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Need help identifying ground problem

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Need help identifying ground problem

Postby Solist » 19 Oct 2017 17:25

I wanted to listen to music the other day, when I have noticed that something was off. When I turn on everything there is this sound coming from the speakers, and I cant figure out what is causing it. It seems like its a ground issue, because if I detach the ground wire from the phono preamp nothing changes. Any idea how to identify the source that is causing it?
Here is a short video:


https://vimeo.com/238962835
"And those who were seen dancing were thought to be insane by those who could not hear the music." - Nietzsche
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Re: Need help identifying ground problem

Postby jdjohn » 20 Oct 2017 01:28

Do you mean the sound starting at about the 20 sec mark? Seemed to be more of a hissing than humming, but maybe the video recording is not conveying the sound correctly.
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Re: Need help identifying ground problem

Postby Solist » 20 Oct 2017 15:20

jdjohn wrote:Do you mean the sound starting at about the 20 sec mark? Seemed to be more of a hissing than humming, but maybe the video recording is not conveying the sound correctly.


Its hard to hear on the video. The sound at 20s is when I turn the volume up. The speakers were dead silent until this week. Now I am getting this hiss like white noise everytime I turn them on.
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Re: Need help identifying ground problem

Postby jdjohn » 20 Oct 2017 16:22

A few more questions:
- Did you change or add anything new to your setup this week?
- Is the hiss present on all inputs like phono, CD, radio, etc?
- What kind of amp/receiver are you using, and how old is it?

A grounding problem would present itself as a hum, not hiss, so likely not a grounding issue in this case.
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Re: Need help identifying ground problem

Postby josephazannieri » 20 Oct 2017 17:20

Yo Solist:

Try unplugging the preamp and the turntable from the amp/receiver. Then turn it way up. This could be some organic failure within your amp/receiver. I agree with jdjohn that it is not likely a grounding problem. These usually show up as hums or buzzes.

I also agree that you should see if you have added something new or changes something about the system. If you detach the ground wire from the phono preamp, you should get a change, adding either a hum or a buzz.

For the h**l of it, try attaching the turntable ground wire directly to the amp/receiver chassis directly. The fact that the noise comes and goes suggests that it is caused by something loose. Check your phono plugs where they plug into the amp/receiver, and squeeze the outside ring on the phono plug to be sure that it grips the jack tightly.

And good luck from the old "try this" experimenter,

Joe Z.
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Re: Need help identifying ground problem

Postby Solist » 21 Oct 2017 00:47

Thank you both for the suggestions. I did some modification to my turntable in order to minimize the engine vibrations, but I doubt that is it since when I have unplugged the preamp and TT the hiss was still present. I have a Dual cv80 amp. It worked perfectly the last time I plugged it in.. Can this be because of the really old caps?
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Re: Need help identifying ground problem

Postby jdjohn » 21 Oct 2017 14:41

Bad caps are very likely, especially if it has been sitting awhile unused. Regular usage is the best way to keep solid state gear in order.
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Re: Need help identifying ground problem

Postby josephazannieri » 22 Oct 2017 04:19

Yo Solist:

This begins to look like a failure in the amplifier. If you still get the noise with the turntable and the preamp unplugged, then it's an organic failure in the amp/receiver, that will need some service. If you are willing to open up the unit, you can look at the capacitors and see if there are any that show bulges or other deformations. These are likely places where a failure has occurred.

Looks like the problem is somewhat identified, but the solution is not. You also have the option of locating a sound receiver or amp and replacing the Dual with it.

And good luck from the old experimenter,

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