Lundahl LL1664-60 Output Transformer for Tube Amplifiers 60mA

The Lundahl LL1664-60 is a 60 mA version of the LL1664 tube amplifier output transformer, built around a four-section dual-coil C-core for a 3 k:8 ohms impedance ratio.

Highlights of the Lundahl LL1664-60

• Tube amplifier output transformer for 3 k:8 ohms impedance matching
• 60 mA single-ended version of the LL1664 series
• Four-section dual-coil C-core construction
• High internal isolation with foil between each copper layer
• Turns ratio of 9.6 + 9.6:1 or (3.2+6.4)+(3.2+6.4):1
• 1.35 kg transformer with 4 kV winding-to-winding isolation

Product details Lundahl LL1664-60

Lundahl LL1664-60 Tube Amplifier Output Transformer 3 k:8 Ohms 60 mA

The Lundahl LL1664-60 is designed for tube amplifiers requiring a 3 k:8 ohms output transformer. Its four-sectioned dual-coil layout uses a Lundahl audio C-core and supports both 9.6 + 9.6:1 and split (3.2+6.4)+(3.2+6.4):1 turns-ratio configurations.

For robust electrical separation, the LL1664-60 uses Lundahl’s high internal isolation technique, with isolation foil between each copper layer. Isolation is rated at 4 kV between windings and 2 kV between windings and core, making it a serious amplifier accessory for demanding valve amplifier projects.

Key electrical values include 74 ohms static resistance for each primary, 0.5 ohms static resistance for the secondary, and 8 mH primary leakage inductance with the primaries in series. The 60 mA version supports a maximum primary signal of 180 Vrms at 30 Hz and up to 10 W output power into an 8 ohms speaker load at 30 Hz.

The LL1664-60 is suitable for single-ended output stages with a 3 k primary impedance at an 8 ohms load. The winding arrangement also includes 33% ultra-linear taps for push-pull use within the LL1664 family, giving builders flexibility in audio components and tube output-stage design. The transformer weighs 1.35 kg and uses four M4 mounting holes for secure installation.