[ale] OT: One for the EE's, Amp noise?

[Robert L. Harris]

So effectively short the 2 center pins to 1 (as if going mono) and then cut
one of the grounds out completely?




On Sat, Aug 10, 2013 at 4:41 PM, Alex Carver <agcarver+ale at acarver.net>wrote:

> On 8/10/2013 14:55, Robert L. Harris wrote:
>
>> So I have a Yamaha RX-A1010 receiver.  It's been great so far but not
>> enough volume when we want to have a party, etc.  So I picked up an
>> external Amp by Gemini.
>>
>> When I plug the pre-out from the Yamaha into the Gemini I get a low hum
>> that almost sounds like static.  If I plug my DVD player or Phone into the
>> Gemini using an adapter ( 1/8th -> RCA ) the noise goes away, crisp clear
>> sound.  If I use the Yamaha speaker out no noise either.  It seems to only
>> be from the Yamaha to the Gemini.  I can use either of the pre-out ( front
>> or surrount ) or the headphone jack on the front and the sound persists.
>>
>> Any thoughts on how I can clear it up?  The yamaha is out of warranty (
>> 2.5yrs old) and a great unit but just too quiet on occasion.
>>
>
> Without actually hearing the sound I'm inclined to believe you have a
> ground loop.  You can test for a ground loop issue by making an RCA patch
> cable that connects only the center pins together and leaves the ground on
> one end unconnected.  If the sound goes away it's a ground loop and you
> just either use that patch cable with the lifted ground or get a
> transformer-based ground loop isolator.
>
> It won't happen on your phone because the phone isn't grounded.  The DVD
> player may have isolation in it (or it may not be grounded at all, either,
> if it's got a two-prong plug).
>
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Robert L. Harris

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