Autoformer + Jfet Buffer

[happyrabbit]

Using an Intact Autoformer, I added a LSK489 buffer based on the White Cathode Follower. Its a dual mono configuration using a 28v switching supply. The input cap is level shifted allowing a single supply design. Also added a muting shunt relay for noise free operation during power up & down. The jfet adds some 2nd harmonics. The 3rd order shown in the pic is mostly from the 8bit usb scope. I find the preamp surprisingly enjoyable and resolved. See attached. I plan on developing a linear power supply version(+/-24v) in the near future.

 

[dimitri]

This is very good idea, I did similar things with S+B TVCs. I can send you schematics.

 

[happyrabbit]

THANKS ! You can post them here if you like.

 

[Tachyon666]

This looks great, happyrabbit 🙂. What 'scope is that? A PicoScope 2000?

 

[happyrabbit]

Yes, it’s the 10mhz model. It’s good but not well suited for audio. The signal generator is pretty noisy ! I need to obtain this model :

16 bit high resolution oscilloscope | Overview