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Bob Richard Bob Richard is offline
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Default Balanced output to two inputs, one of which is unbalanced

From Rane Note 110, the archives of this newsgroup, and dim memories of
other things I've read, I've pieced together a partial understanding of
cables to send a balanced output to an unbalanced input. As far as I can
tell, unless the output is transformer balanced, "floating balanced",
"cross-coupled", or "servo balanced", then I use:

balanced Hot to unbalanced Hot
balanced Cold is not connected
balanced Shield to unbalanced Shield

If the output is differential balanced, I lose 6 dB of level; if the output
is impedance balanced, I do not.

My question is this: suppose that the balanced output is also multiplexed
to a second input using a wye cable, and the second destination is balanced.
Is this going to cause problems, for example because the load impedance now
differs between the hot signal and cold signal? (The hot signal sees the
combined inpedance of two inputs, while the cold signal only sees one.) Or
because of something else I haven't thought of?

Thanks in advance for your help!

--Bob Richard


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Mike Rivers Mike Rivers is offline
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Default Balanced output to two inputs, one of which is unbalanced


Bob Richard wrote:

My question is this: suppose that the balanced output is also multiplexed
to a second input using a wye cable, and the second destination is balanced.
Is this going to cause problems


No, as long as the balanced input is OK being fed from an unbalanced
source.

for example because the load impedance now
differs between the hot signal and cold signal?


Once you unbalance a source, it's always unbalanced. Tie the "cold"
side of the balanced input to ground and pretend it's unbalanced.

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Julian Julian is offline
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Default Balanced output to two inputs, one of which is unbalanced

On 3 Jul 2006 17:54:30 -0700, "Mike Rivers"
wrote:


for example because the load impedance now
differs between the hot signal and cold signal?


Once you unbalance a source, it's always unbalanced. Tie the "cold"
side of the balanced input to ground and pretend it's unbalanced.


The nature of his question seems to imply he intend to run the
balanced device off of plus minus ground and the unbalanced off plus
and ground.

Unbalancing both signals as you suggest does seem to be a possible
good solution.

Julian


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Bob Richard Bob Richard is offline
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Default Balanced output to two inputs, one of which is unbalanced

"Julian" wrote in message
...

The nature of his question seems to imply he intend to run the
balanced device off of plus minus ground and the unbalanced off plus
and ground.


Yes, exactly. But Mike's response appears to say that it doesn't matter how
I wire the two destination devices; the circuit as a whole will be
unbalanced regardless. Correct?

Thanks again for you help.

--Bob Richard


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Bob Richard Bob Richard is offline
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Default Balanced output to two inputs, one of which is unbalanced

"Julian" wrote in message
...

The nature of his question seems to imply he intend to run the
balanced device off of plus minus ground and the unbalanced off plus
and ground.


Yes, exactly. But Mike's response appears to say that it doesn't matter how
I wire the two destination devices; the circuit as a whole will be
unbalanced regardless. Correct?

Thanks again for you help.

--Bob Richard





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Mike Rivers Mike Rivers is offline
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Default Balanced output to two inputs, one of which is unbalanced


Bob Richard wrote:

Yes, exactly. But Mike's response appears to say that it doesn't matter how
I wire the two destination devices; the circuit as a whole will be
unbalanced regardless. Correct?


"Balanced" (in the electrical context) is one of those words like
"square" or "pregnant." Either it is or it isn't. If you have a bipolar
output with equal voltages of opposite polarity with respect to ground
and at the same source impedance, and connect this to a differential
input, you have a balanced connection. If you then tap off the "high"
side and connect that to another input, you've unbalanced your
connection. The reason for this is that you've put the input impedance
of your unbalanced input in parallel with the output impedance of the
"high" side of the source, therefore unbalancing that path.

You might be able to get it back to being balanced by connecting a
resistor equal to the input impedance of your unbalanced input between
the low side of the source and ground. But unless it's very accurately
matched to the unbalanced load, you'll still be unbalanced. However, it
might not be any worse than the balanced connection that you get with a
single ended "impedance balanced" output.

However, unless you're running long cables and have a lot of EMI,
you're better off just treating your source as single-ended and hooking
it to the two inputs accordingly.

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Bob Richard Bob Richard is offline
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Default Balanced output to two inputs, one of which is unbalanced

"Mike Rivers" wrote in message
ups.com...

[...] If you have a bipolar
output with equal voltages of opposite polarity with respect to ground
and at the same source impedance, and connect this to a differential
input, you have a balanced connection. If you then tap off the "high"
side and connect that to another input, you've unbalanced your
connection.


Thanks! The new (to me) lesson here is that it is the whole circuit that is
balanced or unbalanced, rather than any given output or input by itself.

--Bob Richard

P.S. I apologize for the duplicate post an hour or so ago. Outlook Express
is not being my friend.


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Richard Crowley Richard Crowley is offline
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Default Balanced output to two inputs, one of which is unbalanced

"Bob Richard" wrote ...
Thanks! The new (to me) lesson here is that it is the whole circuit that
is
balanced or unbalanced, rather than any given output or input by itself.


An individual input or output can still be capable of being
balanced (by its inherent design), but once somebody grounds
one side, nobody gets the benefit of a balanced circuit.

P.S. I apologize for the duplicate post an hour or so ago.
Outlook Express is not being my friend.


More likely your NNTP server is not being your friend.
OE (or any other news client) likely has nothing to do with it.

Postings I make to the NNTP server here in the office show
up *instantly* in OE. Postings I make to Supernews take
many minutes to show up in the same OE.


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Julian Julian is offline
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Default Balanced output to two inputs, one of which is unbalanced

On Wed, 5 Jul 2006 18:46:42 -0700, "Bob Richard"
wrote:


Thanks! The new (to me) lesson here is that it is the whole circuit that is
balanced or unbalanced, rather than any given output or input by itself.

--Bob Richard


Not necessarily Bob. I suggested a way that you could run one device
balanced and the other unbalanced, but I like Mike's idea better.

Julian


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Goaty Goaty is offline
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Default Balanced output to two inputs, one of which is unbalanced

These are much a better idea and handle level control between +4 and -10
as well

http://www.audiotelex.com.au/contractor.html#sc2


Cheers
Goaty
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