Loud buzz through the speakers. Marantz Cinema 30

[GAmark]

Any Ideas it is loud and can be mitigated somewhat by grounding the amp to the AVR, but is still there. Any other ideas? It can be heard from the speakers at about 8-10 feet. Just a little history this is the first time I have run RCA cables from anything to an amplifier. I have always used XLR. I started with an 8805A which had an internal problem sent back to Crutchfield the 8805A was on backorder so I am trying the Cinema 30, even with the amps in the AVR turned off and set to preamp only this happens with multiple amps. None of these amps had this issue with my prior processor or the Marantz 8805A in balance mode. Any thoughts would be greatly appreciated.

 

[TLS Guy]

Any Ideas it is loud and can be mitigated somewhat by grounding the amp to the AVR, but is still there. Any other ideas? It can be heard from the speakers at about 8-10 feet. Just a little history this is the first time I have run RCA cables from anything to an amplifier. I have always used XLR. I started with an 8805A which had an internal problem sent back to Crutchfield the 8805A was on backorder so I am trying the Cinema 30, even with the amps in the AVR turned off and set to preamp only this happens with multiple amps. None of these amps had this issue with my prior processor or the Marantz 8805A in balance mode. Any thoughts would be greatly appreciated.

It sounds like a classic ground loop.

You have to get to one ground.

The first step is to just connect pre/pro and power amps and see if you have a buzz. That means passive speakers only and no powered sub.
Now connect peripherals one by one and see which if any bring on the buzz.

If you have a buzz with only the pre/pro and power amps connected, then one or both of the units have a badly constructed ground plane.

 

[GAmark]

Yep, I have gone through the entire process and Cinema 30 is the problem.

 

[TLS Guy]

Yep, I have gone through the entire process and Cinema 30 is the problem.

Does the Cinema 30 hum if it powers the speakers and the power amp is not connected?

 

[GAmark]

No, if you only use the Cenima 30 it is dead silent.

 

[PENG]

No, if you only use the Cenima 30 it is dead silent.

Are you using rca to xlr cable to your power amp? If yes, try using one that has the pin 1 and ground connected correctly. If using rca, try another pair of interconnect, and better still try rca to xlr as mentioned.

AN Dealing with legacy pin 1 problems (hypex.nl)
Benchmark RCA to XLRM Adapter Cable for Analog Audio - pin 3 to RCA sh - Benchmark Media Systems
Amazon.com: Monoprice XLR Male to RCA Male Cable - 6 Feet - Black, 16AWG Shielded Twisted Pair Oxygen-Free Copper Braid Conductors, E21 Gold Plated Connectors - Premier Series : Electronics

If none of those steps eliminate, or greatly reduced ground loop hum, then ask your dealer for an exchange, as the C30 may in fact be the issue. I would think that the good/right interconnect cable has a good chance to fix it for you.

I had used rca, and rca to xlr with my Denon avr and Marantz avps, never had the issue, but a few people did, if you browse through forums such as AVSF. The worse seemed to be the AV7005, yet I never had issue with that one either, so I guess Marantz's quality assurance system may not be too great, in the grounding schemes (likely just connections related issues, as I trust their designs).

 

[GAmark]

Nope RCA to RCA. As stated above I have always used XLR to XLR and will be sending back the Cenima 30 and getting another processor AVM70/90.

 

[highfigh]

Any Ideas it is loud and can be mitigated somewhat by grounding the amp to the AVR, but is still there. Any other ideas? It can be heard from the speakers at about 8-10 feet. Just a little history this is the first time I have run RCA cables from anything to an amplifier. I have always used XLR. I started with an 8805A which had an internal problem sent back to Crutchfield the 8805A was on backorder so I am trying the Cinema 30, even with the amps in the AVR turned off and set to preamp only this happens with multiple amps. None of these amps had this issue with my prior processor or the Marantz 8805A in balance mode. Any thoughts would be greatly appreciated.

Do you use a cable TV provider for TV, internet and/or phone? If so, make sure the coax is grounded near the point where it enters the house/building. This should be passing through a grounding block at the electrical meter box or if it enters farther from the meter box, it should be grounded to a cold water pipe or the breaker panel. If the building has PEX or some other non-conductive plumbing, this is difficult but IT IS REQUIRED by the National Electrical Code in articles 770, 805, 810, 820, 830 and 840. It's also covered by ANSI/TIA-607-B.

Cable installers frequently neglect to ground the cable feed and it can not only cause this kind of noise, it's a safety hazard- NEC REQUIRES grounding-it's not optional and if it's not grounded, the provider should repair this code violation.

Disconnect the cable at the modem or cable box and if the noise stops, call the provider and demand that they make it right.

If they refuse, you have at least two options- change providers or install a DC block on the cable, but the latter won't work if the cable company needs a direct connection to their system.

 

[TLS Guy]

No, if you only use the Cenima 30 it is dead silent.

If you do that, you will be back where you started more likely than not. In these complicated systems like you have and are putting together, installation is complex, and there are plenty of snake pits for the unwary.

When putting together a complex system then designing and installing the ground plane is a complex and not a simple task. The inexperienced will drop into the snake pit.

I would bet that if I were in your home, I could solve your problem.

I note that your cinema 30 is double insulated and has now ground for the AC cord. This sometimes helps and sometimes it is a problem.

You have to understand that ground loops are errors in the installation of equipment and not usually the fault of the equipment per se.

A ground loop is always caused by a resistance between ground, so that a current can flow between grounds.

So the key to prevention is to have ONE good ground and everything flow to that ground.

You did not state what your power amp is, and whether it has two or a three pin power plug and cable.

So we need to start with that information.

One other point is that sometimes these problems reside within the house wiring.

One thing I can say, that this problem is very likely solvable without returning equipment.

 

[PENG]

I bet the vast majority of the Cinema 30 owners are happy owners without issue, but if the OP wants to simply send his back and grab an AVM90, that's good for him lol... We all know as much as all tried in the past, it's not easy to help people solve noise issues, even if it is just cause by ground loops. It is a fact that most AV hobbyist are not very technical oriented and may not find it easy to solve technical issues, even if just settings related ones and not defects as such, because AV devices nowadays are much more complex than those years ago. Fortunately, ground loop issues (the relatively difficult to troubleshoot/solve ones), while not uncommon, don't seem to happen to too many users.

 

[highfigh]

Fortunately, ground loop issues (the relatively difficult to troubleshoot/solve ones), while not uncommon, don't seem to happen to too many users.

They may not show up here, but they're common enough that knowing the cable guy didn't ground the service is well known in the AV industry. If I had a dollar for every time a cable installer for a provider did a crappy job, I'd have a lot of money.

This photo is from a job I did and it shows at least two electrical code violations- a breaker panel is required to have three feet of open space in front of the door, so it can be opened in case breakers need to be opened and nothing is supposed to be fastened by using the screws for the front panel. Strike two.

I wasn't there when this work of art was completed, but the first guy was one of the Time Warner/Spectrum contractors but almost every time Time Warner/Spectrum went there to do something, it wasn't done correctly, they canceled, or equipment didn't work.

 

[GAmark]

The AVM-90 with XLR to my ATI 4005 is dead silent and sounds amazing with my Warfdale Elysian's.

 

[TLS Guy]

The AVM-90 with XLR to my ATI 4005 is dead silent and sounds amazing with my Warfdale Elysian's.

That sounds like a significant black mark against the Cinema 30. Somehow the RCA outputs must not be true ground.

In any event you are much better off with an AVP rather than a AVR. It is basically a good day when you get rid of an AVR.

 

[GAmark]

That sounds like a significant black mark against the Cinema 30. Somehow the RCA outputs must not be true ground.

In any event you are much better off with an AVP rather than a AVR. It is basically a good day when you get rid of an AVR.

Yes, that was my first AVR in 40 years. And I tried ground everything etc.. MY uncle just got the Cinema 50 and uses a Parasound amp and is having the same problem.

 

[TLS Guy]

Yes, that was my first AVR in 40 years. And I tried ground everything etc.. MY uncle just got the Cinema 50 and uses a Parasound amp and is having the same problem.

From what you say, there must be a serious error in the ground place. I suspect there are internal resistances between grounds. This is most likely because there is too high a resistance from all those power amps to the ground return.

Anyhow, you are much better off with an AVP. Putting all those power amps in one box and voltage preamp stages with digital circuitry is asking for trouble in my view.

I have never used a receiver and don't intend to.

 

[highfigh]

From what you say, there must be a serious error in the ground place. I suspect there are internal resistances between grounds. This is most likely because there is too high a resistance from all those power amps to the ground return.

Anyhow, you are much better off with an AVP. Putting all those power amps in one box and voltage preamp stages with digital circuitry is asking for trouble in my view.

I have never used a receiver and don't intend to.

I think I would want to check the building's wiring, especially the outlets. If the wires were 'back stabbed', the clips can lose some of their spring tension and that isn't good. The contact area is ridiculously small and I'm actually amazed that it would ever have been allowed. I would also make sure the outlets on the circuit legs aren't in series- that almost guarantees problems when one or more pieces of AV equipment are using a different outlet. It also makes the chance of having dead outlets not only possible, it becomes likely.

If any wiring has been changed in the room fairly decently, I would definitely be looking at these.

The one good thing about having the pre-pro section in the same box as the power amplification is that it will be free from noise, if used by itself. The problem is the quality is lower than separates. The other way the noise could be eliminated is by using an optical link between any outboard devices, but that would have required forethought and it costs more.

I think you may be forgetting that AVRs are made to be affordable and compromises must be made, but it's the reality. I'm not saying that a $2000 AVR is reasonable or affordable for most, but I also think the engineering at the manufacturer end needs to look at how these are used, the problems that exist in many homes WRT grounding and finding a way to make those problems moot.

 

[highfigh]

Yes, that was my first AVR in 40 years. And I tried ground everything etc.. MY uncle just got the Cinema 50 and uses a Parasound amp and is having the same problem.

Which Parasound?

 

[TLS Guy]

I think I would want to check the building's wiring, especially the outlets. If the wires were 'back stabbed', the clips can lose some of their spring tension and that isn't good. The contact area is ridiculously small and I'm actually amazed that it would ever have been allowed. I would also make sure the outlets on the circuit legs aren't in series- that almost guarantees problems when one or more pieces of AV equipment are using a different outlet. It also makes the chance of having dead outlets not only possible, it becomes likely.

If any wiring has been changed in the room fairly decently, I would definitely be looking at these.

The one good thing about having the pre-pro section in the same box as the power amplification is that it will be free from noise, if used by itself. The problem is the quality is lower than separates. The other way the noise could be eliminated is by using an optical link between any outboard devices, but that would have required forethought and it costs more.

I think you may be forgetting that AVRs are made to be affordable and compromises must be made, but it's the reality. I'm not saying that a $2000 AVR is reasonable or affordable for most, but I also think the engineering at the manufacturer end needs to look at how these are used, the problems that exist in many homes WRT grounding and finding a way to make those problems moot.

I think you theory is very unlikely. I would bet that Cinema 30 has an incompetently designed ground plane.

All those amps are going to take gobs of current. I would bet that the grounding wires are just on small wire snap in connectors. So that is producing ground plane gouging and hum, when connected to a device that is actually true ground.

In a unit like that the ground plain should be constructed from massive copper cables or wide copper board line circuits on the boards. Having designed quite a few ground planes, I can tell you it only takes a minute voltage on a ground line to cause one Hell of a hum.

These AVRs with all those power amps for Atmos are the daftest products to ever see the light of day. I predict they will bring nothing but grief.

 

[AcuDefTechGuy]

I know plenty of people with the Cinema-30 and Cinema-40 hooking to external amps and they have absolutely no ground loop humming noise.

 

[TLS Guy]

Yes, that was my first AVR in 40 years. And I tried ground everything etc.. MY uncle just got the Cinema 50 and uses a Parasound amp and is having the same problem.

Are the AVRs and power amps plugged into the same circuit and ground?