A75 front-end unwanted output signal

[ckwong99]

Hi All,

Can anyone help me about my A75 , it almost be completed but it response with square wave input would have a little spur signal in output waveform raising edge, out of this all is normal and well .

Actually, I do not use folded cascode (without R21 & C6) and the feedback resistor R81=700 ohm. When measuring the front-end output did not connect the power FET but have C8 and R31 connected to GND.

How can I vanish this unwanted signal and why it will happen ?

Analogy

[norb]

hi ckwong99,

i have attached a picture with a signal that i suppose is what you describe in you request.
If it is like this, there is no reason to be afraid, this is normal behaviour as the amp tries to adapt to the new voltage level of the signal as fast as possible. Since the amp is not indefintely fast - and no amp is - you will see this slight overshoot.

So enjoy your A75, it´s a great amp and a ear-opening experience.

Greetings
Norbert