Lundahl LL1527 High Level General Purpose Transformer

Highlights of the Lundahl LL1527

• General purpose audio transformer for mic input, line input, output, splitting and galvanic isolation
• 1+1:1+1 turns ratio with multiple connection options, including 1:1 and 1:2 configurations
• Two-coil construction with electrostatic shielding between primary and secondary windings
• High-permeability mu-metal core housed in a mu-metal can
• Wide frequency response of 10 Hz to 150 kHz ±0.2 dB with 800 Ω source and 4 kΩ load
• Compact PCB-mount format measuring 38 x 24 x 17 mm and weighing 48 g

Product details Lundahl LL1527

Lundahl LL1527 High Level General Purpose Transformer 1+1:1+1

The Lundahl LL1527 is designed as a truly general purpose transformer for professional audio circuits. It is suitable for microphone or line input stages, output coupling, one-direct-plus-one-isolated signal splitting and galvanic isolation between units. This makes it a practical choice for builders and service technicians working with demanding audio components where clean signal transfer and isolation matter.

Internally, the LL1527 uses two coils, each with one primary and one secondary winding. The primary and secondary windings are separated by an electrostatic shield, while the high-permeability mu-metal core and mu-metal can help protect performance in sensitive audio environments. For electromechanics applications in audio equipment, this construction provides a robust and compact transformer solution.

The transformer has a 1+1:1+1 turns ratio and supports several connection alternatives. Parallel-parallel wiring provides a 1:1 configuration, serial-serial wiring also provides 1:1 operation for line input use, and parallel-serial wiring provides a 1:2 option for microphone input applications. It can also be wired for splitting one direct output plus one isolated output, such as feeding front-of-house and a recording console.

Performance specifications include a frequency response of 10 Hz to 150 kHz ±0.2 dB with an 800 Ω source and 4 kΩ load in serial connection, with approximately 0.4 dB midband loss. Each primary has a static resistance of 43 Ω and each secondary 56 Ω. The LL1527 offers a self-resonance point above 200 kHz, 4 kV isolation between windings and 2 kV isolation between windings and shield. PCB installation is supported with a recommended 1.5 mm hole diameter, 5.08 mm pin spacing and 27.94 mm row spacing.