The Next Generation Low Voltage Hybrid
The SOHA II was specifically designed to fix a few of the limitations on the original SOHA amplifier. As I see it (and as do many of the SOHA's builders) the SOHA has these four drawbacks:
- A poor board design that limits the amp
- CCSs that can be complicated
- A trimpot for setting the plate voltage of the input tube
- No provision for a discrete sand buffer
I spent quite a bit of time trying various ideas to solve these problems while still maintaining simplicity and low voltage. After many theoretical designs and one prototype by Don Basel (dBel84), I finally was able to relieve the limitations on the SOHA. The SOHA II is born.