Struggling with ground loop hum on phono 1 ii

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musicgeek

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Struggling with ground loop hum on phono 1 ii
« on: Yesterday at 06:57 pm »
Hi everyone!

I recently got back into a vinyl system, and bought a mofi Studiodeck. I hooked it up to my phono-1 that was sitting unused for a year but this time, I get a very loud hum/buzz from the speakers (tt off, nothing playing). I guessed it was a ground issue so I connected a grounding cable from the tt to different parts of the chassis (screw, the box directly at the seams), to no real avail. It went down a little bit on one screw, but still very high.

To test further, I bought a cheapo art dj-ii that has a ground lug to see if that was the issue. And yes, the ground noise reduced a lot with that. But I miss the sound quality of the Vista.

Is there anything I can do to ground it? Is there an "upgrade" function to the vista 2 with a trade in of sorts?
I'm trying to stay in a fixed budget, and have only 20-30 hours on the vista -1.

Thanks!

Audiovista

Re: Struggling with ground loop hum on phono 1 ii
« Reply #1 on: Yesterday at 07:31 pm »
Hello and great to hear that you’re coming back to vinyl and Vista  :D

You can try connecting the grounding wire directly to your amplifier chassis, or the grounding screw, if available. If your amplifier has a 3-pronged power plug it is likely to have chassis grounded and that will most likely solve the problem.

If not, we can think of the next steps.

All the best,
Boris

musicgeek

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Re: Struggling with ground loop hum on phono 1 ii
« Reply #2 on: Yesterday at 10:13 pm »
Hi Boris!

Thanks for the prompt reply! I just tested the ground on both my connected power amps and the preamp(a classe preprocessor) -straight to different points of the chassis and screws, to no luck. Still a very loud hum/buzz that increases with volume, keeping to almost half the level of the music playing.


toocool4

Re: Struggling with ground loop hum on phono 1 ii
« Reply #3 on: Yesterday at 11:02 pm »
Have you got your phonostage near any power supply or near your amp or something? Try moving your phonostage to a different location.

musicgeek

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Re: Struggling with ground loop hum on phono 1 ii
« Reply #4 on: Today at 06:31 am »
So far I tried a couple different positions (as far as cables allowed me), different power socket and strip, same electrical point as the rest of the amps etc.

The art in the same position is giving significantly (but not zero) lower hum/buzz.

toocool4

Re: Struggling with ground loop hum on phono 1 ii
« Reply #5 on: Today at 12:30 pm »
With everything you have tried so far, the problem appears to not be the phonostages.

You will need to trace everything else to pinpoint where the issue is coming from.
A few things I would check is , are you connecting your phonostage to the same input on your amp, if so try a different input. By the way what is the amp?

If you try that and you still get the same issue, try removing the phonostage and turntable from the equation. Once that is done if no issues. Try connecting your turntable directly to your amp, I guess it’s an integrated amp? Yes I know it will not produce any meaningful sound but it may or may not produce the hum / buzz. You are just trying to pinpoint where the hum / buzz is starting from.

Audiovista

Re: Struggling with ground loop hum on phono 1 ii
« Reply #6 on: Today at 01:28 pm »
All the good advice in the above posts. If it doesn't work we have a bit of mystery.

Is it safe to assume that there is no hum when TT is not connected to the preamp? There may be some noise if the inputs are not shorted,  but no hum.

One thing to try is touching the TT grounding wire to the ground on the input/output terminals, or on the preamp connectors, just to see if that changes anything.

musicgeek

  • Jr. Member
  • Posts: 42
Re: Struggling with ground loop hum on phono 1 ii
« Reply #7 on: Today at 02:49 pm »
Thank you all, I'll try to connect straight to the amp.

There's no hum when the TT isn't connected to the vista. Dead silent.

The preamplifier in the system is a Classe sigma ssp, it has had zero issues playing dead silent before. I played a full record on the cheapo phonostage yesterday with no issues, it just doesn't sound like the vista. Power amps are Odyssey Khartago mono blocks, and speakers I've built myself.

@Boris, if I were to open the chassis of the Vista, could I ground my TT straight to the PCB somehow easily, without having to solder/do any permanent changes?