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August 23, 2008 - 2:26am
#1
And another brand of "most transparent".
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Can a phono preamp be balanced? I thought that phono by its very architecture was single ended. Am I right or can a phono stage be truly balanced?
I was told by it's very nature all phono amps start out balanced and then go out (usually) single ended...
The output of a phone cartridge is balanced.
Elk has the right answer, as always. A phono cartridge is just a coil, so it is inherently balanced. If you attach one wire to ground it's then unbalanced. If the phono preamp has a balanced input, then the system stays balanced and rejects hum common to both of the coil's wires.
--Ethan
Quoting from scripture ("Noise Reduction Techniques in Electronic Systems" - Henry W. Ott):
So yes, a phono catridge output can loosely be considered balanced as the impedance seen by both conductors to ground is undefined. The picture changes though when that output is connected to an amplifier. A single-ended phono amp connects one side to ground and the other side sees the input impedance of the amp. With a differential amp, both conductors see what should be the equal impedances of each input and would, therefore, qualify for being "balanced". As Ethan desribed, a well-designed differential input can deliver much better noise performance over a single-ended design.
LOL, now that's my kind of scripture!
--Ethan