Hello All,@wayne and All,
I have seen the errors of my ways.
Previously while I was setting the series output voltage of the new Keysight bench power supply I entered 19Vrms thinking that in series it would be double that for the + / - series output, it was not. Now the output voltage is corrected to + / - 19 Vrms for a total of 38Vrms. Each 7815 and 7915 on the P3 PCB has volts to regulate 15Vrms + / - at the output of each.
So now The P3 with 4 each 2SK209's functions as expected. Built with Pioneer Kit recommended part values. Thanks to @6L6
Input is 5mv
Gain is 50.39dB
output volts is 1.653Vrms
THD+N is 0.004%
SINAD is 87dB
The above measurements were taken with APx555 analyzer. My expectation is that the limting factor will be the Turntable MM cartridge.
See the updated P3 FFT with 2SK209 Jfets below.
Thanks DT
View attachment 1284978
Today I got around to adjusting the resistance values in the U1A feedback loop.
With the build Document recommended values and J2 jumper in place I got the test results in post #2777.
SINAD is really good and the gain is 50.4dB, too high for my mm cartridge, probably okay if there are no ticks or pops on the vinyl.
Tonight I removed J2 and soldered a 100R resistor where C16 would go. The gain went down by 5dB to 45.36dB and the SINAD went down 16.3dB to 70.7dB. Or THD+N 0.087%
This is good news for the gain and bad news for the SINAD / THD+N.
It looks to me that this P-3 wants to be a moving coil pre-amplifier after all.
Thanks DT
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