SE to Balanced cable wiring question

[emilvv]

Hello,

I have RCA SE signal and need to send it to balanced input with TRS.
( never used balanced devices .... and need to keep the smoke in 🙂 with your help ... )

After some schematic / wiring search found attached wiring - I hope it is correct ?
( RCA RED --> TRS RED - it is OK for me - it is logical 🙂 ..... no questions here .... )

BUT why ? ...
1. RCA ground ( black ) is connected to TRS black ( negative ) and not connected to TRS Shield ? What is the 'logic' or explanation of this ?

Please, explain to me why we use Positive and Negative pins on TRS to send the signal into device ?

Thank you for your time and help,

Emil

 

[Galu]

I think I can explain it simply thus:

The balanced connection amplifies the voltage difference between its two inputs (T & R).

The cable in the attachment will allow the balanced connection to amplify the voltage difference between the tip (T) and sleeve (S) of the RCA plug.

The shield only has to be connected at one end to provide e/m screening. To connect at both ends may produce hum.

 

[Speedskater]

Yep, attach the cable shield to XLR pin 1 or TRS (S) sleeve.

 

[JensH]

You will probably also need a connection between the chassis of the two units. Otherwise you could have a very high level of common mode noise, perhaps exceeding the allowed common mode range. At least if one (or both) does not have protective earth to connect them.

 

[Speedskater]

The balanced input won't care about the Common Impedance Coupling noise.