DENON AU-103

Second-hand. In excellent conditions. Free from visible signs of wear. Comes with original packaging and manual (Japanese).

The Denon AU-103 is a passive step-up transformer designed to fully enhance the performance of moving coil (MC) cartridges, particularly low-output models such as the legendary Denon DL-103. Engineered with the meticulous precision typical of the Japanese brand, this transformer serves as an ideal interface between MC cartridges and the MM (Moving Magnet) phono inputs of amplifiers or standalone phono preamps.

Inside, the AU-103 features 1:10 step-up transformers, providing approximately 20 dB of gain—enough to bring the signal from a low-output MC cartridge up to a level compatible with standard MM inputs. Its fully passive and shielded design ensures quiet operation with minimal interference, preserving a clean, faithful, and detailed audio signal.

Sonically, the AU-103 is known for its warm, full-bodied, and natural musical presentation. It favors a smooth and fluid delivery, with rich, well-articulated midrange and a solid, well-controlled bass response. Rather than aiming for hyper-analytical transparency, it delivers a deeply engaging and musical listening experience—highly appreciated by analog purists.

The AU-103 pairs perfectly with the Denon DL-103 but also performs excellently with many other MC cartridges featuring similar internal impedances (around 30–40 ohms). It is highly recommended for those seeking a simple, reliable, and effective passive MC signal amplification solution—without adding active stages or external power supplies into the audio chain.

Compact, robust, and easy to integrate into any hi-fi system, the Denon AU-103 is an ideal choice for those wanting to explore the world of step-up transformers through a well-built, sonically inspired, and historically respected product.

Technical Specifications:

• Type: Step-up transformer for MC (Moving Coil) cartridges
• Boost ratio: 1:10
• Output balance: 0.5 dB or less
• Compatible cartridge impedance: 3 to 40 Ω
• Recommended load resistance: 47 kΩ
• Frequency response: 20 Hz ~ 50 kHz (with 40 Ω cartridge)
• External dimensions: Width 135 mm; Height 52 mm; Depth 102 mm
• Weight: 1.3 kg