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

[Robert L. Harris]

I finally got a chance to try this.  I did it as your diagram removing the
shielding and I get the same noise.



On Sat, Aug 10, 2013 at 6:10 PM, Robert L. Harris <robert.l.harris at gmail.com
> wrote:

>
> Nice description.  I'll find a set of RCA's I can cut open.
>
>
> On Sat, Aug 10, 2013 at 5:54 PM, Alex Carver <agcarver+ale at acarver.net>wrote:
>
>> No, no shorting, just disconnect the ground on each RCA from one side of
>> the cable.  You want to keep the shield working but you don't want current
>> to flow on the shield.  So choose only one side (could be the Yamaha or the
>> Gemini but not both) and cut the shield on each audio wire (left/white and
>> right/red) at that end.  Leave everything else intact.
>>
>> How about some good old fashioned ACII art? :)  I'm going to pick the
>> Gemini side, but it works either way:
>>
>> Yamaha                                           Gemini
>> RCA-Left Audio Center pin ----------------------- RCA-L Center pin
>> RCA-Left Shield ----------------------------x x- RCA-L Shield
>>
>> RCA-Right Audio Center pin ---------------------- RCA-R Center pin
>> RCA-Right Shield ----------------------------x x- RCA-R Shield
>>
>>
>> Cut the shield (and only the shield) at the -x x- marks.  Verify that you
>> have no electrical connection from the shield on one end of the cable to
>> the other.  Leave everything else alone.  If the hum goes away you have a
>> ground loop.
>>
>>
>>
>> On 8/10/2013 15:58, Robert L. Harris wrote:
>>
>>> 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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>>>>
>>>>
>>>
>>>
>>>
>>>
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>
>
>
> --
> :wq!
> ---------------------------------------------------------------------------
> Robert L. Harris
>
> DISCLAIMER:
>       These are MY OPINIONS             With Dreams To Be A King,
>        ALONE.  I speak for                      First One Should Be A Man
>        no-one else.                                     - Manowar
>



-- 
:wq!
---------------------------------------------------------------------------
Robert L. Harris

DISCLAIMER:
      These are MY OPINIONS             With Dreams To Be A King,
       ALONE.  I speak for                      First One Should Be A Man
       no-one else.                                     - Manowar
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