Adcom GPT-450 pre-amp/turner Humming sound

[eyzhang]

Dear Experts,

I have purchased a 2nd hand Adcom GTP-450 pre-amp/turner.
The unit is in excellent condtion except that produces this
constant humming sound as long as it is plugged into the outlet
(In my case, a Belkin surge protector) even when it is off.

It is not connected to any VCR/TVs. I removed all the
connections and the sound is still there. The previous
owner told me that the humming sound has always been
there since since its purchase. Its plug doesn't have
a ground pin.

Can you let me know what causes this and how it
can be fixed? Is this a well known problem for Adcom GPT-450?
Is it a good idea to power everything off (amp, preamp,cd player)
throught a master switch on the surge protector when they are
not in use?

Thank you in advance for your help! Please reply to the group
or email me at:




Best Regards,
Eugene

[Raymond]

Eugene wrote
>I have purchased a 2nd hand Adcom GTP-450 pre-amp/turner.
>The unit is in excellent condtion except that produces this
>constant humming sound as long as it is plugged into the outlet
>(In my case, a Belkin surge protector) even when it is off.

Sounds like grounding trouble.

>It is not connected to any VCR/TVs. I removed all the
>connections and the sound is still there. The previous
>owner told me that the humming sound has always been
>there since since its purchase. Its plug doesn't have
>a ground pin.

I'm not to up on this unit or what shape it's in but I've always had good luck
with tying low and ground together (or lifting ground) to help with noise.

[Scott Dorsey]

eyzhang > wrote:
>
>I have purchased a 2nd hand Adcom GTP-450 pre-amp/turner.
>The unit is in excellent condtion except that produces this
>constant humming sound as long as it is plugged into the outlet
>(In my case, a Belkin surge protector) even when it is off.

Is this humming coming from the audio, or is it an acoustical noise
from the box?
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[eyzhang]

The humming noise is from the box. Not from the speaker.


"Scott Dorsey" > wrote in message
...
> eyzhang > wrote:
> >
> >I have purchased a 2nd hand Adcom GTP-450 pre-amp/turner.
> >The unit is in excellent condtion except that produces this
> >constant humming sound as long as it is plugged into the outlet
> >(In my case, a Belkin surge protector) even when it is off.
>
> Is this humming coming from the audio, or is it an acoustical noise
> from the box?
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

[eyzhang]

It's has 2 plugs (without the ground). Does that mean you method
is not applicable?

Thanks for helping a newbie!

Eugene


"Raymond" > wrote in message
...
> Eugene wrote
> >I have purchased a 2nd hand Adcom GTP-450 pre-amp/turner.
> >The unit is in excellent condtion except that produces this
> >constant humming sound as long as it is plugged into the outlet
> >(In my case, a Belkin surge protector) even when it is off.
>
> Sounds like grounding trouble.
>
> >It is not connected to any VCR/TVs. I removed all the
> >connections and the sound is still there. The previous
> >owner told me that the humming sound has always been
> >there since since its purchase. Its plug doesn't have
> >a ground pin.
>
> I'm not to up on this unit or what shape it's in but I've always had good
luck
> with tying low and ground together (or lifting ground) to help with noise.

[Scott Dorsey]

eyzhang > wrote:
>The humming noise is from the box. Not from the speaker.

Consider shock-mounting the power transformer, then.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[xy]

Don't lift the ground. That's way dangerous. The smart ciruit guys
always say DON'T DO THIS!!! And they get so passionate about it, like
it's really important. So I'd listen to the smart people.


> >a ground pin.
>
> I'm not to up on this unit or what shape it's in but I've always had good luck
> with tying low and ground together (or lifting ground) to help with noise.