Hi,
What change to adapt this pre-emp 75µS to 50µS :



Thanks

In theory (though I haven't tested this), changing the 330pF capacitors circled in red with 220pF ones should do the job.

Rev

The Rev is exactly right. Use accurate 220pF capacitors (not cheap ceramic ones), and be careful in setting up the HF clipper - it's easy to overdo it! It's also worth using slightly lower frequency filters (16 kHz is getting a bit too close to the 19 kHz stereo pilot). My filters use "gyrator" networks (to emulate inductors), and go over like a cliff at 15.15 kHz. By 19 kHz, they're around 74 dB down.