THÖRESS F2a11 Integrated Amplifier

The THÖRESS F2a11 Integrated Amplifier is a purist, all-tube statement piece built around the legendary F2a11 power tube. Originally designed by Siemens & Halske for demanding post and telegraph applications (Postleitröhre), the F2a11 is revered for its unmatched build quality and sonic neutrality. In this amplifier, THÖRESS utilizes these vintage professional pentodes in Single-Ended Triode (SET) operation, delivering 6 watts of exquisite, class-A power. Designed specifically for high-efficiency loudspeakers, the F2a11 Integrated offers a sonic presentation that rivals classic 300B or 2A3 designs but with a distinctively powerful, clear, and natural character. Handcrafted in Germany with meticulous point-to-point wiring, this amplifier is not merely an audio component; it is a lifetime investment in musical truth.

Key Features:

• F2a11 Single-Ended Triode Mode: Utilizes NOS Siemens F2a11 power pentodes wired in triode mode for 2x 6 Watts of pure Class-A output.
• Zero Feedback Topology: A minimalist circuit design with absolutely no global negative feedback ensures dynamic integrity and phase coherence.
• Vintage Driver Stage: employs a highly linear 12SN7GT double-triode (octal base) driver tube for perfect synergy with the output stage.
• Manual Dual-Mono Volume: Features separate high-grade ALPS rotary potentiometers for each channel, allowing precise balance adjustment without a dedicated balance circuit.
• In-House C-Core Transformers: Equipped with proprietary output transformers (OPT) and a mains transformer wound in-house by THÖRESS for ultra-low noise and optimal load matching.
• Versatile Load Matching: Solderable jumpers on the output transformers allow precise matching to 4, 8, or 16-ohm loudspeakers.
• Industrial Build Quality: Non-magnetic aluminum chassis with a powder-coated finish and anodized printing, evoking the aesthetic of 1950s professional laboratory equipment.

The F2a11 Advantage

The F2a11 tube is a marvel of German engineering, originally built to last 10,000 hours in critical telecommunications repeaters. When strapped in triode mode, it exhibits linearity comparable to the finest directly heated triodes (DHTs). THÖRESS exploits this to create an amplifier that combines the "glow" and texture of a SET amp with the speed and resolution typical of professional gear. It is the perfect engine for high-sensitivity horns or full-range drivers (93dB+ recommended).

Purist Control

To maintain the integrity of the signal, the F2a11 Integrated eschews remote control and complex switching. Volume is controlled via two independent knobs (one for left, one for right), allowing the user to set perfect channel balance manually. The input selector is a high-quality rotary switch located near the rear jacks to minimize signal path length, operated via an extension shaft.

Meticulous Construction

Inside the retro-styled chassis lies a work of art. The circuit is constructed entirely by hand using point-to-point air wiring—no printed circuit boards interfere with the signal. High-grade foil-in-oil capacitors and precision resistors are used throughout. The power supply features a vibration-isolated mains transformer and high-grade electrolytic capacitors made in Germany, ensuring a noise floor that is virtually non-existent.

The Listening Room Difference

We’re a third-generation family business with a brick-and-mortar showroom in Chestertown, Maryland, and a reputation built on trust, not hype. Whether you’re visiting in person or ordering online, we bring decades of experience, personalized service, and honest guidance to every interaction. We don’t just ship boxes. We help build systems, answer your questions like real humans, and make sure every detail of your setup is right, from the cables to the final connection. Our passion is helping you get the most out of your gear, with support that lasts well beyond the sale.

Specifications