G-System: What is Pseudo Balanced?

Question

Please explain what "Pseudo Balanced" means?

Answer

A pseudo-balanced cable can be used to avoid or reduce ground loops when connecting unbalanced equipment to balanced inputs — for example a guitar to a multi-fx processor. The basic idea being to avoid any direct connection between the ground of the unbalanced source and the ground of the balanced input, while still conveying the signal.

The normal arrangement when an unbalanced source is connected to a balanced input is that the cold side of the balanced input is shorted straight to ground, effectively unbalancing the input completely and providing a potential ground loop path. However, a balanced input is designed to detect the voltage difference between its two input connections, and the pseudo-balanced cable takes advantage of this by applying the unbalanced signal between these two inputs. So, the unbalanced signal (ie. the tip connection of the unbalanced jack plug) is connected to the 'hot' side of the balanced input as normal, while the screen/ground connection of the unbalanced source (ie. the sleeve connection of the jack plug) is connected to the 'cold' side of the balanced input.


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