Motown Direct Amplifier-inspired Preamp?
- Thread starter untune
- Start date
Help Support GroupDIY Audio Forum:
Further tests:
The 20 pf feedback cap and the 5.6K resistor takes care of the sq wave ringing so the 4.7K grid stopper on stage two makes no difference if it is installed or not so i yanked it out.
A bad solder joint on stage two grid resistor was not the problem causing the ringing,
The transformer primary has no effect on the scope shots for sq wave and phase shift
This was verified by doing before and after scope shots with the wire connected to the output cap or not.
Frequency response test - sine wave
at the lowest gain setting, 50% roll off occurs at 330KC KC
at the highest gain setting on the pot the roll off point is at 54KC
The 20 pf feedback cap and the 5.6K resistor takes care of the sq wave ringing so the 4.7K grid stopper on stage two makes no difference if it is installed or not so i yanked it out.
A bad solder joint on stage two grid resistor was not the problem causing the ringing,
The transformer primary has no effect on the scope shots for sq wave and phase shift
This was verified by doing before and after scope shots with the wire connected to the output cap or not.
Frequency response test - sine wave
at the lowest gain setting, 50% roll off occurs at 330KC KC
at the highest gain setting on the pot the roll off point is at 54KC
