The Pleiades 2 K117 (9 volt) RIAA preamplifier

At your risk. It started as the inteligent Le Pacific Walters, Hiraga 2 K170 preamplifier which is elegant and simple. It consumes about if memory is correct 5mA per junction field effect transistor. So the 2 garage remote control 12V batteries whent down in a few minutes. Then the idea came to see if it would work with just a 9 Volt battery. It did not as the large Idss (5mA) created such large voltage drop at the drain resistor that the drain went down to a few millivolts. Then source bias resistors where added to reduce drain current, it worked. Then drain resistors when increaed from 2K4 to 10Kohms, to increase gain to 22Kohms and now to 100Kohms at the first stage. Drain current is just about 40 microamps and it sounds amazing and low noise as known from fascination with low currents on this Euroelectron blog. Sony does this too if your see the schematics of the ECM series electret condencer battery powered microphones. Again a few decades of microamps on the sensitive low voltage and low current music fed 1st stage. It is so low noise... The second stage has a drain resistor of 10 KOhms so as to be able to drive the 2N3053 power amplifier. The passive RIAA filter between 1st and 2nd stage is based on the Heathkit tube integrated amplifier built in kit form by Antonis Kaskampas who kindly almost donated this amplifier long time ago. The series resistor is 220K, the capacitor at this branch is 15nF and then a 5nf cuts the treble. The preamp had been tested with the inverse Lipshitz RIAA network and it is almost flat so far with + 3dB at 20Hz something which should be corected later on. So overal the schematic of the Pleiades 2 K117 9 volt batterey powered RIAA MM preamplifier is: input - cartridge terminated by 47K - coupling capacitor of 470nF - 1M sourse resistor - 10K source bias resistor in parallel with a 220uF electrolytic capacitor- 100K drain resistor of K117 - 220K series resistor in series with 22K in series with 15nF for the 3180ms and 318ms bass turnover frequencies and signal taken from the junction of the 2 resistors with 5nF to ground for the 75ms high cut (a small series resistor is added in series to 5nF according to The Tube Amp Cookbook - Allen Wright to stop cutting treble forever with respect to frequency increase) - signal is then fed to second K117 JFET gate resistor of 1M - RL2 is 10K - RS2 is 560R and the in parallel capacitor is 220uF - signal is taken from drain by a 820nF dc blocking capacitor - output. That's it. 2 such channels can feed 2 Pleiades 2N3053 power amplifiers. Amazing sound. If an Altec 5:1 or a Belclaire 10:1 output transformers are connected to the output of the RIAA preamp then the Sennheiser HD-580 300 Ohm per each drive unit headphones can be driven to a comfortable not loud volume.