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Old 15th February 2017, 08:32 PM   #1
gin8330 is offline gin8330  Denmark
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Default Resistors for Balanced input signal

Hello everybody,
Just got Anaview AMS0100 and reading manual came across his:
"It is quite common to have a series resistance of 50ohm or more on the signal output so if the same resistance is placed in the opposite side of the signal of either sending or receiving side of the cable the CMRR rejection is intact."
Is wright should look like this ?
Any answer to mine questions would be appreciated :
1.What is optimum value for resistor in W an Ohm ?
2. Wat type of resistor it is god choice ?

I have found this on ebay .Can those be used ?
Or just simply forget about resistors and use amp as it is.

Thank you guys
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File Type: jpg Balanced input signal.jpg (627.6 KB, 98 views)
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Old 15th February 2017, 09:06 PM   #2
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Quote:
Originally Posted by gin8330 View Post
Hello everybody,
Just got Anaview AMS0100 and reading manual came across his:
"It is quite common to have a series resistance of 50ohm or more on the signal output so if the same resistance is placed in the opposite side of the signal of either sending or receiving side of the cable the CMRR rejection is intact."
Is wright should look like this ?
Any answer to mine questions would be appreciated :
1.What is optimum value for resistor in W an Ohm ?
2. Wat type of resistor it is god choice ?

I have found this on ebay .Can those be used ?
Or just simply forget about resistors and use amp as it is.

Thank you guys
Sorry, but it's not clear to me what you are asking.

Are you attempting to connect a single-ended circuit over an balanced interconnection?
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Old 15th February 2017, 09:16 PM   #3
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I think you are referring to an imaginary resistance in the cable.
It is true with RF signals and Ethernet cabling that the cable must be matched to the 75R or 50R load but not for unbalanced or balanced audio.
Never does anyone place a resistor in series with the loudspeaker!
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Old 15th February 2017, 10:49 PM   #4
MAAC0 is offline MAAC0  Portugal
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If I learned well, the series resistance on the output is to protect the output from short, determining the output impedance and prevent oscillations on long capacitive cables.

For RF frequencies you need to cable and appliance impedances, but for audio simply follow the old rule: low impedance output into high impedance input (Bridging) or you will hear a thin sound.
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Old 15th February 2017, 11:15 PM   #5
gin8330 is offline gin8330  Denmark
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The questions Im asking actually based on advise in manual
.I will post same relevant pages from manual.
From that I understood as it is god idea to use resistors. Question was what kind resistors should be used ? What type an what value ?
But could be I misunderstood.

In mine set up I have Hypex UcD34MP . Those people advised to use balanced cables but not resistors, I do have balanced cables with XLR from miniDSP 2x4HD to amplifier but not resistors.
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File Type: pdf PDS AMS0100.pdf (746.9 KB, 7 views)
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Old 16th February 2017, 12:07 AM   #6
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I would use amp as is unless you have a very noisy environment.
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Old 16th February 2017, 12:41 AM   #7
gin8330 is offline gin8330  Denmark
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Thank Nigel,
I don't suffer from noise in environment.
It is about input impedance because is not is not the same on both inputs and this why Anaview advising to by having the same source resistance on both the inputs.
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Old 16th February 2017, 12:48 AM   #8
cbdb is offline cbdb  Canada
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Common mode rejection of balanced systems needs equal impedance on both conductors. Even small mismatches can greatly reduce the CMRR. Adding these resistances probably evens out the impedance mismatch of the cable to restore some of the CMMR. But as someone else said, if you don't have a hum, or noise problem, no point in doing it. Here's a lot more info. It's starts about a 1/3 of the way in.

http://www.aes-media.org/sections/pn...lock_pnw05.pdf
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Old 16th February 2017, 12:59 AM   #9
gin8330 is offline gin8330  Denmark
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Thank you guys,
This what i will do-stop worry about it because i don't have noise issues.
Just for sake of discussion there is a picture what resistors was fuss about it.

Thank you again
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File Type: jpg AMS0100.jpg (318.1 KB, 78 views)
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Old 18th February 2017, 12:14 AM   #10
MAAC0 is offline MAAC0  Portugal
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Those resistors are there to maintain the same impedance on both wires to reduce CMRR.

Balanced Transmitter and Receiver II

Look at the last part about cheating.
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