Re: need help choosing between line level cables

"Eeyore" <rabbitsfriendsandrelations@[EMAIL PROTECTED]
> wrote in message 
news:4805950F.8A921702@[EMAIL PROTECTED]
>
>
> Serge Auckland wrote:
>
>> "Eeyore" <rabbitsfriendsandrelations@[EMAIL PROTECTED]
> wrote
>> > Serge Auckland wrote:
>> >
>> >> To paraphrase I think, John Linsley Hood, you can always cut down on
>> >> safety margins if you have complete control over cir***stances.
>> >
>> > There is NOTHING unsafe about Class II equipment. In fact it has to
be
>> > intrinsicly SAFER than earthed kit.
>> >
>> >
>> >> In your case, anyone making an equipment change at some stage in the
>> >> future could set up a hum-loop.
>> >
>> > COULD ? Why WOULD they.
>> >
>> > You're inventing fictional problems again.
>>
>>
>> Not so much a case of inventing fictitional problems, just good 
>> engineering
>> practice. Whenever I implement any solution to a problem, I try and
think 
>> of
>> what could possibly go wrong in the future and try to plan for it.
>
> All very well but if you introduce a hum loop you can add transformers 
> THEN !
> They're simply not NEEDED here !
>
>
>> If you're sure there won't be any future changes, and you're only
trying 
>> to
>> avoid hum
>> loops, then your solution is probably fine.
>
> It will be.
>
>
>> That, by the way, is what I
>> meant in paraphrasing J L-H. I wasn't suggesting your solution is
unsafe,
>> just that if you solve a problem in the minimum way possible, you 
>> sacrifice
>> the flexibility of a better solution.
>>
>> Interesting that your AV equipment is all ungrounded. Mine isn't. Some 
>> items
>> are ungrounded - DTTV box, DVD player, DVD recorder, but the main TV is
>> grounded, my CD player, pre-amp, and active 'speakers are all grounded.
>> Turntables are all grounded. It's a mixture, so your solution isn't
>> generally applicable.
>
> A turntable does not need to be physically GROUNDED. Just connect its 
> chassis to
> the chassis of the amplifier with the cartridge preamp.
>
> I haven't seen a TV with a ground conductor since just about forever
btw.
>
> Graham
>


In my case, two of my turntables (EMT 948 and AEG TRS9000) have built-in 
electronics (both audio and control) and require a ground at least for 
safety. There is a separate ground-lift facility to float the audio ground

from safety ground, and/or to connect the audio ground to Technical
Ground, 
separate again from safety ground. The outputs are transformer balanced, 
fully floating. My other two turntables are conventionally grounded
through 
the pre-amp, which in my case has a ground.

As to the TV, it is a Sony Plasma, and definitely has a safety ground 
connected to the rear metalwork.

Your earlier comment about laptop power supplies is spot-on. I've recently

had a lot of trouble curing a hum from my laptop which was only apparent 
when connecting to my unbalanced hi-fi, but was completely absent when
using 
a balanced connection. (The sound card is a Digigram VXPocket, which has 
balanced ins and outs). I finally solved the problem by finding a power 
supply that didn't cause the hum, presumably because this one has a 
different arrangement of capacitors. It also has only a 2 wire input
whereas 
the original supply had a three-wire mains input.

S.


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