Hammond 1140-LU-D 600 Ohm +24 dBu 1:1 Line Output Transformer

The 1140-LU-D is a 600:600 line output transformer with a 1:1 turns ratio, part of the 1140 Series of studio grade impedance matching transformers. Its bi-filar windings on a 49% Ni core give low distortion and good output levels, and it can drive 600 Ω loads up to +24 dBu at 20 Hz, making it a choice for output stages that need extra headroom.

Rated figures are 0.080% THD at 20 Hz and a frequency response of -0.18 dB at 20 Hz and +0.03 dB at 20 kHz. The drawing lists typical THD of 0.001% at 1 kHz and 0.08% at 20 Hz (4 dBu), common mode rejection of 105 dB at 60 Hz and 75 dB at 3 kHz, and phase shift of 0.23° at 20 Hz and -0.7° at 20 kHz.

Primary and secondary DCR are each 40 Ω at 20 °C. Typical primary input impedance is 680Ω and secondary output impedance 80Ω at 1 kHz and 0 dBu. Capacitance to shield and case is 20 nF primary and 50 pF secondary, and dielectric strength is 250 Vrms. Due to the Ni core, the drive signal should have no DC component and the source impedance should be as low as possible.

The 1140-LU-D is open style (not Mu Metal) for chassis mounting, with colour-coded leads at least 8" long: brown/orange primary and green to green/yellow secondary. It is RoHS and REACH compliant, made in Canada, and ships at 0.2 lbs (0.09 kg).