Buzz between Marantz SR5008 and Mcintosh C2300

I had the same issue with my MC205 and Marantz AV7701. I spoke with Oppo, Mcintosh and Furman, after all the tests they had me go through, they all came to the conclusion it was the Marantz. I swapped out the AV7701 for the AV8801 for testing purpose and there was no buzz. I called Marantz, and explained the issue, they told me the reason it doesnt buzz with the AV8801 is better shielding and its built better lol. So i swapped out the Marantz and got a Yamaha CXA5000. I would try to get a cheap AVR from a local store that has a friendly return policy and see if it really is the Marantz. BTW, i went through three different AV7701 and all the same issue, and i also have the Furman elite 20.

See if this will work for you. I skimmed so you may have tried something like this. I did the same as you where I disconnected the coax and still had the buzz. The buzz is coming from the cable box.

http://forum.audiogon.com/cgi-bin/fr.pl?bhome&1333386303

All interesting but am I correct to assume that since the buzz did not go away with the cable/satellite coax disconnected at the wall that it's been eliminated as a source of the buzz? And that the process of elimination will be using cheaters on each piece of gear connected to the Furman?

Thanks for the continued feedback!

Its a satellite cable btw. The ground is connected to the satellite chassis mounted on the roof. The other end is connected to gang box connected to the house ground.
03-25-14: Tccaux

Well that does make a difference. For one the Jensen ground loop isolator will not work on a satellite system.

"The other end is connected to gang box connected to the house ground."

Gang box??? Connected to the house ground? Do you know where the connection is made?

Quote from link provided below.

Grounding the lead-in antenna cables and the mast help prevent voltage surges caused by static discharge or nearby lightning strikes from reaching the center conductor of the lead-in coaxial cable. Because the satellite dish sits outdoors, wind creates a static charge on the antenna as well as on the cable attached to it. This charge can build up on both the antenna and the cable until it jumps across an air space, often passing through the electronics inside the low-noise block down converter feed horn (LNBF) or receiver. Connecting the coaxial cable and dish to the building grounding electrode system (grounding) helps to dissipate this static charge.

Although nothing can prevent damage from a direct lightning strike, grounding with proper surge protection can help reduce damage to the satellite dish and other equipment from nearby lightning strikes.

The grounding electrode conductor must terminate in accordance with (1), (2), or (3).

(1) Buildings or Structures With an Intersystem Bonding Termination. The grounding conductor for the antenna mast and antenna discharge unit must terminate to the intersystem bonding terminal [Art. 100 and 250.94], as shown in Fig. 1. Bonding all systems to the intersystem bonding termination helps reduce induced potential (voltage) differences between the power and the radio and television systems during lightning events.

(2) In Buildings or Structures Without Intersystem Bonding Termination. The grounding conductor for the antenna mast and antenna discharge unit must terminate to the nearest accessible location on the following:

• Building or structure grounding electrode system [250.50].

• Interior metal water piping system, within 5 ft from its point of entrance [250.52(A)(1)].

• Accessible means external to the building, as covered in 250.94.

• Metallic service raceway.

• Service equipment enclosure.

• Grounding electrode conductor or the grounding electrode conductor metal enclosure.

http://ecmweb.com/qampa/code-quandaries-7

http://ecmweb.com/qampa/code-quandaries-7
.

I removed the cheater from the C2300 but left on the PS DAC and the buzz came back. I put the cheater back on the C2300 and, upon really close listening, it's apparent that the buzz doesn't entirely go away. It just gets barely audible.

Traveling again this week so will wait until I'm home and have time to pull things out and try the cheater on other units in the chain. For the moment, it's just nice to be listen to HT without a noticeable buzz.

Its a satellite cable btw. The ground is connected to the satellite chassis mounted on the roof. The other end is connected to gang box connected to the house ground.

Thanks

Should have mentioned that. Interestingly, the coax is also going through the Furman. I disconnected the coax at the wall and the buzz did not go away. I by-passed the Furman direct to the SR5008 and buzz remained. I'd previously checked the cable ground to the main grounding and it visually seemed properly connected. Am I missing other possible confirmation to eliminate coax as source?
03-23-14: Tccaux

I by-passed the Furman direct to the SR5008 and buzz remained.

Not sure what you mean. Remember the SR5008 does not use the safety equipment grounding conductor. The power cord that came with the unit is only a 2 wire cord and plug. The SR5008 can pass a ground loop potential, voltage, current from any RCA line input to any RCA output through the outer shell of the RCA jacks. All the signal grounds are common, connected together, in the SR5008.

Interestingly, the coax is also going through the Furman. I disconnected the coax at the wall and the buzz did not go away.

First thought if you disconnected the coax cable from the wall, there by breaking the connection from incoming CATV provider's signal coax cable, that would isolate the Cable TV from the rest HT and 2 channel audio system......
So if we assume the CATV is not causing the ground loop hum what is?

You think it is being caused by the PS Audio DAC . If that is true then you should be able to remove the ground cheater from the C2300 and still not hear the hum.

Edit:
[quote]"I'd previously checked the cable ground to the main grounding and it visually seemed properly connected."
[/quote]
Just curious, when you traced, followed, the ground wire from the CATV grounding block located on the outside of your house where does the other end of the wire connect to?

Should have mentioned that. Interestingly, the coax is also going through the Furman. I disconnected the coax at the wall and the buzz did not go away. I by-passed the Furman direct to the SR5008 and buzz remained. I'd previously checked the cable ground to the main grounding and it visually seemed properly connected. Am I missing other possible confirmation to eliminate coax as source?

Many thanks

Tccaux,

Just curious, did you try disconnecting the Cable Company's CATV coax cable from the cable box and see if that stopped the hum? If not all you did was break the ground loop circuit by installing two ground cheaters in the AC mains safety equipment ground.

IF the ground loop problem is being caused by the Cable Company's CATV coax cable that means the lightning protection grounding block on the outside of your house may not be properly grounded to the main grounding system of your home.

If it is the CATV coax cable causing the ground loop problem this will also break the ground loop and stop the hum. It will not correct the CATV coax cable grounding problem though.
http://www.amazon.com/Jensen-VRD-1FF-Digital-Isolator-Jensen/dp/B00AQV04FE

Well, it was the PS Audio dac that was the main source of the gound loop. I put a cheater on the C2300 and the buzz decreased. I added a cheater to the PS Audio and it went away. I haven't tried removing the cheater off the C2300 since I'm feeling good about NO buzz!

Now, all I have left to figure out is why the power trigger from the SR5008 is constantly on which keeps the C2300 powered on in passthrough mode. I have to unplug the mini plug from the SR5008 to power down the C2300. Been through all the menus, even disengaged all trigger on's on the SR5008. No difference.

Thanks again for the suggestions! Much appreciated.

Tccaux

Very helpful all. Thanks for the responses. I won't be able to test until this weekend so I'll report back with results.

Theo, I have disconnected the C2300 and the buzz goes away in the other channels.

Jim - Yes, I'm pretty sure all is connected to the Furman, even the cable box.

More info this weekend. Thanks!

I might be uncomfortable doing a ground lift but given the Furman configuration, where would you suggest putting the cheater? On the C2300 at the Furman?
03-18-14: Tccaux

For a test only,.... on the plug of the C2300. Do no install a ground cheater on the AC feed power plug of Furman.

From your original post it sounds like you have some type of a ground loop that is causing the buzz. Could the buzz you are hearing actually be a low level hum?

AND, the problem is a low volume buzz in the sparkers - all channels. I've plugged and unplugged everything, plugged every configuration on the Furman and the only remedy is to take the C2300 out of the chain. No buzz SR5008 to the Sanders. No buzz in the 2 channel set up.

Somewhere in the chain of IC connected equipment a difference of potential, voltage, exists on the equipment ground that is connected to the chassis of 3 wire cord and plug equipment. You say in your original post everything is plugged into the Furman. Correct? To me the only other earth grounded source that could be the reason for the difference of potential, voltage, causing the ground loop buzz/hum is the shield on the TV Cable provider's CATV coax cable.

Just one scenario for the circuit path of the closed ground loop.

CATV coax shield to Cable TV box, receiver >>> through all IC connected equipment >>> to the C2300 out through the power cord on the equipment grounding conductor >>>> to the Furman power conditioner >>>> to the equipment grounding conductor at the wall receptacle >>> to the earth grounded service neutral conductor of your main service electrical panel.

IF the above scenario is the case temporarily disconnecting
the CATV coax cable from the Cable TV box will break the closed ground loop circuit.

No buzz SR5008 to the Sanders. No buzz in the 2 channel set up.

The Marantz SR5008 does not use a safety equipment grounding conductor. The AC power wiring inside the Marantz is double insulated. Worth noting though if a piece of equipment that uses the safety equipment grounding conductor and if the designer/manufacture of the equipment also connects the signal ground to the chassis with the safety equipment grounding conductor, when said equipment is connected to the Marantz by ICs the case/chassis of the Marantz becomes connected to the safety equipment grounded equipment.
Jim

I would lift the ground at the furman as that would be easiest. But Jea48, raises an interesting point as well. I have at one time or another had ground hum induced by sat TV boxes. And re-reading your comments, have you disconnected the 2300 and determined if the buzz occurs in the remaining channels with just the Marantz on? Also you might try lifting the ground on the Marantz. I don't envy you I have chased these buzzes/hums many times but eventually they do reveal their source of irritation.

Cable TV?

For a test disconnect the CATV coax cable from the CATV cable box then check for the buzz. Post back your findings.
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Hmmm? The buzz happens when the FL and FR pre out from the Marantz are connected to an input which has been designated as Passthrough on the C2300. In Passthrough mode the Marantz drives unity gain (if I'm understanding you correctly). The buzz is also heard in the other channels which have their speakers being driven directly by the Marantz,

The buzz does not happen when using the C2300 as 2 channel but I must disconnect the Marantz - even if the Marantz is powered off. So wouldn't that eliminate a failing tube?

I might be uncomfortable doing a ground lift but given the Furman configuration, where would you suggest putting the cheater? On the C2300 at the Furman?

Talking to Mac support seems a good idea. Many thanks!

I take it that you are using the unity gain on the C2300 and is that whe the Buzz occurs? Is the buzz present when using the C2300 as 2 channel only? If it is present, is the rest of the system (everything connected to the Marantz) off? You may try lifting the ground on the C2300, I have had a few McIntosh pre-amp processors and had grounding issues with a phono pre-amp buzzing and lifting the ground cleared it right up. Also you may give McIntosh tech support a call and see what they suggest. I have always found them to be very helpful. One last question, is the C2300 the only unit in the group that has tubes? Could it be a failing tube?