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analog33
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I need hum help

I'm enjoying my new entry level system - Rega P1 turntable, Epos ES11 speakers, and Rega Brio amplifier. But intermittently the system will produce a VERY loud hum - much louder in volume than the music that is playing. The strangest thing is that I can get the hum to stop by tapping or flicking the amplifier with my finger pretty much anywhere - front, side, volume knob. I can also make it stop by jiggling the input cable (red/white RCA) from my turntable, though this only works if I jiggle it near where the cable connects to the amplifier. This also works vice-versa - if the system is not humming I can make it start by doing those things. When the humming is on and I use my finger to tap on the amplifier, I can hear the finger tap coming out through the speakers!

I tried unplugging the turntable from its power source, but the humming problem still existed. However, when I unplugged the turntable input cable (red/white RCA) from the amplifier, I could not recreate the humming problem! What does this mean?!? Any ideas would be greatly appreciated. Thanks!

Jan Vigne
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Re: I need hum help

It could be one of several things but it sounds like a bad interconnect or plug/jack. Does the problem cease when you touch or move one channel's RCA connector? If so, reverse the channels by moving each RCA connector to the opposite channel input and test whether the problem moves with the change in connections or stays in the same channel.

dbowker
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Re: I need hum help

Also make sure your Tuntable ground is correctly hooked up the post on your amp (or phono amp). It reminds me of a problem I had once and it was a loose RCA jack.

analog33
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Re: I need hum help

Thanks for the quick reply! On your advice, I tried switching the channels and I tried one channel at a time, but the problem persisted throughout. I'm thinking the problem is with the amplifier, not the cables. What do you think?

Jan Vigne
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Re: I need hum help

Unplug everything other than the amp to the speakers. If the noise persists, it's the amp that needs service. It still sounds like a bad jack so gently work with the input jacks to ascertain whether they could be poorly soldered.

analog33
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Re: I need hum help

I had considered that, but the Rega P1 did not come with any kind of ground cable. The instruction manual says, "The arm earth (or ground) is automatically connected
through the arm cable screening. No other earthing should
be necessary." I'm not sure exactly what all that means, but I think it's saying I don't need a ground cable.

I'm interested about your loose RCA jack. I just discovered that if I am firmly pressing the RCA cable into the amplifier, the humming doesn't happen. But as soon as I release pressure, it can come back.

analog33
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Re: I need hum help

When I unplug everything other than the amp to the speakers, there is no hum. When you say input jack, are you talking about the holes in the back of the amp that the RCA cable plugs into? If so, I think you are correct in saying it is a bad jack. How can that be fixed?
Thanks again!

Jan Vigne
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Re: I need hum help

The Rega arm has its earth ground tied to the left channel neutral so there is no separate grounding cable on a Rega arm.

RCA "jacks" are the female portion of the connector and are typically on the amplifier. RCA "plugs" are the male portion typically found as the termination on an interconnect cable and they, natually, plug into the jacks. If you can recreate the problem with nothing plugged into the amp other than your speaker connection, the problem would appear to be in your amplifier. If you cannot recreate the problem with no connections made to the amplifier, the problem would then appear to be in the cables or plugs. Plug one cable at a time into the amp until you can create the hum. This would then be your bad connector. You should then be able to determine whether you have a bad cable, plug or jack. Depending on the location of the problem, a simple resoldering job could solve the problem. But don't attempt this yourself. You will void the warranty. Call your dealer with your findings.

fred333
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Re: I need hum help

From my past experience, every time I have gotten a hum it was from a grounding issue.

Ergonaut
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Re: I need hum help

I could spend all day talking about Hum - Variances in center taps on transformers - eddy current pathways resitive and capacitive properties of interconnects... but I wont

Here have this

https://secure4.vivid-design.com.au/jaycar2005/images_uploaded/humloop.pdf

CECE
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Re: I need hum help

Trying playing a song that the sytem knows so it doesn't have to just hum and fake it. That usually cures humming.

Jan Vigne
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Re: I need hum help


Quote:
From my past experience, every time I have gotten a hum it was from a grounding issue.

From my past experience, every time I got a buzz it wasn't a grounding issue.

Ergonaut
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Re: I need hum help

I hum ! ............ I need a bath

cyclebrain
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Re: I need hum help

Dynamo Hum, Dynamo Hum, Where's this dynamo cumming from?

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