so why do top phono stage designers use RCA inputs?
Tradition- rather than performance.
Take a very close look at phono cart signal generators. Doesn’t matter if the cart is MI, MM or MC. They are NOT balanced, they are single-ended with a + and - pole. One strand of wire that runs from the hot side of the connector to the ground side. No neutral.
This statement is false.
bpoletti, it seems to me that your misunderstanding is the idea that in balanced operation there has to be a ’neutral’ connection- like a center tap on a transformer or the like. IOW, are you expecting that if a cartridge is balanced, it would have six connections? It really doesn’t work that way! How it *does* work is that the winding of the cartridge floats with respect to ground, IOW neither side is tied to ground, instead the arm tube is the ground (its a shield) and other than shielding, the arm tube is not involved with the signal in any way. That is how a balanced system is supposed to work.
If there was a center tap on the cartridge winding, and if it were tied to ground, performance would be reduced because the center tap could never be perfectly placed. That is why balanced systems don't have a center tap- the coil always floats whether its a cartridge, microphone or transformer.
When you run the cartridge single ended, you wind up with the weird ground wire that no other single-ended source seems to need. That is because you are taking a balanced source and running it single ended- and you wind up with a ground wire.
So when we run the cartridge signal into our MP-1 (which in 1989 was the world’s first balanced line preamp), the tone arm ground wire is tied to pin 1 of the XLR, which is ground. The ’+’ output of the cartridge is tied to pin 2 and the minus to pin 3 (pin 2 being either the red or white wire of the tone arm, depending on which channel). This is why a 5-pin DIN tone arm connector is a true balanced connection, since neither channel is tied to the ground and the ground is thus the shield of the interconnect cable.
The advantage of this system is you simply don’t have to have an expensive cable to get it to sound right, a low capacitance cable that is constructed properly is all that is needed, and it will easily keep up with any exotic tone arm cable made, cost no object. Its a pretty clear (if you will pardon the expression) advantage.
