Предусилители — Trafomatic Audio LARA

The LARA is a tube line preamp made by Trafomatic Audio, laid out as a two-chassis unit with the power supply in a separate box. It was announced in April 2016. Trafomatic describes it as a fully balanced, remote controlled class A line stage that carries over design principles from the reference and top models in its range, and positions it as a way to reach that engineering at a lower cost than those designs.

Key specs that matter

The current input panel carries three RCA inputs and two XLR inputs. Outputs comprise one XLR and one RCA socket, switchable between each other, plus an independent subwoofer output. Output impedance measures 1 kohm at the XLR and RCA sockets alike. Gain is fixed at 20 dB, and the frequency response starts at 10 Hz at its lower -1 dB point. A selector sets the unit for 230 V at 50 Hz or 115 V at 60 Hz mains. The main unit is 400 mm wide and 310 mm deep, and the preamplifier weighs 10 kg.

Engineering and use context

Two 6N30P tubes do the amplifying, a type Trafomatic selected for its linearity. The circuit runs in class A and is balanced from input to output. Incoming line signals pass through LL1592 input transformers, a high level line input type with mu-metal cores, and the output stage is transformer coupled as well, giving transformer coupling on the way in and on the way out. The external power supply uses a low induction toroidal transformer, custom made chokes and Mundorf MLytic HV capacitors, which keeps the mains transformer and chokes out of the main enclosure that holds the valves and signal transformers. Volume is adjusted by remote handset as well as on the unit, so level can be set from the listening seat. Trafomatic does not fit a phono stage, a digital input or a headphone output, so the LARA is a pure line level control unit.

Pairing

The balanced XLR output suits power amplifiers with balanced inputs, such as the Trafomatic EOS+ stereo power amplifier, while the RCA output covers single-ended designs. Because the RCA and XLR outputs are switched rather than live together, one main amplifier is driven at a time, and the separate subwoofer output can feed an active subwoofer alongside it. With five line inputs in total, the LARA can accept several line level sources, while records need an outboard phono stage.

Alternatives

Trafomatic Audio also lists the Evolution Line One, a valve stereo line preamplifier from its Evolution series.