Hammond 1140-LN-B 10K 1:1 Line Input Transformer, +20 dBu, Shielded

The 1140-LN-B is a 1:1 line input transformer in the 1140 Series of studio grade impedance matching transformers. It is designed for input stages with wide bandwidth and low distortion, and the drawing notes it can be used for balancing input stages on any high impedance input. Console designers, preamp builders and integrators adding balanced inputs to high-impedance circuitry are the intended users.

Both windings are 10K, giving a 10K:10K impedance ratio and a 1:1 turns ratio. Rated performance is +20 dBu maximum input at 20 Hz, 0.020% THD at 20 Hz and a response of -0.03 dB at 20 Hz and +0.10 dB at 20 kHz. Typical drawing values are 12K primary input impedance and 2.1K secondary output impedance at 1 kHz and +4 dBu, THD of 0.015% at 1 kHz and 0.005% at 20 Hz (-20 dBu), and common mode rejection of 70 dB at 60 Hz and 55 dB at 3 kHz.

The windings use a nickel alloy core inside a mu metal can with dual shields. Primary and secondary DCR are both 1.03 K at 20 °C, capacitance to shield and case is 525 pF for each winding, and dielectric strength is 500 Vrms.

The 1140-LN-B is chassis mounted with colour-coded leads: brown/orange primary, green and green/yellow secondary, grey and grey/white shields, violet can ground. It is RoHS and REACH compliant, made in Canada and ships at 0.2 lbs (0.09 kg).