S/N ratio Balanced input vs. Unbalanced input


Hi, is it normal that signal to noise (S/N) ratio at rated output of balanced input (XLR) is lesser than unbalanced input (RCA) ?

eg. Accuphase E280 , S/N ratio balanced is 96dB, unbalanced is 107dB.

 

Also E280 , at preamp stage , dB gain : balanced/unbalanced to pre output is 18dB gain, power amp stage dB gain : 28dB, total of 46dB.

What about other integrated amplifiers specs for comparison ? 

S/N ratio (balanced) :

S/N ratio (unbalanced):

Preamp gain :

Poweramp gain: 

 

auronthas

Showing 1 response by atmasphere

@auronthas The reason your amp is noisier with the balanced input is that the amp itself has a single-ended input; its not internally balanced. So the balanced input goes thru a separate circuit which adds noise.

IMO/IME this is a sloppy way of doing things since the balanced operation is more of an afterthought whereas again IMO it should be the star of the show.

Normally if the internal circuitry were balanced-differential, the single-ended input would be noisier as there would be less noise cancellation.

This also explains why there is less noise when the balanced DAC is connected; the opamp that does the balanced to single-ended conversion is able to pick up noise with no input load.