The Lundahl LL1620-PP is a push-pull tube amplifier output transformer with a highly sectioned winding structure, low leakage inductance and a wide frequency range. It is built on Lundahl’s special audio C-core and designed for open-frame mounting inside an amplifier housing.
Highlights of the Lundahl LL1620-PP
- Push-pull output transformer for tube amplifier designs
- Highly sectioned windings with harmonically sized sections for minimum leakage inductance
- Low-capacitance winding technique for wide frequency performance
- Special Lundahl audio C-core with 25 µm air gap for push-pull operation
- Primary load impedance options of 11.5 kΩ, 6.0 kΩ or 3.3 kΩ depending on secondary connection
- Open-frame construction with 4 x M4 mounting holes for installation inside an amplifier housing
Product details Lundahl LL1620-PP
Lundahl LL1620-PP Output Transformer for Tube Amplifier Push-Pull
The Lundahl LL1620-PP is part of Lundahl’s tube amplifier output transformer range and is intended for push-pull output stages. It uses the same core size, winding structure and secondary arrangement as related models in the series, with a primary winding configuration tailored to the LL1620 impedance level. For builders working with high-quality audio components, it provides a robust transformer platform for demanding valve amplifier designs.
The transformer is highly sectioned with harmonically sized sections, helping to keep leakage inductance low. Combined with a low-capacitance coil winding technique, this construction supports a wide frequency range. The LL1620-PP features a special Lundahl audio C-core and, as a push-pull version, uses a 25 µm core air gap to allow for a small DC unbalance in the output circuit.
For push-pull use, the LL1620 offers primary load impedance options of 11.5 kΩ, 6.0 kΩ and 3.3 kΩ depending on the selected secondary connection and loudspeaker load. It has a turns ratio of 4 x 19.2 : 8 x 1, a primary static resistance of 308 Ω with all primary windings in series, an average secondary resistance of 0.4 Ω per secondary, and 11 mH primary leakage inductance with the primary connected in series.
With all primary windings in series, the maximum primary signal voltage for push-pull operation is 860 V RMS at 30 Hz. The transformer provides 3 kV isolation between primary and secondary windings and 1.5 kV isolation between windings and core. Its open-frame construction is suitable for mounting inside amplifiers, with 4 x M4 mounting holes, 5.08 mm pin spacing, physical dimensions of 118 x 90 x 85 mm, and a weight of 2.5 kg.
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