Lundahl LL2765-30 Output Transformer for Tube Headphone Amplifier

Highlights of the Lundahl LL2765

• Output transformer for tube headphone amplifier applications
• Three-sectioned, dual-coil C-core construction
• Turns ratio of 6+6 : 1+1+1+1
• Connection alternatives for 32, 150 and 600 ohm headphones
• Available in push-pull and single-ended versions
• 4 kV isolation between windings and 2 kV between windings and core

Product details Lundahl LL2765

Lundahl LL2765 Output Transformer for Tube Headphone Amplifier

The Lundahl LL2765 is a specialist audio component for tube headphone amplifiers. It uses a three-sectioned, dual-coil design built around Lundahl’s own audio C-core, with high internal isolation and isolation foil between each copper layer.

With a turns ratio of 6+6 : 1+1+1+1, the LL2765 offers flexible secondary connection alternatives for different headphone impedances. It can be configured for 32 ohm headphones with a 12:1 ratio and approximately 4.6 k primary impedance, or for 150 ohm and 600 ohm headphones with 6:1 and 3:1 ratios respectively, both giving approximately 5.4 k primary impedance.

The transformer supports both push-pull and single-ended use, with versions available for each application. With primaries in series, the push-pull version provides 170 H primary inductance and a maximum primary signal of 370 V RMS at 30 Hz, while the single-ended version provides 64 H primary inductance and a maximum primary signal of 160 V RMS at 30 Hz.

Electrical details include 75 ohm static resistance per primary, 3.5 ohm static resistance for secondary windings 2-4 and 7-9, and 4.5 ohm for secondary windings 3-5 and 8-10. The maximum recommended DC current through the primary windings is 180 mA, with 5 W heat dissipation, and the unit weighs 1.3 kg.