VTL Lohengrin Reference – 400 Watts of Tube Power

American tube amplifier manufacturer VTL (Vacuum Tube Logic) has unveiled the VTL Lohengrin Reference Monoblock monoblock power amplifier. This is a very large and heavy unit capable of delivering 400 watts of output power – something you don’t often see in tube designs. The new model supports multiple operating modes for the output stage tubes and allows the sound to be fine-tuned.

The VTL Lohengrin power amplifier is housed in a chassis with an extruded-aluminum front panel and extensive ventilation. The tubes sit behind a viewing window. The design is optimized for low operating temperatures and high reliability – especially important given the power consumption: at least 350 watts at idle and up to 900 watts at full load. The enclosure measures 29 × 49 × 50 cm, and a single monoblock weighs as much as 77 kg.

The output stage of the VTL Lohengrin monoblock uses eight KT88 or 6550 tubes which, according to the manufacturer, deliver 400 watts in tetrode mode. The amplifier can also operate in triode mode, where the maximum power output drops to a “mere” 200 watts. That headroom enables confident control even over large floorstanding speakers with challenging impedance curves.

Using vacuum tubes – which are easier to run in parallel than semiconductor devices – within this concept is intended to distribute current more evenly and keep operating conditions stable. In practice, the designers say, this translates into more assured low-frequency control and high power even with complex musical signals.

In the VTL Lohengrin, the manufacturer employs separate regulated power supplies for the plate (anode) voltage and the screen-grid voltage in order to keep tube operating points stable even under heavy load. This is complemented by wideband, multi-section output transformers. According to the manufacturer, the approach supports clean high-frequency reproduction and low distortion.

The amplifier operates without global negative feedback, which – by the engineers’ intent – should provide high transient accuracy. In addition, an adjustable damping factor allows the output impedance to be matched to a specific loudspeaker system. This is a practical tool for precisely tuning bass performance and tonal balance in any room.

One of the key development goals was everyday usability. The VTL Lohengrin features microprocessor-controlled automatic bias, so manual idle-current adjustment is no longer required. This is backed up by multi-stage protection and monitoring systems that intervene if tube faults are detected or operating parameters deviate.

Connectivity includes a balanced XLR input and an unbalanced RCA input. The component also offers an RS-232 interface, enabling not only remote control but also the transmission of diagnostic data – useful in complex high-end installations and custom systems.

The VTL Lohengrin Reference Monoblock will go on sale in Europe in March 2026 with a recommended retail price of €125,000 per pair of monoblocks.