When we use general-purpose small-signal transistors, we usually end up having to include a base junction resistor to reduce the high voltage of the ceramic cartridge. Audiophiles should love this circuit as it is minimal, and easy to build on stripboard. Simultaneously, I am using a MOSFET that has very high gate impedance, which eliminates cartridge loading issues almost entirely, and consequently the sound quality is excellent to say the least. The secret to the circuit is that I am using an equalization network that provides feedback to the gate junction, which has the effect of lowering the input impedance. Some of the transistors that I tried were the MPSA13 Darlington, 2N3904, and 2N2222 however the 2N7000 MOSFET produced the best sound out of all. I tested it with readily available general purpose NPN transistors and they worked up to a point, however, there was a limitation to the absolute maximum input voltage the base junction could accept before distortion occurred. My design concept was to produce a circuit that would provide the best possible sound, using the most commonly available and lowest-cost components. Many of them such as crystal cartridges can have extremely high output voltages that are outside the input voltage range of this circuit, and therefore they will not work. Hence, please only use this circuit with that cartridge as I do not know how it will perform with all the different modern and vintage, types, and makes of ceramic cartridges out there. Universal Ceramic Cartridge and Stylus available on eBay. Ceramic cartridges of capacitance range 800 pF to 12,000 pF, and absolute maximum voltage of up to 900 mV could theoretically be used however I have tested it only with that cheap It uses the 2N7000 MOSFET transistor, with minimal biasing overhead. This ceramic cartridge preamplifier circuit requires the least number of components and produces a decent sound with minimal loss of bass and treble inherent with such cartridges.
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