Return to Main Article

10/17/2000: Updated section on power supply.

10/19/2000: Added section on impedance converter.

10/24/2000: Charles King suggested rating the plate resistors at 1W.

4/9/2002: Major revision to article: expanded discussion of original Morgan Jones design and added sections on the optimized Morgan Jones amplifier schematics by Alex Cavelli. Also added section on simulating Morgan Jones circuit using OrCAD Lite.

6/3/2002: Added schematics and descriptions for power supplies by Bryan Ngiam and Rudy van Stratum (figures 12-14). They both built the optimized version of the MJ amp without feedback. Here are pictures of Ngiam's and Stratum's amps:

More information about Bryan Ngiam's power supplies is available at Bryan Ngiam's Home Page.

3/3/2003: The author updated the 6DJ8 model in the triode library used in the OrCAD simulations of the Morgan Jones amp. He also revised value of R4 from 150 Ohms to 120 Ohms for the optimized amps (figures 5 and 10). He writes:

I'm including a new triode library. I have modified the 6DJ8 model based on some other work that I was doing. The parameters are slightly different from the previous version and they are more accurate. You should use this library and replace it in the ZIP you're making available on the website. Because of this better model, I am recommending that the plate resistor for the MJ be lowered from 150 ohms to 120 ohms. Closer to 1/Gm.

Return to Main Article

Questions or comments? Visit the HeadWize Discussion Forums.