Hammond 1750W 100W Twin Reverb Output Transformer, 4 Ohm

The 1750W is a 100 watt push-pull output transformer for tube guitar amplifiers, designed as a drop-in replacement for the original unit in a range of Fender 100 watt amplifiers: the Bassman 100, Quad Reverb 100, Showman, Super Six Reverb 100, Twin Reverb and Twin Reverb 65 Reissue. It is listed as similar to Fender part numbers 125A29A, 022689, 022889, 022899 and 037612.

It matches a 2,000 ohm centre-tapped primary (blue and brown with a red centre tap) to a single 4 ohm secondary (white, with black common). Typical DC resistance is 22.8 ohms brown-blue on the primary and 0.410 ohm black-white on the secondary. At 1.0 kHz, 1.0 V open circuit, primary inductance is 2.50 H (15.45 Kohm), and primary leakage inductance is 1.31 mH.

The drawing lists a frequency response of 70 Hz to 15 kHz (0/-1.0 dB reference @ 1 kHz) and distortion under 1% at 70 Hz. The winding is paper, with materials and design specifications kept as close as possible to the original part to preserve the stock tone, in a unit constructed to look similar to the factory original where possible.

The open-style transformer has 9.0 in minimum leads. Drawing dimensions are A 4.063 in, B 3.450 in, C 3.500 in, D 3.500 in, E 2.500 in and F 2.800 in, with G 0.187 x 0.300 in. It is rated 2000 VRMS and -40 to 105 degC, is RoHS and REACH compliant, and ships at 4 lbs (1.81 kg).