Building a Cathode Follower Preamp with Art Dudley's Inspiration

As we approach the end of the year, it's time to reflect on our passion for tube amplification and share some exciting projects with each other. Today, I'd like to introduce you to my design of a 6SN7 (6N8S) based preamp with parallel sections of the tubes.

Inspired by Art Dudley's work, I decided to tie the two sections of the double triode in parallel, using just two tubes, one for each channel. This design allows me to create a unique and balanced sound that is reminiscent of my beloved 76/6SN7 line stage.

The MiniTron amplifier was actually designed as an entry for the Circuit Cellar / Microchip design contest, where it won one of the category prizes. As a result, it should be featured in the upcoming issue of Circuit Cellar magazine and on their website soon.

When designing this preamp, I experimented with different tube configurations to achieve the perfect balance between warmth and clarity. After trying out various options, my ears finally chose the 7AF7 as the voltage amplifier for the line stage. I also made an exception by wiring the line stage in a way that allows me to exploit the unique characteristics of the 7AF7 versus other tubes.

While it's not typical for me to split halves of twin triodes between left and right channels, this design worked surprisingly well as a zero feedback single stage line amp. However, I did have to make some adjustments to ensure that each channel was balanced properly.

Ultimately, it was the ubiquitous 7N7 (loctal 6SN7) that gave me the tonal balance I wanted, with the 7AF7 serving as an alternate option. This design is a testament to the versatility of tube amplification and the importance of experimentation in finding the perfect sound.

For those interested in building their own cathode follower preamp, I recommend checking out the recommended circuit on audio-talk.com, which provides a wealth of information on DC coupled cathode followers.

Happy holidays and best wishes for the new year! May your passion for tube amplification continue to inspire you to create innovative designs that bring joy and music to your ears.

Cathode follower preamp