On Sun, 30 Mar 2008 19:28:38 -0700, jamesgangnc wrote
(in article <fspi8m0ddl@[EMAIL PROTECTED]
>):
> "Sonnova" <sonnova@[EMAIL PROTECTED]
> wrote in message
> news:fspc0q02bc8@[EMAIL PROTECTED]
>> On Sun, 30 Mar 2008 14:47:24 -0700, Dallas wrote
>> (in article <fsp1pc02uac@[EMAIL PROTECTED]
>):
>>
>>> My NAD 314 has developed both a nasty little hiss and a hum. I'm
>>> wondering
>>> if there are some rules of thumb for tracking down these symptoms.
>>>
>>> I use generic cheap (Radio Shackish) RCA cables, I'm not sure if they
are
>>> really ****elded. Could that be it?
>>>
>>> I do have the ground terminal connected to the NAD, disconnection it
>>> makes
>>> no difference.
>>>
>>> Any ideas?
>>>
>>> Dallas
>>
>> Try making sure that all components in your system that use
three-pronged
>> grounding mains cables plug into the SAME wall outlet (via a plug
strip)
>> Using different wall sockets for different components is BEGGING for a
>> ground
>> loop.
>>
>> And you should really be using quasi-balanced interconnects (the ones
with
>> the arrow on the cable somewhere pointing in one direction). All of
them
>> should be pointing away from your control center. The arrow means that
>> ****eld
>> is floating (not connected to anything) on the end that the arrow is
>> pointing
>> toward. Make sure that all of the ****elds terminate at your control
center
>> (whether that be a preamp or an integrated amp or a receiver. The
>> arrow-end
>> of the cables should then connect to the power amps (if applicable),
the
>> CD/DVD player, the tuner, the tape deck (both record out and monitor
>> connectors). I'm not suggesting that this methodology (called a star
>> grounding technique) will solve your current problems (but it might).
It's
>> just good practice because regular coaxial interconnects are only half
>> ****elded as the ****eld is also the signal return. In quasi-balanced
cinch
>> (or
>> RCA) cables the ****eld carries NO signal and is only a ****eld for the
two
>> current-carrying conductors inside.
>
> Ok, I'll bite. How does that work? Rca only has 2 connections. One is
the
> ground.
>
Easy. You have a piece of ****elded cable with a braided or foil ****eld,
and
TWO center connectors. One of the two center conductors goes to the tip on
the RCA connector on both ends and the other center conductor goes to the
barrel of the RCA connector on both ends. Then, the ****eld goes to the
barrel
also, but ONLY on one end. On the other end it is NOT connected to
anything.
Thus it's grounded on one side and acts as an extension of that side's
chassis enclosing the two inner conductors which are carrying the "hot"
side
and the "return" of the signal. Since the ****eld is an open circuit, and
has
no complete path, it carries no signal. and is just a grounded covering,
i.e.
a ****eld. The reason for the arrows is to point away from a common ground
point. In a system with separate amp and preamp, the preamp serves as the
central grounding point because ALL signals originate or terminate there.
You
connect all of your quasi-balanced cables so that all of the arrows point
away from the preamp. many people have the mistaken idea that the arrows
correspond to signal flow so that the arrows point from, say, the CD
player
to the preamp and then from the preamp TO the power amp, but this is
wrong.
The preamp is "ground" zero and all the ****eld's should ground at that
point.
This is called a star grounding or star ****elding system, and this is
sound
engineering practice. Many have re****ted quieter systems because of it.
Unfortunately, ground loops and hum are a voodoo aspect of audio and while
there are well known practices that can be employed to attenuate or
eliminate
them, nobody can tell you which one will work for sure.
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