Motown Direct Amplifier-inspired Preamp?
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- 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
MidnightArrakis
Well-known member
There is nothing wrong with your computer monitor.
Do not attempt to adjust the picture.
We are controlling transmission.
We will control the horizontal.
We will control the vertical.
We can roll the image; make it flutter.
We can change the focus to a soft blur or sharpen it to crystal clarity.
For the next hour, sit quietly and we will control all that you see and hear.
We repeat: there is nothing wrong with your computer monitor.
You are about to participate in a great adventure.
You are about to experience the awe and mystery
which reaches from the inner mind to "The Outer Limits".
/
Do not attempt to adjust the picture.
We are controlling transmission.
We will control the horizontal.
We will control the vertical.
We can roll the image; make it flutter.
We can change the focus to a soft blur or sharpen it to crystal clarity.
For the next hour, sit quietly and we will control all that you see and hear.
We repeat: there is nothing wrong with your computer monitor.
You are about to participate in a great adventure.
You are about to experience the awe and mystery
which reaches from the inner mind to "The Outer Limits".
/
Last edited:
Don't, worry, I am about to bolt the base plate on and call this thing good now that we have come full circle back to the original schematic,
Dave you have a good simulator, which one are you using?
FYI: open loop gain was measured at 278 before the transformer.
Somewhere down the line I might wind a SE transformer and try a class A output stage just for kicks.
Dave you have a good simulator, which one are you using?
FYI: open loop gain was measured at 278 before the transformer.
Somewhere down the line I might wind a SE transformer and try a class A output stage just for kicks.
