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    Xlr inputs for vta st 70

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    islanddave

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    Join date : 2012-10-15

    Xlr inputs for vta st 70 Empty Xlr inputs for vta st 70

    Post by islanddave on Wed Feb 27, 2019 1:10 pm

    Is it viable to rewire the rca inputs to become xlr balanced inputs?
    How would this be done?
    erhard-audio
    erhard-audio

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    Join date : 2017-04-07
    Age : 61
    Location : Tucson, AZ

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    Post by erhard-audio on Wed Feb 27, 2019 1:55 pm

    there are two ways to get balanced in and outputs.
    The 'faux' way, by simply wiring the XLR socket as an unbalanced connection, that is, shorting pins 1 & 3 on the XLR socket, that being ground and pin 2 being signal.
    If you wish to have true balanced in and outputs, you'll need to use audio transformers, such as the Lundahl LL1544A, which will 'split' the signal on the XLR side to +ve, -ve and ground/shield, or you can use certain Op-Amps to do the same, but then you will also need a bipolar power supply to run the Op-Amps, such as + & - 12VDC.
    So, for the ST-70, stick with the unbalanced RCA, because you are really gaining nothing by going balanced.
    The only time where balanced signals are good is when used in recording studios or on stage, where long cable runs are the norm and where interference/noise pickup can be a real issue!
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    islanddave

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    Post by islanddave on Wed Feb 27, 2019 5:20 pm

    erhard-audio wrote:there are two ways to get balanced in and outputs.
    The 'faux' way, by simply wiring the XLR socket as an unbalanced connection, that is, shorting pins 1 & 3 on the XLR socket, that being ground and pin 2 being signal.
    If you wish to have true balanced in and outputs, you'll need to use audio transformers, such as the Lundahl LL1544A, which will 'split' the signal on the XLR side to +ve, -ve and ground/shield, or you can use certain Op-Amps to do the same, but then you will also need a bipolar power supply to run the Op-Amps, such as + & - 12VDC.
    So, for the ST-70, stick with the unbalanced RCA, because you are really gaining nothing by going balanced.
    The only time where balanced signals are good is when used in recording studios or on stage, where long cable runs are the norm and where interference/noise pickup can be a real issue!

    Pretty well why I would like this set up. I want to keep speaker cables short........amp between speakers......then a long xlr run to dac source and preamp......
    keeps all the sources galore......out of sight at the side of the room
    Was led to believe that this is audio nirvana

    Please send help lol
    erhard-audio
    erhard-audio

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    Post by erhard-audio on Wed Feb 27, 2019 5:24 pm

    XLR balanced for home use is one of those urban myths and sales pitches....absolutely not necessary for 99.9% of home setups! Unless the distance to your dac source, preamp etc is tens of feet long or in another room...you know what I mean..... no need to go with balanced.
    sKiZo
    sKiZo

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    Location : Michigan USA

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    Post by sKiZo on Wed Feb 27, 2019 5:52 pm

    Probably not a bad idea to add a switch to "float" the ground if you go that route. Gives you more flexibility in the future if you end up with a pre that objects to the tied pins.
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    rayton

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    Post by rayton on Sat Mar 02, 2019 12:48 pm

    erhard-audio wrote:
    The only time where balanced signals are good is when used in recording studios or on stage, where long cable runs are the norm and where interference/noise pickup can be a real issue!

    It's depend, I would have disagree with your statement in my experience. For the sound quality, nothing much different but the hum is one of the cause.

    I got problem just 6 " RCA to Revel sub and Mark Levinson amp, I got hum when using RCA but not XLR. The hum doesn't make the sound quality bad but it's kinda annoy when the music stops playing.

    I have thinking about audio transformers instead of Op-Amps which doesn't need power. It's for my other preamp & amp that don't have XLR connection.

    erhard-audio
    erhard-audio

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    Post by erhard-audio on Sat Mar 02, 2019 1:08 pm

    rayton wrote:
    erhard-audio wrote:
    The only time where balanced signals are good is when used in recording studios or on stage, where long cable runs are the norm and where interference/noise pickup can be a real issue!

    It's depend, I would have disagree with your statement in my experience. For the sound quality, nothing much different but the hum is one of the cause.

    I got problem just 6 " RCA to Revel sub and Mark Levinson amp, I got hum when using RCA but not XLR. The hum doesn't make the sound quality bad but it's kinda annoy when the music stops playing.

    I have thinking about audio transformers instead of Op-Amps which doesn't need power. It's for my other preamp & amp that don't have XLR connection.


    And that is what I indicated. Balanced XLR is used to ensure hum free and general noise free connections in challenging environments, such as recording studios and stages.
    If you are experiencing hum issues at a mere 6", then you have an issue that I feel needs to be addressed. Using balanced XLR may well solve it, but in all reality, it is only a 'band aid' solution!
    deepee99
    deepee99

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    Xlr inputs for vta st 70 Empty Back to basics?

    Post by deepee99 on Sat Mar 02, 2019 2:45 pm

    Most hum issues I've encountered over the years involve (assUming there ain't something funky in the equipment) the proximity of power cords and unbalanced interconnects running parallel to one another. If there's no other way to route your cables except real cozy-like, always cross the power cord(s) and signal interconnects at 90 degrees. Holger's right about XLRs. There's a time and a place for them, but most of it is showroom and cable-maker hype. Keep your high-power AC cords at 90 degrees to your unbalanced coaxial cables and you can let 'em touch each other with no worries 9 times out of 10.

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