French  English  
 

SK25

sk25 profil

The SK25 is a discrete Op-Amp that we developed as a replacement for the API* 2520. Our electronic and listening tests show that it behaves extremely close to the original.

 

Highlights

  • Pin compatible with API 2520 and 99 DOA's
  • Two cascaded differential stages on input
  • Matched transistors
  • Constant current source on the first stage
  • Symmetrical drive of the output stage with a current mirror
  • Short circuit protected output

 

More details...

The current in the first stage settles around 55uA in each transistors. For this reason, the SK25 will give its best noise performances with high impedance sources like high ratio input transformers (1:4 and above).

 

Measurements

Typical values measured with an HP8903A Audio Analyser, a Fluke 187 multimeter and a Tektronix 475 oscilloscope.
Measurement Conditions Value
Open loop gain @20Hz 112dB
Bandwidth Gain=+40dB
Deviation=-3dB		 DC to 180KHz
Slew rate   6V/us
Input DC offset   6.5mV
Input bias current   100nA
EIN Input shorted
Bandwidth=0-30KHz		 1uV or -118dBu
Max output voltage Supply ±18V
RL=150Ω		 23.5dBu
Peak output current   +230mA/-270mA
Supply voltage   ±15V to ±18V
Supply current Supply ±18V 26mA

 

sk25 top

* API is a registered Trademark of Automated Processes Inc.