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    JJ239 High-End, Single Ended Class A1, All Triode monoblock, 10 W into 4 and 8 Ohm

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    J239 uses one ECC99 and one 2A3-40 JJ Electronic tube. The JJ Electronic triode 2A3-40, introduced at the 2003 Las Vegas CES show, has, in contrast to the triode 300B, a heater voltage of only 2.5V. This, when combined with a heater center tap, results in a smaller potential difference with respect to the bias voltage and larger active cathode surface. The result is a better sound quality. For the audiophiles who prefer the 300B as a power tube, we offer alike monoblocks under the name JJ309. The output power of 10W may seem low, but the JJ239 monoblocks are intended for speakers of the highest quality, with high sensitivity: for example WLM, Lowther, Fostex, Cabasse, Loth-X, and so on. When multiple-way speakers are used, we recommend bi-amping, using 4 x JJ239. These 4 x 10W can make many audiophiles’ ultimate sound dreams come true.
    The JJ239 operates in a clean Class A in all stages. Signal path capacitors, as well as anode supply smoothing capacitors are high quality, very fast (100V/uS) custom made polypropylene types. Both tubes use DC voltage for heater supply. Anode voltage filtration is achieved through a pi-network using JJ Electronics electrolytic capacitors with a total capacitance of 1050uF. The result then is a good separation from hum (<300uV/8Ohms). JJ239 features an anode voltage soft start circuit with a time constant of 25 seconds. The power transformer contains an electrostatic shield between the primary] and heater windings. Bias for power triode is set via a potentiometer on the back panel. Turn the potentiometer until the LED light barely comes on. This represents the setting of the 2A3-40 anode current of 80mA. This is the optimum current for Ub=420 V and output transformer impedance of 3700 Ohms. Output transformer is a double C-core output transformer.