Предусилители — Trafomatic Audio Evolution Line One

The Evolution Line One is a full valve stereo line preamplifier from Trafomatic Audio of Serbia, operating in single-ended class A. Trafomatic presents it as a logical extension of the Evolution series power amplifiers, and it follows the same 450 x 320 mm footprint with a lower 105 mm height and a weight of 10 kg. There is no phono stage, so all five inputs are for line-level sources. Sharing width and depth with the Evolution Elegance and Elegance Evolution, the preamp can sit on top of either one as a matched stack, since it is less than half their height.

Key specs that matter

Sources connect through five RCA inputs, which feed one main stereo line output, a fixed-level tape output and a subwoofer output. Gain can be selected between 22 dB and 25 dB. Input impedance is 47 kohm. Output impedance is 150 ohm on the main line output, 47 kohm on the tape output and 22 kohm on the subwoofer output. Distortion is 0.3 percent at 1 kHz with 4 V output, and signal to noise is 85 dB. Bandwidth runs from 12 Hz at -1 dB to 65 kHz at -3 dB. The unit consumes 50 VA and switches between 230 V at 50 Hz and 115 V at 60 Hz.

Engineering and use context

One ECC88 double triode is assigned to each channel. The first triode provides the voltage gain, and the second half inside the same glass envelope is wired as a cathode follower to bring the output impedance down, which makes the main output tolerant of long cable runs and of power amps whose input impedance is modest. The tape output, by contrast, is meant only for a recorder with a high-impedance input. A single ECL82 (6BM8) valve works as a stabiliser in the supply. Power comes from a toroidal transformer, followed by diode rectification and a C-L-C filter. Volume is adjusted by remote control, and the selectable gain lets the owner choose between the two settings depending on how sensitive the power amplifier is.

Pairing

The natural partners are Trafomatic's own power amplifiers, such as the Evolution Elegance with its high input sensitivity figure, where the higher gain setting can help, or the EOS Power Amp. Because all connections are RCA, power amplifiers with balanced-only inputs would need adapters. An active sub gets its own feed from the separate subwoofer jack without using the main outputs, and the tape output feeds a recorder at fixed level.

Alternatives

The Trafomatic Reference Line One is another valve line preamplifier from the brand with 23 dB gain and an 11 kg chassis.