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New member Username: Bob_aPost Number: 1 Registered: Dec-05 | I'm sure discussions about fixing hum problems has been asked may times. Unfortunately I couldn't find what I need using search ... so here is my question: I recently purchased a marantz PM7200 integrated amp and all is well except for an annoying hum when I have my cd player on pause with the sound turned up. When trying to diagnose the problem I found the hum when much louder when I touched the chassis of the cd player. The problem went completely away when I connected a ground wire from the chassis of the cd player to the ground screw (used for the phono ground) on the pm7200. Is this a safe way to correct this hum problem? The amp is now very silent when the input devices are on pause or in quiet selections with the volume turned up. |
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Anonymous | I can't help with your specific problem but I used advice given on this thread to cure my ground hum issue. Some of it may be relevant to you. Good luck. http://www.avforums.com/forums/showthread.php?t=170017&highlight=bfd |
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New member Username: Bob_aPost Number: 2 Registered: Dec-05 | Thanks Anon, I'll check it out. |
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Anonymous | Changing a reliable interconnection might sovle the problem |
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Anonymous | I have a Marantz PM7200 and a Sony CD player. I put the CD player in stop and turned up the volume all the way to maximum before I heard only the slightest hum. I then unplugged the cords from the CD player and repeated this, and the hum was a bit louder, but only at max, which I never ever get anywhere near when using the player. Next I unplugged the jacks from the Marantz, and turned up the volume to max, and there was absolutely no hum. Conclusion: the hum was louder with the jack connected to the Marantz, but not the CD player. so it was niether the fault of the marantz nor the sony. The cord was producing the hum in interaction with the marantz. Another possibility: Some sonys have two jacks in the back, one controlled by the volume control on the CD. If you have the volume on the CD turned low, controlled by a knob near the headphone out on front, you would have to turn up the marantz loud enough to hear the hum. either turn up the volume or use the line out jacks without volume control. but certainly the next place to look is at a better cord. also try a different component in the marantz cd in and see if the problem still occurs. or try the sony in a different input. this should provide some clue to where the problem is. |
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Silver Member Username: Sun_kingLeeds, West Yorkshire UK Post Number: 303 Registered: Mar-04 | The Marantz PM7200 emits a hum, period. This shouldn't be passed onto the speakers though and if it does you have a problem that shouldn't be there. Earthing the unit as you would a turntable will be fine, that's what it's there for. Congratulations on a quick fix! |
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New member Username: Bob_aPost Number: 3 Registered: Dec-05 | Thanks Sun King. The setup is very quiet with the ground wire from the Sony chassis to the marantz ground for phono. I was just concerned that somehow by doing this I could damage my new PM7200. My only disappointment is that I sent the same query directly to marantz on December 5th using the support form on their site, and have heard nothing from them. Not an great first impression of their customer service. |
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Anonymous | Sun King, do you own a PM7200? I do. And there is no hum. Period. I own a high end Sony CD player and DVD player. There is only the faintest trace of noise when they are put on pause. And that is at the maximum volume. I have used two Marantz PM7200s. Neither had a hum. |
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Anonymous | And I am not grounding any of the components. |
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Anonymous | And on the unused inputs there is absolute silence at maximum volume, in both A and AB mode. Even with the CD playing. The only hum comes from the transformer, itself, when in the class A mode. But you have to have total silence in the room and put your ear next to the amplifier to hear it faintly. I just checked. You would not be able to hear it with any music playing at even the lowest volume setting. And just to make this absolutely clear: There is NO hum through the speakers. At any volume setting. |
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Anonymous | As to contacting Marantz with a query, if you register your product, you should not have a problem getting a response. That's been my experience when I had a very minor problem with my Marantz receiver (I accidently lost a cover to the optical inputs). I have not had a problem with the 7200. |
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Silver Member Username: Sun_kingLeeds, West Yorkshire UK Post Number: 304 Registered: Mar-04 | That's what I said mate, there is a hum from the unit itself. I didn't say it was normal for the hum to be transferred to the speakers and yes, I have owned a PM7200 and know of several other people who own them and they all emit a transformer hum. |
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nout Unregistered guest | Sun King is right. My PM 7200 has a hum too, you can hear it when you're near the amp, but also through headphones, in the left channel, when you switch off both speaker buttons (1 and 2). The hum (while listening through headphones) disappears when you switch one speaker button on, so when you only have one pair of speakers, connected to system 1, you can switch on speaker button 2 and there will be no hum in the left channel, using your heaphones. Or switch the amp in class a and no matter what speaker button is on, there will be no hum, when listening through headphones, I suppose this hum will be noticable too when playing through very sensitive speakers, mine are 8 ohm and only when I put my ear on the left speakers tweeter I can hear a faint hum...big deal... |
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nout Unregistered guest | The hum (while listening through headphones) disappears when you switch one or both speaker button on, so when you only have one pair of speakers, connected to system 1 and you want to listen through headphones, hum-free while not disturbing others you can switch off speaker button 1 and switch on speaker button 2 and there will be no hum in the left channel when using your heaphones. |
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nout Unregistered guest | LOL, why do I even bother to write and edit this... "thank you nout for sharing this with us" |
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Silver Member Username: Sun_kingLeeds, West Yorkshire UK Post Number: 305 Registered: Mar-04 | Aw, I'm sure somebody appreciated your findings! |