This gets us into some sticky territory when using bal/unbal adaptors because you have to know how the adaptor routes the single-ended's ground: i.e does it connect the (RCA) ground to the balanced adaptor's neutral, or to its barrel, or (quite often) to both? The neutral pin (usually pin 1) of a balanced connector, is neutral relative to the plus-and-minus signal conductors (pin 2 and 3) but is NOT the same as the "ground" in an RCA connector. When a balanced cable is connected to a chassis socket, the shield is connected to the chassis. Even though balanced connectors have three pins/sockets, there are really four connections - the fourth one being the barrel of the connector, which is attached to the cable's shield. Another detail newbies always miss regarding bal versus unbal interconnections, is shielding. So if you're in a pinch for some reason, and only have a balanced interconnect available to connect your preamp's unbalanced outputs to your amp, it's OK to use the adaptor on the preamp end, but you must also use one on the amp end so you can go throught the amp's unbal (single-ended) inputs thus sending the signal through the splitter/inverter circuit first.ģ. It just enables you to send an unbal signal through a bal cable. It doesn't make a bal signal out of an unbal one. If you feed the amp an unbal (single ended) signal through its bal inputs, there is no splitter/inverter between the bal inputs and the amplifier's gain stages, so the amp is literally getting only half a signal! An unbal-to-bal adaptor doesn't do the same thing as a splitter/inverter circuit. If you feed the amp an unbal (single ended) signal (through its RCA inputs), the signal first goes through a splitter/inverter circuit which changes the unbal signal into a balanced signal. Conventional amplifiers (both tube and ss) use what's known as a push-pull circuit, which requires a balanced signal to fuction properly/optimally. So there goes the noise rejection advantage.Ģ. So if, via an adaptor, one sends a single ended signal ONLY (in other words, half of a balanced signal) through a balanced cable, common mode rejection doesn't come into play. Balanced cables are only "quieter" if carrying a balanced signal (a plus and a minus referenced to a neutral conductor) in which case noise in the normal (non-inverted) signal cancels with the noise in the inverted signal - this is known as common mode rejection.
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