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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.

Eureka!, Just 3 transistors from MM record player cartridge to Loudspeaker, everything in single ended class A operation, (electrons flowing all the time)

At your risk. It is so simple with minimum components and it sound amazing, huge bass, great mid smoothness and anazing treble. On a good record (see below) cymbals sound so good one can almost visualise the sound as what is seen when a small objest falls on a calm sea. This is how the attack sutain and decay of the cymbal feels like. And when the program material becomes busy as on the end guitar solo of To France - Mike Oldfield nothing sounds tiring to the ear, the sound is still big and clean. All this with so small power consumption. The RIAA preamplifier comsumes less than a millamper at 8 volts, and the power amplifier about 10-14 milliamperes at 24 Volts. Yet the sound level is ordinary comfortable without being loud of course. The transistors used are 2 K117 JFETs per channel for the RIAA preamplifier and one 2N3053 bipolar transistor per channel for the power amplifier. Signal path: Just the Way you Are - Billy Joel from a foreign pressing LP - Technics SL1200 MKII turntable - Stanton 680 or 681 cartridge - EEE AR stylus - Pleiades 2 K117 RIAA preamplifier with a 9 volt battery - Pleiades 2N3053 power amplifier powered by 24 volts (2x12V batteries in series with fuse), (Pleiades output transformers, see older post) - Celestion Ditton 150 speakers - small reverberent room - listener So far the other song played is To France - Mike Oldfield from a Hellenic pressing LP at the no longer existing Columbia factory in Athens.

Wago makes electronics as simple as drawing

At your risk. Wago 2 or 3 or 5 terminal connectors have been used to build easily the Pleiades 2N3053 single transistor class A audio power amplifier. Everything had been connected with Wago connectors, bias resistor, transistor, coupling capacitor, output transformer, fuse, battery, speaker. The transistor is fitted as follows. 3 IC like wirewrap female beens joined together are each wound with blue for collector, green for base and yellow for emitter solid wire cables. The transistor is inserted and the logers colored wires are inserted and fasten on Wago connectors. Wago connectors can be orianted so that the connecting holes look towards the ceiling, so for example a resistor can be fitted from above when its body is parallel to sea level and its legs are bent 90 degrees like the hellenic PI letter. So components are inserted from above like on a breadboard and the connections are done like what is seen on the electronic schematic. So far 3 monoblock power amplifiers had been built. The Pleiades 2 JFET K117 RIAA preamplifier has so far been built on ordinary breadboard from Korea which are very nice too for expeiments.