Lundahl LL1948 transformer

LL1948 is a high-level line input transformer designed with audiophile applications in mind. The LL1948 combines Cardas high purity copper wire windings with our own cobalt-based amorphous core. The transformer is suitable for preamplifier or power amplifier line input with or without phase splitting. The windings are arranged to give perfect symmetry and high noise immunity. The two coil structure also greatly improves immunity to external magnetic fields from e.g. power supplies and motors. Primary and secondary windings are separated by electrostatic shields. The transformer is housed in a mu-metal can. 

Turns Ratio:      1+1 : 1+1

Technical Details:

• Dimensions  (L x W x H above PCB, in mm)                                                        43 x 29 x 23

• Spacing between pins                                                                                            5.08 mm  (0.2")

• Spacing between rows of pins                                                                               30.5 mm  (1.2")

• Rec. PCB hole diameter:                                                                                       1.5 mm

• Weight:                                                                                                                    81 g

• Static resistance of each primary:                                                                        75 ohms

• Static resistance of each secondary:                                                                     75 ohms

• Distortion  (primaries connected in series,                                                             + 25 dBU  0.2% @ 50 Hz

          source impedance 600 ohms ):                                                                                + 28 dBU  < 1  %  @ 50 Hz   

• Self resonance point:                                                                                             > 120 kHz 

• Frequency response (source 600 ohms, load 10 k ohms, serial connection):       10 Hz -- 100 kHz +/- 1.0 dB

• Phase response  (deviation from linear phase)                                                      20 Hz – 30kHz, +/- 0.5°

• Isolation between windings/ between windings and shield:                              3 kV / 1.5 kV