Lundahl LL1935 Audio transformer

The transformer consists of two coils, each with one primary and one secondary winding separated by an electrostatic shield, and a high permeability mu-metal core. The high impedance windings are wound using a special low capacitance winding technique. The transformer is encapsulated in a mu-metal case for magnetic shielding. For best performance, the high impedance side of the transformer (5 + 5) should be connected in series.

Pin layout (viewed from component side) and winding schematics:

Turns ratio: 1 + 1 : 5 + 5
Length: 38mm
Width: 23mm
Height above PCB:  16mm
Spacing between pins: 5.08 mm (0.2")
Spacing between rows of pins: 27.94 mm (1.1")
Offset of earth pin from adjacent row: 2.54 mm (0.1")
Weight: 46 g
Recommended PCB hole diameter: 1.5 mm
Static resistance of each primary (pins 5-6 and 7-8): 650 Ohm
Static resistance of each secondary (pins 1-2 and 3-4): 17 Ohm

Frequency response (reference 1.0 kHz)
10:1, source 100 kO , secondary open: 20 Hz ? 20 kHz +0 / -3 dB 10:1, source 100 kO, load 1 kO 10 Hz ? 45 kHz +0 / -2 dB
1:10, source 200 O, secondary open 10 Hz ? 80 kHz +/- 1dB
Distortion
For practical reasons measured in 1:10 configuration. -5 dBU input level, +14 dBU output level
< 0.1%="" thd="" @="" 50="">
Source 150O, load 10k (Audio Precision portable) +7 dBU input level, +26 dBU output level < 1%="" thd="" @="" 50="">

Self resonance point: None detected in above configurations
Isolation between windings/ between windings and shield: 4 kV / 2 kV

Recommended wiring, connection for Guitar and Bass recordings: