Lundahl LL3733 Output Transformer for Tube Amplifiers Push-Pull

The Lundahl LL3733 is a push-pull tube amplifier output transformer with 50% ultra-linear taps, a separate 2% feedback winding, 5 Ω and 8 Ω secondary taps, and 140 W maximum output power at 30 Hz.

Highlights of the Lundahl LL3733

• Push-pull tube amplifier output transformer with 50% UL taps
• Separate winding for 2% negative feedback
• 5 kΩ to 8 Ω and 5.4 kΩ to 5 Ω application ratios
• 140 W maximum output power at 30 Hz
• Frequency response of +0 / -2 dB from 5 Hz to 30 kHz
• High-quality grain-oriented silicon steel C-core

Product details Lundahl LL3733

Lundahl LL3733 Push-Pull Tube Amplifier Output Transformer 5 kΩ 8 Ω / 5.4 kΩ 5 Ω

The Lundahl LL3733 is designed for push-pull tube amplifiers that require a robust output transformer with ultra-linear operation. It provides 50% UL taps and a dedicated 2% negative feedback winding, supporting precise feedback implementation without relying on the main secondary winding.

Internally, the transformer uses two coils, each built from three sections with one primary and two secondary sections. The secondary windings are tapped for both 5 Ω and 8 Ω loads, giving practical flexibility for tube amplifier designs and high-performance amplifier accessories applications.

The winding arrangement is engineered to minimize destructive capacitive coupling between primary and secondary windings, while also keeping phase error between the anode and UL tap extremely small. A high-quality grain-oriented silicon steel C-core from Lundahl’s own production provides the magnetic foundation for stable performance.

Key electrical specifications include 270 H primary inductance, 22 mH primary leakage inductance, 850 V RMS maximum primary signal voltage at 30 Hz, and 1 dB signal loss across the transformer. The LL3733 weighs 2.5 kg and supports up to 170 mA recommended primary DC current through the windings, with up to 340 mA DC from B+.