The One That Started it All

The Cavalli-Jones headphone amplifier came in a series of steps that started when I built my Fender Tone Stack headphone project. This amp was an experiment where I wanted to try out a few things, including the White Cathode Follower as an OTL tube output stage. I did some research on the WCF and discovered some really good information on John Broskie's brilliant Tube Cad Journal.

After completing the amp I asked Chu Moy of Headwize if he would be interested in an article on this amp. Chu expressed interest and we began to work on the article. Chu noticed that the WCF output stage in my amp was the same as the output stage in the Morgan Jones amp that had already been written up in a other Headwize article. Chu asked me if the Broskie optimization (see the Design section) that I had used would also apply to the MJ amp. Of course it did and so Chu further asked me to optimize the MJ for better performance. Which we did.

The amp with these changes became known as the Optimized MJ. Several headwizers built it and got good results.

As I began to collaborate with other headwizers on WCF output stage amplifiers it became clear that in order to handle headphones ranging from 32Ω to 300Ω it was necessary to apply different amounts of NFB. To accomplish this I introduced a shunt feedback network into the Optimized MJ amplifier and then made the NFB adjustable using a pot connected as a rheostat. This amp is called the Cavalli-Jones Amplifier. Many headwizers have built the Cavalli-Jones with good success.