Mediaelettra Audio, Amplificatori a Valvole, amplificatori valvolari, tube amplifier, preamplificatori, valvolari, vacuum tube

In 1994, JJ Electronic started with the production of three types of tubes. Today, we offer an assortment of more than 20 types of tubes. In 1999, capacitors and tube amplifiers were added to the JJ Electronic manufacturing program.

JJ Electronic began development and production of vacuum tubes in 1994. Since that time, we have successfully introduced 17 more tubes into production. In 1999 we began production of tube amplifiers. The first model was the JJ322, a class A amplifier, powered by four JJ Electronic 300B triodes. Today, we manufacture four power amplifier and two preamplifier models. All these products have been safety certified for use around the world. Also in 1999, we introduced the production of electrolytic capacitors. Three years later, we started production of polypropylene capacitors. These capacitors received certification from international test authorities. We started our company with about 700 sq meter production facilities; today JJ Electronic owns more than 12000 sq meters of production floor

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THE TUBE AMPLIFIERS

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

Output power: 10 W	Noise level: less than 0,8 mV
Load impedance: 4; 8 Ohm	Output transformers: Double „C.cores“
Input impedance: 50 kOhm	Dumping factor: 3,5
Input sensitivity: 0,775 V at 10 W	AC power: 230 V 50/60 Hz
Tubes: 1 x JJ ECC99, 1 x JJ 2A3 (300B)	Nom. consumption: 80 W
bandwidth: 20 Hz - 20 000 Hz (-1 dB) top plate: 24 carat gold platted	Dimensions: 340 x 380 x 255 mm Weight: 23 kg

Output power: 20 W + 20 W	Global negative feedback: 0 dB
Load impedance: 4; 8 Ohm	Noise level: less than 1 mV
Input impedance: 50 kOhm	Output transformers: Double „C.cores“
Input sensitivity: 350 mV at 20 W	AC power: 230 V 50/60 Hz x 240 W
Power bandwidth: 18 Hz - 25 000 Hz (-1 dB)	Tubes: 4 x JJ 300B, 2 x JJ E88CC,2 x JJ ECC83, 2 x JJ EM84
Channel separation: 72 dB/1 kHz	Dimensions: 570 x 380 x 255 mm x 42 kg
Finish: transf. covers: brown, top plate 24 carat gold platted