (heard) once one of the two unbalanced connections is made.

note: this is an apartment and I moved all equipment today to the opposite side of the room and noticed line faults on both the Panamax and another surge suppressor so I will have to argue with mgmt to fix it correctly and that would be enough to make me think this is the cause but I tested the outlets that were previously used and don’t see a line fault indicator. I’m not sure what the line fault designates andif the fact that some show faults and some do not whether that shows they are on physically different circuits.?.?

thank you all for your responses.

 

[GuyInLA]

Since switching cables has not solved the situation, I think you might have a defective connection or chip and possibly a defective capacitor in the related pre-out circuit.

You would have to look for a reliable repair outfit in your area, preferably one authorized by Marantz.

I will certainly do that if needed, but need to find a trustworthy servicer….and I don’t have the best luck trusting most!
Thank you

 

[Verdinut]

I will certainly do that if needed, but need to find a trustworthy servicer….and I don’t have the best luck trusting most!
Thank you

Faulty line connections might just be the cause of your problem. The management of your apartment building should get all your AC outlets verified. It's a must and the first step in my opinion.

 

[Verdinut]

Faulty line connections might just be the cause of your problem. The management of your apartment building should get all your AC outlets verified. It's a must and the first step in my opinion.

With regard to having a reliable service place, I suggest that you verify with the Marantz website. They should be able to give you the name of at least one authorized service outlet near your area.

 

[TLS Guy]

Yes I was inclined to think ground loop as well. Onviously, simplifying the setup is a great approach for diagnosing but just thinking…in the same room (same outlet circuits likely) I also have a denon x4400h connected to ml motion 60 XT (no pre-out/external amp) and I have zero issues.
I have not connected the denon to the mc275 because it’s too hard to get to the wiring as is.

the 5010/275 setup is connected to a panamax mr5100 (to provide enough outlets) but I don’t believe this is introducing the loop.

can anyone suggest a definitive procedure other than my current method of continually swapping cables to determine where the loop might be happening (meter across the pre-outs or something similar)?

I read about these isolator plugs but uncertain about them. If I were to go that way, might I need to acquire 4 ( 2 for the power on montis, 1 for the 5010 and 1 for the 275)? I wouldn’t guess this is emi over the interconnect, so the ground loop would result from the power connection, even if the loop is only noticed (heard) once one of the two unbalanced connections is made.

note: this is an apartment and I moved all equipment today to the opposite side of the room and noticed line faults on both the Panamax and another surge suppressor so I will have to argue with mgmt to fix it correctly and that would be enough to make me think this is the cause but I tested the outlets that were previously used and don’t see a line fault indicator. I’m not sure what the line fault designates andif the fact that some show faults and some do not whether that shows they are on physically different circuits.?.?

thank you all for your responses.

Isolating a ground loop is not difficult if you are logical about it. A ground loop is defined as a potential (voltage) between grounds. If you have one ground in a system then you can NOT get a ground loop.

Grounds occur not only from three pin AC connectors, but also from cable systems , satellite systems and wired Ethernet connections. The latter three are notorious for causing ground loops

So the first step is to disconnect the above three. Does the ground loop stop? If it does, then connect them back one at a time and see which one causes the ground loop. If they are blameless, then get "cheater" plugs so that you break the grounds of all your gear with three point AC plugs, except one.

Is the hum gone? If not, it is not a ground loop. If it is gone, then remove each cheater plug one at a time, and see which unit is causing the ground loop.

Once you have identified it, then bond the chassis to another grounded unit with a large braided copper cable, that should solve it.

 

[highfigh]

One easy way to test for a solution is to connect the shield for the audio cable going to the sub to the ground on an electrical outlet- if it goes away, find a way to make it more permanent. All you need to do is remove the wall plate and connect a wire from the metal tabs where the outlet screws to the box and the shield.

Also, make sure the sub't input jack(s) hasn't broken- I saw that last week and noticed that somehow, the screw holding the jacks loosened and when the plug was pushed in, the connection broke, so it hums unless I moved it in a particular way.

 

[GuyInLA]

Th

Isolating a ground loop is not difficult if you are logical about it. A ground loop is defined as a potential (voltage) between grounds. If you have one ground in a system then you can NOT get a ground loop.

Grounds occur not only from three pin AC connectors, but also from cable systems , satellite systems and wired Ethernet connections. The latter three are notorious for causing ground loops

So the first step is to disconnect the above three. Does the ground loop stop? If it does, then connect them back one at a time and see which one causes the ground loop. If they are blameless, then get "cheater" plugs so that you break the grounds of all your gear with three point AC plugs, except one.

Is the hum gone? If not, it is not a ground loop. If it is gone, then remove each cheater plug one at a time, and see which unit is causing the ground loop.

Once you have identified it, then bond the chassis to another grounded unit with a large braided copper cable, that should solve it.

thank you.

 

[lovinthehd]

The one major ground loop issue I had was in my previous place that the main ground and a cable-installer ground was different. Didn't matter up to a point, but when I added some gear it did.....

 

[PENG]

I use the marantz for the built in connectivity and wireless. So I’m not thinking this is a regular ground loop as I can get clean sound skipping the pre out.

Please clarify what you meant by built in connectivity and wireless. Did you mean using its built in power amps for some channels, while also use pre outs for other channels such as the LCR channels?

Does anyone have a Suggestion how I could further troubleshoot or remedy this easily? Other than a catchall troubleshooting step, is there a reason to think a reset may help? (Im pretty sure I tried this months ago).
I’d rather not have to send in for service but maybe that’s the answer? Maybe this is a common eventuality?

It is worth trying but I don't think it will fix the hum issue.

If the hum only comes from the woofers, is it the same from all channels that have the same Montis woofer?
If it does then either there is, as others commented, you likely have a ground loop between the Marantz pre out and the Montis woofers, or if they all hum then may be your power line is having too much "d.c. offset".

If it is due to d.c. offset, the hum noise would be from the woofer's power supply transformer but not the woofer speaker cone itself and in that case the hum will still be there even if you disconnect the input signal to the woofer.

It is hard to imagine you would suddenly have a ground loop though.

There are quick fix for both ground loop and d.c. induced hum but you need to first find out which one it is.
I don't believe the SR5010 is the source of the problem though it is possible

 

[GuyInLA]

Al, thank you so much for the suggestions. This was a loose-nut-behind-the-keyboard moment…something I used to refer to as looking under the hood for the 710 cap….

i unplugged power from the 5010 and still had the noise. In the rack, I didn’t see the black hdmi cable plugged into the 5010 hdmi out into the tv (Samsung one box). I disconnected and the him went away.
Was strange that it went away!

on another note, when troubleshootingthe outlets, found 6 that are open neutral! So those breakers wouldn’t work, and neither did the gfi outlet trip when I tried to force it with the tester. A few months ago as I was leaving for work,I heard a strange sound. It was the outlet with gear plugged inthat caught fire on the inside. Idiot maintenance worker said I had too much plugged in. He was a dolt but it didn’t occur to me to check all of the outlets then.It burned the outlet and my Panamax plug. Burnt it to a crisp and arced so much that the plug tines were half disintegrated. Would have likely burned down the whole place if I hadn’t Noticed that morning.
300 units. If 25 percent of outlets are miswired…
Crazy.

Everything is working well now. Thank you.

btw- Peng, what Imeant about connectivity was I use the marantz for airplay, etc. and send through the mc275 to the montis.