Re: need help choosing between line level cables

On Tue, 15 Apr 2008 13:41:20 +0100, "Serge Auckland"
<sergeauckland@[EMAIL PROTECTED]
> wrote:

>"Don Pearce" <nospam@[EMAIL PROTECTED]
> wrote in message 
>news:480497bb.538411812@[EMAIL PROTECTED]
>> On Tue, 15 Apr 2008 07:52:51 -0400, "Arny Krueger" <arnyk@[EMAIL PROTECTED]
>
>> wrote:
>>
>>>"Eeyore" <rabbitsfriendsandrelations@[EMAIL PROTECTED]
> wrote in
>>>message news:4804960C.2046F6A0@[EMAIL PROTECTED]
>>>
>>>> Balanced wiring only gives you an advantage if the
>>>> equipment is balanced. With clever wiring it's only
>>>> actually necessary for either the 'sending' or
>>>> 'receiving' equipment to have a balanced input or ouput
>>>> but you need to know what you're doing in this case.
>>>
>>>I know the strong advantage that balanced inputs give, but what
advantage 
>>>do
>>>you get from an electronically-balanced output driving an unbalanced 
>>>input?
>>>
>>
>> Provided you have an appropriate balun, like a transformer at the
>> input, you get all of the advantages.
>>
>> d
>>
>> -- 
>>
>> d
>
>Yes but then you're driving a balanced input aren't you ;-)  If you have
an 
>electronically balanced output (hence usually but not always referred to 
>ground) driving an unbalanced input, I can't see what real benefit you
will 
>get however clever you are with wiring. What you use a balanced system
for 
>is to get rid of common-mode noise, usually in the form of hum, but also 
>higher frequencies. Unbalancing at the receiving end will remove the 
>common-mode rejection.
>
You are right of course. Maplin have stereo audio transformers that
work very transparently for isolation at under £10 apiece.

http://www.maplin.co.uk/Search.aspx?criteria=vw43w&source=15&SD=Y


>If I were doing what the OP is doing, I would wire my house with CAT5/6 
>cable which is really cheap these days, then use equipment with balanced 
>I/O.  As already mentioned, CAT5/6 can carry 4 balanced audio signals, so

>you either get 2 stereos or a send and return stereo pair in each cable. 
>Crosstalk isn't an issue with balanced operation. If suitable balanced 
>equipment isn't available, then there are some alternatives. Transformers

>are definitely one, and they have the advantage of fully-floating
operation 
>and galvanic insulation. However, good transformers are expensive,
although 
>it's not necessary these days to have transformers which will drive 600
ohm 
>lines, 10k-10k transformers are somewhat cheaper. Other alternatives are
to 
>get some pro units like the Henry Matchbox which lists at $225 for a 
>bi-directional interface, therefore equivalent to 4 transformers.  I
would 
>guess that the street price for the Matchbox is under $200 and as these 
>things don't wear out, it may be possible to buy these on EBay for half
that 
>price.
>
>Whatever way you do it, I would not even think about using unbalanced
wiring 
>however well screened, as once incor****ated in the house, it can't be 
>changed.

CAT5 is possibly the way to go. Are you sure about the crosstalk
though? With digital signals it is only necessary to get better than
about 10dB of isolation. I would want better than 90dB for audio,
particularly if carrying unrelated signals.


-- 

d