Lundahl LL1517 Line Output Transformer for Tube Amplifiers

Highlights of the Lundahl LL1517

• Audio output transformer for balanced or unbalanced drive
• 1 + 1 : 1 + 1 turns ratio
• Dual three-section coil construction with electrostatic shields
• Audio C-core in a mu-metal housing
• 10 Hz to 80 kHz frequency response, ±0.3 dB with 10 Ω source and 600 Ω load
• Maximum output level of +24 dBU at 30 Hz before saturation with 600 Ω load

Product details Lundahl LL1517

Lundahl LL1517 Line Output Transformer for Tube Amplifiers

The Lundahl LL1517 is built as an audio output transformer for tube amplifiers and supports both balanced and unbalanced drive configurations. Its 1 + 1 : 1 + 1 winding arrangement makes it suitable for line output stages where flexible primary and secondary connection options are required.

Internally, the transformer uses two three-section coils, with the primary and secondary windings separated by electrostatic shields. This construction is combined with Lundahl’s own audio C-core and a mu-metal housing, giving this audio component a carefully controlled magnetic and shielding structure for demanding audio circuits.

The LL1517 delivers a wide frequency response of 10 Hz to 80 kHz within ±0.3 dB when used with a 10 Ω source and 600 Ω load. With the secondaries in series and a 600 Ω load, it reaches a maximum output level of +24 dBU at 30 Hz before saturation. In a mixed feedback drive circuit, distortion is below 0.03% at 20 dBU and 30 Hz.

Practical specifications include 47 x 34 x 18 mm dimensions above the PCB, 5.08 mm pin spacing, 35.56 mm row spacing and a weight of 105 g. The recommended PCB hole diameter is 1.5 mm. Primary-to-secondary isolation is rated at 4 kV, with 2 kV isolation between windings and core.