Balanced outputs used as inverting & Non-inverting preamplier outputs - diyAudio
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Old 4th September 2008, 03:12 PM   #1
gni is offline gni  United States
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Default Balanced outputs used as inverting & Non-inverting preamplier outputs

I have a Yamaha C-85 that has regular as well as inverting preamplifier
outputs. It allows the bridging of two amplifiers or running two
stereo amplifiers with one channel inverted; potentially while both
channels go positive, each channel will use a different power supply
rail. I have used the C-85 with two Yamaha M-45s in both
configurations and it works well.

So. . .

A balanced output has an inverted and non-inverted signal. It seems
that you should be able to use the balanced output as two unbalanced
outputs--one regular and one inverted. It would be quite easy to
wire up an XLR or TRS plug and split it out to two RCA connectors.
There will be the usual impedance issues but the signals should work
the same.
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Old 4th September 2008, 03:29 PM   #2
gni is offline gni  United States
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Old 4th September 2008, 03:41 PM   #3
AndrewT is online now AndrewT  Scotland
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impedance matching is FAR more important than output voltage.
Impedance is not the side issue you imply.

The two outputs must exactly match impedance wise (and that includes capacitance) to better than 0.1%.
If not then you are wasting your time.

The corollary to this is that one signal could be absent and the balanced impedances would still allow good signal transfer to the balanced input with good common mode (noise+interference) rejection.
regards Andrew T.
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Old 4th September 2008, 10:16 PM   #4
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use the balanced output as two unbalanced outputs
yes you can, if the output voltages are symmetrical to ground and ground referenced.
You have to try it, because the result would depend on the senders and receivers topology.
Chris, Do you mind clarifying your problem/question?
Seems we understand it differently.

such a blanket requirement of yours is wrong.
Source impedance matters with simple differential receivers more than with advanced inputs.
Accidentally we don't know anything of the input circuits.
And any common mode reduction is better than no one.

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Old 19th September 2008, 03:25 AM   #5
gni is offline gni  United States
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Sorry, I've been busy with the grape harvest in Sonoma County.

I want to use the balanced output of my mixer in the same
manner as I use my Yamaha C-85 preamplifier. There are four
output jacks. Two for Left and Two for right, but each second pair
is inverted. So it allows you to bridge an amplifier easily. The tip
of regular output will be swing high while the tip of the inverted
output will swing low(in ref to gnd).

I guess I can just wire up the system and find out. I don't need
balanced outputs for the short runs and the amplifiers have
unbalanced inputs. . .
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