C390dd

[Scott79]

Dear All,

 

Believe it or not this is my first forum entry ever!

 

Reason for joining and making this thread is that I need to convince myself that my newly purchased c390dd is "normal".

 

I got it two weeks ago. Spent I week or so setting up, getting proper cables etc, and have now been using for a week. First off this is an amazing amp. I use it to drive my PM1's and the whole setup sounds great; don't regret a minute... AWESOME!

 

However I have one doubt, and this is where I need your help: When attached to the mains both on, off and when playing, the unit produces a very slight high pith hum. This is only audible when very close and everything around me quiet.... I have tried to contact the dealer and NAD and none of them really know.

 

Note: I have tried with and without speaker/woofer cables attached and running the mains thru linsy 6way mains conditioner.. I have yet to try to ground the unit as recommended in the manual...

 

Everything seems alright and sounds GREAT.. But I need to know; has anybody experienced this; IS THIS NORMAL?

[acg]

My C390DD is silent both at the speakers and the unit itself. Mind you, I have had the music too loud today...

[Axiom05]

Are you saying the sound is coming from the unit itself or through the speakers? If the noise is coming from the unit itself, it may be vibrating transformer plates. If so, I would take it back to where you purchased it and compare it to another sample. If the noise is specific to your unit, have it replaced or repaired under warranty. Make a fuss directly with NAD if you need to. If the noise bothers you, complain because it will never get better, maybe worse.

[Scott79]

Are you saying the sound is coming from the unit itself or through the speakers? If the noise is coming from the unit itself, it may be vibrating transformer plates. If so, I would take it back to where you purchased it and compare it to another sample. If the noise is specific to your unit, have it replaced or repaired under warranty. Make a fuss directly with NAD if you need to. If the noise bothers you, complain because it will never get better, maybe worse.

 

Thanks. Yes the noise is from the amp it self. And yes it dose bother me. Do you have one too? I take it's silent.

 

Thanks to both of you for answering. It seems like this unit might have something wrong with it! I'll take your advice and send it back to the dealer!

[wgscott]

The one I am using is absolutely dead silent. We have crappy third world electricity here in California,

[ForkInBrain]

When attached to the mains both on, off and when playing, the unit produces a very slight high pith hum. This is only audible when very close and everything around me quiet....

 

No high pitch hum from my c390dd. Had my 11 and 12 year old kids verify, as my 41 year olds ears may not pick it up.

 

If it reproduces for you when simply plugged in and nothing else connected, you could try it out in a few different outlets in your house, or even work or a friend's place, to verify it isn't specific to your one outlet.

 

The only oddity I've observed with my c390dd is an extremely quiet buzzing coming from my PM1 tweeters after shutting the unit off (or when playing from a source that is itself off). The buzzing is always gone by morning, so I assume this is a capacitor or similar slowly draining. I must get my ear within 2-3 inches of the tweeter to even hear it -- I only discovered it because silence from the c390dd was so black I went looking for hiss. :-)

[Scott79]

The one I am using is absolutely dead silent. We have crappy third world electricity here in California,

 

Thanks again for your replies!

 

Hmm.. do any of you with silent c390dd's go thru the trouble of grounding?

[wgscott]

It is just grounded with a standard grounded power cable. Are you in the UK? I think they are even more anal about grounding. Did you lift the ground intentionally? Could the grounding be defective? Presumably it wouldbe a 60 or50 Hz hum, nothigh pithed.

[One and a half]

If there is acoustic noise cause, it's a digital amplifier, so no large transformer that you can blame.

 

There's only switch mode supplies, and most likely a choke is loose and resonating with something else close by. This can cause a vibration with something bound to fall off or cause a short. If others have a quiet unit, and yours does not, it's worth to contact the dealer to have it replaced/repaired.

[wgscott]

It is just grounded with a standard grounded power cable. Are you in the UK? I think they are even more anal about grounding. Did you lift the ground intentionally? Could the grounding be defective? Presumably it wouldbe a 60 or50 Hz hum, nothigh pithed.

 

My iPad typing skills kind of suck. Sorry.

[Scott79]

Hi again, Thank you all for your answers. Forums like this are great. I live in Qatar, no one around here knows anything about NAD let alone the c390dd so this was the right place to ask this kinda question. Living in Qatar means the process of replacing this unit it petty much a BIG hassle, but I now sure it's the right thing to do... Hopefully after packing, dealing with DHL and waiting for a LOOONG time I'll get a new one... Don't tell the dealer but I might just have to hear one more song before I send it back... thanks again