Static/hissing/buzzing noise from amp with headphones/speakers

[Trillion]

Hello. I recently bought a Marantz PM6005 and have been concerned about damage after hot-plugging the RCA cables by mistake.

I've noticed that with my more sensitive headphones plugged into the headphone out on the front there is a subtle but noticeable hissing/static sound playing through the headphones - even when the volume on the amp is turned completely down. The same effect is noticeable through the speakers, but only with my ear very close to the speaker cones. I notice a similar noise when I plug my headphones in to my old Onkyo receiver and my PC, however it's very slightly quieter coming from the Onkyo, and slightly louder from the PC. In all 3 cases when the volume is turned down to 0 the hissing is there. I'm pretty surprised that it's more noticeable coming from the Marantz than the Onkyo seeing that the Marantz is brand new and has cost me a lot more. This effect is created whichever input on the Marantz is selected and even if there is no feed to that input. It seems to happen when power is being supplied to the headphones.

Another strange thing I've noticed with the Marantz is this hissing sound increases in volume as the volume knob is turned up to a certain point, and then when it's around 50% volume the noise goes away slightly and returns and increases again when the knob is at 75%.

I DO NOT notice this noise when plugging my headphones directly in to my little Fiio E10K headphone amplifier.

Can anyone confirm this is all normal? I suspect it is but would like to know for sure.

 

[rich51080]

What headphones do you currently have? Could be your headphones showing up the headphone out on your Marantz. This is common and I would not worry.

But however the noise coming and going on your amplifier does not seem right. I would expect the hiss to increase when you turn volume up but not to go away and then come back. This sounds like a circuitry issue. Is your Marantz under warranty? I would send the Marantz back and have it checked out as it could potentially get worse. See the thread I linked beneath.

http://www.whathifi.com/forum/hi-fi/marantz-pm6005-problem-hissing-turns

The Fiio E10K is a dedicated amplifier and has better op amps, circuitry and dac chips than your Marantz headphone output. This is why there would be less noise as it bypasses the Marantz Circuitry. It is not uncommon for headphone outs to have a slight hiss coming from them. My old Rotel used to hiss so i bought a headphone amp and this corrected it as it bypassed the Rotel's circuits.

regards

Rich

 

[Trillion]

Hello Rich, thanks for the response. The headphones that show up noise from the Marantz are Musical Fidelity MF 100 headphones. I don't hear much noise when plugging in my AKG K702s but I suspect that's because they're much less sensitive. The effect is also there with a set of Urban Ear Plattan headphones but less so than the MF 100s. It can also be heard through my Tannoy DC6Ts with my ear very close. What I've noticed is that the noise coming through loud at 25% volume and then quieter at 50% and again louder at 75% only happens with the RCA inputs on the amp and not through the optical input. I don't know if it warrants a return since it's quite hard to notice with my AKG K702s but it is apparent.

I only bought the Marantz very recently so it's within warranty.

Thanks again.

 

[Trillion]

Also should note that inside my unit I can see the capacitors have a '1' written on them with what looks to be a permanent marker - could this be a refurbed unit?

I may sound paranoid and OCD here but there's something else I've noticed - if I mute the sound and turn the volume up to max the amp enters protection mode and shuts itself down. HOWEVER if the source volume is turned down - in this case my Fiio E10K volume output turned down from the PC - the amp does not enter protection mode. Perhaps this is a feature to protect the speakers from damage, but there's no mention of this in the manual.

Can anyone else with this amplifier confirm if it behaves in the same way mine does? If it does I'll leave it as is. Thanks!