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Discussion Starter #1
I just purchased a Marantz SR5009 Receiver. I am planning on using the pre-outs to drive an external amp for my FL and FR speakers. The speakers are Thiel CS1.5 and the amp is a Parasound HCA-1000.

Everything was fine, until I connected the Parasound amp. Even with the amp off, it caused the front center and the two surrounds to hummmm. And when you turn on the amp... the FR and FL then add to the hummmm.

The hum is the same volume regardless of volume setting on the Marantz. The hum is also introduced by just connecting the ground plug on the power cord (the two power prongs not touching the connectors yet).

This amp connects to an older Onkyo without any problems. The Marantz and Parasound are connected to the same power strip. I suspect, if I use one of those 3 prong to 2 prong ground adapters, it will work fine from what I have read. But, I question the safety of removing the ground. Of course it could be a Marantz issue. Haven't talked to Marantz yet. These things can be sketchy... so they might blame my amp.

Any thoughts or suggestions would be appreciated.
 

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If the Parasound is a grounded system and the Marantz, is not.. (one has a ground lug at plug and the other does not) hook up a wire from receiver case to amp case. It will ground both. I was told to do this when I had a very similar issue by Audio Advisers . I had already sent the Parasound back, so I never got to try it. But they stated it is a common problem and a ground between both would have fixed it...
 

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Discussion Starter #3
If the Parasound is a grounded system and the Marantz, is not.. (one has a ground lug at plug and the other does not) hook up a wire from receiver case to amp case. It will ground both. I was told to do this when I had a very similar issue by Audio Advisers . I had already sent the Parasound back, so I never got to try it. But they stated it is a common problem and a ground between both would have fixed it...
I tried the 2-3 prong plug adapter before I read your post. It worked. However, your solution may be better. Although, at the end of the day, I am not sure if there is much difference.

I talked to a neighbor last night who has worked with a lot of audio and video equipment as his regular job. He talked about using some good sized straps to ground equipment together, small wires didn't always work.

I think that I will leave it like this for a while... I'm moving in 2 or 3 months, so I may try the wire then.

Thanks!
 

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Discussion Starter #5
I read somewhere this was a bad idea. Not sure how credible it was.

Read through this - http://www.audioholics.com/home-theater-connection/ground-loops-eliminating-system-hum-and-buzz

I had buzz issue too, likely caused by either 1) wiring in the house or 2) the actual electric coming in. I tried everything and ended up resolving the issue with a jensen isomax transformer. Good luck!
Thanks for the audioholics article. I'll probably stick with my non-recommended solution for now.

Which brings me to another point. Since all of my plugs in my system are 2 prong, except this power amp and the power source for my fiber to the home connection. Is it likely or probable, if I bought another external amp with a 3 prong plug, would it have the same problem?

I noticed that Marantz amps use 2 prong power cords. All of the other amps that I have looked at so far, have 3 prongs.

Another observation... when grounded outlets were a pretty new thing, back in the 70s, almost all new appliances and electronics had 3 prong plugs. It seems to me that there is a move away from 3 prongs for our electronic devices... Not sure where this leads me, but...
 

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I'd say you would have the same problem. I thought of trying class D amps to see if there was buzzing but never did. In my tests I tried two different pre amps with 2 prong, and one pre amp with 3 prong, 3 amps from same manufacturer, and had the same issue in all cases. At my previous residence I briefly used an external amp from another manufacturer and had buzzing as well.
 

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If the external amp has balanced XLR input, use the RCA-XLR cable and it should solve the problem.
I had the same issue and with use of RCA-XLR it's dead silent. (Using Crown X1000 as external amp)
 

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If the external amp has balanced XLR input, use the RCA-XLR cable and it should solve the problem.
I had the same issue and with use of RCA-XLR it's dead silent. (Using Crown X1000 as external amp)
Thank for that thought, Actually, just before reading this, I had the same idea.. that it may work. But darn... it doesn't have balanced inputs. It is an HCA 1000.... not an HCA 1000a. I like the sound better than the built in amp provides. I think the Marantz has really nice presence and air... but it sounds just a little thin. The Parasound to me sounds a little thicker, but just as much presence and air. BTW, how do you like the Crown compared to "Audiophile" amp?
 

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I tried the 2-3 prong plug adapter before I read your post. It worked. However, your solution may be better. Although, at the end of the day, I am not sure if there is much difference.

I talked to a neighbor last night who has worked with a lot of audio and video equipment as his regular job. He talked about using some good sized straps to ground equipment together, small wires didn't always work.

I think that I will leave it like this for a while... I'm moving in 2 or 3 months, so I may try the wire then.

Thanks!
If this needs large straps to bond the two, you have other problems- large conductors are for high current.

Lifting the ground of a grounded amplifier violates the electrical code, but it does show where problems may lie. Is the Parasound plugged into the same circuit as the Marantz? It needs to be.

You would be better off using a ground loop isolator than leaving the chassis of the amp un-grounded. Worst case, if you touch the chassis with one hand and something that's grounded with the other hand it can be dangerous, at best and lethal, at the worst. The power supply is grounded to the chassis- that's why it needs to remain grounded.
 

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Discussion Starter #10
If this needs large straps to bond the two, you have other problems- large conductors are for high current.

Lifting the ground of a grounded amplifier violates the electrical code, but it does show where problems may lie. Is the Parasound plugged into the same circuit as the Marantz? It needs to be.

You would be better off using a ground loop isolator than leaving the chassis of the amp un-grounded. Worst case, if you touch the chassis with one hand and something that's grounded with the other hand it can be dangerous, at best and lethal, at the worst. The power supply is grounded to the chassis- that's why it needs to remain grounded.
Agreed, it isn't the perfect solution. But, it is grounded to the neutral wire... same as the receiver... also through the interconnect. One less ground path.
 

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Agreed, it isn't the perfect solution. But, it is grounded to the neutral wire... same as the receiver... also through the interconnect. One less ground path.
It's not grounded through the interconnect- the Marantz doesn't have a grounded plug. Also, the neutral doesn't contact the ground until it reaches the panel and the chassis of the Parasound isn't grounded at all if an adapter has been used.
 
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