Hammond 1140-LN-A 10K to 20K Line Input Transformer, 1:1.414 Step-Up

The 1140-LN-A is a studio grade line input transformer from the 1140 Series, designed for input stages that need wide bandwidth and low distortion. The drawing notes it can be used for balancing input stages on vacuum tubes, making it a fit for tube preamp builders, console designers and audio equipment manufacturers.

It has a 10k:20k impedance ratio with a 1:1.414 step-up turns ratio per the series ordering table and drawing (the part page lists 1:4). Rated figures are +16 dBu maximum input at 20 Hz, 0.02% THD at 20 Hz and a frequency response of -0.04 dB at 20 Hz and +0.10 dB at 20 kHz. The drawing gives typical 12K primary input impedance and 4.1K secondary output impedance at 1 kHz and +4 dBu, 70 dB common mode rejection at 60 Hz and 55 dB at 3 kHz, and THD of 0.025% at 1 kHz and 0.01% at 20 Hz (-20 dBu).

A nickel alloy core supports the wide bandwidth, and a mu metal can with dual shields provides excellent shielding. DCR is 1.15 K primary and 1.65 K secondary at 20 °C, capacitance is 525 pF from each winding to shield and case, and dielectric strength is 500 Vrms.

The 1140-LN-A mounts to a chassis and uses 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).