What is the schematic different in X.5 and XA.5 series

[im1663]

The XA.5 amps are Class A (low rail voltage and high bias current) and the X.5 amps are high bias AB (high rail voltage and lower bias current).

Beside that, is there any schematic different in the front end?

 

[Zen Mod]

maybe yes , maybe not

I resume - only Papa is entitled to give proper answer

klunk!/?

 

[tiefbassuebertr]

as I know, the X-series contains two power amps in bridge configuration. Each power amp uses only one gain (VAS-) stage (input stage) and one push-pull buffer AB stage.
Each gain stage was realized as folded cascode.
In the simplified schematic from patent under
Wo ist bei den Pass XA Nachbauten die Super Symmetry Schaltung? - Visaton Diskussionsforum
there is only show the input stage.

At first glance there are two discrete operational amplifier in inverting mode.
But on closer inspection this is not the case, because the feedback resistor goes from the positive output not to the positive input resp. from the negative output not to the negative input.

Maybe the XA series uses for the output stage a single ended class A version (like ZEN) and not a push pull AB version (maybe the only difference).
But maybe I am wrong.

 

[generg]

Hi tiefbassübertr,

Maybe you have to adjust your PC watch.......

:--))

 

[Nelson Pass]

The XA.5 amps are Class A (low rail voltage and high bias current) and the X.5 amps are high bias AB (high rail voltage and lower bias current).

Beside that, is there any schematic different in the front end?

Not particularly. Topology is the same, the values are different.